Temporal patterns of domestic and wildlife rabies in central Namibia stock-ranching area, 1986-1996

Abstract

Eleven years (1986-1996) of wildlife- and domestic-rabies data from the agriculture stock-ranching area of central Namibia were studied using time-series analysis. Nine hundred and sixty three rabies cases were observed in domestic ruminants (5.4 cases/mo), black-backed jackals (Canis mesomelas, 1.3 cases/mo), domestic dogs (0.5 case/mo), and bat-eared foxes (Otocyon megalotis, 0.1 case/mo). The incidence of rabies for all species did not change significantly over the whole study period. However, seasonal variations with an increase in the number of cases between June and November of each year, as well as 34 yr cyclical fluctuations were identified in domestic ruminants and black-backed jackals. The black-backed jackal time-series variable was a significant predictor of the domestic-ruminant and dog time-series variables. The rainfall seasonality combined with the seasonal reproductive pattern of the black-backed jackal appeared to be plausible explanations for the seasonal variations of rabies. However, there was no overall significant correlation between the cyclical weather fluctuations and the 3-4 yr cyclical rabies variations.