With food safety becoming a top concern with consumers there is an increasing awareness about foodborne zoonotic diseases such as salmonella, campylobacter, E. coli and most recently listeria.
Every time there is a recall of meat or a disease outbreak caused by other sources such as contaminated water or vegetables it becomes a big media event. This erodes consumer confidence in our food supply, and increases the overall cost to our medical system. And when deaths are involved, the human cost in terms of the psychological, emotional and mental strain this places on families cannot be overstated.
Preventing any zoonotic disease requires a collective effort down the entire path of food production and preparation. With the release of a new E. coli vaccine in Canada and other preventive measures there is an opportunity to better control outbreaks of E. coli 0157:H7 in the future.
The new vaccine Econiche is made by Bioniche, a Canadian company. Canada is the first country in the world to have the vaccine available. Statistics tell us there are upwards of 100,000 human cases of E. coli poisoning in North America each year. Of these an average of five per cent develop Hemolytic Urologic Syndrome which can cause kidney failure and death. The syndrome primarily affects children, the elderly and anyone with compromised immune systems. The vaccine would be the most effective way to reduce the number of organisms present in cattle, the primary shedder.
We know that almost half of these human cases come from food sources other than meat. But when we check out the original source of contamination cattle are often singled out as the primary reservoir. Whether it is
E. coli getting into water sources from manure run-off, vegetables being contaminated through irrigation water or people exposed to cattle at fairs and shows, minimizing the level of infection at the source (cattle) will minimize the risk from these other routes of human infection as well.
Prevalence of E. coli 0157:H7 at the feedlot varies greatly over time but there is a definite increased risk in summer and fall. This corresponds to the greatest demand for ground beef during the North American barbecue season.
Vaccination reduces the shedding of the bacteria into the environment. A reduction of 60 per cent has a dramatic effect on the control of this organism all along the remainder of the food chain.
Infection levels vary widely within cattle populations. High-level or so-called super shedders make up only three per cent of the feedlot population. Some shed a million times more bacteria than other cattle, and represent the greatest risk of E. coli contamination in the remaining cattle population. Yet how do we identify them? They are as healthy as the rest of the cattle.
The use of chlorinated water, bacteriophages and probiotics help control the organisms, but vaccination provides the greatest reduction in fecal shedding. With the vaccine, you are hitting the problem at its very source, before the bacteria numbers get too high.
If we examine other potential management changes at the feedlot now and in the future several points come to mind. A lot of potential contamination at the feedlot comes in the form of tag so any measure to minimize tag is a benefit. Woodchips, sawdust and straw are all used mainly because of availability. In our area woodchips seem to result in the lowest amount of tag but this is an area that must be studied further. Larger feedlots have a greater concentration of cattle and often more limited manpower on a per-head basis for bedding etc.
Climatic conditions vary greatly year to year making control difficult. One research group developed an innovative way to test for the presence of E. coli 0157:H7 in pens of cattle that involves hanging short sections of rope on the feed bunk. Curious cattle lick the ropes which are then collected for culturing. If E. coli 0157:H7 is in the pen, it will show up on the ropes.
Further downstream at the packing plants and beyond several other preventive procedures work synergistically with vaccination. Packing plants already spend over $5 per animal on procedures like steam treating carcasses and cleaning based on a strict HACCP plan. These measures help prevent contamination with E. coli as well as other food source zoonotic diseases. The meat industry is looking at irradiation which is expensive and really only doable at very large plants, but also makes sense as it further ensures the meat is safe when leaving the plant.
The final responsibility for safe food lies directly with the consumer. It is everyone’s responsibility to fully cook their meat regardless of type or source. Washing vegetables thoroughly and keeping the food preparation area clean is simply good kitchen management. Proper food handling should be the last thing you do before putting food in your mouth.
What the future holds for E. coli vaccination is an ever evolving process. Will cattle exhibits and shows insist on vaccination? Will monitoring identify specific feedlots with higher levels of these organisms? Will these feedlots be forced to implement vaccination? During the barbecue season when the consumption of ground beef is peaking, will a premium be paid for cattle identified through our national identification program as “Econiche” vaccinated? Will cattle with lots of tag need to be vaccinated? Will the government help pay for the vaccine as a way to reduce overall health-care costs?
Vaccination together with all the other preventive steps mentioned will hopefully keep this dreaded disease to a minimum and keep consumer confidence in our beef as high as possible.
— Dr. Roy Lewis, DVM
Roy Lewis is a large animal veterinarian in practice at Westlock, Alta.