BVDV in Australian alpacas: natural infection and clinical profiles following co-mingling with a persistently infected heifer.

BACKGROUND: Although predominantly a disease of cattle, bovine viral diarrhoea virus (BVDV) is known to infect other ruminant and camelid species such as sheep and alpacas. The aims of this study were to determine if BVDV-naive alpacas would become acutely infected and seroconvert to the predominant Australian strain of BVDV following co-mingling with a BVDV-1c persistently infected (PI) heifer and to determine what, if any, clinical signs, haematological responses and selected biochemical changes occur with acute BVDV-1c infections in alpacas. METHODS: A PI heifer and four alpacas co-mingled for 2 weeks. Weekly blood samples were collected and twice weekly clinical examinations were performed on the alpacas. RESULTS: Serum analysis by antibody ELISA indicated that all four alpacas were positive for BVDV-specific antibodies between 35 and 54 days after mixing with the BVDV-1c PI heifer. Viral antigen was detected by antigen ELISA in two alpacas on days 21 and 35 after initial mixing. In general, all the physical clinical parameters measured were normal. Serum biochemical and haematological analyses in two of the alpacas revealed marginally low sodium, chloride and elevated potassium concentrations, a lymphocytosis, monocytosis and a neutrophilia at some point during the study period in either one or both of the alpacas. CONCLUSION: This study showed that infection in Australian alpacas readily occurs when a BVDV-1c PI bovine co-mingles with naive alpacas and that acute infections are clinically mild and undetectable without serological testing.