Spatiotemporal patterns and ecological niche modeling of Blackleg in cattle in the Western Amhara region, Ethiopia, 2018-2023.

Blackleg is a soil-borne disease primarily affecting cattle and is caused by Clostridium chauvoei. It is endemic and is one of the bottleneck diseases of Ethiopia's livestock industry. The Amhara region is one of the most highly affected areas by blackleg disease in the country. This study aimed to examine the spatial distribution and temporal patterns, identify hotspot areas, and understand the environmental predictors of blackleg disease in the Western Amhara region. This study was conducted based on blackleg outbreak records. Spatial distributions of blackleg were created using ArcGIS, and temporal analysis was performed using STATA. The statistical significance of the trends was evaluated using Poisson regression. Spatiotemporal cluster analysis was performed using SaTScan for confirmatory cluster detection. The effects of soil nature and environmental conditions on the occurrence of blackleg were estimated using maximum entropy ecological niche modeling. The average incidence of blackleg outbreaks per district over the six years was 4.91, corresponding to 0.82 outbreaks per year, with marked variations in the number of outbreaks between the seasons. The highest incidence (66%) was recorded in the post-rainy season, followed by the rainy (13%) and early rainy seasons (11%), whereas the lowest incidence was recorded in the dry season (10%). The outbreak had a linear trend, with a slight increase in the number of outbreak incidents over time. The northeastern parts of North Gondar and Central Gondar, southern parts of South Gondar and Awi, southeastern parts of West Gojjam, and eastern parts of East Gojjam were hotspot areas with a high intensity of blackleg outbreaks. Nine statistically significant clusters of blackleg outbreaks were identified. The spatial distribution sustainability of C. chauvoei was characterized by a distinct bimodal response to edaphic factors. From the findings, it was possible to conclude that outbreaks were influenced by environmental factors and concentrated in specific periods and geographic areas, which can be used as inputs in planning the prevention and control of black leg.