Serological Surveillance for Non-Rabies Lyssaviruses among Apparently Healthy Dogs in Zaria, Nigeria.

Abstract

Out of the seven recognized and four putative genotypes of lyssaviruses, genotypes 1-3 comprising namely the classical rabies virus (RABV), Lagos bat virus (LBV) and Mokola virus (MOKV) respectively have been reported in Nigeria. The domestic dog, Canis familiaris, is recognized as the reservoir for genotype 1, and the straw-colored fruit bat for genotype 2. The reservoir for genotype 3 remains unidentified. Serum samples were collected by convenient sampling from apparently healthy dogs in Zaria and tested for the presence of neutralizing antibodies to three members of lyssavirus genotypes, namely LBV, MOKV , Duvenhage (DUVV), and a putative genotype, West Caucasian bat lyssavirus (WCBV) using a modification of the rapid fluorescent focus inhibition test (RFFIT). Out of the 189 samples tested, six (3.7%) of them neutralized Lagos bat virus, and two (1.1%) of these additionally showed a neutralizing activity against Mokola virus. There was no serological evidence of WCBV and DUVV. This finding suggests the presence of phylogroup 2 lyssaviruses circulating among dogs in this location. This is important especially since human exposure to dog bite is common in this locality. The possibility of exposure to these genotypes will have great implication with regards to the usefulness of the available vaccines which do not sufficiently protect against members of phylogroup 2. It further emphasizes the poor understanding of the epidemiology of lyssavirus infection, especially among apparently healthy dogs. This calls for enhanced surveillance for lyssaviruses among both domestic and wildlife species in Nigeria to identify the definitive reservoir for Mokola virus.