• A new study warns cassava brown streak disease could expand to about 33.7% of Africa’s land.

• Climate change and infected planting materials may accelerate the virus’s spread.

• West Africa, including Côte d’Ivoire, Ghana, and Nigeria, could face future exposure.

Cassava brown streak disease (CBSD), a viral infection long confined to the coastal regions of East Africa, could spread rapidly westward and expand its potential climatic range across about 33.7% of Africa’s land, scientists warned in a study published on January 16, 2026, in the East African Journal of Science, Technology and Innovation.

The study, titled Predicting the Current and Future Suitable Habitats of Cassava and Cassava Brown Streak Disease in Africa, was conducted by researchers including scientists affiliated with Stellenbosch University in South Africa. The team mapped both current and future areas where cassava cultivation and the disease could coexist using species distribution models.

These statistical tools rely on environmental data — including temperature, rainfall, and elevation — to predict where species may appear or spread over time.

The results show that about 54.6% of Africa’s land area, or roughly 16.2 million square kilometers, currently offers suitable conditions for cassava cultivation. Most of these areas are located in tropical and subtropical regions of sub-Saharan Africa.

At the same time, researchers estimate that around 10.2 million square kilometers — or 33.7% of the continent — provide favorable conditions for cassava brown streak disease, widely considered the most destructive viral disease affecting the crop.

CBSD causes necrosis in cassava roots, the edible part of the plant, rendering harvests unsuitable for consumption. The disease’s main historical hotspots are currently located along the coasts of Tanzania and Mozambique.

According to the study’s projections, the most vulnerable regions in the future include Tanzania’s eastern coast and the lake regions of Tanzania, Uganda, and southeastern Democratic Republic of Congo. Malawi, Rwanda, Burundi, and Angola — where outbreaks have already been reported — also rank among the countries at high risk, along with northern Zambia.

Cassava brown streak disease has not yet been reported in West Africa. However, species distribution models identified environmental conditions that could allow the disease to spread in the region in the coming decades, particularly in Côte d’Ivoire, Ghana, and Nigeria.

Climate change appears to be the main driver behind the projected expansion of the disease. Warmer and wetter conditions, combined with shifting rainfall patterns, are allowing the whitefly (Bemisia tabaci) — the insect that transmits the virus — to expand beyond the altitude limit of about 1,000 meters, once considered unfavorable to its survival.

Several scientific studies have found that the whitefly is gradually adapting to the climatic conditions typical of cassava-growing areas in the African Great Lakes region.

Infected planting material is another major factor behind the spread of CBSD across the continent. Certified systems for distributing disease-free cassava cuttings remain uncommon in much of sub-Saharan Africa.

This contrasts with major Asian cassava-producing countries such as Thailand — the world’s leading exporter of cassava products — where certified disease-free planting material is distributed through structured systems overseen by the state.

At the same time, many high-yield cassava varieties developed to resist cassava mosaic disease (CMD) remain highly vulnerable to cassava brown streak disease, creating a large reservoir of susceptible host plants.

Cassava’s ability to withstand drought and high temperatures has made it a key crop in Africa’s fight against food insecurity, especially as climate change accelerates. But the study warns that containing CBSD will require coordinated action.

Researchers say the most viable responses include breeding cassava varieties resistant to the virus, building systems to distribute certified disease-free planting material, and tightening oversight of informal seed and cutting markets. Without such measures, the disease — sometimes described as the “Ebola of cassava” — could spread far beyond its current range.

Walid Kéfi