holstein calf in hutch

A Holstein calf in a calf hutch, which is typically how dairy and dairy-on-beef are started. Photo by the Holstein Association.

Virologists at the University of Illinois Veterinary Diagnostic Laboratory (VDL) have identified the first U.S. case of boosepivirus in a diarrheal calf. 

A sample arrived from a petting zoo in the fall of 2019 from a 10-day old calf with diarrhea, and the zoo wanted to know what pathogens were present in the fecal sample, partly because of the potential for transmission to human visitors at the zoo.

Metagenomic sequencing was performed to identify possible pathogens by Dr. Leyi Wang, clinical assistant professor in the VDL, who found several common culprits for the gastrointestinal illness: E. coli, cryptosporidium and clostridium perfringens.

Producers already have enough to worry about, and now a novel virus that causes diarrhea in calves—first detected in Japan in 2003—has emerged in the U.S.

Additionally, Wang discovered bovine kobuvirus, which is not presently on the “usual suspects” list for bovine diarrhea. Wang and his team were the first to discover bovine kobuvirus in the U.S. in 2019.

While conducting sequencing of the bovine kobuvirus, Wang found something he wasn’t looking for: boosepivirus. This was the first instance that boosepivirus was detected in a diarrheal calf in the U.S. Boosepivirus was first identified in diarrheal cattle through deep sequencing in Japan in 2009. 

Last year, boosepivirus was proposed as a new genus in the viral family Picornaviridae. The Picornaviridae family includes many viruses that can affect both humans and animals, including foot and mouth disease, encephalitis, the common cold, conjunctivitis, myositis and myocarditis, and hepatitis.

Boosepivirus gets its name from bovine, ovine sapelo-entero-like picornavirus. Boosepivirus has also been identified in sheep and goats.

Adding new herd members represents a significant investment. Typically, producers spend a great deal of time evaluating pedigrees, genomics and phenotypic appearance. However, don’t overlook the health status of the individual animal.

Prompted by their finding, Wang, Dr. Rick Fredrickson, director of VDL, and Dr. Ailam Lim of the Wisconsin VDL, tested 84 samples for boosepivirus. These samples were submitted for a standard bovine diarrheal testing panel in 2019 and 2020. Boosepivirus was identified in five of the samples, four of which had originated in Wisconsin and one in Ohio. The group reported their findings in Transboundary and Emerging Diseases. 

Scientists have since identified three separate types of boosepivirius: BooV-A1, BooV-B1 and BooV-C1, or types A, B and C. In a separate study published in Archives of Virology in 2021, scientists from the Animal Disease Research and Diagnostic Laboratory in the Department of Veterinary and Biomedical Sciences at South Dakota State University detected boosepivirus B in cattle fecal samples from six states. In all cases, boosepivirus was identified simultaneously with bovine coronavirus, bovine rotavirus and cryptosporidium. 

As the Picornaviridae family is growing, Wang suggests the cattle industry take action and have boosepirvirus included in tests on diarrheal calves.

“Calf diarrhea is a multifactorial disease, causing economic loss for cattle producers worldwide,” says Wang. “It is the most common cause of death in young calves. The list of viruses associated with calf diarrhea is expanding and includes rotavirus, coronavirus, torovirus, norovirus, nebovirus, astrovirus, kobuvirus and more. Yet we do not routinely test for many of the newer viruses.” — Charles Wallace, WLJ editor

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