Antibody prevalence to African swine fever virus, Mycobacterium bovis, foot-and-​mouth disease virus, Rift Valley fever virus, influenza A virus, and Brucella and Leptospira spp. in free-ranging warthog (Phacochoerus africanus) populations in South Africa

Abstract

The warthog (Phacochoerus africanus) can be used as a model for investigating disease transmission at the human, wildlife, and livestock interface. An omnivore and scavenger, a warthog moves freely between natural ecotypes, farmland, and human communities and is susceptible to diseases of zoonotic, agricultural, and conservation concern. A retrospective study using 100 individual serum samples collected from May 1999 to August 2016 was performed to determine antibody prevalence to seven pathogens in warthogs from five locations in northeastern South Africa. Higher prevalence of antibodies to African swine fever virus and Mycobacterium bovis were detected in warthogs from the Greater Kruger National Park ecosystem in comparison to lower prevalence of antibodies to M. bovis and no antibodies to African swine fever virus in warthogs from uMhkuze Game Reserve. Low prevalence of antibodies to foot-and-mouth disease virus, Rift Valley fever virus, and influenza A virus was detected in all locations, and no antibodies against Brucella and Leptospira spp. were detected. No statistically significant difference in antibody prevalence was found between sexes for any disease. At the univariate analysis, M. bovis seropositivity was significantly different among age categories, with 49% (35/71) of adults found positive versus 29% (4/14) of juveniles and 9% (1/11) of sub-adults (Fisher’s exact test, P¼0.020), and between the sampling locations (Fisher’s exact test, P¼0.001). The multivariate model results indicated that juvenile warthogs had lower odds of testing positive to M. bovis antibodies than adults (juveniles’ odds ratio [OR]¼0.17, 95% confidence interval [CI]: 0.02–1.0), although this result was not statistically significant at the 5% level (P¼0.052). For warthogs sampled at Satara Buffalo Camp, the odds (OR¼0.22, 95% CI: 0.035–0.96) of being M. bovis antibody positive were significantly lower (P¼0.043) than for warthogs sampled at Skukuza. Of particular interest in this study was the detection of warthogs seropositive for influenza A virus.