Abstract:
Studies comparing canine distemper virus (CDV) strains from Africa with that of previously described
lineages have been hampered due to a lack of field strains for in vitro experiments. Since the
attenuation of the Onderstepoort strain in the 1940s, there have not been any reports of CDV isolations
in southern Africa. Clinical specimens consisting of whole blood, spleen, lungs, brain and
cerebrospinal fluid from dogs with clinical signs compatible with distemper diagnosis were obtained
from private veterinary practices and diagnostic laboratories. The animals all displayed various
catarrhal, systemic, or nervous signs of the disease. One hundred and sixty two specimens from 124
dogs were inoculated into Vero cells expressing canine signalling lymphocyte activation molecule
(Vero.DogSLAM). Cytopathic effects (CPE) in the form of syncytia formation and cell necrosis were
observed in 33 (20.4%) specimens within 24 h of inoculation and the presence of CDV was confirmed
with the aid of the direct fluorescent antibody test and electron microscopy (EM). Four of the CDV positive
dogs had a history of canine distemper vaccinations. Seventy three percent of all positive dogs
were less than 12 months old. Local isolates of wild-type CDV were generated and we conclude that
isolation of CDV using Vero.DogSLAM is a specific and practical method for the antemortem diagnosis
of distemper in dogs.
