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.
Bovine kobuvirus (BKV) was identified by researchers at the University of Illinois by Dr. Leyi Wang and his team in April 2019.
Wang, clinical assistant professor in the College of Veterinary Medicine at the University of Illinois, discovered the virus by analyzing the fecal sample of a calf between 10 to 14 days old. The results showed positive for rotavirus, coronavirus, cryptosporidium, and E. coli, and results for Salmonella were negative.
Using advanced DNA sequencing, the research team found the genome, BKV IL35164, closely matched with four strains of kobuvirus. Additionally, it closely matched kobuvirus associated with sheep and ferrets. The research team identified the kobuvirus in the necropsy of two more calves that died from gastrointestinal issues but did not have diarrhea.
Previous studies of BKV shows that diarrhea was present in 20.9 percent of calves less than 2 months of age in Brazil and 26.7 percent in calves less than 1 month of age in South Korea.
According to the Centers for Disease Control and Prevention report, it appears that detection of the virus is only from fecal samples. Wang wrote that future studies, including “virus isolation and virus challenge to calves,” are needed to further confirm bovine kobuvirus as the causative agent in neonatal diarrhea.
“Farmers cannot tell what pathogens cause diarrhea in cattle since there are multiple bacteria, viruses and parasites that are causing it,” said Wang. “Laboratory differential diagnosis is needed. So far, this is not a reportable disease, and there is no need to report it to state veterinarians or officials.”
Since its discovery in Japan, the virus has spread to eight other countries, including Thailand, China, South Korea, Hungary, the Netherlands, Italy, Brazil and Egypt.
“The prevalence of BKV in the U.S. remains unknown. Continued surveillance is urgently needed to determine rates and distribution of BKV in North America,” the report states.
While the virus is not new, it is relatively new to science and needs to be further studied. Currently, there is no treatment or vaccine for the virus.
“Scientists have access to only a few genetic sequences of this virus in public databases. We need to be sequencing these viruses to learn more about their genetic diversity and evolution.”
It is not clear if the virus is a zoonotic organism that can pass from animals to humans. The virus belongs to a family of viruses known as picornaviridae, which includes rhinovirus, the source of head colds and sinus infections in people, and enterovirus, which attacks the central nervous system and intestinal tract. Among the enteroviruses are poliovirus and echoviruses, which cause rash and meningitis. — Charles Wallace, WLJ editor