Serological Investigation of Equine Influenza Virus in Polo Horses at the 2021 Jos Polo Tournament, Plateau State

Abstract

Equine influenza (EI) is an important respiratory disease of equidae caused by the Equine influenza virus (EIV). The H3N8 and the H7N7  strains of the EIV have been reported in outbreaks of EI. Clinical signs exhibited by infected horses include but are not limited to pyrexia,  dry, harsh cough, clear nasal discharge which may turn purulent a few days later, anorexia and lethargy. In this study, 115 polo horses  from Kaduna, Nassarawa, Niger, Abuja FCT, Bauchi and Adamawa that participated in the 2021 Jos Polo Tournament were screened for  EIV to ascertain the seroprevalence of EIV in these group of horses. Theses sera samples were tested using a specific commercially  available indirect Influenza A Virus Antibody ELISA Test Kit (IDEXX Influenza A Test Kit). An overall prevalence of 51.3% was obtained.  Subset of ELISA reactive sera were analysed by Haemagglutination Inhibition (HI) for subtype H3 and 6 out of 20 (30%) had up to 3log2 HI  titre . In this study, the prevalence of influenza A was highest in female and Argentine horses. The effect of sex breed and location was  statistically not significant. Additionally, this study showed that seropositive horses were present in each of the states represented,  implying that EIV is still circulating in Nigeria. This study therefore highlights the need for regular monitoring and surveillance of equidae population in Nigeria for EIV to improve our understanding of EI and help in the formulation of national control strategies for EI.