Case report: Henipavirus sero-surveillance in horses and pigs from Northern Nigeria

Hendra virus and Nipah virus are considered to be emerging viruses and cause severe zoonotic diseases, which occur in humans who have had close contact with horses and pigs in Australia and Asia, respectively. Both viruses belong to the genus Henipavirus. Although there are large populations of horses and pigs in northern Nigeria, no previous studies in this region have investigated henipavirus sero-surveillance in horses and pigs using the gold standard test, the serum neutralization test (SNT). A total of 536 apparently healthy horses and 508 apparently healthy pigs were sampled in northern Nigeria in 2018. Serum samples were tested for Hendra virus and Nipah virus-specific antibodies using either the Henipavirus Luminex binding assays for horses or the Hendra virus Competitive ELISA and Nipah virus Indirect ELISA for pigs as initial screening tests, followed by the confirmatory Hendra and Nipah virus SNT for both species, according to accredited protocols at the Australian Centre for Disease Preparedness. Although some horse and pig samples crossed-reacted or reacted weakly in the screening test, confirmatory SNT for all of them proved negative. This study reveals the absence of Hendra and Nipah antibodies in horses and pigs in northern Nigeria, which is consistent with the absence of observable disease in the field. However, the continuous inter and intra-trans-boundary animal movement and trade in Nigeria calls for the continuous evaluation of the henipavirus status of susceptible animals to safeguard both animal and human health.