In May 2024, the University of Saskatchewan (USask) shared that a research team from Western College of Veterinary Medicine (WCVM) has developed an aerosol vaccine that is “proving effective” in providing protection for young broiler chicks against necrotic enteritis. This is described as a “deadly disease” for poultry and a One Health issue that affects both animals and humans.
Necrotic enteritis
Necrotic enteritis is caused by intestinal overgrowth of Clostridium perfringens type G in poultry, reportedly contributing to a 50% fatality rate in affected chickens and “numerous” food poisoning cases in people. Dr Hemlata Gautam suggests that the disease is “basically re-emerging” because of “less use of antibiotics” in the poultry industry. Dr Gautum, under the supervision of WCVM’s Dr Susantha Gomis, is investigating “alternative strategies” for controlling and preventing the spread of necrotic enteritis without antibiotics.
Turning away from prophylactic antibiotics
Although antibiotics have been “instrumental” in the prevention of disease, the poultry industry in Canada is “phasing out” prophylactic use of antibiotic drugs in broiler chicken production in response to “overuse and the spread of antimicrobial resistance”. Dr Gautam highlights that there is “no effective control” of the disease at the moment.
“Scientists are working toward finding a preventative strategy. In my research, we have developed a vaccination strategy to prevent this disease.”
The strategy
The new strategy involves making chickens “strong enough to fight infection by the third week” of life, working around maternal antibodies and weak immune systems. Therefore, the strategy must begin very early in the chickens’ lives. In study, Dr Gautam injected synthetic DNA into the eggs just before the birds hatched, to help activate their immune systems. Through the concept of mucosal vaccination, she relied on the “gut-lung axis” to deliver the vaccine.
After the chicks hatch, they are placed in a special nebuliser to receive a single dose of a live, aerosol vaccine through the lungs. At three weeks, Dr Gautam exposed the chicks to Clostridium perfringens for three days. She found that the vaccinated birds had “completely healthy” intestines.
“What we have found is just by giving [chicks] one single vaccine dose by the lungs, we are able to protect them against necrotic enteritis.”
Although these results are positive, Dr Gautam reflects that the vaccine has only been used in experimental trials.
“To say completely how it will work in field conditions, we’ll have to do some field trials.”
However, she is encouraged by its potential and hopes that a similar strategy could be used against other infectious diseases in poultry.
“It’s a growing area right now – how we can give vaccines in the lungs and how it can protect different areas of the intestine. This [vaccination] strategy might be helpful for other infectious diseases as well.”
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