Future climate change is projected to predominantly suppress the transmission potential of the small ruminant parasite Haemonchus contortus in Africa

This paper examines the impact of climate change in Africa on the transmission potential (Q₀) of Haemonchus contortus (H. contortus), a highly pathogenic haematophagous gastrointestinal nematode (GIN) parasite that has significant implications for the health and productivity of small ruminants. Changes in Q₀ were assessed over the period 1981-2070 under a high emission scenario (RCP 8.5). Climate data was sourced from bias-adjusted Coordinated Regional Climate Downscaling Experiment (CORDEX) models for Africa, which was split into 13 subregions based on areas within each having approximately similar rainfall seasons, which also defines typical periods of H. contortus transmission in Africa. Results indicate that while the transmission potential of H. contortus may increase across some months in the Atlas region and in some high-elevation and coastal areas, Q₀ is more widely projected to decrease across much of Africa. While climate change is not expected to alter the length of the transmission season in most areas of Africa, marginally shorter transmission periods are expected in southern East Africa, the Gulf of Guinea, and the Eastern Sahel, while new periods of transmission are projected to occur in western Southern Africa. Future research should focus on optimising the model for Africa and developing a decision-support tool for farmers, advisors and animal health services that classifies Q₀ by hazard severity and provides tailored management recommendations for each category.