Subclinical infections lower resistance to colonization
We have always thought safe food comes from healthy animals, but "healthy" can mean different things.To many peo
ple, animals that do not show obvious signs of illness are "healthy." However, many studies have shown animals with no obvious signs of illness are affected with subclinical disease and develop lesions inside the body. I have examined my cattle after harvest and seen lesions of respiratory disease in nearly 40 percent, yet I had only treated 9 percent for pneumonia (and I thought I was doing pretty well!). Obviously, my "healthy" cattle were really not so healthy.
We have always thought safe food comes from healthy animals, but "healthy" can mean different things.To many peo
ple, animals that do not show obvious signs of illness are "healthy." However, many studies have shown animals with no obvious signs of illness are affected with subclinical disease and develop lesions inside the body. I have examined my cattle after harvest and seen lesions of respiratory disease in nearly 40 percent, yet I had only treated 9 percent for pneumonia (and I thought I was doing pretty well!). Obviously, my "healthy" cattle were really not so healthy.Recent work from Iowa State has shown pigs examined after harvest that had lesions indicative of pneumonia had a greater level of contamination with Campylobacter - an important food-borne pathogen in people.Pneumonia in pigs is not caused by Campylobacter coli, but, apparently, the meat from animals affected with respiratory disease had an increased chance of Campylobacter contamination. Perhaps the disease lowered resistance to colonization by these organisms, or maybe the lesions make it easier for meat to become contaminated at harvest. It is not clear how or why this is, but it does seem contamination and food safety are linked to animal health.
Some recent mathematical modeling has built on this idea and suggested the possibility that antibiotic use in animals may actually improve food safety by improving animal health. This is all very new and is not understood but is interesting to think about.
While we hear much worry in the news about antibiotic use in livestock and many feel antibiotic use in animals should be curtailed (some want them eliminated), they may, in fact, result in a net benefit to public health by decreased food contamination.
The bottom line is safe food comes from healthy animals. While prevention of all disease is the ultimate goal, the fact is, some animals will get sick and need treatment. It may be that effective antibiotic treatment, in addition to improving the welfare of the animal and decreasing stress, may decrease contamination of the meat and thereby improve food safety.This is something we are learning about through our research. People lots smarter than me are working hard right now to figure this out, so we will stay tuned.
Source of Article: http://www.clarionledger.com/
Aporte: Guillermo Figueroa
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