Findings could help to prevent and control respiratory infections

Scientists at the University of Bristol have gained a fresh understanding of bacterial infections found in the noses of healthy cattle.

Published in Scientific Reports, the paper describes how researchers used a ‘one health’ approach to study three bacterial species –Pasteurella, Histophilus and Mannheimia – which can cause serious illness, especially when the infection takes hold in the lower respiratory tract.

Researchers found the carriage patterns of the three bacteria varied remarkably. The findings are significant because, when combined with animal and human health research, they could help to prevent and control respiratory infections. 

In the study, researchers used molecular detection tools to collect nasal swabs from young cattle. The swabs were taken at intervals during the first year of life to detect the presence of bacteria and measure its abundance. 

Researchers detected Pasteurella in most of the animals. Large numbers of the bacteria were usually present, and the bacteria remained in the nose for several weeks or months.

They also found that Histophilus was present in up to half the animals, usually in smaller numbers and the periods it was present were shorter. The team rarely found Mannheimia, although the numbers detected, when present, varied widely.

“These techniques and results offer a way forward in understanding why and how apparently healthy cattle harbouring these bacteria may go on to develop respiratory illness and should help in finding new ways to prevent it,” explained lead author Amy Thomas, who conducted the study as part of her PhD studies in clinical veterinary science.

The team says that, in addition to helping to control respiratory infections, the findings could also be used in the fight against global warming. 

“These studies are particularly important because cattle are known to contribute to greenhouse gas emissions and improving how their diseases are controlled will help mitigate climate change,” commented Professor Mark Eisler, co-author and chair in global farm animal health at Bristol Veterinary School.

“Reducing the use of antimicrobials that treat respiratory diseases in cattle should help reduce the increasing global threat of antimicrobial resistance in animals and humans.”