[Emerging Infectious Diseases]  
[Volume 4 No. 4 /October-December 1998]



Letters

Aedes aegypti in Tucson, Arizona

To the Editor: The highly domestic mosquito species Aedes aegypti, a
tropical, nonnative vector of dengue and yellow fever, has been identified
in several desert communities, including the city of Tucson and the border
towns of Douglas, Naco, and Nogales (1). Ae. aegypti has now been found in
the southern Arizona communities of Benson and Sahuarita Heights, which
indicates that its distribution is probably expanding. Moreover, mosquito
surveillance indicating that Ae. aegypti populations in Tucson are
established throughout the city supports local concerns that the mosquito
poses a public health risk in Arizona's second largest metropolitan area.

Since it was first detected in 1994 on Tucson's west side, the mosquito has
been found in the central downtown and university districts, northern
foothills, and the east and south sides (both in residential areas,
including schools and parks, and in business districts). Between 1995 and
1997, almost 200 adult Ae. aegypti (female and male) were recovered in CDC
CO(sub 2) traps from 26 sites in Tucson by vector biologists from the Arizona
Department of Health Services, Pima County, and the University of Arizona
Veterinary Science Department.

These trapping events occurred between May and October of each year and
were associated with either routine arbovirus surveillance or nonsystematic
Ae. aegypti "spot-checks." Many of the sites were sampled more than once
and 30% contained Ae. aegypti on multiple occasions. Catches from
individual sites contained 1 to 40 adult mosquitoes (mode = 1).

A larval survey of the city has not yet been conducted because of limited
staff and problems associated with oviposition trapping, an important part
of Ae. aegypti larval surveillance (2). Initial attempts at ovitrapping by
state, county (1), and later university personnel were not successful
because the hay infusion water in ovitraps evaporated rapidly in Tucson's
arid climate. However, the few larvae recovered from household containers
suggest that Tucson's urban environment is providing a breeding habitat.
Since the local climate requires full-time vigilance of ovitraps, this
method of surveillance appears too labor intensive for the present.

In 1997, the University of Arizona Entomology Department initiated a
mosquito survey of the city. This multiyear project is funded by the
Entomology Department, the city of Tucson, and the Pima County Health
Department. Neighborhood associations in Tucson were surveyed for their
perceptions of the magnitude of the mosquito problem in their areas. On the
basis of survey results, the city was divided into regions: north, east,
south, west, and central. Four trapping stations were established in each
region for a total of 20 sites spanning the metropolitan Tucson and
outlying areas. The five regions were surveyed for mosquitoes through use
of CO(sub 2) traps approximately every 10 days starting July 1, 1997; traps 
were set in the late afternoon and collected in the late morning. Daytime 
CO(sub 2) trappings were not effective.

The Entomology Department's 1997 surveillance data suggest that the central
part of the city is the most heavily infested. Of 95 adult Ae. aegypti
trapped, 49.5% were from the central region of Tucson, 18.9% from the west
side, 17.9% from the east side, 10.5% from the north side, and 3.2% from
the south side. The mosquito populations appeared to fluctuate with the
weather, increasing in size after rainfall. Long-term trapping and future
larval surveys should shed more light on this association.

Pima County and the University of Arizona Veterinary Science Department
trapping activities in 1997 also produced evidence of Ae. aegypti in two
communities near Tucson. Six adult mosquitoes were recovered in the town of
Benson, 30 miles southeast of Tucson, and seven were trapped in Sahuarita
Heights, 15 miles south of Tucson. The presence of the mosquitoes in these
communities, as well as in Douglas, Naco, and Nogales, demonstrates that
Arizona's smaller desert communities are also susceptible to Ae. aegypti
infestations. The humidity emitted by home evaporative coolers may be
crucial for the survival of tropical mosquitoes, such as Ae. aegypti, in
Arizona's arid climate (N. Monteny, pers. comm.).

Genetic analysis of the Ae. aegypti collected from southeastern Arizona,
Texas, and Mexico is under way at the University of Arizona Ecology and
Evolutionary Biology Department to determine the structure, history, and
origin(s) of the reemergent mosquito populations. Preliminary findings from
mitochondrial DNA sequences suggest that Ae. aegypti in Arizona represent a
single (panmictic) population, which indicates frequent local migration.
More extensive sampling is necessary to confirm these results and determine
a point of origin.

A community outreach program has been developed to inform the public about
Ae. aegypti breeding and control in Tucson. Public involvement will be a
key factor in the control of these urban breeders. Major emphasis will also
be placed on programs for children and teachers as both groups can be
instrumental in maintaining long-term interest in this problem. As these
programs are developed, they can be expanded and amended to meet the needs
of other infested communities in southern Arizona. A mosquito control
abatement district is under consideration in a central part of Tucson. The
primary purpose of this district would be to provide approximately 10,000
homeowners with information on controlling Ae. aegypti breeding on their
property.

Just how long the Ae. aegypti infestation will last is difficult to assess.
Records of the city's earlier infestation indicate the mosquito was present
for at least a 15-year period (1931 to 1946) (1,3,4). Since their
identification in early 1998 summer mosquito samples from Tucson, adult Ae.
aegypti have been part of the city's local environment for at least 5
consecutive years (1994 to 1998). Their continued presence and the abundant
breeding habitat provided by the expansion of Tucson's urban landscape
suggest that Ae. aegypti could survive for an extended period.

T. Michael Fink,* Bosun Hau, Branford L. Baird, Sarah Palmer, Susanne
Kaplan, Frank B. Ramberg, Daniel G. Mead, and Henry Hagedorn
*Arizona Department of Health Services, Phoenix, Arizona, USA; University
of Arizona, Tucson, Arizona, USA; and Pima County Community Prevention and
Public Health Department,Tucson,Arizona, USA

References

  1. Engelthaler DE, Fink TM, Levy CE, Leslie MJ. The reemergence of Aedes
     aegypti in Arizona. Emerg Infect Dis 1997;3:241-2.
  2. Reiter P, Amador MA, Colon N. Enhancement of the CDC ovitrap with hay
     infusions for daily monitoring of Aedes aegypti populations. J Am Mosq
     Control Assoc 1991;7:52-5
  3. Murphy D. Collection records of some Arizona mosquitoes. Entomological
     News 1953;14:233-8.
  4. Bequaert J. Aedes aegypti, the yellow fever mosquito, in Arizona.
     Bulletin of the Brooklyn Entomological Society 1946;41:157.

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Can the Military Contribute to Global Surveillance and Control of
Infectious Diseases?

To the Editor: Numerous networksboth formal (e.g., Ministries of Health
and WHO Collaborating Centers and collaborating laboratories) and informal
(e.g., nongovernmental and humanitarian organizations, the media, and
electronic discussion groups)contribute to WHO's network of networks for
the global surveillance of infectious diseases (1).

A potential source of additional information on infectious diseases is the
network of military health facilities and laboratories throughout the
world. In addition to health facilities serving populations at high risk
for infectious diseases, the military also has laboratories, often among
the better-equipped, in developing countries. To evaluate the feasibility
and potential usefulness of including military laboratories in the WHO
global surveillance network, we conducted three surveys.

The first survey identified military laboratories willing to participate in
global surveillance activities and obtained information about their
infectious diseases reporting systems. Of the 107 countries surveyed, 76
replied. Among them, 53 (70%) reported having a central military laboratory
that coordinates laboratory activities throughout the military, and 62
(82%) reported that military clinical facilities had a reporting system for
infectious diseases.

The second survey quantified laboratory capabilities in the 53 laboratories
identified in the first survey and obtained details about the 62 reporting
systems. Among the 39 (74%) laboratories that replied, all can perform at
least one of the following activities: isolating and identifying bacterial,
viral, or parasitic agents. Twenty-nine (55%) have the capacity for
specialized immunologic or molecular study. In addition, one of these
laboratories has a biosafety level 4 facility, six have a biosafety level 3
facility, and 10 have a biosafety level 2 facility. Twenty-seven (51%) of
the laboratories perform compulsory screening of new recruits for HIV, 17
(33%) for hepatitis B, 7 (13%) for hepatitis C, 39 (74%) for tuberculosis,
35 (67%) for syphilis, 18 (34%) for intestinal parasites, 13 (25%) for
schistosomiasis, 12 (23%) for malaria, and 2 (4%) for Chagas disease.

Among the 54 reporting systems for which further information was obtained,
clinical diagnoses (in some countries laboratory confirmed) are reported
through the hierarchical chain, normally by mail or facsimile, but in two
countries by electronic links. Almost all military reporting systems are
parallel to civilian systems. Thirty-four (63%) of 54 systems feed into the
civilian system, with a built-in mechanism to avoid duplicate reporting; 16
(30%) systems feeding into the civilian system have no such mechanism in
place; and four have no link with the civilian system.

The third survey addressed vaccination policies. Among 52 countries that
replied, 47 (90%) have a compulsory military vaccination schedule: 45 (87%)
for tetanus, 30 (58%) for diphtheria, 23 (44%) for typhoid, 16 (31%) for
bacillus Calmette-Gurin and polio, 12 (23%) for meningococcal meningitis,
and 10 (19%) for measles, mumps, and rubella.

These surveys show that military populations are protected against many
infectious diseases and that a wealth of information is obtained by
military laboratories and health-care facilities on populations at high
risk for infectious diseases. While most of the information collected from
the health-care facilities is reported through civilian systems as well,
incorporating the military network of laboratories into the WHO global
surveillance network could ensure broader coverage.

Raffaele D'Amelio* and David L. Heymann
*Ministero della Difesa, Direzione Generale Sanit Militare, Roma, Italy;
and World Health Organization, Geneva, Switzerland

Reference

  1. Heymann DL, Rodier GG. Global surveillance of Communicable Diseases.
     Emerg Infect Dis 1998;4:362-5.

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Dual Infection with Ehrlichia chaffeensis and a Spotted Fever Group
Rickettsia: A Case Report

To the Editor: In their article, Daniel J. Sexton et al. state, "Well-
documented cases of simultaneous human infections with more than one
tick-borne pathogen are rare" (1) and mention only two reports of such
cases. However, another report should be mentioned because of its
historical interest and the lessons it may teach.

In 1900 to 1905, in the Bitter Root Valley, a tick-borne disease emerged,
which became known as Rocky Mountain spotted fever. Although Ricketts et
al. later published a report (2), which identified the causative agent, in
1904 L.B. Chowning and W.M. Wilson published Studies on Pyroplasma hominis
(3). They reported finding Pyroplasma (since changed to Babesia) in the
blood of approximately 20 patients with spotted fever. They studied this
organism in detail and even found the reservoir for it in the local rodent
species. Wilson et al. thought that the organism was the causative agent of
spotted fever. On the basis of their excellent plates and descriptions, it
is clear that the organism they were describing was what we later came to
know as Babesia microti.

The work of Wilson and Chowning was ignored and forgotten for many years.
They had incorrectly concluded that spotted fever was caused by a parasite.
For many years it was "well known" that Babesia infections became apparent
in human patients only on removal or inactivation of the spleen. That
persons with functional spleens were subject to infection with B. microti
was finally established by the so-called Nantucket outbreak (4) and
subsequent publications.

Therefore, Wilson and Chowning's work reports several cases of simultaneous
infections of humans by two tickborne pathogens; i.e., patients had spotted
fever and B. microti in the blood. More poignant was that an "emerging"
disease of humans was missed and not discovered again for some 70 years.

Alexander J. Sulzer
Fellow, American Academy of Microbiology; Fellow, emeritus, Royal Society
of Tropical Medicine and Hygiene; Member, emeritus, American Society of
Tropical Medicine and Hygiene

References

  1. Sexton DJ, Corey GR, Carpenter C, Kong LQ, Gandhi T, Breitschwerdt E,
     et al. Dual infection with Ehrlichia chaffeensis and a spotted fever
     group rickettsia: a case report. Emerg Infect Dis 1998;4:311-6.
  2. Ricketts HT. Some aspects of Rocky Mountain spotted fever. Rev Infect
     Dis 1909;1227-40.
  3. Wilson LB, Chowning WM. Studies on Pyroplasma hominis. Rev Infect Dis
     1904;1:31-57.
  4. Ruebush TK, Juranek DD, Chisholm ES, Snow PC, Healy GR, Sulzer AJ.
     Human babesiosis on Nantucket Island. N Engl J Med 1977;297:825-87.

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Dual Infection with Ehrlichia chaffeensis and a Spotted Fever Group
Rickettsia: A Case ReportReply to Dr. Sulzer

To the Editor: Several investigators have suggested that some of Wilson and
Chowning's patients may have had coinfection with Babesia and Rickettsia
rickettsii (1-4). Furthermore, the organisms that Wilson and Chowning
observed in red cells of 20% of the local Columbian ground squirrels are
consistent with later reports of various species of Babesia in the
erythrocytes of other species of squirrels (4). However, most
rickettsiologists who have commented on Wilson and Chowning's paper have
concluded that intraerythrocytic organisms observed in blood samples did
not contribute substantially to the illnesses of the 23 patients described.
Although Stiles, Wenyon, and Brumpt concluded that the organisms in human
blood samples observed by Wilson and Chowning were artifacts or malarial
parasites (5-7), contemporary experts who have reviewed the colored plates
that accompanied Wilson and Chowning's 1904 paper believe that there is
"little" or "no doubt" that Wilson and Chowning actually described
organisms of the genus Babesia (1,2,8).

In a commentary that followed the republication of Wilson and Chowning's
landmark paper in 1979 (9), Richard Ormsbee reviewed the sequence of events
that followed the publication of Wilson and Chowning's report in 1904 (10).
After more than 200 hours of careful microscopy, C.W. Stiles could find no
evidence of Pyroplasma in the blood of 12 patients with Rocky Mountain
spotted fever (RMSF). He refuted Wilson and Chowning's findings (5) and
challenged Chowning, who was also in the Bitter Root Valley, to demonstrate
the presence of organisms in the blood of a person with a typical case of
RMSF. Chowning was unable to find Pyroplasma in blood smears from these
patients (10). Ricketts did not arrive in the Bitter Root Valley to begin
his studies of RMSF until 1906 (11); thus he could not have published his
classic paper on the etiology of RMSF in volume 1 of the Journal of
Infectious Diseases.

To our knowledge, ecologic studies done in the Bitter Root Valley have not
demonstrated endemic foci of babesial infection. A serologic survey of 246
Bitter Root Valley residents in 1978 showed no antibabesial antibodies
(12). Although it is possible that 4 of the 23 patients with RMSF described
by Wilson and Chowning had incidental preexisting latent babesial
infection, the clinical and autopsy data they presented suggest that the
patients had typical R. rickettsii infection. There is no proof that any of
the patients described by Wilson and Chowning had simultaneous acute
babesial and rickettsial infection, and we agree with Ormsbee that the
significance of the "Pyroplasma hominis" described in the blood smears of
several of Wilson and Chowning's patients is "... a mystery that persists
to this day" (10).

Daniel J. Sexton* and David H. Walker
Duke University Medical Center, Durham, North Carolina, USA; and University
of Texas Medical Branch at Galveston, Galveston, Texas, USA

References

  1. Gorenflot A, Mourbri K, Precigout E, Carcy B. Human babesiosis. Ann
     Trop Med Paristol 1998;92:489-501.
  2. Hoare CA. Comparative aspects of human babesiosis. Trans R Soc Trop
     Med Hyg 1980;74:143-8.
  3. Ruebush TK II, Cassaday PB, Marsh HJ, Lisker SA, Voorhers D, Mahoney
     EB, et al. Human babesiosis on Nantucket Island. Clinical features.
     Ann Intern Med 1977;86:6-9.
  4. Pinsky RL, Lutwick LI. Spotted fever and babesiosis. Rev Infect Dis
     1979:1:895.
  5. Stiles CW. A zoological investigation into the cause, transmission,
     and source of Rocky Mountain "spotted fever." Hygienic Laboratory
     Bulletin . Washington: Government Printing Office; 1905. Publication
     No 20:7-119.
  6. Wenyon CM. Protozoology. Vol 2. London: W. Wood; 1926.
  7. Brumpt E. Precis de parasitologie. 5th ed. Paris: Masson et Cie; 1936.
     p. 497.
  8. Pruthi RK, Marshall WF, Wiltsie JC, Persing DH. Human babesiosis. Mayo
     Clin Proc 1995:70:853-62.
  9. Wilson LB, Chowning WM. Studies in Pyroplasmosis hominis (`spotted
     fever" or "tick fever of the Rocky Mountains). Rev Infect Dis
     1979;1:540-58.
 10. Ormsbee RA. Studies in Pyroplasmosis hominis ("spotted fever" or "tick
     fever" of the Rocky Mountains) by Louis B. Wilson and William A.
     Chowning. Rev Infect Dis 1979;1:559-62.
 11. Harden VA. Rocky Mountain spotted fever research and the development
     of the insect vector theory, 1900-1930. Bull Hist Med 1985;59:449-66.
 12. Chisholm ES, Ruebush TK II, Sulzer AJ, Healy GR. Babesia microti
     infection in man: evaluation of an indirect immunofluorescent antibody
     test. Am J Trop Med Hyg 1978:27:14-9.

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Reemergence of Plasmodium vivax Malaria in the Republic of Korea

To the Editor: In "Reemergence of Plasmodium vivax malaria in the Republic
of Korea" (1), the term eradication was, in my judgment, inappropriately
used. In 1981, Yekutiel proposed that eradication is "The purposeful
reduction of specific disease prevalence to the point of continued absence
of transmission within a specified area by means of a time limited
campaign" (2). In 1984, Hinman proposed an important addition that
eradication must have followed a "deliberate effort" (3). At the Dahlem
Workshop in 1997 (4), a more comprehensive definition was proposed. This
definition states that eradication is "Permanent reduction to zero of the
worldwide incidence of infection caused by a specific agent as a result of
deliberate efforts; intervention measures are no longer needed" (4). At the
same conference, two other terms were also defined. Elimination of disease:
"Reduction to zero of the incidence of a specified disease in a defined
geographic area as a result of deliberate efforts; continued intervention
measures are required." Elimination of infection: "Reduction to zero of the
incidence of infection caused by a specific agent in a defined geographic
area as a result of deliberate efforts; continued measures to prevent
reestablishment of transmission are required."

These definitions promote unanimity in using the term eradication and avoid
misconceptions over accomplishments.

Philip S. Brachman
The Rollins School of Public Health of Emory University, Atlanta, Georgia,
USA

References

  1. Feighner BH, Pak SI, Novakoski WL, Kelsey LL, Strickman D. Reemergence
     of Plasmodium vivax malaria in the Republic of Korea. Emerg Infect Dis
     1998;2:295-7.
  2. Yekutiel P. Lessons from the big eradication campaigns. World Health
     Forum 1981;2:465-81.
  3. Himnan AR. Prospects for disease eradication or elimination. New York
     State General Medicine 1984;84:502-6.
  4. Ottesen EA, Dowdle WR, Fenner F, Habermehl KO, John TJ, Koch MA et al.
     In: Eradication of infectious diseases. Dowdle WR, Hopkins DR,
     editors. New York: John Wiley and Sons; 1997. p. 48.

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Paratyphoid Fever

To the Editor: The letter on paratyphoid fever by Kapil et al. (1) stated
that an outbreak of enteric fever due to Salmonella paratyphi A has never
been reported. A large (227 cases) outbreak of enteric fever secondary to
S. paratyphi A occurred in the Arabian Gulf nation of Bahrain in 1987. The
clinical and epidemiologic details of the outbreak were reported in a local
medical society journal (2). Like the outbreak described by Kapil et al.,
the Bahraini outbreak was associated with sewage leaking into the water
supply.

Mark R. Wallace
Naval Medical Center San Diego, San Diego, California, USA

References

  1. Kapil A, Sood S, Reddaiah VP, Das B, Seth P. Parayphoid fever due to
     Salmonella enterica serotype paratyphi A. [Lett]. Emerg Infect Dis
     1997;3:407.
  2. Al-Madani R. Paratyphoid Outbreak in children. Journal of the Bahrain
     Medical Society 1989;1:60-3.

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Hospitalizations After the Persian Gulf War

To the Editor: Knoke et al., Naval Health Research Center, San Diego,
California, published two articles on military hospitalizations in Persian
Gulf War veterans, the most recent in Emerging Infectious Diseases (1,2).

Although the titles of both articles indicated general hospitalizations,
Knoke et al. studied just military hospitalizations among selected, mostly
healthy, active-duty Persian Gulf War veterans enlisted as of 1994. They
compared military hospitalizations of active-duty Gulf War veterans (cases)
with military hospitalizations of active-duty era veterans not in the
Persian Gulf between 1990 and 1991 (controls). "Healthy warrior" effects
would have predicted low military hospitalization rates for both cases and
control populations (3), but both were high.

The studies were "restricted to active-duty personnel" hospitalized in
military facilities because active-duty personnel were "rarely hospitalized
outside of DoD facilities" (1). However, of 150 surgical procedures, mostly
intestinal and skin biopsies, performed on 85 sick active-duty and
reservist Persian Gulf veterans from Pennsylvania between 1991 and 1995,
more than one third, 58 (39%), were performed in private facilities (4).
Most of the federal procedures were done in Veterans Administration (VA),
not military, hospitals. Many active-duty, sick Persian Gulf veterans in
Pennsylvania, Texas, and California deliberately avoided military, and some
VA, hospitals between 1991 and 1997 because of concerns about competence,
convenience, confidentiality, and career opportunities during this era of
downsizing and closing of military bases (3,5).

In addition, Knoke et al. excluded at least five groups of sick veterans
from their limited case studies: 1) those treated in VA and private
hospitals, 2) those from the Reserves and National Guard, 3) those who
retired early largely because of illness, 4) those who consented to long
military hospitalizations within the DoD Comprehensive Clinical Evaluation
Program (CCEP) for Gulf War Veterans, and 5) those who had obstetric
complications after returning home from the Gulf War. Thus, many sick
veterans were excluded from the case studies.

If we hypothesize that one or more new infectious agents like Leishmania
tropica, Brucella species, Bacillus anthracis, Mycoplasma fermentens
(incognitus), Coxiella burnetti, or obscure fungi or molds might be
involved, comprehensive research studies in the future would do better to
include all workers from the Arabian desert, reservists as well as
active-duty personnel.

Few Gulf veterans with Gulf-related illnesses were welcomed by military
hospitals and about half of 452 Persian Gulf veterans surveyed by the U.S.
General Accounting Office sought health care outside the VA for health
problems they believed were related to service in the Persian Gulf (5). An
alternative interpretation of Knoke's hospitalization study might be that
admitting officers in military facilities prevented sick Persian Gulf War
veterans from obtaining medical care within their facilities.

Not only were the case populations studied unusual; recent workers and
travelers to the Middle East were not excluded from the control population.
"Nondeployed" controls included recently deployed Persian Gulf military
personnel as long as nondeployed personnel worked in the Gulf after 1991.
Some of those late-deployed Persian Gulf workers also fell ill with the
same illnesses as veterans deployed between August 1990 and 1991. Illnesses
from late Persian Gulf deployments might explain excess hospitalizations
seen in nondeployed controls. All late-deployed personnel from the Middle
East should also have been excluded from the nondeployed control
population.

Finally, medical ICD-9 diagnoses, while interesting, were incomplete and
nonspecific. Medical diagnoses common to Gulf veterans should have been
listed in addition to unexplained illnesses. Knoke's condensed diagnostic
list, like patient charts we have seen from DoD hospitalizations, may have
failed to capture common clinical and laboratory abnormalities seen in many
sick Gulf veterans, including (but are not limited to) ulcerative colitis,
Crohn colitis, inflammatory bowel disease, intestinal bleeding due to
inflammatory colonic polyps, skin acne, nodules, plaques, psoriasiform skin
rashes, nose ulcers, nose bleeds, leukocytosis, neutropenia, elevated
alanine transaminase (SGPT/ALT) liver enzymes, hepatosplenomegaly,
thrombocytopenia, nephrolithiasis (kidney stones), and fevers of unknown
origin (4,6). In addition, more than one unexplained illness category
should have been tabulated per patient, because "Gulf War Syndrome" is a
multisystem illness (4,6-9).

More research is needed on hospitalizations in addition to deaths and new
diseases found in Persian Gulf War veterans (3). Civilian scientists and
physicians must collaborate closely with other diverse federal and
nonprofit organizations to study Gulf War illnesses objectively (5,9). The
health problems seen in Gulf War veterans may be part of a new complex of
emerging desert-associated illnesses (9-14).

Katherine Murray Leisure,* Nancy L. Nicolson, and Garth L. Nicolson
*Infectious Diseases, Travel Medicine, Lebanon, Pennsylvania, USA; and
Institute for Molecular Medicine, Huntington Beach, California, USA

References

  1. Gray GC, Coate BD, Anderson CM, Kang HK, Berg SW, Wignall RS, et al.
     The postwar hospitalization experience of U.S. Persian Gulf War
     veterans compared with other veterans of the same era. N Engl J Med
     1996;335:1505-13.
  2. Knoke JD, Gray GC. Hospitalizations for unexplained illnesses among
     U.S. veterans of the Persian Gulf War. Emerg Infect Dis 1998;4:211-19.
  3. Haley RW. Bias from the "healthy warrior effect" and unequal follow-up
     in three government studies of health effects of the Gulf War. Am J
     Epidemiol 1998;148:315-23.
  4. Murray-Leisure KA, Sees J, Zangwill B, Suguitan E, Legaspi C, Bagheri
     S, Mucha P, Brinser E, Kimber R, Kurban R, Greene W.
     Mucocutaneous-intestinal-rheumatic Desert Syndrome (MIRDS): Incubation
     & histopathology findings. Abstract K 48, American Society for
     Microbiology, ICAAC, Sept. 18, 1995.
  5. U.S. General Accounting Office. Gulf War Illnesses: Improved
     Monitoring of Clinical Progress and Reexamination of Research Emphasis
     are Needed. GAO/NSIAD-97-163. June 1997.
  6. Sostek MB, Jackson S, Linevsky JK, Schimmel EM, Fincke BG. High
     prevalence of chronic gastrointestinal syndromes in a National Guard
     unit of Persian Gulf Veterans. Am J Gastroenterol 1996;91:2494-7.
  7. Centers for Disease Control. Unexplained illness among Persian Gulf
     War veterans in an Air National Guard unit: Preliminary report, Aug
     1990-March 1995. MMWR Morb Mortal Wkly Rep 1995;44:443-7
  8. Fukada K, Nisenbaum R, Stewart G, Thompson WW, Robin L, Washko R, et
     al. Chronic multisystem illnesses affecting Air Force veterans of the
     Gulf War. JAMA 1998;280:981-8.
  9. Nicolson G, Nicolson N. Gulf War illnesses. Medicine, Conflict, and
     Survival 1998;14:156-65.
 10. Magill AJ, Grogl M, Gasser RA, Wellington S, Oster CN. Viscerotropic
     leishmaniasis caused by Leishmania tropica in soldiers returning from
     Operation Desert Storm. N Engl J Med 1993;328:1383-7.
 11. Magill AJ, Grogl M, Johnson SC, Gasser RA. Visceral infection due to
     Leishmania tropica in a veteran of Operation Desert Storm who
     presented two years after leaving Saudi Arabia. Clin Infect Dis
     1994;19:805-6.
 12. Ferrante MA, Dolan MJ. Q Fever meningoencephalitis in a soldier
     returning from the Persian Gulf War. Clin Infect Dis 1993;16:489-96.
 13. Seaman J, Mercer AJ, Sondorp E. Epidemic of visceral Leishmaniasis in
     western upper Nile, southern Sudan: Course and impact from 1984 to
     1994. Int J Epidemiol 1996;25:862-71.
 14. Zilinskas RA. Iraq's biological weapons. JAMA 1997;278:418-24.

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Hospitalizations after the Gulf WarReply to K.M. Leisure et al.

To the Editor: We studied all active-duty Persian Gulf Warera veterans who
remained on active duty at the conclusion of deployment (July 31, 1991),
not as Leisure et al. stated in their letter "selected, mostly healthy,
active-duty Persian Gulf War veterans enlisted as of 1994."

Our study was restricted to hospitalizations of active-duty service members
because these were the only service members whose records were available on
computerized files. No one was excluded from the defined target population.
However, there are "sick Gulf War veterans" and healthy Gulf War veterans
not in the target population. The difficulty is in studying either a random
sample or the entire population of Gulf War veterans. The only published
study we know of the entire population is the mortality report of Kang and
Bullman (1).

The suggestion that we should have excluded from the control group service
members who had ever been in the Gulf War area would have been appropriate
for a report of exposure to the Persian Gulf region; ours was a report of
exposure to the Persian Gulf War. That we should have studied a different
collection of ICD-9 diagnoses also suggests a different report.

While our study may have limitations, we have not seen objective data that
support the anecdotal observations of Leisure et al.

James D. Knoke and Gregory C. Gray
Naval Health Research Center, Sand Diego, California, USA

Reference

  1. Kang HK, Bullman TA. Mortality among U.S. veterans of the Persian Gulf
     War. N Engl J Med 1996;335:1498-504.



Emerging Infectious Diseases
National Center for Infectious Diseases
Centers for Disease Control and Prevention
Atlanta, GA

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