Exposure of lions (Panthera leo) to classical rabies virus and Mokola virus in provincial and private game reserves in Mpumalanga province, South Africa

Abstract

This study was undertaken to determine the prevalence of neutralising antibodies to two genetically distant lyssaviruses, classical rabies virus (RABV) and Mokola virus (MOKV), the latter being one of the three rabies-related viruses encountered in South Africa, in 160 banked serum samples originating from lions in private and provincial game reserves adjacent to the Mnisi communal area (n = 20) in Mpumalanga and in the greater Kruger National Park (KNP) (n = 140) of South Africa. The KNP lion serum samples were collected between 1995 and 2000, and the rest much later, between 2010 and 2012. The serum samples were tested for neutralising antibodies to RABV and MOKV using the fluorescent antibody virus neutralisation test. Lion sera collected between 1995 and 2000 (n = 140) had a 2.1% and 0.7% prevalence of RABV and MOKV neutralising antibodies, respectively, whereas sera collected between 2010 and 2012 (n = 20) had prevalence values of 65.0% and 36.8%, respectively. Based on these findings, it can be concluded that lions from KNP have been exposed to both RABV and MOKV at low frequencies (≤ 2.0%) between 1995 and 2000, while the sample sizes of the lions from other game reserves were too small to make a valid conclusion.
Conservation implications: These data suggest that lions, like other wild carnivores, are constantly and naturally exposed to viral pathogens, including lyssaviruses, in their natural habitat. These exposures present a risk of population decline of the endangered lion species, exacerbated by intra-group transmission and disruption of predator–prey dynamics, destabilising ecosystems, including the viability of other endangered wildlife species. Other implications include increased human–lion conflict influencing existing conservation efforts because of heightened fear of lions and the potential for co-infection and viral mutation because of concomitant rabies and/or other virus infections complicating disease prevention and control efforts in lion populations.