Active Surveillance of African Swine Fever and Japanese Encephalitis in Southern Nigeria: A Dual-Pathogen Investigation

Pig farms in Southern Nigeria face threats from both enzootic and emerging viral infec-tions, yet active surveillance remains limited. In this study, a dual-pathogen surveillance project targeting African swine fever virus (ASFV) and Japanese encephalitis virus (JEV) was undertaken to assess their circulation. Using serology, molecular testing of both swine blood as well as arthropods, 40 pig farms and two abattoirs across four states were assessed. ASFV was detected in 100% of pigs sampled during known African Swine Fever outbreaks, while no viral presence was found in pigs during periods in which no outbreak was recorded. Ticks were consistently negative for the presence of ASFV. Farm-level risk evaluations revealed widespread biosecurity lapses, identifying them as key drivers of ASFV circulation. For JEV, molecular tests failed to reveal the presence of the virus in any pigs or mosquitoes. However, a high degree of seropositivity (57.1%) was noted in the pig samples. In the absence of any positive detection of the virus, cross-reactivity with other flaviviruses cannot be excluded.