Emergence of Pestiviruses in Cattle and Swine With Atypical Clinical Outcomes and Lesions

This issue of Veterinary Pathology contains the report “Natural Outbreak of BVDV-1d-Induced Mucosal Disease Lacking Intestinal Lesions” by Bianchi et al. ¹ This report continues a recent trend seen among pestiviruses worldwide, with atypical being the watch word. At the recent Seventh BVDV Symposium, Evolution of Ecology of BVDV: Implications for Health and Control, held December 6–7, 2016, in Chicago, Illinois, reports were given on continued emergence of Hobi-like viruses in ruminants and 3 emerging pestiviruses in swine: atypical porcine pestivirus, Bungowannah virus, and reduced-virulence classical swine fever virus. Atypical porcine pestivirus was identified in 2015 and detected in newborn pigs with congenital tremor. Bungowannah virus was first described nearly a decade ago as the putative agent of a porcine myocarditis syndrome. Reduced-virulence classical swine fever virus poses the greatest risk due to misdiagnosis based on clinical signs. With this article by Bianchi et al, ¹ BVDV type 1d joins the list of pestiviruses that exhibit atypical clinical signs and lesions. The animals exhibited clinical signs and gross lesions consistent with vesicular disease with little evidence of the expected clinical signs or lesions of BVDV infection. They had no mucosal erosions or ulcers of the Peyer’s patches that have characterized classic mucosal disease associated with persistent infection with BVDV. The lack of mucosal ulcers has also been reported in 6 calves that were necropsied from a group of 23 persistently infected with BVDV2a. ² All 23 of these calves died without any clinical signs of mucosal disease. ² This article ¹ provides a further reminder that a full diagnostic workup needs to be done to ensure that new atypical syndromes of well-characterized viruses like BVDV are identified and the etiologic agents documented.