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Japanese encephalitis virus (JEV) is a zoonotic arbovirus that causes abortion, stillbirth, and congenital defects in pigs, and epidemic encephalitis in humans. Currently, there is scarcity of information on JEV infection in pigs in Nigeria. Since the Culex tritaeniorhynchus vector of JEV is present in Nigeria and considering recent anecdotal reports of abortions and birth of weak piglets in some pig farms in southwestern Nigeria, there is a need for studies on the presence of the virus and its true burden among pig populations in the country. Serum samples (n=368) obtained from farm-reared pigs in four States of southwestern Nigeria were screened for JEV-specific IgG antibodies using a commercial ELISA kit. An overall JEV seropositivity of 35.1% (95% CI: 30.18 - 39.93%) was obtained, with detectable antibodies in pigs of all age groups, breeds, sex, and locations. Our results suggest natural exposure of these unvaccinated intensively reared pigs to JEV circulating silently in the swine population with significant association of the seropositivity with location (state/community in which the pig farms exist) and breed of the pigs studied. This first report of detection of anti-JEV antibodies in pigs in Nigeria indicates that JEV circulated among these pigs and underscores the need for active surveillance for JEV in humans, pigs, and mosquitoes to provide valuable epidemiological data for the design of effective control strategies against the virus, thus forestalling potential future outbreaks of the infection.

Toxoplasma gondii (T. gondii), an obligate intracellular protozoan parasite is a known etiological factor of reproductive problems and encephalomyelitis in animals and humans. This study investigated the seroprevalence of T gondii infection in recreational horses in two metropolitan cities of southwestern Nigeria. Serum samples were randomly collected from a total of 157 horses in Lagos and Ibadan. Samples were assayed for the presence of T gondii antibodies using the Modified Agglutination Test (MAT). A total of 22 (14%) of the 157 sampled horses were positive for T gondii antibodies by MAT with titers of 1:20 in 12 samples (54.5%), 1:40 in 8 samples (36.4%), 1:80 in 1 sample (4.1%) and 1:160 in 1 sample (4.1%). Seroprevalence varied among gender, breeds, age groups and sampling locations but there was no statistically significant association (p < 0.05) of any of the factors to T. gondii infection. This study showed that recreational horses in southwestern Nigeria are exposed to T. gondii and appropriate measures should be adopted to prevent and control the infection in horses in this region. The zoonotic implication of the disease is also discussed. This is probably the first report on seroprevalence of Toxoplasma gondii in horses in southwestern Nigeria.

Objective: To determine some virulent trait-related properties of poliovirus isolates from children with acute flaccid paralysis following vaccination with oral polio vaccine (OPV)., Design: Six polioviruses earlier characterised into wild, vaccine-derived and OPV-like were studied using the plaque morphology and growth kinetics at supra-optimal temperature., Setting: Department of Virology, University of Ibadan, Nigeria., Subjects: Polio isolates from six children who developed acute flaccid paralysis following vaccinations with various doses of OPV were used. All the children were located in the Northern part of the country where poliovirus is still circulating., Main Outcome Measures: The two vaccine-derived polioviruses acquired wild type characteristics., Results: All the six poliovirus isolates developed different forms of plaques ranging from tiny, small and large. The plaque formed could however not be used to identify the different isolates. Growth of the different isolates at supra-optimal temperature showed that the three wild polioviruses grew to a higher titre when compared with the Sabin 2 control. The two vaccine derived isolates behaved like the wild poliovirus while the OPV-like virus acquired an intermediate characteristics between wild and sabin., Conclusion: The wild polioviruses represented in this study are among the last vestiges of the circulating polioviruses found in the world. It is possible that the observed biological properties of wild types 1 and 3 described in the study are typical of the West African polioviruses. These properties will provide useful previews to the final identification of some important clinical isolates especially type 1 which may grow rapidly in cell culture.