E. coli and farmers

[js_dukelow@ccmail.pnl.gov (James S Jr Dukelow)]

On Wed, 17 Dec 1997 Mike Krzesniak wrote:

A question came up from a colleag who has some cows.  How long can 
the bacteria live outside an animal, in feces etc. ?   Why aren't 
farmers with livestock sick all the time?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I have not had a change to dig into my E. coli file and I don't know the 
answer to the first question offhand.  Regarding the second question, roughly 
three months ago I was asked the same question by another subscriber to the 
FOODSAFE mailing list:

> Your argument about possibly cross-contamination by handling raw meat is 
> more well-founded, since certain lots are known to be contaminated with 
> the virulent pathogen. However, this would be more of an OSHA concern to 
> the workers in the cook operation, rather than to the consumer of the 
> cooked product. By the way, have you never wondered why continuous 
> epidemics of E. coli O157:H7 are not observed in farmers and meat 
> packing and processing workers and their families? 

I responded:

This is more than an OSHA issue, since the cross-contaminated food may 
be eaten uncooked.  Regarding epidemics in farmers and meat processing 
workers: Since E. coli infection often tends to be sub-clinical, I would 
expect, and some evidence suggests, that most farmers and meat 
processing workers and their families have been exposed and have 
developed immunity.  

See D. Reymond et al., Neutralizing antibodies to Escherichia coli 
Verotoxin 1 and antibodies to O157 lipopolysaccharide in healthy farm 
family members and urban residents, J. of Clinical Microbiology, v.34, 
pp. 2053-2057  and  J.B. Wilson et al., Vero cytotoxigenic Escherichia 
coli infection in dairy farm families, J. of Infectuous Diseases, v.174, 
pp.1021-1027.  Our library doesn't have either of these journals, but I 
was able to get an abstract of Reymond et al. from Medline.  Reymond et 
al. found that farm family members were almost three times as likely to 
have antibodies to O157 lipopolysaccharide (12.5% vs. 4.7%, p < 0.01) as 
urban controls and dairy farm family members were almost six times as 
likely to have antibodies to verotoxin 1 (42.0% vs. 7.7%, p < 0.001) as 
the urban controls. 

In addition to my FOODSAFE posting, there is the following new item.  
U.S. New & World Report had a cover story around Thanksgiving on food 
safety and/or emerging diseases that featured a New England farm family, 
almost all of who caught the "hot", antibiotic-resistant strain DT104 of 
Salmonella from their dairy herd.  The wife almost died.  DT104 showed 
up about a decade ago in the UK and Europe, but has become quite 
prevalent in the U.S. in the last few years.

Best regards.

Jim Dukelow
Pacific Northwest National Laboratory
Richland, WA

js_dukelow@pnl.gov

The thoughts are mine and have not been reviewed and/or approved by my 
management or by the U.S. Department of Energy.