Equatorial Guinea moving towards achieving Onchocerciasis elimination as public health problem

Equatorial Guinea is on the cusp of a historic achievement: the elimination of onchocerciasis as a public health problem. Groundbreaking findings from a recently published study in Infectious Diseases of Poverty reveal that mainland Equatorial Guinea has achieved near-zero transmission, with an overall seroprevalence of just 0.3%. This research, which employed cutting-edge diagnostic techniques, positions the country as a leading candidate for elimination certification, following in the footsteps of Niger.

The study, conducted between September and December 2019, covered over 70 communities across mainland Equatorial Guinea. Researchers used a combination of Ov16 ELISA tests, skin snip biopsies, and PCR sequencing to assess onchocerciasis transmission levels. Out of 3,951 individuals tested, only one skin snip biopsy amplified Onchocerca volvulus DNA, and no microfilariae were detected. Notably, no anti-Onchocerca antibodies were found in children under 21, suggesting that transmission has been interrupted for decades. The study also evaluated lymphatic filariasis (LF), finding an overall seroprevalence of 4.6%, but with no evidence of active Wuchereria bancrofti infections through microscopy or molecular testing.

Dr. Jorge Cano, ESPEN Surveillance Officer and co-author of the manuscript, emphasized the importance of these results, stating: “The findings obtained through this research indicate that onchocerciasis may no longer constitute a public health problem in Equatorial Guinea, positioning the country on the verge of achieving elimination. Equatorial Guinea could follow Niger as a leading example in Africa in declaring the elimination of onchocerciasis as a public health problem.”

Beyond disease elimination, the study underscores the value of integrated NTD surveillance. By combining diagnostics for onchocerciasis and LF in a single survey, the research maximized resource efficiency while providing actionable insights for both diseases. The findings also stress the need for cross-border collaboration with Gabon and Cameroon, where onchocerciasis transmission persists, to address potential importation risks. Moving forward, the researchers recommend a focused survey of children to conclusively verify the absence of onchocerciasis transmission and entomological studies in border areas.

This landmark study not only brings Equatorial Guinea closer to achieving the World Health Organization’s 2030 NTD roadmap goals but also serves as a model for other countries striving to eliminate NTDs. The full manuscript can be accessed here.

Ncogo, P., Hernández-González, A., Ta-Tang, TH. et al. Approaching onchocerciasis elimination in Equatorial Guinea: Near zero transmission and public health implication. Infect Dis Poverty 13, 86 (2024). https://doi.org/10.1186/s40249-024-01254-9