# Presentation: 682727

## Ongoing Research and Outreach Efforts Targeted at Non-O157 STEC

**Ongoing Research and Outreach Efforts Targeted at Non-O157 STEC**

**Hussein S. Hussein, PhD**

## Introduction

**Since the first *****E. coli***** O157:H7 outbreak in 1982, research efforts in the U.S. and in other countries have been devoted to increase our understanding of:**
**	****	****- its prevalence in ****cattle****, ****beef****, and other foods ****	****	****	****(e.g., ****fresh leafy vegetables****)**
**	****	****- its infection to humans**
**	****	****- its pathogenic factors**
**	****	****- possible identifications of pre- and post-harvest control ****	****	****measures to reduce its prevalence in cattle and ****	****	****infection to humans**

## Introduction

**Non-O157 STEC outbreaks started to emerge:**
**	****- ****Argentina**** (1982 – 1991)**
**	****	****- 433 cases (****ground beef****)**
**	****	****- O1, O2, O15, O25, O75, and O111**
**  **
**	****- ****Italy**** (1992)**
**	****	****- 9 cases (****ground beef****)**
**	****	****- O111:H****–**
**  **
**	****- ****Canada**** (1992)**
**	****	****- 6 cases (****raw milk****)**
**	****	****- O80:H****–****, O91:H14, O103:H2, O119:H25, O132:H****–****, and ****	****	****O146:H21**
**	**

## Introduction

**Non-O157 STEC outbreaks started to emerge:**
**	****- ****U.S.**** (MT; 1994) **
**	****	****- 4 cases (****raw milk****)**
**	****	****- O104:H21**
**  **
**	****- ****Australia**** (1994 – 1995)**
**	****	****- 161 cases (****beef sausage****)**
**	****	****- O111:H7, O111:H****–****, O157:H****–****, and O160:HUT  **
**	****- ****Germany ****(2000)**
**	****	****- 6 cases (****beef sausage****)**
**	****	****- O26:H11****	**
**	**

## Introduction

**Pathogenic STEC produce one or more ****virulence factors****:**
**	****- Shiga toxin 1 (****Stx1****)**
**	****- Shiga toxin 2 (****Stx2****)**
**	****- ****α****-hemolysin (****HlyA****)**
**	****- EHEC-hemolysin (****EHEC-HlyA****)**
**	****- Intimin**
**These virulence factors are encoded by ****various genes****:**
**	****- *****stx*****1**
**	****- *****stx*****2****, **
**	****- *****hly*****A **
**	****- EHEC-*****hly*****A **
**	****- *****eae***

## Introduction

***Cattle as a Reservoir of STEC***
**STEC strains are not host specific**
**STEC have been shown to be more prevalent in cattle than in other animals**
**STEC infection in humans has been traced, in most cases, to cattle,  their products (especially beef), and vegetables or water contaminated with cattle feces  **
**Non-O157 STEC prevalence in beef cattle:****  up to ****70.1****%**
**STEC strains belonged to ****341**** serotypes**
**~ ****36****% of these serotypes are pathogenic**
**Non-O157 STEC prevalence in dairy cattle****:  up to ****74.0****%**
**STEC strains belonged to ****152**** serotypes**
**~ ****49****% of these serotypes are pathogenic**

## Our Research

***University of Nevada, Reno ******	******            University of California, Davis***
**Hussein S. Hussein, PhD ****	****	****Edward R. Atwill, DVM, PhD**
**Mark R. Hall, PhD****	****	****	****      ****- Owners/managers of farms,**
**	****- Laurie M. Bollinger****	****	****                            ranches, feedlots, and dairy**
**	****- Toshie Sakuma****	****	****	****            operations**
**	****- My Truong****	****	****	****	****        - USDA veterinary medical**
**	****- Michelle Kelly****	****	****	****            officers**
**	****	****	****	****	****	****        ****- Cooperative extension farm**
**	****	****	****	****	****	****             ****advisors **
**Funded by **
**the Integrated Research, Education, and Extension Competitive Grants Program — National Integrated Food Safety Initiative (****grant No. 2001- 51110-11463****) **
**of the USDA Cooperative State Research Education,**
**and Extension Service**

## Objectives

***Main Objective***
***  ***
**To identify on-farm factors that influence prevalence of O157 and non-O157 STEC in cattle**
***Specific Objectives***
**1) To assess prevalence, human health risks, and pre-harvest control measures of STEC in beef and dairy cattle in various production systems in *****Nevada****** *****and***** ******California***** over 1 year**
**2) To integrate the knowledge gained from achieving the first objective and from published reports on pre-harvest control measures into an education program on food safety with emphasis on developing ****pre-harvest control**** strategies to assure**** ****beef safety**

## Methods & Results

***Nevada***
**Small size operations (~ ****100**** cattle tested per ranch)**
**Dairy heifers, beef heifers (pasture), beef heifers (range), and culled beef cows**
**STEC prevalence rates ranged from ****4.0**** to ****22.7****%**
***Serotypes***
**	****O6:H49, ****O6:H****–****, ****O8:H****–****, ****O26:H****–****, O39:H****–****, O105:H****–****, ****O113:H****–****, O116:H****–****, ****O118:H****–****, O138:H****–****, ****O141:H****–****, ****O157:H7****, and ****OUT:HUT**
**HUS**
**Other illnesses**

## Methods & Results

***California***
**Larger-scale operations ranging in size from ****13,000**** to ****46,000**** cattle for feedlots, from ****38**** to ****1,300**** cows on pasture, from ****65**** to ****225**** cows on the range, and an average herd size of ****713**** cows and heifers for dairy farms**
**Prevalence rates ranged  from ****1.9**** to ****4.3****% in feedlot cattle         (*****n = 642*****), from ****1.9**** to ****5.0****% in cattle grazing irrigated pastures    (*****n = 638*****), from ****0.7**** to ****18.6****% in those grazing rangeland forages (*****n = 774*****), and from ****0.8**** to ****3.2****% in dairy cattle (*****n = 1,268*****)**
***Serotypes***
**	****The STEC isolates from beef cattle in the feedlot, beef cattle on pasture, beef cattle on the range, and dairy cattle belonged to ****14****, ****13****, ****35****, and ****16**** serotypes, respectively**

## Results

***California***
***Serotypes - Beef cattle in the feedlot***
**	****O86:H19, O114:H2, O125:H19, O127:H19, O136:H12, O136:H****–****, O153:H****–****, ****O157:H7****, O165:H7, OUT:H5, ****OUT:H12****, OUT:H20, ****OUT:H****–****, and ****OUT:HUT**
** **
***Serotype - Beef cattle on pasture***
**	****O1:H2****, ****O5:H16****, ****O5:H****–****, ****O26:H8****, ****O26:H11****, ****O84:H****–****, ****O103:HUT****, ****O111:H8****, O125:H2, O125:H19, O137:H16, ****O157:H7****, and O169:H19**
** **
***Serotype - Beef cattle on the range***
**	****O1:H2****, ****O5:H****–****, ****O26:H11****, O39:H****–****, ****O84:H2****, ****O84:H****–****, O86:H2, O96:H19, O111:H16, ****O111:H****–****, O116:H2, O116:H36, O125:H2, O125:H16, O125:H19, O125:H27, O125:H28, O125:H****–****, O127:H2, O127:H19, O127:H28, ****O128:H2****, O128:H16, O128:H20, ****O146:H21****, ****O157:H7****, O158:H16, O158:H19, O158:H28, O166:H2, O166:H6, O166:H20, ****OUT:H2****, ****OUT:H19****, and ****OUT:H****–**
** **
***Serotypes - Dairy cattle***** **
**	****O15:H****–****, O116:H****–****, O125:H20, O127:H19, O128:H20, O136:H2, O136:H10, O136:H12, O136:H19, O136:HUT, ****O157:H7****, O166:H6, OX13:H19, OX13:H20, ****OUT:H7****, and ****OUT:H****–**

## Results

***California***
**Of the ****161**** STEC isolates:**
**	****27**** O157 **
**	****134**** non-O157**
**	****83.2****% non-O157 STEC**
***Pathogenicity of the non-O157 isolates*****	****	****	****	**
**	****- All lethal to Vero cells **
**	****- 78 had and expressed only *****stx*****1**
**	****- 16 had and expressed only *****stx*****2**
**	****- 40 had *****stx*****1**** and *****stx*****2**** **
**	****	****- 3 expressed only *****stx*****1**
**	****	****- 2 expressed only *****stx*****2**
** ****	****	****- 35 express both *****stx*****1**** and *****stx*****2**** **
**	****- 10 had and expressed *****hly*****A**
**	****- 84 had EHEC-*****hly*****A but only 56 expressed it **
**	****- 53 had *****eae***

## Results

**Because STEC strains lacking the attaching and effacing gene or the hemolysin genes have been shown to cause human illnesses ****(Neill, 1997)****, it was suggested that these genes are not absolutely required for pathogenicity and each STEC strain should be considered a potential EHEC ****(Bürk et al., 2002)****. **

## Results

***California***
*29**** *****Serotypes – Not reported previously in cattle or their products**** ****O86:H2, O86:H19, O114:H2, O116:H2, O116:H36, O125:H2, O125:H16, O125:H19, O125:H20, O125:H27, O125:H28, O125:H****–****, O127:H2, O127:H19, O127:H28, O128:H16, O128:H20, O136:H10, O136:H19, O137:H16, O158:H19, O158:H28, O166:H2, O166:H6, O166:H20, O169:H19, OX13:H19, OX13:H20, and OUT:H20**

## Results

***Examples of the on-farm factors tested:***
**Season, water (e.g., source, location, and cleanliness), animal factors (e.g., sex, age, source, parity, stage of lactation, and health), pen size, body weight, shelter type, manure handling, dietary factors (e.g., diet composition, feed ingredients, bunk type, location, and cleanliness)**
**  **
***Factors with high potential to decrease STEC prevalence:***
**Dairy**
**	****Feeding soybean meal as the protein supplement**
**  **
**Feedlot**
**	****Maintaining heavier cattle, clean feed bunks, and increasing dietary forage from 10 to 15%**

## Results

***Factors with high potential to decrease STEC prevalence:***
**Irrigated pasture**
**	****Offering running drinking water (streams or springs versus ponds or ditches) and shortening the calving season (≤ 2 months)**
**  **
**Range**
**Animal factors**
**	****Decreasing stock density (≤ 1 cow/acre), early separation of calves (≤ 6 mo), increasing the size of calving pasture (> 120 acres), and absence of diarrheic calves (2 to 4 mo) prior to fecal sampling  **
**Dietary factor**
**	****Molasses supplementation to pregnant cows ****	**

## Outreach

***Our past and current efforts:***
**The prevalence and pre-harvest control data from our studies have been incorporated into:**
**	****1) outreach publications such as:**
**	****	****- The annual extension proceedings (Cattlemen’s Update) ****	****   ****	****	****published by the University of Nevada-Reno **
**	****	****- Other miscellaneous publications**
**	****2) Presentation to farmers, ranchers, farm advisors, and extension ****	****specialists by Dr. Atwill (Extension Veterinarian)**
** **
***Our future efforts:***** ****	**
**	****With new funding, we plan to establish a food safety website focusing on STEC to provide a continuously updated database on STEC prevalence in U.S. cattle, pathogenicity of the isolates, and pre- and post-harvest control measures with high potential to decrease cattle carriage and contamination of their edible products with these foodborne pathogens**

## Questions

**Questions**