Epidemiology of wild animal rabies in Namibia from 2001 to 2019 : implications for controlling the infection in domestic animals

Abstract

BACKGROUND : Rabies is an acute, fatal zoonosis of mammals that is endemic in Namibia. Wild animals have been implicated as reservoirs of the infection around the world. In this retrospective study, passive surveillance data (2001–2019) for wild animal rabies in Namibia were retrieved from the Directorate of Veterinary Services and analysed. The number, spatiotemporal epidemiology, and clinical presentation of rabies cases were assessed and compared among animal species, land use systems and regions. RESULTS : The overall positive rate was 64.8% (1059/1635). Rabies infected 33 out of 52 wild animal species tested. The majority of cases were in Greater Kudu (Tragelaphus strepsiceros) (71.3%, n = 755/1059), followed by the black-backed jackal (Canis mesomelas) (17.1%, 181/1059), eland (Taurotragus oryx) (5.1%, 54/1059), and 30 other wild animal species with low infection rates. Most positive cases (72.8%, 771/1059), and infected wild animal species (n = 26) were from commercial farms. Rabies cases were clustered in the central-western regions of the country (Otjozondjupa, n = 373; Khomas, n = 210; Erongo, n = 123; Omaheke, n = 105; and Kunene, n = 154). Local Moran analysis revealed that the Otjozondjupa region was a significant high-risk cluster of rabies (p = 0.0096). The global Moran’s I analysis by Monte Carlo permutations confirmed significant positive spatial autocorrelation of overall rabies cases from wild animal species in Namibia (Moran’s I = 0.13; p = 0.042). Rabid animals presented the typical clinical signs of rabies. Jackals were responsible for most human and domestic animal bites (80%, 76/95). The number of rabies cases fluctuated over the years, but a clear decline was apparent from 2014 to 2019. The aggregated rabies cases were higher from January to June and lower from July to December. CONCLUSIONS : The results of this study confirm that rabies affects various wild animal species in Namibia, which may act as reservoirs of infection and hinder the control and elimination of dog-mediated rabies. A multi-sector One Health approach towards rabies control anchored on pet vaccination is recommended at Namibia’s human-wildlife-livestock interfaces. Innovative strategies for controlling kudu and jackal rabies are required to reduce incidence in the wild.