Banana bunchy top disease in Africa-Predicting continent-wide disease risks by combining survey data and expert knowledge

Across Africa, banana bunchy top disease (BBTD) severely impacts banana production and livelihoods of millions of smallholder farmers. Mapping vulnerability of landscapes to monitor BBTD establishment and spread is crucial for proactive measures of disease exclusion. To highlight current and future risks of BBTD in Africa, the relationship between 1160 field observations from 14 BBTD surveys and environmental covariate maps was determined using logistic regression. From these relationships, we inferred the environmental suitability of the African landscape for the possible wider spread of BBTD. Using this information and expert knowledge, we generated a map highlighting the main banana production areas at risk of BBTD entry and establishment. We combined these maps to create a priority map that highlights the areas that need most attention in combating BBTD through surveillance and measures to prevent its spread. Our analysis shows that BBTD is widespread across tropical Africa, with dispersal over several hotspots. Central and Western Africa are most favourable for the development of BBTD. Central, West and South-East Africa are most at risk of BBTD entry and initial establishment. Areas in West and Central Africa, in the Great Lakes Region in Eastern Africa and in South-East Africa, particularly in Malawi and Mozambique, score high on the prioritization index for surveillance and mitigation efforts. Recent reports of BBTD presence in north-western Uganda and western Tanzania support these risk predictions. For these and other not-yet-infected areas, measures for close surveillance and proactive management of the disease are needed.

Automated summary

Banana bunchy top disease (BBTD) has a severe impact on banana production and smallholder farmers in Africa. Mapping vulnerability of landscapes to monitor BBTD establishment and spread is crucial for proactive measures. Through logistic regression, the relationship between field observations and environmental covariate maps was determined to highlight the current and future risks of BBTD. Using this information, a priority map was created to identify areas that need the most attention in combating BBTD through surveillance and prevention measures.