Primary bovine viral diarrhoea virus infection in calves following direct contact with a persistently viraemic calf.
Six calves, aged 24 to 58 days and not previously exposed to bovine viral diarrhoea virus (BVDV), were infected with this agent by nose-to-nose contact with a persistently BVDV viraemic calf. The study was conducted in two trials, using 3 calves in each. All 6 calves showed a peak interferon level in serum at 4 days post infection (dpi), and they seroconverted to BVDV at 16-21 dpi. The calves in trial 1 had diarrhoea for 2 or 3 days between 2 and 6 dpi and one calf again from 9 to 11 dpi. During the periods of fever, the calves were slightly depressed. Those in trial 2 were more depressed and their oral and nasal mucous membranes were reddened but they never had diarrhoea. In both trials, fever (up to 41.3 degrees C) was a prominent symptom at 8 to 9 dpi and 2 calves showed a diphasic fever course. Respiratory affection was mild and no medical treatment was required. Haematological assessment demonstrated a transient but significant leukopenia and lymphopenia at 4 dpi (P less than 0.01 and P less than 0.05 respectively) and 11 dpi (P less than 0.05 and P less than 0.01 respectively). A significant decrease in thrombocyte count was seen at 4 dpi (P less than 0.05, n = 3). This study has demonstrated that nose-to-nose contact is an effective way of transmitting BVDV from persistently infected to susceptible cattle.
Tråvén
M
M
Swedish University of Agricultural Sciences, Department of Cattle and Sheep Diseases, Uppsala.
Alenius
S
S
Fossum
C
C
Larsson
B
B
D000818:Animals; D001912:Bovine Virus Diarrhea-Mucosal Disease / Q000097:blood / Q000276:immunology / Q000635:transmission*; D002417:Cattle; D007372:Interferons / Q000097:blood; D007958:Leukocyte Count / Q000662:veterinary; D008297:Male; D014766:Viremia / Q000097:blood / Q000276:immunology / Q000662:veterinary*
D007372:Interferons