Fighting HUS E coli by Studying How to Kill it in Cattle
A microbiologist at Washington State University has received a $1 million grant from USDA’s Agriculture and Food Research Initiative to study if previous research into stopping the bacteria at its source – cattle – may be more effective once different strains of the disease are considered.
A press release from the university in Pullman, Washington, said Tom Besser, professor of veterinary microbiology has three years to delve into the subject. He says there has been promising work over the past 15 to 20 years by scientists interested in reducing the rate at which cattle get infected with E. coli O157:H7.
Besser says vaccines, beneficial bacteria or “probiotics,” and certain feeds have had some good results, but not all of the research took different E. coli strains into account. He wants to identify the seasonal variations and processes that kill clinical genotypes of E. coli O157:H7 — the types most dangerous to humans. Bovine-biased genotypes cause only a small percentage of illnesses.
A vaccine, for example, could cut incidence ofE. coli O157:H7 in half. “That could be really good if the half that it’s cutting it by is mostly clinical genotypes,” said Besser.
In humans, E. coli O157:H7 releases a powerful toxin that attacks the lining of the intestine, causing severe abdominal cramps followed by watery, then bloody diarrhea that subsides within a week or so. Sometimes the diarrhea is accompanied by vomiting and a low-grade fever.
In more than 5 percent of cases, the Shiga toxins enter the bloodstream, causing HUS E. coli, or hemolytic uremic syndrome, which can lead to kidney failure, anemia, internal bleeding, and the destruction of vital organs. About 5 percent of children who develop E. coli HUS are killed by it. Those who survive are often left with permanent disabilities, including brain damage or paralysis.
USDA Should Ban More Types of Shiga-Toxin E. coli From Meat
Dana Boner lost her 14-year-old daughter to E. coli O111 in 2007.
Now she is a member of Chicago-based S.T.O.P.-Safe Tables Our Priority, which is renewing its plea to the USDA to declare disease-causing E. coli types other than E. coli O157:H7 as adulterants in beef and begin testing for them. National food safety law firm Pritzker Olsen and many other supporters of S.T.O.P. have made the same request.
The USDA declared E. coli O157:H7 an adulterant in ground beef in 1994 in the aftermath of a west coast outbreak that sickened over 700 people and killed at least 4. Adulterant status makes it illegal to sell contaminated product — knowingly or unknowingly. With it comes an obligation to test for the pathogen.
The Centers for Disease Control and Prevention (CDC) has identified 6 additional strains of shiga-toxin producing E. coli (STEC) — O26, O111, O103, O121, O45 and O145 — that are associated with severe illness and death. Shiga-toxin — whether it comes from the O157:H7 bug or any other bug attacks red blood cells with the same life-threatening result.
Just like E. coli O157:H7, these other STEC strains are found in cattle and get into our beef supply when feces contaminate the meat during slaughter and processing. The powerful toxin, which has no antidote, can lead to renal failure, cause strokes, damage neuro systems and create heart problems. It leads to hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP), two life-threatening complications of STEC infection.
“You can’t find what you’re not looking for and USDA needs to start actively looking for these pathogens,” Dana said in a press release issued by S.T.O.P. ”It’s too late for Kayla, but not too late for others.”
Nancy Donley, S.T.O.P.’s President, whose 6-year-old son died from E. coli O157:H7-contaminated ground beef, said that in 2007 and 2008 USDA had public meetings on this issue, but failed to enact any prevention-based strategy. Instead, USDA declared that it would first conduct testing of ground beef and components to determine the extent of non-O157 STEC and implement a regulatory program if needed.
“While S.T.O.P. has no objection to conducting a baseline study, we object to holding up declaring these additional E. coli strains as adulterants in beef,” Donley said.
Battlefront Shifts in Fight Against Beef E coli Outbreaks
The Centers for Disease Control and Prevention (CDC) estimates about 73,480 people are infected each year with E. coli O157:H7, resulting in 600 deaths. Contaminated beef is a leading source of these illnesses and the chronic nature of beef E. coli outbreaks and recalls remains a constant focus of attention among regulators and industry.
Already since December 24, more than 1 million pounds of beef products have been recalled because they had potential to be contaminated with E. coli O157:H7.
Separate stories this week by USA Today reporter Elizabeth Weise and by Scott Canon of the Kansas City Star highlight an important trend in the battle: Intervention at the farm and feedlot level to reduce levels of the bacteria in animals’ guts and hides before they reach slaughter.
“The theory is that animals are carrying higher levels of E. coli during the summer months, and sometimes they may overwhelm the systems in place to control pathogen contamination in (processing) plants,” said James Marsden, a professor of food safety and security at Kansas State University.
As the USA Today story noted, new interventions are intended to flatten out the curve between winter months when less bacteria is entering the system and the April-September period when cattle shed higher concentrations of E. coli O157:H7 and external temperatures are more suitable for the pathogens to cluster.
Each new method, it is hoped, might take down the incidence of E. coli O157:H7 by a factor of 100. Together they could substantially lower the toll inflicted by the disease, which can cause cramps, bloody diarrhea, kidney failure and death. More than 5 percent of infections lead to life-threatening hemolytic uremic syndrome (HUS) or thrombotic thrombocytopenic purpura (TTP).
What follows is a quick run-down on some of the methods being employed to reduce the overall universe of E. coli O157:H7 in cattle:
- Phages: Cattle walk through a car-wash-like spray of bacteria-eating viruses called phages. These viruses are harmless to humans and have been successfully used to kill a spotting bacteria on tomatoes and peppers in agricultures.
- Probiotics: Basically these are bacterial cultures much like those in yogurt, given to cattle in their feed. They’re called “competitive exclusion” cultures because they out-compete the bad bacteria and exclude them in the animals’ guts. The challenge to these is that they are hard to consistenting administer in large feedlot conditions.
- Diet: Research in Texas, Kansas and Idaho has shown that switching cattle from grain to a more expensive diet of high quality hay before slaughter may lower E. coli O157:H7 rates, though the findings have not always been consistent.
- Vaccine: Cargill Meat Solutions is in the midst of an active vaccination program in 100,000 cattle that will reach slaughter this spring. At an estimated cost of $3 to $10 per animal, vaccination against E. coli appears to have the potential to dramatically hinder the population of E. coli in the guts of cattle. A Minnesota-made vaccine called Epitopix already is in trial in the U.S. and Canada has its own E. coli vaccine that could possibly gain approval in the U.S.
From an epidemiologic standpoint, it’s clear that these pre-slaughter interventions lower the E. coli O157:H7 burden in the cattle, says Guy Loneragan, a professor of animal science and expert in O157:H7 in cattle at West Texas A&M University in Canyon, Texas.
More Vaccines in Works To Thwart HUS E coli
A pair of USDA researchers in Ames, Iowa, have applied for patents on two vaccines they developed to curtail the growth of E. coli O157:H7 in cattle.
The research adds to similar efforts in the private sector that are now in use and in trial in the U.S. and Canada.
The vaccines are designed to prevent E. coli O157:H7 from proliferating inside cattle, which would reduce contamination of meat at the packinghouse and have other benefits.
E. coli ground beef outbreaks have been numerous in the past two years and there is currently an active restaurant steak E. coli outbreak that has involved a major recall of beef products from five restaurant chains, including Applebees and Olive Garden.
Besides combatting the dangerous spread of E. coli O157:H7 in beef, reduced shedding of the microbe into the animals’ manure would help protect produce fields, too. Manure-borne E. coli can be moved by rainfall into irrigation water, and can contaminate fruits, vegetables or other crops, increasing risk of a E. coli HUS outbreaks of foodborne illness.
The USDA vaccines were developed by Agricultural Research Service microbiologists Vijay K. Sharma and Thomas A. Casey. In preliminary tests, Holstein calves were immunized at age 3 months with a placebo or either form of the vaccine. Six weeks later, the animals were given a dose of E. coli O157:H7, and, for the next 18 days, their manure was tested for evidence of the microbe. Calves that received either vaccine had reduced or non-detectable levels of E.coli in their manure within only a few days after being inoculated with the bacteria, Sharma and Casey found.
E. coli At Stock Show Prompts Call for Families, Schools to Take Precautions
By Kathy Will
Eating contaminated food is still far and away the most common way for people to become infected with E. coli O157:H7, a deadly pathogen that sickens more than 70,000 Americans each year.
But national food safety law firm PritzkerOlsen Attorneys is reminding families early in 2009 that contact with animals at livestock shows, petting zoos and other exhibits is another proven way for the organism to travel.
The law firm’s warning stems from a current E. coli O157:H7 outbreak in Colorado. Health officials there are investigating an apparent connection between a growing number of genetically matched infections and attendance at the recent Western National Stock Show in Denver.
According to numerous press reports, at least 20 people who live on the Front Range in Colorado have been infected with the same strain of E. coli. Sixteen of the illnesses are in children who attended the animal exhibit, including a child who is 17 months old. The two-week show drew more than 643,000 attendees before it ended January 25 and health officials expect the number of E. coli O157:H7 infections in the current outbreak to grow.
“This outbreak should not have happened and could have been prevented,” said Fred Pritzker, founder and president of PritzkerOlsen. “When stock shows encourage or permit public contact with animals, there is a well known risk of E. coli O157:H7 infection and equally well known measures that should be in place to prevent such infections.”
Pritzker said the Centers for Disease Control and Prevention (CDC) and the National Association of State Public Health Veterinarians, Inc. (NASPHV) published a compendium of such infection prevention measures almost four years ago.
“Although the matter is still under investigation, it seems likely that rules of this sort were not implemented or followed,” he said.
Escherichia coli O157:H7 is a rare variety of E. coli that produces a toxin that causes severe damage to the lining of the intestine. Specifically, the acute disease caused by E. coli O157:H7 is hemorrhagic colitis. E. coli O157:H7 can also result in hemolytic uremic syndrome (HUS), the leading cause of kidney failure in children in the United States.
With the understanding that children are more at risk for being seriously injured or killed by E. coli O157:H7 infection, it is imperative for families and school groups to take precautions while attending petting zoos, livestock shows and other animal exhibits.
Based on guidelines set by the (CDC) and the National Ag Safety Database, PritzkerOlsen presents the following strategies to reduce the risk of E. coli transmission in settings with animals:
- Locate hand-washing stations and always wash your hands after being in an area with animals, even if you don’t touch them. Bacteria can be spread by shaking hands, touching railings or coming in contact with soil.
- Running water and soap are best for hand washing. Where there is no running water, hand sanitizing gel is better than nothing.
- Don’t consume food or drinks in any area shared with animals.
- Older adults, pregnant women, people with weakened immune systems and young children should be extra careful.
- Avoid hand-mouth activities such as smoking, drinking or nail biting in any area shared with animals.
- Do not eat or drink raw (unpasteurized) milk or other dairy products.
- Children younger than 5 years old need adult supervision around animals.
- Never allow children to put their hands, toys, pacifiers or other objects in their mouths while around animals.
- Supervise the hand washing of children.
- Even after hand washing, be aware that exposure to E. coli O157:H7 can come from shoes, contaminated clothing or even strollers that were in areas shared with animals.
