Abstract:
BACKGROUND : Although anthrax is endemic in Lesotho, limited information is available on the patterns of
the disease among livestock animals. This study investigated temporal patterns of anthrax
outbreaks and cases among livestock animals in Lesotho.
METHODS : Secondary data of anthrax outbreaks reported to the Department of Livestock Services
between January 2005 and December 2016 was used for this study. Proportions of anthrax
outbreaks and cases, and their corresponding 95% confidence interval were calculated and
compared across year, season, month and region using the Chi-square or Fisher's exact
test. The autoregression model was used to evaluate annual trends of anthrax outbreaks
and cases. RESULTS : A total of 38 outbreaks were reported in the Lowlands districts of Lesotho. District was significantly
(p<0.0001) associated with outbreaks and cases, with the highest proportions of outbreaks
(52.6%) and cases (70.2%) reported in Maseru. Significantly (p = 0.0004) higher
proportions of anthrax outbreaks (78.9%) and cases (95.1%) were reported in the rainy-hot
season compared to the dry-cold season. Five hundred and twenty-six (n = 526) anthrax
cases were reported with significantly (p<0.0001) higher proportion of cases (70.3%) in cattle
compared to other species. Higher proportion of anthrax cases (35.9%) were reported in
2008 and during the months of February (30.8%) and April (30.2%). There was no significant
annual trend in anthrax outbreaks (r = 0.0282; p = 0.6213) and cases (r = 0.0873; p = 0.3512) over the study period. CONCLUSION : The burden of anthrax in Lesotho is significantly higher in cattle. Anthrax outbreaks occur
only in the lowland districts and follow a seasonal pattern. Therefore, more effort should be targeted at curbing the disease in cattle and the lowlands districts. Furthermore, there
should be heightened monitoring of cases in the rainy season to ensure that resultant carcasses
are disposed of appropriately to minimise future outbreaks.
