Producer costs | E. coli vaccine can reduce risk, but industry has yet to adopt it in a significant way
LINDELL BEACH, B.C. — Three-year-old Rachel Peck was thrilled to visit the petting zoo at a major Canadian agricultural exhibition in 2010, where she and her sister fed the calves and petted other baby animals.
However, her parents had no idea of the ordeal their daughter was about to face following that visit.
Rachel had diarrhea within 24 hours. Two days later it was bloody.
The family from Frankford, Ont., took her to the local hospital, where Rachel was rushed to the Hospital for Sick Children in Toronto.
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A stool sample tested positive for E. coli O157:H7, a toxic bacteria found in the intestinal tract of cattle.
Rachel was diagnosed with infectious colitis. She was discharged from hospital, but her anxious parents were given a list of symptoms in case the infection became worse and Rachel developed haemolytic uremic syndrome (HUS), a condition characterized by the breakdown of red blood cells and kidney failure.
Rachel’s urine darkened within 24 hours as her kidneys began to fail. She was airlifted back to Toronto where, over the next several weeks, she received four blood transfusions, an albumin transfusion, an injection to promote the formation of red blood cells in the bone marrow, four antibiotics and physiotherapy to help her walk again.
The strain of E. coli that infected Rachel is the most dangerous of the bacteria group. Hundreds of other E. coli strains are harmless and serve as digestive aids helping gut flora to break down food.
Numerous studies have shown that beef and dairy cattle are the primary reservoirs of E. coli O157:H7, but it is also found in sheep, goats and deer. The animals are not affected by it.
However, the animals can pass the bacteria to humans where they can cause a cascade of symptoms from several days of diarrhea to, in eight to 10 percent of cases, the extreme conditions of HUS.
“The weird thing about this disease is that in cattle it is an asymptomatic infection, meaning they are infected but they have no symptoms, no illness,” said Rick Culbert, president, Bioniche Food Safety, a division of Bioniche Life Sciences Inc. in Belleville, Ont.
“They are not supposed to have these bacteria. They are just a carrier and a vaccine is of no benefit to the health of the cattle or the productivity of the cattle.”
The bacteria live in cattle’s intestines but can contaminate the hide when shed in feces and then spread in the environment. Hide removal and dissection at the packing plant may contaminate meat destined for consumers.
Vaccines exist to reduce E coli levels, but they are of no direct benefit to the animal. As a result, few cattle producers administer them, viewing it as an unnecessary overhead.
“Less than five percent of the market share of farmers use a vaccine to protect against E. coli,” said Culbert.
However, vaccines can significantly control the level of E. coli shedding. A recent study by Kansas State University showed two doses of a commercial vaccine that normally recommends three doses could reduce E. coli levels by more than 50 percent.
The researchers studied 17,000 cattle in a commercial feedlot over 85 days and used a commercial, three-dose SRP vaccine and a low-dose, direct-fed microbial.
The positive results from a two-dose program as opposed to three doses would help reduce costs for ranchers and feedlot managers.
The study results were published in the journal Vaccine.
“We wanted to evaluate the vaccine in accordance with how the feedlot would be most likely to use the vaccine, and a two-dose program is probably more logistically and financially feasible in most commercial production systems,” said David Renter, the associate professor of epidemiology who was principal investigator on the project.
“The suggested volume (two millilitres per dose) was given twice, three weeks apart, so the volume per dose did not change.”
The study also showed that the low-dose, direct-fed microbial product was less effective than the vaccine.
“We have quite a bit of data on two doses with Econiche,” said Culbert.
“We’ve published four or five papers. There is quite a large body of data that states that two doses will work fine. It makes it more practical to fit into a field situation. Our product has been fully approved for sale in Canada since 2008 and has been on the market just over four years now. We are the world’s first.”
However, the real hurdle remains mired in the bottom line economics of cattle production. The vaccine is of no health benefit to cattle, so why incur the expense?
Culbert said ranchers are in the commodity business and beef cattle, as a commodity, are sold at auction. Their focus is to keep costs down while hopefully hitting the market at a time when prices are high. Dairy farmers are less driven on the commodity front because their industry functions on a milk quota system.
Yet the wider issue about public health prevails.
Culbert said more people get sick from E. coli by eating vegetables, drinking water and visiting fair grounds and through human to human contact, but the primary source for the illnesses is from cattle.
“In 2006, there was a huge spinach recall,” he said. “A spinach field contaminated with E. coli was traced back to a cattle farm further uphill.”
Three deaths and 205 illnesses were attributed to that outbreak in California.
Bioniche markets its product, Econiche, as the world’s first licensed on-farm vaccine against E. coli O157.
The cost per injection is $3 and one, two or three doses can be selected, depending on the ranch or farm’s inoculation program and veterinary advice.
