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Campylobacter Vaccine for Poultry Targets Human Foodborne Illness
By moniquegarcia on Tue, 09/10/2013 - 9:15am
Most people are familiar with Salmonella and its potential to make people ill. But few know about Campylobacter jejuni, even though it competes yearly with Salmonella in making people sick. Campylobacter is one of the main causes of bacterial foodborne disease in the United States and worldwide. Raw chicken is one of the most common carriers of the bacteria. In the U.S. alone, Campylobacter is the second most common cause of foodborne diarrheal illness, causing an estimated 1.3 million cases annually, resulting in health care costs between $0.8 billion and $5.6 billion per year. Per capita consumption of chicken in 2011 was a substantial 84.2 pounds, according to statistics reported by the National Chicken Council, indicating consumers’ frequent exposure. New performance standards adopted in July 2011 for chicken processing establishments allow no more than 8 positive Campylobacter samples out of a 51-sample set on chicken. These strict standards will be difficult to meet with current intervention strategies and plants risk being shut down with significant economic effect.
Description of Action:
Funded by the USDA, faculty and graduate students in the UA Department of Veterinary Science and Microbiology have developed a new poultry vaccine using an attenuated strain of Salmonella to express Campylobacter proteins in chick intestines. The vaccine reduces the number of Campylobacter cells within the intestine, so ultimately less Campylobacter is transferred to humans and therefore significantly fewer foodborne illnesses will occur. The vaccination process is simple; it is easy to produce and safe. The Salmonella is engineered to live long enough to stimulate antibody production, is attenuated so it cannot produce disease in chicks or humans, and dies before the chicks are harvested. The goal is to halt the contamination before it spreads and survives on raw chicken sold in stores. The vaccine may be publicly available in two to three years.
The researchers are also refining the delivery method for the vaccine and are currently testing other Campylobacter genes in the Salmonella vector strain. They are searching for two or three genes that can be incorporated into the vaccine, which together may express Campylobacter to a degree that will prevent colonization completely.
Ongoing research trials show the vaccine has significantly reduced the pathogen’s ability to colonize young chickens’ intestines. Risk assessment indicates that a 2-log, or 99 percent reduction of the Campylobacter load on chickens, such as that supplied by the vaccine in development at the University of Arizona, would reduce the incidence of campylobacteriosis associated with chicken meals by a factor of 30, or a reduced incidence of 300 cases per 100,000 population down to 10 per 100,000 population. A patent application for the UA vaccine was submitted in February 2013. The goal is to produce a vaccine for eventual commercial scale, cost-effective use within a few years.
The vaccine’s effect could be significant, as the U.S. has the largest broiler chicken industry in the world, producing approximately 8.41 billion broiler chickens in 2012. Europe has similar broiler production figures. The 8.6 billion broilers produced in 2011 (49.7 billion pounds) had a farm receipt value of $23.2 billion, according to USDA figures. The retail equivalent would be about $45 billion, according to USDA figures for 2010.
Successful vaccination of chickens would lead to compliance with the new USDA performance standards for Campylobacter in chickens by improving the safety of poultry, allowing processors to maintain their operations and significantly reduce human illness.