Health Hazard Evaluation Report 2013-0113-3198 Page 1

Evaluation of Coccidioides Exposures and 

Coccidioidomycosis Infections among Prison 

Employees

Report No. 2013-0113-3198

January 2014

Marie A. de Perio, MD

Gregory A. Burr, CIH

U.S. Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health
Page 2 Health Hazard Evaluation Report 2013-0113-3198

Contents

Highlights...............................................i

Abbreviations ..................................... iv

Introduction......................................... 1

Methods ............................................... 2

Results .................................................. 5

Discussion .......................................... 16

Conclusions........................................ 20

Recommendations............................. 21

Appendix A ........................................ 24

Appendix B......................................... 25

Appendix C......................................... 26

References.......................................... 27

The employer is required to post a copy of this report for 30 days at or near the 

workplace(s) of affected employees. The employer must take steps to ensure 

that the posted report is not altered, defaced, or covered by other material.

The cover photo is a close-up image of sorbent tubes, which are used by the HHE 

Program to measure airborne exposures. This photo is an artistic representation that may 

not be related to this Health Hazard Evaluation. Photo by NIOSH.
Health Hazard Evaluation Report 2013-0113-3198 Page i

We were asked to 

determine the incidence 

of coccidioidomycosis 

among prison employees 

and assess ways to reduce 

potential employee 

exposures. We found 

103 confirmed cases of 

coccidioidomycosis among 

employees over a 41⁄2-year 

period. Employees are likely 

exposed to Coccidioides in 

the outdoor and indoor 

work environment, as well 

as outside of work. 

Highlights of this Evaluation

The Health Hazard Evaluation Program received a request from managers on behalf of a state 

correctional and rehabilitation agency and a state correctional health care services agency. They 

were concerned about potential employee exposure to the fungus Coccidioides at two state prisons 

(prison A and prison B) in the Central Valley of California. 

What We Did

● We visited the prisons in June 2013.

● We looked at work and occupational health policies and practices.

● We reviewed medical and work information for the cases of coccidioidomycosis among 

prison employees.

● We privately interviewed prison employees and asked 

them about their work practices and exposures.

● We met with prison staff to learn about efforts to reduce 

employee and inmate exposures to Coccidioides.

● We looked at the ventilation systems in some 

buildings. We chose buildings where more employees 

worked such as clinics and offices. We also looked at 

the ventilation in some inmate housing units.

What We Found

● Both prisons were in areas where Coccidioides 

naturally occurs.

● We identified 65 confirmed cases of 

coccidioidomycosis among prison A employees and 

38 confirmed cases of coccidioidomycosis among 

prison B employees over a 41⁄2-year period.

● We do not know if each confirmed case of 

coccidioidomycosis among prison employees was due to an exposure at work or 

outside of work.

● Employees may be potentially exposed to Coccidioides in the outdoor and indoor work 

environment, as well as outside of work. 

What the Employer Can Do

● Wet soil before disturbing it, and continuously wet it while digging to keep dust levels down.

● Install door sweeps and seal gaps around doors and windows. Keep doors and windows 

closed as much as possible.

● Replace air filters in the ventilation systems as needed.
Page ii Health Hazard Evaluation Report 2013-0113-3198

What the Employer Can Do (continued) 

● Provide education and training during work hours to all prison employees on 

coccidioidomycosis and ways to minimize exposure.

● Consider closing the prison yards and advising inmates and employees to stay indoors 

during dust storms and unusually windy or dusty days.

● Consider offering the coccidioidal spherulin skin test to employees when it becomes 

commercially available. This test may help employees evaluate their personal risk for 

coccidioidomycosis.

● Encourage prison employees to report suspected symptoms of possible 

coccidioidomycosis to a supervisor.

● Review injury and illness records for reports of coccidioidomycosis infections among 

prison employees to look for trends over time.

What the Employees Can Do

● Keep doors and windows closed as much as practical.

● Avoid driving vehicles off pavement to keep dust levels down.

● Follow agency policies, including those regarding excavation safety and 

respiratory protection.

● Report suspected symptoms of possible coccidioidomycosis to a supervisor.
Health Hazard Evaluation Report 2013-0113-3198 Page iii

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Page iv Health Hazard Evaluation Report 2013-0113-3198

Abbreviations

CDC Centers for Disease Control and Prevention

CDPH California Department of Public Health

CSTE Council of State and Territorial Epidemiologists 

cfm Cubic feet per minute

CFR Code of Federal Regulations

MERV Minimum efficiency reporting value

NIOSH National Institute for Occupational Safety and Health

OSHA Occupational Safety and Health Administration
Health Hazard Evaluation Report 2013-0113-3198 Page 1

Introduction 

The Health Hazard Evaluation Program received a request from managers at a state 

correctional and rehabilitation agency and a state correctional health-care services agency. 

It concerned potential employee exposure to the fungus Coccidioides at two state prisons 

(prison A and prison B) in the Central Valley of California. We were asked to determine the 

incidence of coccidioidomycosis among prison employees and to assess ways to minimize 

exposures. We evaluated the prisons in June 2013.

Background 

At the time of our evaluation, the state correctional and rehabilitation agency operated 

33 adult prisons statewide. In May 2013, the in-state inmate population was 124,741 

and the parole population was more than 52,730 [California Department of Corrections 

& Rehabilitation 2013]. The agency had approximately 69,000 employees, including 

custody and support staff. The state correctional health care services agency, responsible 

for providing medical care to inmates, was placed under a federal receivership in 2005. 

At the time of our evaluation, this health care services agency was still under the federal 

receivership. This agency had approximately 7,000 employees, including health care 

personnel and administrative staff. 

Prison A opened in 1994 and provided long-term housing and services for minimum, 

medium, and maximum custody inmates. Located in Fresno County in the Central Valley 

of California, it covered 640 acres. The prison A inmate population in May 2013 was 3,558 

[California Department of Corrections & Rehabilitation 2013]. In 2013, staff, including 

custody and support staff, numbered over 1,300.

Prison B opened in 1987 and provided long-term housing and services for minimum and 

medium custody inmates. Located in Kings County in the Central Valley of California, it 

covered 640 acres. The prison B inmate population in May 2013 was 4,538 [California 

Department of Corrections & Rehabilitation 2013]. In 2013, staff, including custody and 

support staff, numbered over 1,500. The prisons are located within 11 miles of each other.

Coccidioidomycosis

Coccidioidomycosis, also known as valley fever, is a disease caused by a fungus of the 

Coccidioides species, which grows in the soil in semiarid areas. Coccidioidomycosis is 

endemic (native and common) in the southwestern United States, the Central Valley of 

California, Mexico, and parts of Central and South America [CDC 2013a]. The disease 

is considered hyperendemic in six California counties (Kern, Kings, Fresno, San Luis 

Obispo, Tulare, and Madera) that historically have consistently had the highest incidence 

of coccidioidomycosis. It is a reportable disease in states where it is endemic, including 

California, New Mexico, Arizona, Nevada, Texas, and Utah. About 150,000 new infections 

occur annually in the United States [Galgiani et al. 2005] though only over 22,000 cases were 

reported in 2011 in the United States, suggesting that the disease is greatly underreported 
Page 2 Health Hazard Evaluation Report 2013-0113-3198

[CDC 2013b]. The incidence of reported coccidioidomycosis increased substantially from 

1998 to 2011, from 5.3 per 100,000 population in the endemic area (Arizona, California, 

Nevada, New Mexico, and Utah) in 1998 to 42.6 per 100,000 in 2011 [CDC 2013b].

Coccidioidomycosis is acquired by inhaling Coccidioides arthrospores, or spores, that get 

into the air when construction, natural disasters, or wind disturb soil contaminated with the 

fungus [CDC 2013a]. It has been suggested that human illness could be caused by a single 

spore [Pappagianis 1988; Galgiani 1993]. Additional information on the Coccidioides fungus 

can be found in Appendix A. The infection cannot be spread from to person to person, or 

from animals to people. Most people who get the disease live in or visit places where the 

fungus is in the soil and engage in activities that expose them to soil dust. Such activities 

include construction, agricultural work, military field training, and archeological exploration 

[CDC 2013a]. 

About 60% of coccidioidomycosis infections are asymptomatic [Chiller et al. 2003]. People 

who develop symptoms may experience a flu-like illness with fever, cough, headache, 

rash, and muscle aches that are self-limited. Symptoms usually resolve on their own 

without treatment, but antifungal medications can be used. A small percentage of infected 

persons (< 1%) may develop widespread disseminated infection [Chiller et al. 2003]. 

People at increased risk for severe pulmonary disease are the elderly, those with diabetes 

or recent smoking history, and people of low socioeconomic status [CDC 2014]. People 

at greater risk for developing disseminated infection include people of African American 

and Asian (particularly Filipino) descent, pregnant women during their third trimester, and 

immunocompromised persons [CDC 2013a]. Coccidioidomycosis has been shown to be 

costly and debilitating, with nearly 75% of patients in whom the disease has been recognized 

missing work or school because of their illness and more than 40% requiring hospitalization 

[Tsang et al. 2010].

Diagnosis of coccidioidomycosis can be made by looking for Coccidioides antibodies or 

antigens in blood or other body fluids. Diagnosis can also be made through a tissue biopsy, 

in which a small sample of affected tissue is taken from the body and examined under 

a microscope or by culture where the fungus can be grown from the sample on special 

nutrient plates. Beginning in the 1940s, skin testing was used to determine if a person has 

been exposed to Coccidioides. The skin test indicated exposure to the fungus but not when 

exposure occurred. However, Coccidioides skin test reagents have not been commercially 

available in the United States for more than a decade [Ampel 2003]. No vaccine against 

coccidioidomycosis is currently available.

Methods

The purpose of our evaluation was to (1) determine the incidence of coccidioidomycosis 

among employees at the prisons, (2) assess the ventilation systems at the prisons, and (3) 

recommend ways to improve coccidioidomycosis-related occupational health and infection 

control practices. During visits in June 2013, we observed workplace conditions and work 
Health Hazard Evaluation Report 2013-0113-3198 Page 3

processes and practices and spoke with employees. We excluded inmate employees from this 

evaluation because inmates were the focus of another concurrent Centers for Disease Control 

and Prevention (CDC) investigation.

Our evaluation included the following methods: (1) a review of relevant occupational health 

policies and practices, (2) a review of work and medical information about confirmed 

coccidioidomycosis cases among prison employees (Appendix B), (3) confidential medical 

interviews with employees, (4) assessment of the ventilation systems in selected buildings, and 

(5) assessment of environmental mitigation practices to reduce exposures to Coccidioides.

Review of Occupational Health Policies and Practices 

We reviewed relevant work and occupational health policies and practices obtained from the 

corrections agency and the correctional healthcare services agency. These included excerpts 

from the supplemental operations manual, the written respiratory protection plans, the aerosol 

transmissible diseases exposure control plans, and the excavation safety plan for prison B.

Review of Coccidioidomycosis Among Prison Employees

Coccidioidomycosis Confidential Morbidity Reports 

We obtained annual employee rosters for each prison from 2009–2013 from the correctional 

agency and the prisons. With assistance of the California Department of Public Health 

(CDPH) Infectious Diseases Branch, we matched the names on these rosters to the 

CDPH database that contains confidential morbidity report data on reported confirmed 

coccidioidomycosis cases in California. CDPH uses the Council of State and Territorial 

Epidemiologists (CSTE) case definition for coccidioidomycosis, which includes clinical and 

laboratory criteria [CDC 2012a]. Details about the case definition can be found in Appendix 

B. We identified 276 possible matches at prison A and 216 possible matches at prison B. We 

then obtained more information from agency headquarters and the prisons on the possible 

employee matches, including sex, dates of birth, last four digits of social security numbers, 

home addresses, and dates of employment, to confirm that these coccidioidomycosis cases 

reported to CDPH occurred in individuals employed at either prison. We considered a match 

to be a coccidioidomycosis case reported to CDPH with the same name and same date of 

birth and/or same last four digits of social security numbers. For cases reported to CDPH that 

were missing date of birth or social security numbers, we considered a confirmed match if the 

employee was listed as a correctional facility employee in the confidential morbidity report. 

We excluded coccidioidomycosis cases among employees that were reported to CDPH prior 

to their date of hire. 

We calculated the crude (unadjusted) 4-year incidence and the crude average annual 

incidence of coccidioidomycosis for prison A employees and prison B employees. First, we 

calculated the crude 4-year incidence by dividing the total number of coccidioidomycosis 

cases among employees at each prison during 2009–2012 by the mid-point number of 

employees at the respective prison between 2010 and 2011. We then divided this crude 

4-year incidence by 4 to obtain the crude average annual incidence during 2009–2012. 
Page 4 Health Hazard Evaluation Report 2013-0113-3198

Using information from the confidential morbidity report and the corrections agency, we 

described personal and work characteristics of the employees with coccidioidomycosis.

Coccidioidomycosis Reports from Other Sources 

We obtained and reviewed information on the coccidioidomycosis-related reports from the 

Occupational Safety and Health Administration (OSHA) 300 Logs of Work-Related Illnesses 

and Injuries from 2009 through mid-2013 for both prisons. Employer representatives at each 

prison extracted all entries that reported coccidioidomycosis infection, and we eliminated 

duplicate entries. According to agency representatives at the time of the evaluation, 

employees were not required to submit laboratory documentation of infection.

We attempted to obtain coccidioidomycosis-related Doctor’s First Reports of Occupational 

Injury or Illness from the California Department of Industrial Relations for employees at 

both prisons from 2009–2013. These reports are required to be completed by an employee’s 

physician within 5 days of initial examination for every occupational injury or illness. 

These reports are then sent to the employer’s workers’ compensation insurance carrier or the 

insured employer.

Confidential Medical Interviews with Employees 

We invited employees from all job categories working during regular business hours and 

employees working first, second, and third watch (a non-probability, convenience sample) 

to participate in individual, semi-structured confidential medical interviews to obtain 

information about working conditions and possible risk factors for disease. During these 

interviews, we discussed their work, time spent outdoors at work and outside of work, work 

tasks such as soil disrupting activities, respirator use, pertinent medical history, and residence 

in areas where Coccidioides is found.

Assessment of Environmental Practices

We met with headquarters and local facilities and engineering staff at both prisons to learn 

about environmental mitigation efforts to minimize employee and inmate exposures to 

Coccidioides. We obtained copies of soil stabilization plans proposed for both prisons using 

Soil-Sement® (a water-based acrylic and polyvinyl acetate polymer). We reviewed policies 

and practices that could disturb the soil, such as excavation, mowing, soil disking (shallow 

plowing), and security sweeps along the perimeter of the prisons.

Ventilation Assessment 

We met with facilities and engineering staff to discuss the ongoing upgrade to the air filters 

used in many of the ventilation systems at the prisons. We visited offices, health clinics, and 

inmate housing units to observe the types of ventilation systems and air filters used in these 

systems, and to look for evidence of mold or water intrusion. Because of the expansiveness 

of the prisons, where dozens of structures were spread across 600+ acres at each complex, 

we selected buildings where more prison employees worked (such as health clinics and 

administrative offices). Because the inmate living units were structurally similar within each 
Health Hazard Evaluation Report 2013-0113-3198 Page 5

prison complex, we randomly selected one or two living units at each prison for our walkthrough building survey and ventilation assessment. We measured temperature, relative 

humidity, and carbon dioxide. Carbon dioxide levels are used to evaluate the adequacy of 

ventilation systems in providing outdoor air to occupied spaces. We used ventilation smoke 

tubes to visually evaluate airflow patterns, and a TSI Model EBT731 Balometer to measure 

the amount of air provided by air handling units to some occupied spaces. 

Results

Review of Occupational Health Policies and Practices 

We reviewed excerpts from the supplemental operations manual, the written respiratory 

protection plans, the aerosol transmissible diseases exposure control plans, and the 

excavation safety plan for prison B. According to the June 2013 supplemental operations 

manual for both prisons, the watch commander can put an institutional yard recall into place 

for prolonged power outages during non-daylight hours. An institutional yard recall means 

that all inmates on the exercise yards must return to their assigned housing units. The watch 

commander can also initiate limited visibility operations when the guards at the perimeter 

tower posts are unable to see one another clearly and distinctly. Implementing limited 

visibility operations means that yard exercise and outdoor programs within the security 

perimeter must stop. At the time of the evaluation, neither prison had procedures for stopping 

yard exercise and outdoor programs for dust storms or unusually dusty or windy days. At 

prison A, the chief medical executive reportedly had the authority to instruct custody staff 

to make announcements to the general inmate population on days with high winds, advising 

them to refrain from outdoor recreation and to remain indoors. This was an unwritten policy.

The February 2011 aerosol transmissible diseases exposure control plan covered both the 

corrections agency and the correctional health care services agency. This plan included 

sections on engineering and work practice controls and personal protective equipment, 

respiratory protection, medical services, training, and record keeping. Appendix B of this 

plan contained a list of aerosol transmissible pathogens or diseases for the purposes of 

Section 5199 of the California Aerosol Transmissible Diseases standard [8 CCR 5199]. 

This list identifies diseases and pathogens requiring airborne infection isolation, such as 

tuberculosis and measles, and those requiring droplet precautions, such as influenza and 

bacterial meningitis. The list does not include Coccidioides. Generally, this standard does not 

apply to Coccidioides outside of the laboratory setting [8 CCR 5199].

At the time of the evaluation, the respective fire chiefs managed the respiratory protection 

programs for prisons A and B. Both programs covered employees and inmate workers and 

contained the basic elements required by the OSHA respiratory protection standard, including 

respirator selection, medical evaluation, respirator training, fit testing, respirator use, and 

handling of disposable respirators [29 CFR 1910.134]. The programs also listed employees 

assigned to areas or jobs that required the use of respiratory protection. The list for prison A 

included most plant operations employees as well as hazardous material specialists. The list 

for prison B included some plant operations employees, all custody employees, and some 
Page 6 Health Hazard Evaluation Report 2013-0113-3198

healthcare employees. Neither program included procedures for using respirators to protect 

employees or inmate workers from potential exposures to Coccidioides. However, in June 

2013, a memorandum was issued to all prison A employees by the chief medical executive, 

which recommended that staff wear an N95 filtering facepiece respirator when outdoors on 

windy or dusty days. 

The associate warden for business services directed the excavation safety program at prison 

B. This written program included information on training, excavation requirements such 

as use of structural ramps and ladders, protective system requirements such as sloping and 

benching systems, and accident investigations. This program did not include procedures 

for wetting down surfaces prior to excavation. The program had information about using 

eye protection, hard hats, harnesses with lifelines, and hearing protection, but respiratory 

protection was not mentioned.

Review of Coccidioidomycosis Among Prison Employees

Coccidioidomycosis Confidential Morbidity Reports

We identified 65 confirmed cases of coccidioidomycosis reported to CDPH among prison 

A employees from January 1, 2009, to June 10, 2013. We identified 38 confirmed cases of 

coccidioidomycosis reported to CDPH among prison B employees from January 1, 2009, to July 

16, 2013. The coccidioidomycosis cases were reported among prison A and B employees by nine 

California counties of residence during this time period. Reporting counties included Fresno, 

Kings, Tulare, Kern, San Luis Obispo, Santa Clara, Madera, Riverside, and Los Angeles. 

We calculated crude 4-year and crude average annual incidence rates of coccidioidomycosis 

for prison A and B employees from 2009 to 2012. The crude 4-year incidence rate of 

coccidioidomycosis among prison A employees was 4,156 cases per 100,000 employees from 

2009 to 2012. The average annual incidence for prison A employees was 1,039 cases per 

100,000 employees over this time. The crude 4-year incidence rate of coccidioidomycosis 

among prison B employees was 2,044 cases per 100,000 employees from 2009 to 2012. The 

average annual incidence for prison B employees was 511 cases per 100,000 employees over 

this time.

For the confirmed cases among employees in 2009–2012, the 12-month combined incidence 

over this 4-year period did not display a clear seasonal pattern (Figure 1). 

Of the 65 confirmed cases of coccidioidomycosis among prison A employees, 57 (88%) were 

male, and 8 (12%) were female. The median age of cases was 41 years (range: 24–67 years). 

Two deaths were reported; the number of hospitalizations is unknown. The median amount of 

time worked at the prison before onset of symptoms was 4 years (range: 2 months–16 years). 

Other demographic and work characteristics of the 65 employees are shown in Table 1. All 

but two employees with confirmed cases of coccidioidomycosis resided in one of the six 

hyperendemic California counties (Table 1).
Health Hazard Evaluation Report 2013-0113-3198 Page 7

Figure 1. Number of coccidioidomycosis cases among prison A and B employees by month of 

symptom onset during 2009–2012. 

The most common job categories at the time of diagnosis, as collected from agency employee 

rosters, of the 65 prison A employees with confirmed coccidioidomycosis were custody (n = 

48), healthcare (n = 7), and administrative (n = 5). Only seven cases had occupation/job title 

and occupational setting recorded in the confidential morbidity report that was submitted to 

CDPH. One case incorrectly had a school listed as the occupational setting. For the other 57 

cases, these fields were blank.

Of the 38 cases of coccidioidomycosis among prison B employees, 27 (71%) were male, 

and 11 (29%) were female. The median age of cases was 44 years (range: 24–63 years). One 

death was reported; the number of hospitalizations is unknown. The median amount of time 

worked at the prison before onset of symptoms was 8 years (range: 2 months–23 years). 

Other demographic and work characteristics of the 38 employees are shown in Table 1. 

All but one employee with confirmed cases of coccidiodomycosis resided in one of the six 

hyperendemic counties (Table 1). 

The most common job categories at the time of diagnosis, as collected from agency employee 

rosters, were custody (n = 26), administrative (n = 5), and healthcare (n = 4). Only three 

cases had occupation/job title and occupational setting recorded in the confidential morbidity 

report that was submitted to CDPH. For the other 35 cases, these fields were blank.
Page 8 Health Hazard Evaluation Report 2013-0113-3198

Table 1. Demographic characteristics of employee cases of coccidioidomycosis

Demographic characteristic No. (%) prison A employees

n = 65

No. (%) prison B employees

n = 38

Male 57 (88) 27 (71)

Race

White 17 (26) 9 (24)

African-American/Black 3 (5) 3 (8)

Asian 2 (3) 1 (3)

Other 2 (3) 1 (3)

Unknown 40 (62) 24 (63)

Ethnicity

Hispanic/Latino 16 (25) 10 (26)

Non-Hispanic/Non-Latino 11 (17) 6 (16)

Unknown 38 (59) 22 (58)

California county of residence

Fresno 34 (52) 13 (34)

Kings 22 (34) 13 (34)

Tulare 4 (6) 6 (16)

Madera 3 (5) 0 (0)

Kern 0 (0) 3 (8)

San Luis Obispo 0 (0) 2 (5)

Other 2 (3) 1 (3)

Job Category

Custody 48 (74) 26 (68)

Administrative 5 (8) 5 (13)

Healthcare 7 (11) 4 (11)

Plant operations 2 (3) 0 (0)

Education/vocation 0 (0) 1 (3)

Other* 3 (5) 2 (5)

*Job titles in the other category included chaplain, industrial supervisor, and correctional supervisory 

cook.

Coccidioidomycosis Reports from Other Sources

We reviewed coccidioidomycosis-related reports from the OSHA Logs from 2009 to 2013 for 

both prisons. Prison A recorded 61 employees with reported work-related coccidioidomycosis 

in the OSHA Logs from 2009 to May 23, 2013. Forty (66%) of these employees were also 

reported to CDPH as confirmed coccidioidomycosis cases. 

Job title groups of the 61 employees included custody (n = 43), healthcare (n = 7), 

administration (n = 5), plant operations (n = 4), and other (n = 2). Of these 61 employees, 41 

(67%) were reported to miss days from work. The median number of days away from work 

for these 41 employees was 70 (range: 2–367 days). 
Health Hazard Evaluation Report 2013-0113-3198 Page 9

Prison B recorded 42 employees with reported work-related coccidioidomycosis in the 

OSHA Logs from 2009 to June 12, 2013. Job title groups of the 42 employees included 

custody (n = 22), healthcare (n = 8), administration (n = 5), other (n = 5), education/vocation 

(n = 1), and plant operations (n = 1). Of these 42 employees, 29 (69%) were reported to miss 

days from work. The median number of days away from work for these 29 employees was 

95 (range: 11–730 days). Only 21 (50%) of the 42 employees in the OSHA Logs were also 

reported to CDPH as confirmed coccidioidomycosis cases. 

We were unable to obtain physician documentation or laboratory testing results for cases 

reported in the OSHA Logs from each prison. We were also unable to obtain the Doctor’s 

First Reports of Occupational Injury or Illness from the California Department of Industrial 

Relations from 2009–2013.

Confidential Medical Interviews with Employees

At prison A, we interviewed 98 of 99 invited employees. At prison B, we interviewed all 74 

invited employees.

Demographic and Health Characteristics of Interviewed Employees 

The median age of interviewed employees was 45 years (range: 25–74 years) at prison A and 

48 years (range: 27–67 years) at prison B. Most employees were male (64% at prison A and 

70% at prison B). Only one employee reported being pregnant at the time of the interview. 

Interviewed employees most commonly self-reported their race as white (64% for prison 

A and 54% for prison B). Between 5%–6% of interviewed employees at both prisons selfidentified their race as Filipino and between 2%–3% self-reported their race as black/African 

American. Forty-two percent of interviewed employees at both prisons self-reported their 

ethnicity as Hispanic/Latino.

The median number of years that employees reported living in one of the six hyperendemic 

California counties was 35 (range: 0.5–67 years) at prison A and 34 years (range: 6–61 years) 

at prison B. The median number of years employees reported living in one of the six endemic 

states or Mexico was 38 (range: 6.5–67 years) at prison A and 40 years (range: 14–63 years) 

at prison B.

Work Characteristics of Interviewed Employees

All interviewed prison employees were employed full time. The median hours worked per 

week was 40 hours for both prisons, although some employees reported working up to 80 

hours. The median time worked at the prison was 7 years (range: 6 months–19 years) at 

prison A and 8 years (range: 4 days–22 years) at prison B. Other work characteristics are 

shown in Table 2. 
Page 10 Health Hazard Evaluation Report 2013-0113-3198

Table 2. Work characteristics of interviewed employees

Work characteristic No. (%) prison A employees

n = 98

No. (%) prison B employees

n = 73–74*

Job title group

Custody 46 (47) 32 (43)

Administration 19 (19) 11 (15)

Plant operations 13 (13) 9 (12)

Healthcare 12 (12) 10 (14)

Education/vocation 8 (8) 4 (5)

Other† 0 (0) 8 (11)

Work shift

First watch 12 (12) 9 (12)

Second watch 24 (25) 16 (22)

Third watch 14 (14) 17 (24)

Business hours 48 (49) 31 (42)

Has another job 9 (9) 5 (7)

*Sample sizes varied because of missing values.

†Other more common job title groups included cook and prison industry employee.

The median time spent outdoors during the workday was 2 hours (range: 10 minutes–8 

hours) for prison A, and 1.5 hours (range: 0–9 hours) for prison B. Work activities of the 

interviewed employees are shown in Table 3.

Table 3. Work activities of interviewed employees

Work activity No. (%) prison A employees

n = 97–98*

No. (%) prison B employees

n = 73–74*

Eat outside during work 10 (10) 13 (18)

Outside work activities

Walking from building to building 98 (100) 73 (99)

Security checks 27 (28) 15 (20)

Patrolling 22 (22) 13 (18)

Maintenance 12 (12) 9 (12)

Landscaping 3 (3) 2 (3)

Delivery 12 (12) 7 (9)

Other† 33 (34) 32 (43)

Soil disruption activities 29 (30) 13 (18)

Outside in dust storm during job 78 (80) 63 (85)

*Sample sizes varied because of missing values.

†Other outside work activities included alarm testing and response, escorting, supervising inmates, 

and riding in carts.

In total, 30% of prison A employees and 18% of prison B employees who were interviewed 

reported that their job involved disruption of soil. At prison A, of the 29 employees who 

reported disrupting soil, they reported doing this constantly (n = 2), sometimes (n = 14), and 

rarely (n = 13). At prison B, of the 13 employees who reported disrupting soil, 4 reported 
Health Hazard Evaluation Report 2013-0113-3198 Page 11

doing this constantly, and 9 reported doing this sometimes. The most commonly reported 

soil disruption activities at both prisons included grid searches and digging for contraband 

in the soil by custody employees, and drilling/digging for maintenance and repairs by plant 

operations employees. Equipment used included shovels, rakes, pick axes, backhoes, and 

garden tractors.

All 172 interviewed employees reported having heard of coccidioidomycosis or valley fever 

prior to the start of the interview. At each prison, 66% of interviewed employees reported 

having received training on coccidioidomycosis related to their work. Types of training 

reported by employees included on-the-job training, pamphlets in paychecks, memos, 

bulletin board posters, department safety meetings, classroom training (given by the medical 

director at prison A), and modules as part of annual block or in-service training.

Regarding respirator access, 67 (68%) employees at prison A and 55 (76%) employees at 

prison B reported having access to an N95 filtering facepiece respirator or other respirator. 

In total, 24 (25%) employees at prison A and 21 (28%) employees at prison B reported ever 

using an N95 filtering facepiece respirator or other respirator when exposed to dust during 

their work at the prisons. At prison B, the most common facial protection devices reported to 

be used were N95 filtering facepiece respirators (n = 19), half-mask elastomeric air purifying 

respirators (n = 3), and non-National Institute for Occupational Safety and Health (NIOSH) 

approved masks including surgical masks (n = 7) and dust masks (n = 7). At prison B, the 

most common facial protection devices were N95 filtering facepiece respirators (n = 18) 

and non-NIOSH approved masks including surgical masks (n = 13) and dust masks (n = 1). 

Employees reported using respirators or masks when walking or working outside during 

dusty days or during dust storms, digging/jackhammering, and changing air filters in the 

ventilation systems. At prison B, employees reported wearing respirators or masks when 

passing out medications during pill call. Employees dispensed medication to inmates through 

an open window, and many wore respirators to protect themselves from outdoor dust that 

would blow into the building. 

Potential Exposures Outside of Work 

The median time spent outdoors outside of work was 2 hours per day (range: 10 minutes–6.5 

hours) for prison A employees and 2.5 hours (range: 0–14 hours) for prison B employees. 

Only one employee from prison B reported spending no time outdoors outside of work. The 

most common outdoor activities of interviewed employees outside of work included hiking, 

walking, running, gardening, biking, golf, and other outdoor sports.

Health Characteristics of Interviewed Employees

In total, 21 (21%) employees at prison A and 14 (19%) employees at prison B reported 

having at least one current underlying medical condition placing them at higher risk for 

disseminated disease. These conditions included lung disease such as asthma or emphysema, 

diabetes mellitus, taking immunosuppressive medications, heart disease, kidney disease, 

and cancer requiring chemotherapy or radiation therapy. At each prison, 9% of employees 

reported smoking tobacco at the time of the interviews.
Page 12 Health Hazard Evaluation Report 2013-0113-3198

At prison A, 13 (13%) employees reported being diagnosed with coccidioidomycosis since 

starting work at the prison. Symptom onset ranged from 1999–2012, and three employees 

reported being hospitalized. Of the 13 employees, 11 reported this illness to their employer, 

and employees reported being absent from work from 0 days to 5 months for this illness. 

Job title groups of these employees included custody (n = 9), education/vocation (n = 2) 

healthcare (n = 1), and plant operations (n = 1). The median number of years these 13 

employees lived in the Central Valley was 34 (range: 2.5–49 years). None of these 13 

employees self-identified as Black or African American or Filipino; seven reported being of 

Hispanic or Latino ethnicity. Only one of the 13 employees reported having an underlying 

medical condition (diabetes) placing him/her at higher risk for disseminated disease.

At prison B, three (4%) employees reported being diagnosed with coccidioidomycosis since 

starting work at the prison. Symptom onset ranged from 2001–2011, and one employee 

reported being hospitalized. All three employees reported this illness to their employer, 

and they reported being absent from work from 7 days to 7 months for this illness. Job title 

groups of these employees included custody (n = 1), and other (n = 2), which consisted of 

cook and prison industry employee. The median number of years these three employees 

lived in the Central Valley was 45 (range: 12–54 years). None of these three employees selfidentified as Black or African American or Filipino; two reported being of Hispanic or Latino 

ethnicity. Only one of the three employees reported having an underlying medical condition 

at higher risk for disseminated disease.

Of the five prison A employees who reported a coccidioidomycosis diagnosis between 2009 

and the time of the interviews, three had their diagnoses reported to CDPH. The one prison 

B employee who reported a coccidioidomycosis diagnosis between 2009 and the time of the 

interviews had his diagnosis reported to CDPH.

Assessment of Environmental Practices

The facilities and engineering staff at both prisons reported not conducting major soil 

disruption activities when wind speeds were “unusually high.” Dry road sweeping was not 

done, and water was used to suppress dust during major soil disrupting activities. Staff at 

both prisons reported reducing the amount of soil disking at the perimeter of the prison 

complex. Disking was done for security because it removed unwanted vegetation and evened 

the ground, thus minimizing potential hiding spots for inmates and contraband. Prison B staff 

estimated they had reduced disking by 90% in 2013 compared to prior years, and had stopped 

disking inside the prison fence. Prison B also limited mowing to between February and April. 

Soil stabilization had been done at prison A in 2011, but not at prison B. New plans called 

for stabilizing approximately 93 acres at prison A, and 276 acres at prison B. Most of the 

stabilized acreage was at the perimeter of each prison complex, although soil surrounding 

inmate housing units, offices, and clinics was also scheduled for treatment. 

We discussed re-vegetation plans with the facilities and engineering staff at both prisons. 

Because the prisons are areas with arid climates, state and county water restrictions and the 
Health Hazard Evaluation Report 2013-0113-3198 Page 13

cost of purchasing water present challenges to maintaining vegetation. At the time of our 

evaluation, the inmate exercise yards at both prisons were grass-covered. However, much of 

the soil around clinics, offices, and along the perimeter of the prison complex was bare or 

covered with gravel. The facilities and engineering staff at prison B told us that watering the 

inmate exercise yards had restarted in the spring of 2013, and that prior to this the exercise 

yards had bare soil. Re-vegetation efforts elsewhere at prison B had slowed because of the 

cost of purchasing water.

In discussions during and after our site visit, prison managers asked us about the usefulness 

of environmental sampling for dust and for Coccidioides and monitoring wind speed and 

direction at the prisons to predict environmental conditions that may place prison employees 

at greater risk of exposure to this fungus. At the time of our evaluation, no environmental 

sampling for dust or Coccidioides had been done. A meteorological station at prison A 

recorded wind direction, wind speed, and rainfall. However, according to prison managers, 

these data were used for wastewater treatment reporting requirements and not to monitor for 

high wind conditions. We were also asked about the effectiveness of respiratory protection in 

minimizing employee exposures to Coccidioides.

Ventilation Assessment

Both prisons were replacing minimum efficiency reporting value (MERV) 8 air filters with 

MERV 13 or 14 rated air filters at the outdoor air supply for air handling units, beginning 

with inmate housing units. No air filter upgrades had yet been made to the mechanical 

heating and air-conditioning units (package units) serving the clinics and administrative 

offices. However, some clinic buildings that we evaluated were already using high efficiency 

air filters per their original ventilation design. 

During our walk-though evaluations of selected offices, clinics, and inmate housing units, 

we looked for visual evidence of mold or water intrusion and saw none. We measured 

temperature, relative humidity, and carbon dioxide. We used the latter to evaluate the 

adequacy of ventilation systems in providing outdoor air to occupied spaces. Most of 

the offices and clinics that we surveyed were mechanically ventilated (air-conditioned). 

Temperatures were within recommended summer comfort guidelines of 75°F to 80.5°F, 

assuming slow air movement and 50% relative humidity [ASHRAE 2010a]. ASHRAE 

also recommends maintaining relative humidity at or below 65%, which it was. Excessive 

humidity can promote the excessive growth of microorganisms and dust mites [ASHRAE 

2010a]. Finally, indoor carbon dioxide concentrations were similar to outdoor concentrations, 

suggesting that an adequate amount of outdoor air was being provided [ASHRAE 2010b].

Inmate housing units were cooled with roof-mounted indirect and direct evaporative units 

(described in detail below). Because the housing units were not air-conditioned, temperature 

and relative humidity levels were generally higher than in the offices and clinics, and 

occasionally exceeded ASHRAE summer comfort guidelines of 75°F to 80.5°F, assuming 

50% relative humidity.
Page 14 Health Hazard Evaluation Report 2013-0113-3198

Prison A Ventilation Assessment 

At prison A, the inmate living units, except for the administrative segregation building 

that we did not evaluate, had two-person cells positioned across three of the four sides 

of each two-story living unit. The inmate housing units were cooled with roof-mounted 

indirect and direct evaporative units. Per design, the evaporative coolers switched from 

indirect evaporative cooling to indirect and direct evaporative cooling based on indoor air 

temperature. Heat was provided by natural gas. 

We visually examined evaporative air cooler #2 in inmate living unit B5. The state 

correctional and rehabilitation agency had installed testing equipment on this air cooler 

to evaluate the impact of the new air filters. The evaporative air cooler appeared well 

maintained with no evidence of microbial contamination, and the air filters appeared clean 

and correctly installed. 

We examined the airflow patterns in two inmate housing units (B4 and B5) using ventilation 

smoke tubes to see if the buildings were under positive pressure relative to the outdoors as 

is recommended, meaning that indoor air would flow from an open door or window to the 

outdoors. When measured at the one entrance door in each building, B5 was under positive 

pressure, and B4 was under negative pressure relative to the outdoors. There was a gap 

around both entrance doors when closed. We observed a similar airflow pattern at the single 

operable window in the second floor control booth in each building. The window in building 

B5 was slightly open, and the control booth was under positive pressure relative to the 

outdoors. The window in building B4 was open about halfway and this control booth was 

under negative pressure relative to the outdoors. We were told that the control booth officer 

decided whether the exterior window was opened. The airflow direction at the entrance door 

and operable window could change depending on ambient wind direction and wind speed.

We measured the airflow provided to the second floor control booths in B4 and B5. Unlike 

the inmate housing areas, the control booths were air-conditioned and heated by roofmounted package units. The unit serving the B4 control booth was not initially operating 

when we arrived, and the thermostat in the control booth had been turned off. The bathroom 

exhaust fan in the B4 control booth was also not operating. The airflow measured at the 

ceiling diffusers ranged from 97–299 cubic feet per minute (cfm) in the B4 control booth and 

224–336 cfm in the B5 control booth. 

We visually examined two of the roof-mounted package units that served the clinical 

treatment center. Air handler RTU-6 had a metal mesh prefilter and a high-efficiency 

particulate air filter (Airguard Variflow VMB-604). The duct lining near the return air duct 

in RTU-6 was dirty and damaged. Another package unit (RTU-5) was not operating (cause 

unknown). The main entrance to the clinical treatment center was under positive pressure 

relative to the outdoors with the door closed. However, when we arrived at the clinical 

treatment center, the entrance door had been propped open with a rock. This practice allows 

unfiltered air to enter the building. An employee in the clinical treatment center explained 

that the entrance door was propped open during inmate transfers. 
Health Hazard Evaluation Report 2013-0113-3198 Page 15

The airflow pattern at the main (west) entrance to office building 800 was positive to 

the outdoors. The airflow pattern at the east doorway leading from the office building to 

the prison yards was in the opposite direction, meaning that air flowed into the building. 

However, airflow direction at either entrance could change depending on prevailing wind 

direction and wind speed. Several restrooms and one inmate restroom/custodial closet in 

building 800 were under positive pressure relative to the hallway. This is not recommended 

because odors from these restrooms could enter occupied areas.

Prison B Ventilation Assessment 

At the time of the evaluation, inmates lived in open dormitories with no individual cells 

except for administrative segregation. We toured the “270 building” and “E bed” dormitory 

styles. The direct evaporative coolers for the inmate living units were on the roof (“270 

buildings”) or on the back wall (“E-bed”). A central power plant provided steam or hot water 

for building heat, showers, laundry, and cooking. Most of the clinics and administrative areas 

were mechanically cooled and heated with roof-mounted package units. 

According to facility managers, for approximately the past 10 years, the direct evaporative 

coolers for the inmate living units used MERV 8 panel air filters and no sock filters 

even though the evaporative coolers were designed for both. In 2013, the prison began 

installing MERV 13 panel prefilters and MERV 14 sock filters (as the secondary filter) in 

the evaporative coolers. Because such an air filter upgrade could affect the quantity of air 

provided by the ventilation system to the indoor spaces, we measured the airflow to inmate 

dorms in building 410 under different air filter arrangements. The evaporative air cooler that 

we evaluated appeared well maintained with no evidence of microbial contamination, and the 

air filters were clean and correctly installed. 

Airflow to the inmate dorms decreased by as much as 10% when the MERV 8 filter was 

replaced by MERV 13 and 14 filters (Appendix C, Figures C1 and C2). In response to inmate 

concerns regarding perceived poor ventilation in building 410, we measured airflow from 

all three evaporative air coolers. As shown in Table 4, airflow averaged 286 cfm among the 

eight dorms serviced by unit C, compared to an average of 551 cfm among the dorms serviced 

by unit A, and 607 cfm among the dorms serviced by unit B. We visually checked unit C; 

it appeared to be operating normally, and the dampers inside the supply air diffusers in the 

inmate dorms were open. We were unable to determine why the airflow varied between these 

identical air coolers in building 410.
Page 16 Health Hazard Evaluation Report 2013-0113-3198

Table 4. Airflow to inmate dorms in Building 410 at prison B, June 6, 2013

Evaporative cooler Floor Inmate dorm Airflow (cfm) Comments

Unit A*

1st

1 673

2 675

3 185 Damper closed

4 738

2nd

13 636

14 447 Plastic on bottom of grill

15 757

16 300 Plastic inside grill

Unit B*

1st

5 849

6 659

7 708

8 809

2nd

17 409

18 572

19 383

20 466

Unit C*

1st

9 317

10 223

11 370

12 436

2nd

21 207

22 276

23 287

24 178

cfm = cubic feet per minute

*Airflow measurements were taken with MERV 13 prefilters and MERV 14 sock (secondary) filters 

in place.

In response to concerns from some clinic employees about outdoor dust entering their 

work area, we checked the airflow patterns in two rooms in the old clinic used to dispense 

medication to inmates. Using ventilation smoke tubes, we found that outdoor air flowed 

into the room when employees opened an exterior pass-through service window in order to 

dispense drugs to the inmates.

Discussion

We identified 65 confirmed cases of coccidioidomycosis among prison A employees and 38 

confirmed cases among prison B employees from January 1, 2009, through mid-2013. The 

crude average annual incidence of coccidioidomycosis between 2009 and 2012 was 1,039 

cases per 100,000 employees at prison A and was 511 cases per 100,000 employees at prison 

B. We are unable to state whether the difference between the prisons reflects a real difference 

in risk and, if so, whether it is related to work or non-work factors.
Health Hazard Evaluation Report 2013-0113-3198 Page 17

The crude average annual incidence among prison employees appears to be higher than the 

crude average annual incidence reported among the general non-inmate adult population in 

the surrounding Fresno (40 cases per 100,000 persons) and Kings (110 cases per 100,000 

persons) [Mohle-Boetani 2013; Tabnak 2013]. However, comparisons of crude incidence 

rates between employees and the adult population of the surrounding county should be 

interpreted cautiously because of unmeasured confounding factors in the background 

population. We were not able to obtain age-, sex-, and race-adjusted incidence calculations 

for the comparison populations, and therefore, avoided making any statistical comparisons. 

It is also possible that reporting or testing bias (or increased reporting or testing among 

the employees) due to heightened awareness and concern could have contributed to the 

difference in crude incidence rates.

It was not possible to determine if each confirmed case of coccidioidomycosis among prison 

employees was due to an exposure at work or outside of work. The vast majority of prison 

employees with confirmed cases of coccidioidomycosis resided in a hyperendemic area, 

and our interview findings revealed that employees are likely exposed to Coccidioides both 

at work and outside of work. At work, almost all interviewed employees at each prison 

reported spending some time outdoors. Even walking from building to building could pose 

a risk for exposure to Coccidioides. Almost one-third of interviewed employees reported 

having a job that involved disruption of soil. Activities included grid searches and digging 

for contraband in the soil by custody employees and drilling/digging for maintenance and 

repairs by plant operations employees. These activities could increase the risk of exposure to 

Coccidioides. The excavation safety plan for prison B did not include wetting down soil prior 

to excavation, although it was reportedly done in practice. The written respiratory protection 

program did not include guidance for respirator use during soil disruption activities.

About 80%–85% of interviewed employees reported being outside in dust storms during 

their job. This could increase their risk of exposure to Coccidioides. According to the 

supplemental operations manual we reviewed, there are no written procedures for ending 

yard exercise and outdoor programs for dust storms or for unusually dusty or windy days.

Environmental mitigation efforts, such as reducing soil disking, less frequent mowing, 

paving roads, and wetting soil before it is disturbed, can reduce the dust levels. Soil 

stabilization can reduce a form of wind erosion called saltation, the direct entrainment of fine 

dirt and dust particles by wind. Saltation contributes to an effect called sandblasting, where 

airborne dirt and dust particles repeatedly impact the soil surface downwind, dislodging even 

more particles in the process. Researchers have speculated that saltation may rupture the 

fungal structure of Coccidioides, and sandblasting can disperse the airborne Coccidioides

spores at wind speeds lower than those required to directly entrain either the fungus or its 

spores [Zender and Talamantes 2005]. However, naturally occurring dust storms, combined 

with ongoing soil disturbing activities such as farming and construction that occur on land 

adjacent to each prison, can recoat stabilized soil and may reduce or shorten the possible 

benefit of soil treatment. Consultation with the local Air Pollution Control District may be 

valuable when considering environmental mitigation projects for dust control.
Page 18 Health Hazard Evaluation Report 2013-0113-3198

The prisons also face ongoing challenges to maintain and/or restore vegetation around office 

buildings and clinics and to maintain grass in the inmate exercise yards. These challenges 

result from external state and county water restrictions and the cost of purchasing water 

above their allotment. Like soil stabilization, maintaining grass and other vegetation can 

reduce saltation and sandblasting. 

Regardless of the environmental mitigation effort, little to no data exists that demonstrate 

the effectiveness of these measures in reducing airborne dispersal of Coccidioides [Brown 

et al. 2013]. For example, airborne spores can travel for miles, and focal Coccidioides

sites may be small and/or unevenly distributed within endemic areas [Kirkland and Fierer 

1996; Fisher et al. 2000; Brown et al. 2013]. Although these dust reduction measures may 

lower the risk for localized airborne dispersion of Coccidioides, they neither eradicate 

the organism from the soil nor prevent exposure to dust from areas outside of the prison 

grounds. Nevertheless, reducing dust is a reasonable risk-based strategy to help to try to 

reduce occupational coccidioidomycosis.

Managers from the state correctional health care services agency asked whether measuring 

wind speed or doing air sampling for Coccidiodes may be useful in deciding how to reduce 

employee’s exposure to Coccidiodes. Collecting local meteorological data, specifically wind 

speed, may be useful in defining “unusually windy” conditions and making risk management 

decisions on when outdoor work or exercise is permitted. However, we do not have specific 

guidance on acceptable or unacceptable wind speeds in relation to the risk of exposure. 

Regarding sampling, sensitive DNA-based methods for air or surface sampling specifically 

for Coccidioides have not been widely accepted [Nguyen et al. 2013]. Though current limited 

sampling methods are not likely to be helpful in assessing employee exposures or developing 

risk-based control measures, future research to explore how improved testing and strategies 

may yield valuable information are needed.

Our observations and discussions with employees during our walk-through surveys and 

environmental assessments indicate that exposure to dust can occur indoors and outdoors. 

For example, we saw open doors and windows in several buildings that allowed unfiltered air 

to enter the occupied space. Employees can carry dust indoors on their clothing and shoes. 

The practice of dispensing medication to inmates through an open exterior window in the old 

clinic building at prison B resulted in an unnecessary employee exposure to outdoor dust.

Switching from a medium efficiency (MERV 8) filter to a higher efficiency (MERV 13 or 14) 

filter should reduce employee and inmate exposure to dust while indoors. However, this filter 

change will affect the performance of the ventilation system. For example, at prison B we 

measured a 10% reduction in the volume of conditioned air provided to inmate housing units 

after MERV 8 air filters were replaced by both MERV 13 prefilters and MERV 14 secondary 

filters. This decrease in supplied air could affect occupant comfort. A lower efficiency and 

less expensive prefilter could be used that would extend the life of the more expensive 

secondary MERV 14 filter. Regardless, switching from lower to higher-efficiency air filters 

will require developing a new replacement schedule to prevent filter overloading and possible 

damage to the ventilation system. We understand that consideration was being given to 
Health Hazard Evaluation Report 2013-0113-3198 Page 19

further upgrading to MERV 16 (or higher) filters. Such a decision should balance concerns of 

reduced air flow, higher air filter cost, and more frequent maintenance. While there would be 

a modest increase in efficiency in removing very small particles, Coccidiodes spores adhere 

to soil particles of a wide size range [Das et al. 2012]. Thus, the benefits of modest increases 

in filter efficiency may not be realized. 

While evaluating the air filter changes, we responded to inmate concerns regarding perceived 

poor ventilation in building 410 at prison B. We found differences in the quantity of outdoor 

air supplied by three apparently identical air handling units serving the inmate living areas 

(Table 8). The amount of outdoor air supply also differed between floors and between 

inmate living areas. We saw one supply air diffuser that was closed, and several that were 

partially blocked with plastic debris. These ventilation problems are unrelated to the primary 

objectives of this evaluation, but they can contribute to poor indoor environmental quality.

All interviewed employees reported living in one of the six counties hyperendemic 

for coccidioidomycosis, and the majority had spent many years in the area. Almost all 

interviewed employees at each prison reported spending time outdoors outside of work. 

Over 50% of employees reported gardening, another potential soil disruption activity. Thus, 

employees are at risk of exposure to Coccidioides outside of work. The relative contributions 

of work and nonwork exposure to the overall risk cannot be determined.

Nevertheless, coccidioidomycosis has been a recognized problem in inmates of state prisons 

in the San Joaquin Valley of California, particularly prisons A and B. Annual incidence was 

noted to be higher among inmates at these two prisons than in the general population of the 

surrounding counties from 2000–2010 [Pappagianis 2007; California Correctional Health 

Care Services 2012]. If this discrepancy in rates reflects actual differences, the reasons for 

the higher rates among inmates are not entirely clear, but may include the possibility that 

the inmate population includes a high proportion of immune-naïve or previously unexposed 

inmates relocated from less-endemic areas [Brown et al. 2013]. It is also possible that testing 

bias due to heightened awareness and health care access in the inmate population also could 

have contributed to high rates.

Most employees with confirmed coccidioidomycosis and most employees with 

coccidioidomycosis-related OSHA Log reports worked as custody employees. However, 

since custody employees make up the majority of the employee population, they do not 

appear to be represented in disproportionate numbers among cases. We do not know how 

much time these employees spent outdoors during their job, or whether their infection was 

due to an occupational exposure. We do know, however, that many custody employees 

have outdoor job activities such as performing security checks, patrolling, escorting and 

supervising inmates, and digging for contraband that may put them at risk. However, 

administrative and healthcare employees, whose job duties do not typically involve outdoor 

work, were also among the affected employees. We found that four licensed vocational 

nurses were among the confirmed cases. These employees have responsibilities that include 

handing out medications. At prison B nurses dispensed medication to inmates using pass-
Page 20 Health Hazard Evaluation Report 2013-0113-3198

through windows that allowed unfiltered outdoor air to enter the pill room, unnecessarily 

exposing the nurses to outdoor dust.

Only 8%–11% of employees with confirmed coccidioidomycosis had occupation and job 

setting information included in their confidential morbidity reports. Enhanced efforts by the 

county and state health departments to ensure completeness of reporting, especially of the 

occupation and job information, are needed to improve occupational coccidioidomycosis 

surveillance and help identify future clusters in the prisons.

Our evaluation has several additional limitations. First, our analysis of the confirmed 

coccidioidomycosis cases among employees was limited to the information in the 

confidential morbidity report. This report did not contain information on what type of clinical 

illness, including disseminated disease, these case employees had. Therefore, we could not 

determine the severity of the illness for each case. We also did not have information on what 

personal risk factors these case employees had. Because employees sought medical care 

from several different health care providers and clinics, we did not obtain all of their medical 

records. Approximately 60% of these reports had missing race and ethnicity information. 

Completeness of reporting race and ethnicity information to the county and state health 

department will help to better characterize the epidemiology of coccidioidomycosis. 

Second, we did not calculate 1-year crude incidence rates of coccidioidomycosis among 

employees due to the small number of cases each year and the difficulty in distinguishing 

random fluctuation from true changes in the underlying risk of disease inherent to rates based 

on small numbers. Therefore, we were limited in identifying annual trends. 

Third, we were unable to obtain detailed information about the coccicioidomycosis-related 

OSHA Log reports. Thus, we are unable to explain the discrepancy between the confirmed 

cases reported to CDPH and the OSHA Log reports. Because the agency does not require 

physician and laboratory documentation for the OSHA Log reports, it is possible that some of 

the cases were not actually confirmed cases according to the CSTE definition. 

Finally, we interviewed only a small subset of the more than 1,300 employees at each prison. 

Thus, the self-reported health characteristics and work practices may not be generalizable to 

the entire employee population.

Conclusions 

Prisons A and B are located in hyperendemic areas for coccidioidomycosis, and prison 

employees are exposed to Coccidioides both at work and outside of work. We identified 103 

confirmed cases of coccidioidomycosis among employees at the two prisons over a 41⁄2-year 

period. Measures such as wetting soil before it is disturbed, maintaining grass on exercise 

yards, stabilizing soil, paving roads, improving building ventilation, and changing work 

practices (such as reducing time spent outdoors) would be expected to reduce dust exposures to 

varying degrees. However, none of these measures will eliminate exposure to Coccidioides, and 

their relative effectiveness in reducing occupational coccidioidomycosis is unknown.
Health Hazard Evaluation Report 2013-0113-3198 Page 21

Recommendations 

On the basis of our findings, we recommend the actions listed below to create a more 

healthful workplace. We encourage the state correctional and rehabilitation agency and the 

state correctional health care services agency to use a labor-management health and safety 

committee or working group to discuss the recommendations in this report and develop an 

action plan. Those involved in the work can best set priorities and assess the feasibility of 

our recommendations for the specific situation at the two prisons. Our recommendations are 

based on the hierarchy of controls approach. This approach groups actions by their likely 

effectiveness in reducing or removing hazards. Additional recommendations can be found in 

CDPH’s fact sheet “Preventing Work-Related Coccidiodomycosis (Valley Fever)” at http://

www.cdph.ca.gov/programs/hesis/documents/CocciFact.pdf. 

Engineering Controls 

Engineering controls reduce employees’ exposures by removing the hazard from the process or by 

placing a barrier between the hazard and the employee. Engineering controls protect employees 

effectively without placing primary responsibility of implementation on the employee. 

As stated in our discussion section, wide-scale measures to reduce airborne dispersal of 

Coccidioides such as watering the soil during construction projects, paving roads, planting 

grass or other vegetation, and stabilizing the soil could reduce employee exposure to soil or 

dust. However, little to no data exists that demonstrate the effectiveness of these measures 

[Brown et al. 2013]. Although these dust reduction measures may lower the risk for localized 

airborne dispersion of Coccidioides, they neither eradicate the organism from the soil nor 

prevent exposure to dust from areas outside of the prison grounds. Nevertheless, reducing 

dust is a reasonable risk-based strategy to try to reduce occupational coccidioidomycosis.

1. Consider ongoing efforts to evaluate the effectiveness of environmental mitigation 

projects, such as soil stabilization, paving roads, and planting grass and other 

vegetation in reducing occupational coccidioidomycosis. Analyzing inmate and 

employee cases of coccidioidomycosis before and after an environmental mitigation 

project may be one method but may not be an accurate measure of the project’s 

effectiveness considering the natural presence of Coccidioides and its inherent 

variability due to climate changes and other factors (such as construction or farming 

activities occurring near but outside the prison complexes). 

2. Include soil-wetting procedures in the excavation safety plan.

3. Keep doors and windows in the office buildings, clinics, and inmate housing units 

closed except when entering or exiting.

4. Install door sweeps and seal gaps around doors and windows.

5. Develop a new inspection and replacement schedule following installation of the 

higher-efficiency air filters.
Page 22 Health Hazard Evaluation Report 2013-0113-3198

6. Consult with a ventilation engineer to examine the air handling units in building 410 at 

prison B. Consider expanding this ventilation assessment to the remaining buildings at 

both prisons.

7. Reduce outdoor dust exposures to employees in the old clinic building at prison B 

when they dispense inmate medication. Employee exposures could be reduced by 

maintaining positive pressure in the dispensing room relative to the outdoors, or 

ending the need to dispense inmate medication through an open window. 

Administrative Controls

Administrative controls are management-dictated work practices and policies to reduce or 

prevent exposures to workplace hazards. The effectiveness of administrative changes in work 

practices for controlling workplace hazards is dependent on management commitment and 

employee acceptance. Regular monitoring and reinforcement are necessary to ensure that 

control policies and procedures are not circumvented in the name of convenience.

1. Provide education and training during working hours to all prison A and B 

employees on hire and annually thereafter on the symptoms and transmission of 

coccidioidomycosis, the risk factors for disseminated disease, and ways to minimize 

exposure both at work and outside of work. Training should be tailored to education 

level and job category. Additional information on coccidioidomycosis can be found at 

the following websites:

a. CDC website at http://www.cdc.gov/fungal/coccidioidomycosis/ 

b. CDPH website at http://www.cdph.ca.gov/healthinfo/discond/Pages/

Coccidioidomycosis.aspx

2. Encourage state correctional and rehabilitation agency employees to promptly report 

suspected symptoms of possible coccidioidomycosis to a supervisor. They should 

receive prompt medical care.

3. Review the OSHA Logs yearly for reports of coccidioidomycosis infections among 

employees to assess trends over time and across job title groups. 

4. Avoid driving vehicles on unpaved roads.

5. Close the prison yards and advise inmates and employees to stay indoors during dust 

storms and unusually windy or dusty days.

6. Consider hardship transfer requests from employees who have medical risk factors for 

disseminated coccidioidomycosis such as an immunocompromising condition and who 

wish to work in a geographic area with a lower incidence of coccidioidomycosis.

7. Consider the use of the coccidioidal spherulin skin test on employees when it becomes 

commercially available. Determination of prior Coccidioides exposure at baseline 

could be valuable to each employee to evaluate his or her personal risk for disease. 

This determination should not be used to terminate or reassign an employee to a 

different job class or work location. Rather, employees should discuss test results 

along with other personal risk factors with their personal physicians. More research 

is needed on determining the sensitivity and specificity of the test, improving these 
Health Hazard Evaluation Report 2013-0113-3198 Page 23

characteristics, and determining how effective it may be in decreasing the burden of 

coccidioidomycosis among employees. Consideration in using this test should include 

who does the testing, how the results are used, and how often testing is done on 

employees.

Personal Protective Equipment

Personal protective equipment is the least effective means for controlling hazardous 

exposures. Proper use of personal protective equipment requires a comprehensive program 

and a high level of employee involvement and commitment. Personal protective equipment 

should not be the sole method for controlling hazardous exposures. Rather, personal 

protective equipment should be used until effective engineering and administrative controls 

are in place. The effectiveness of respiratory protection in preventing coccidioidomycosis 

has not been determined, and additional research is necessary in this area. Nevertheless, it is 

reasonable to expect that use of respiratory protection may confer some benefit to employees 

with high risk exposures by reducing dust exposures.

1. Consider the use of NIOSH-approved respirators for employees who must work 

outside during unusually dusty or windy conditions or for employees with job duties 

that may disturb soil such as disking, digging, excavating, and gardening. Given 

that the effectiveness of respirators in preventing coccidioidomycosis has not been 

evaluated, the conditions upon which respirators should be used (level of respiratory 

protection, voluntary vs. required use) are unclear. However, reduction in exposure to 

soil dust conferred by using respirators may provide benefits to employees. Respirator 

use must be in conformance with the California OSHA respiratory protection standard 

(http://www.dir.ca.gov/title8/5144.html). If required, the employees must be included 

in a written respiratory protection program, and be medically evaluated, trained, 

and fit-tested. If respirator use is voluntary, employees do not need to be included in 

the respiratory protection program but must be provided with Appendix D from the 

California OSHA respiratory protection standard (http://www.dir.ca.gov/title8/5144d.

html). Because these prisons are located in areas that have very high daytime 

temperatures, it is important to consider the additional heat stress effects that may 

occur with respirator usage. Additional information on the symptoms and treatments 

for heat related illnesses and recommendations to reduce risk can be found at http://

www.cdc.gov/niosh/topics/heatstress/. 

2. If the use of respiratory protection is considered, consult the following documents 

in selecting respiratory protection against Coccidioides, based on job tasks and 

environmental conditions:

a. “Histoplasmosis—Protecting Workers at Risk,” [http://www.cdc.gov/niosh/

docs/2005-109/pdfs/2005-109.pdf] 

b. “Preventing Work-Related Coccidiodomycosis (Valley Fever),” [http://www.

cdph.ca.gov/programs/hesis/documents/CocciFact.pdf] 
Page 24 Health Hazard Evaluation Report 2013-0113-3198

Appendix A: Coccidioides 

Coccidioides 

Coccidioides is a fungus that thrives in climates with hot summers and gentle winters, 

without harsh freezes, with an annual rainfall of about 4–20 inches [Pappagianis 1988; 

Laniado-Laborin 2007]. The fungus is found in soil, commonly about 2–12 inches beneath 

the surface [Pappagianis 1988; Fisher et al. 2000]. The organisms can have a sporadic or 

patchy distribution within a given locality. Environmental conditions, including drought, 

precipitation, temperature, and wind speed, appear to have an impact on coccidioidomycois 

incidence [Comrie 2005]. Previous studies have hypothesized that Coccidioides spores 

(vegetative fungal cells in a resting state) are most abundant in the soil after heavy rains and 

may be most effectively dispersed during dry, hot periods, such as prolonged droughts [Smith 

et al. 1946; Schneider et al. 1997; Kolivras and Comrie 2003; Comrie 2005]. Thus, increased 

incidence of infection often occurs after a heavy wet season followed by a prolonged dry 

spell [Zender and Talamantes 2005]. Incidence in California is thought to be seasonal, with 

peak incidence occurring during the winter months [Kirkland and Fierer 1996].

Coccidioides spores exhibit several properties including easy dispersion, respirability, and 

infectivity. Spores are thought to be 2–5 μm in diameter and are able to reach terminal 

bronchioles and alveoli [Converse and Reed 1966; Schmelzer and Tabershaw 1968]. 
Health Hazard Evaluation Report 2013-0113-3198 Page 25

Appendix B: Coccidioidomycosis Case Definition

Coccidioidomycosis is on the list of National Notifiable Diseases, although not all states have 

made it reportable [CDC 2012b]. California is among the states where coccidioidomycosis is 

a reportable condition. CDPH uses the CSTE case definition for coccidioidomycosis [CDC 

2012a]. A confirmed case meets the clinical case definition and is laboratory confirmed. A 

clinical case is defined as an illness characterized by one or more of the following:

● Influenza-like signs and symptoms

● Pneumonia or other pulmonary lesion, diagnosed by chest radiograph

● Erythema nodosum (a deep skin inflammation) or erythema multiforme rash

● Involvement of bones, joints, or skin by dissemination

● Meningitis

● Involvement of viscera and lymph nodes

A confirmed case must also meet at least one of the following laboratory criteria for 

diagnosis:

● Culture, histopathologic, or molecular evidence of presence of Coccidioides, or

● Positive serologic test for coccidioidal antibodies in serum, cerebrospinal fluid, or other 

body fluids by:

○ Detection of coccidioidal immunoglobulin M by immunodiffusion, enzyme 

immunoassay, latex agglutination, or tube precipitin, or

○ Detection of coccidioidal immunoglobulin G by immunodiffusion, enzyme 

immunoassay, or complement fixation, or

○ Coccidioidal skin-test conversion from negative to positive after onset of clinical 

signs and symptoms

Coccidioidomycosis became laboratory reportable in California in 2010. Since 2008, the 

laboratory component of the CSTE definition has included cases with a single positive 

serologic test. Fresno County, in which prison A is located, and Kings County, in which 

prison B is located, use the CSTE definition. 
Page 26 Health Hazard Evaluation Report 2013-0113-3198

Appendix C: Figures 

Figure C1. Airflow in cubic feet per minute (cfm) from air handler B to first floor inmate dorms in building 410 at prison B.

Figure C2. Airflow in cubic feet per minute (cfm) from air handler B to second floor inmate dorms in building 410 at prison B. Airflow (cfm) Airflow (cfm)
Health Hazard Evaluation Report 2013-0113-3198 Page 27

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Keywords: North American Industry Classification System 922140 (Correctional Institutions), Coccidioidomycosis, Coccidioides, valley fever, prison, correctional facility, infectious diseases, ventilation, fungal disease.
Health Hazard Evaluation Report 2013-0113-3198 Page 31

The Health Hazard Evaluation Program investigates possible health hazards in the workplace under the 

authority of the Occupational Safety and Health Act of 1970 (29 U.S.C. § 669(a)(6)). The Health Hazard 

Evaluation Program also provides, upon request, technical assistance to federal, state, and local agencies 

to investigate occupational health hazards and to prevent occupational disease or injury. Regulations 

guiding the Program can be found in Title 42, Code of Federal Regulations, Part 85; Requests for Health 

Hazard Evaluations (42 CFR Part 85).

Disclaimer

The recommendations in this report are made on the basis of the findings at the workplace 

evaluated and may not be applicable to other workplaces.

Mention of any company or product in this report does not constitute endorsement by the National 

Institute for Occupational Safety and Health (NIOSH).

Citations to Web sites external to NIOSH do not constitute NIOSH endorsement of the sponsoring 

organizations or their programs or products. NIOSH is not responsible for the content of these Web 

sites. All Web addresses referenced in this document were accessible as of the publication date.

Acknowledgments 

Desktop Publishers: Mary Winfree and Greg Hartle

Editor: Ellen Galloway 

Industrial Hygiene Field Assistance: R. Todd Niemeier; Jennifer McNary, California Department of 

Public Health 

Logistics: Donnie Booher and Karl Feldmann

Medical Field Assistance: Kimberly Brinker, CDC; Jason Wilken, California Department of Public 

Health 

Surveillance and Statistical Support: Lynne Pinkerton; Lauren Lee, Alyssa Nguyen, and Farzaneh 

Tabnak, California Department of Public Health; Michael Maclean and Sharon Soong, 

Kings County Public Health Department; Faisal Aranki and Robert Oldham, Fresno County 

Department of Public Health

Subject Matter Consultation: Lauren Lee, California Department of Public Health; Benjamin Park, 

Anne Purfield, CDC

Availability of Report

Copies of this report have been sent to the employer, employees, and union at the call center. The state and 

local health department and the Occupational Safety and Health Administration Regional Office have also 

received a copy. This report is not copyrighted and may be freely reproduced. 

This report is available at http://www.cdc.gov/niosh/hhe/reports/pdfs/2013-0113-3198.pdf.

Recommended citation for this report:

NIOSH [2014]. Health hazard evaluation report: evaluation of Coccidioides exposures 

and coccidioidomycosis infections among prison employees. By de Perio MA, Burr GA. 

Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control 

and Prevention, National Institute for Occupational Safety and Health, NIOSH Report No. 

2013-0113-3198.
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