Detection and isolation of Lyssaviruses from apparently healthy unvaccinated local breed of dogs in some rural communities in Southwestern Nigeria

Abstract

Background: Existence of rabies virus-carrying and virus-secreting but apparently healthy dogs, referred to as rabies carriers, has been reported in Nigeria. This subclinical, in-apparent and non-fatal infection of rabies or related-viruses in the carrier dogs has compounded the risk of human exposure to the infection. Methods: This study was designed to investigate the presence of subclinical or in-apparent Lyssavirus infection in apparently healthy unvaccinated local dogs in sonic rural communities in southwestern Nigeria. Oral swab specimens from 89 apparently healthy unvaccinated dogs in 5 rural communities in Oyo State were examined for Lyssaviruses using tissue culture isolation test (TCIT) and direct fluorescent antibody test (dFAT). Results: Eighteen (20.2%) of the specimens were positive for rabies or related Lyssaviruses by TCIT, 24 (26.9%) by dFAT and 27 (30.3%) overall. Among age groups, the rate of virus infection was higher among younger than older dogs. The rate of virus infection was also higher among the female than the male dogs; however, the difference was not significant. The rate of detection of virus was higher by dFAT than TCIT. The carrier state of Lyssavirus infection found in this study suggests that ecological equilibrium exists between the strains of the viruses and the dogs, hence the absence of clinical rabies in the dogs. Conclusion: This finding is disturbing and requires urgent attention to evaluate the role of domestic dog (Canis lupus familiaris) in the epidemiology of Lyssavirus infection and its threats to humans in rural communities in Nigeria