Submitted to: American Association of Bovine Practitioners Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/22/2005
Publication Date: 9/22/2005
Citation: Ridpath, J.F., Neill, J.D. 2005. Outbreaks of severe acute BVDV in Quebec, Ontario and New York State, occurring between 1993 and 1995, linked to the same strain of BVDV type 2. In: Proceedings of the 38th Annual Convention of the American Association of Bovine Practitioners, September 22-24, 2005, Salt Lake City, Utah. p. 288-289. Interpretive Summary:
Technical Abstract: When first described by Cornell University researchers in 1946, bovine viral diarrhea (BVD) was characterized as an acute transmissible viral infection marked by severe leukopenia, high fever, depression, diarrhea, gastrointestinal erosions and hemorrhages. While the first report of BVD in the literature described a severe acute disease, the most commonly observed form of acute BVDV in ensuing years was clinically mild. Acute BVD infections came to be regarded as clinically unimportant and the transmission of the virus between healthy immunocompetent cattle was considered insignificant. However this mindset began to change in the late 1980’s when severe acute BVD cases were reported with increasing frequency in North America. These outbreaks were particularly devastating in the Canadian provinces of Quebec and Ontario. In the province of Quebec, a BVD epidemic starting in early 1993 resulted in the death of 32,000 out of 143,000 (22.4%) animals in the 1993 veal calf crop. A virus, called IAF 103, was isolated from an outbreak of severe acute BVDV in Quebec by the Institut Armand-Frappier in Quebec, Canada. An epidemic of severe acute BVDV, beginning in 1993 and waning in 1995, was reported In Ontario. It was estimated that 150 dairy, 660 beef and 100 veal calf herds were affected in this epidemic with death seen in all age groups and economic losses reaching $100,000 in severely affected herds. Two viruses, called 1373 and 24515 were isolated from animals housed on two different farms involved in the Ontario epidemic, by the Animal Health Laboratory, University of Guelph, Guelph, Ontario. The spread of BVDV during these outbreaks was described as explosive and were not linked to the presence of persistently infected animals. Concurrently a BVDV2 strain called NY 93 was isolated in 1993 from an outbreak of severe acute BVD observed in one dairy herd following the importation of an apparently acutely infected heifer from Canada. This strain was isolated at the Diagnostic Laboratory, New York State College of Veterinary Medicine, Cornell University Ithaca, New York. All four viruses isolated from these outbreaks were typed as BVDV2 genotype strains, but no comparison was made between these strains. In this study we compared the virulence and genetic sequence of these four strains to each other and to strains isolated in North America from 1989 to 1996.