The Way to a Safer Rare or Medium Rare Steak: Vaccination of the Cows against E. Coli
Zoonoses are animal diseases or infections that can be transmitted to humans directly from the animal, or indirectly, through the environment. They may be bacterial, viral, parasitic or may involve unconventional agents (World Health Organisation). Some of the most known zoonoses are: Anthrax, Brucellosis, Cat Scratch Fever, Leptospirosis, Listeriosis, Mycobacterium infectious (non-tuberculosis), Psittacosis, Salmonellosis (Gastroenteritis), Streptococcus suis, Tuberculosis, Escherichia coli O157 (E coli O157).
According to the Royal Veterinary College at the University of London, the risk of getting one of the most common of these diseases- Escherichia coli, can be reduced by 85% through the process of vaccinating the cattle against E. coli bacteria.
Escherichia coli (E. Coli) is a rod-shaped bacterium commonly found in the lower intestine of warm-blooded organisms (endotherms). Even if most of the E. coli strains are harmless, some E coli types, like E coli O157 can cause serious food poisoning in humans. The symptoms of the infection with the E coli O157 baterium include severe fatigue, fever, abdominal cramps, bloody diarrhea, nausea, vomiting. Untreated, the worst type of E. coli causes kidney failure and even death. These problems are most likely to occur in children and in adults with weak immune systems.
Cattle have been implicated as the most important source of E. coli O157:H7. The infection spreads by consuming contaminated food or water and most often ground beef. The British researchers from the Royal Veterinary College at the University of London observed that the risk of infection is particularly significant during the brief periods when cattle are “super-shedding” extremely large amounts of the bacteria in their feces.
“If the vaccine has an impact on these animals at that time, the risk to humans is disproportionately reduced.” said Stuart Reid, senior study author and a principal at the Royal Veterinary College. Previous researches have predicted that the vaccination of cattle could reduce E. coli risk by 50 percent. In the opinion of the British researchers, “those studies did not take into account the effect of vaccination on super-shedding”.
They also admitted that, to have the risk of E. coli infection reduced with 85% percents, it is necessary a governmental intervention. Farmers do not show too much interest in vaccinating their cattle, because the cows are not affected by this bacterium. The cow does not become healthier or more productive after the vaccine, so a government intervention is required for widespread vaccination to occur. The impact on the public health should be a motivation strong enough for any health institution to support and promote the cattle vaccination against E coli.
Anyway, an E.coli vaccine should not replace the hygiene measures for processing and cooking the beef and the dairies. The meat and the milk have to be processed at temperatures higher than 71 degrees Celsius.
Stuart Reid, principal, Royal Veterinary College, University of London; Sept. 16, 2013, Proceedings of the National Academy of Sciences;