Sao Tome and Principe on the verge of eliminating lymphatic filariasis as a public health problem: evidence from IDA impact assessment surveys

Sao Tome and Principe implemented three rounds of mass drug distribution against lymphatic filariasis between 2018 and 2020, achieving high epidemiological coverage (86.4% in 2018, 74.2% in 2019, and 80.0% in 2020). A survey conducted in 2022 evaluated 14,132 adults and identified 21 positive cases (0.15%), while a follow-up survey from December 2024 to January 2025 evaluated 14,653 adults and detected seven positive cases (0.05%). Among 28 antigen-positive individuals, no microfilariae were detected. National morbidity records documented 190 cases of lymphedema and nine cases of hydrocoele. Infection indicators remain well below World Health Organization thresholds, suggesting that lymphatic filariasis transmission is unlikely to be sustained. Sao Tome and Principe appears to be close to eliminating lymphatic filariasis as a public health problem.