Patterns of Animal Rabies Prevalence in Northern South Africa between 1998 and 2022

Abstract

Rabies is endemic in South Africa and rabies cycles are maintained in both domestic and wildlife species. The significant number of canine rabies cases reported by the World Organization for Animal Health Reference Laboratory for Rabies at Onderstepoort suggests the need for increased research and mass dog vaccinations on specific targeted foci in the country. This study aimed to investigate the spatiotemporal distribution of animal rabies cases from 1998 to 2017 in northern South Africa and environmental factors associated with highly enzootic municipalities. A descriptive analysis was used to investigate temporal patterns. The Getis-Ord Gi statistical tool was used to exhibit low and high clusters. Logistic regression was used to examine the association between the predictor variables and highly enzootic municipalities. A total of 9580 specimens were submitted for rabies diagnosis between 1998 and 2022. The highest positive case rates were from companion animals (1733 cases, 59.71%), followed by livestock (635 cases, 21.88%) and wildlife (621 cases, 21.39%). Rabies cases were reported throughout the year, with the majority occurring in the mid-dry season. Hot spots were frequently in the northern and eastern parts of Limpopo and Mpumalanga. Thicket bush and grassland were associated with rabies between 1998 and 2002. However, between 2008 and 2012, cultivated commercial crops and waterbodies were associated with rabies occurrence. In the last period, plantations and woodlands were associated with animal rabies. Of the total number of municipalities, five consistently and repeatedly had the highest rabies prevalence rates. These findings suggest that authorities should prioritize resources for those municipalities for rabies elimination and management.

A Perspective of the Epidemiology of Rabies in South Africa, 1998–2019

“…Both of these clusters also overlapped to some extent with the significant disease clusters observed for domestic animals ( Figure 5 ), suggesting potential virus spill-over between co-habiting wildlife species and unvaccinated domestic dogs [ 18 , 19 , 50 ]. In support of this finding, the interface between sylvatic and domestic dog species had previously been investigated in both the LP [ 50 ] and NW provinces [ 16 ]. In the first study, the authors found that blacked-backed jackals in the LP province were known to encounter free-roaming dogs in the villages adjacent to farming areas, allowing for continuous interaction between affected individuals [ 18 ].…”

“…This would suggest that the livestock cluster in the LP province was caused by wildlife species, most notably black-backed jackals. This is not surprising as black-backed jackals in western LP have been shown to maintain rabies independently from domestic dogs and also coincides with geographic localities where farming activities are abundant [ 17 , 32 , 50 ].…”

“…With regard to the clusters observed for the non-mongoose wildlife species, Clusters 1 and 3 were both observed within the LP and NW provinces where black-backed jackals are known to be the primary sylvatic reservoir species of RABV [ 50 ] ( Figure 10 ). Both of these clusters also overlapped to some extent with the significant disease clusters observed for domestic animals ( Figure 5 ), suggesting potential virus spill-over between co-habiting wildlife species and unvaccinated domestic dogs [ 18 , 19 , 50 ]. In support of this finding, the interface between sylvatic and domestic dog species had previously been investigated in both the LP [ 50 ] and NW provinces [ 16 ].…”

“…Lastly, significant rabies disease clusters in livestock species in South Africa was evaluated. As livestock species are considered a dead-end host for rabies, rabies infection in livestock animals are either as a result from interactions with domestic dogs or wildlife species [ 50 , 61 ]. It was thus not surprising that the highest numbers of rabies cases in livestock originated from the eastern half of the country where rabies cases in domestic dogs were most prevalent.…”