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New UNH research is seeking to address the levels of Campylobacter jejuni 鈥� a bacteria that can affect herd health as well as cause food-borne illness in humans 鈥� in dairy cows.

Andrea Ayala, assistant professor of natural resources and the environment in the College of Life Sciences and Agriculture (COLSA), is focusing on the role small birds play in transmitting the bacteria to cows at dairy farms in New Hampshire and across the U.S. While the final analyses are still underway, early observations indicate that house sparrows likely play a much larger role in the spread of Campylobacter and other bacteria harmful to animal health than previously thought.

If confirmed, the findings would reinforce the value of vaccinating cows against Campylobacter infection and installing netting to keep the birds away from barns and feed storage areas.

鈥淥ur research is revealing whether small birds such as house sparrows frequently carry Campylobacter and, because they鈥檙e highly mobile, whether they play a role in spreading it from farm to farm,鈥� says Ayala. 鈥淚f we can show clearly that sparrows are initiating Campylobacter infections in cows, it demonstrates to farmers that mitigation strategies are well worth it.鈥�

A closer look at the birds

On farms, dairy cows are known to carry Campylobacter, and studies have shown that up to 50% of cows are colonized with them. When colonized in a steady state, however, the bacteria typically aren鈥檛 present in numbers that pose a health threat for either cows or humans. But sparrows could carry additional Campylobacter populations that tip the balance toward more bacterial growth and infection. 听

Campylobacter presence in birds has not been extensively studied, so Ayala and her team set up bird nets as close as possible to the cows and feed at UNH鈥檚 Organic Dairy Research Farm and Fairchild Dairy Teaching and Research Center as well as two private New Hampshire dairy farms. And while they caught a variety of species, the vast majority of the birds they caught next to the cows were house sparrows.

鈥淎 lot of other birds, such as pigeons, are found around dairy barns, but most of them don鈥檛 go right into where the feed and cows are like house sparrows do,鈥� says Ayala. 鈥淐ampylobacter is spread through feces, so the sparrows may be contaminating the cows鈥� feed and environment.鈥�

For the study, Ayala is analyzing blood samples for antibodies, which will identify past infections, as well as a fecal sample that will reveal current infections. There are more than 20 species of Camplylobacter, but Ayala is focused on jejuni because of its impact on human, animal, and environmental health.

While the current data are being analyzed, Ayala and her team are working to set up a colored banding system to be able to identify individual birds via camera traps in collaboration with UNH Associate Professor Rem Moll and his lab. The project will provide more insight into which sparrows are interacting with the cows and feed and provide a more thorough determination of who is actually infecting who in the dairy setting.

An illness to avoid

Food-borne illness is at best a highly unpleasant experience, and at worst can cause serious health problems. Outbreaks caused by Escherichia coli and Salmonella capture headlines, but campylobacteriosis, which can be contracted by consuming contaminated chicken, milk, or water, is more common, afflicting about 1.5 million people annually in the U.S. While few cases become clinically severe, symptoms such as diarrhea, abdominal pain, and fever that can last a week make campylobacteriosis disruptive and something to avoid.