The World Health Organisation (WHO) says yellow fever transmission remained active across Africa and the Americas from January to May 2026, with 95 confirmed human cases recorded across affected countries during the period.

In a statement on Wednesday, WHO said six countries in the Americas reported 79 confirmed infections and multiple epizootics, while three African countries recorded 16 cases during the review period.

The organisation said 32 suspected cases were being investigated in five additional countries, raising concerns about possible under-detection and continued virus circulation in areas with limited surveillance capacity currently.

It said, “WHO’s rapid risk assessment concluded that unvaccinated populations in areas with a history of yellow fever transmission face the greatest threat. The highest risk occurs where low vaccination coverage overlaps.”

According to WHO, transmission in the Americas continued into 2026 following an increase in cases recorded during 2025, reflecting persistent viral circulation and heightened public health concerns across affected regions.

The organisation said, “Multiple epizootics in non-human primates confirm active sylvatic circulation, signalling ongoing virus activity in forest mosquitoes and heightened spillover risk to humans.”

The WHO said sustained yellow fever activity continued across Africa, affecting 13 high-risk countries participating in the Eliminate Yellow Fever Epidemics (EYE) Strategy aimed at reducing outbreak risks continent-wide.

The organisation said that outbreaks recorded between October 2025 and May 2026 coincided with seasonal ecological factors, including rainfall patterns, temperature changes and increased mosquito abundance levels.

“These conditions increase vector density and human exposure, especially where vaccination coverage is low. No imported cases were detected outside the two affected WHO regions so far.

“However, expanding vector suitability, rapid urbanisation, climate shifts, and increased human mobility create conditions conducive to international spread,” WHO noted.

It also highlighted emerging risks to global public health.

According to the WHO, strengthening active surveillance, timely laboratory testing, cross-border coordination and information sharing remain essential for detecting infections early and containing outbreaks before wider transmission occurs.

“Early detection in both human and animal populations is critical to prevent urban transmission cycles. Vaccination remains the primary means for prevention and control of yellow fever.

“WHO continues to support countries in expanding routine immunisation programmes and preventive vaccination campaigns to boost population immunity and reduce outbreak risk,” the organisation added.

(NAN)