Confirmatory mapping for lymphatic filariasis in districts previously considered nonendemic in Ghana

Objectives: Lymphatic filariasis (LF) elimination efforts in Ghana have been ongoing since 2001, achieving substantial progress through mass drug administration (MDA). However, despite significant advances, LF transmission persists in certain areas. Some districts previously classified as nonendemic have reported lymphedema and hydrocele cases, raising concerns about LF endemicity. To address these gaps, a confirmatory mapping survey was conducted to reassess LF prevalence in districts with uncertain morbidity. Methods: A cross-sectional survey using the WHO-approved LF confirmatory mapping tool was conducted in 38/261 districts Ghana. Schoolchildren aged 9-14 years were randomly selected using the TAS Survey Sample Builder tool. Circulating filarial antigen (CFA) levels were measured using the Filaria Test Strip (FTS). Districts were classified as endemic if more than three positive cases were identified out 480 sampled. Subdistrict-level community surveys were conducted to confirm findings. Results: A total of 18,459 children were tested across the selected districts. Positive antigen cases were detected in 17 districts, with two districts (Nkoranza South and Wenchi Municipal) exceeding the critical threshold of three positive cases. Subdistrict surveys further confirmed high antigen prevalence of 1.68% (95% CI, 0.92-2.80; range: 1.00-5.00) and 4.73% (95% CI, 3.35-6.46; range: 0.96-14.29) in the Nkoranza South and Wenchi Municipal districts respectively. Conclusion: The confirmatory mapping survey revealed ongoing LF transmission in two previously classified nonendemic districts. These districts were reclassified as endemic, requiring MDA. Treatment has therefore been initiated in the Nkoranza South and Wenchi Municipal districts. This study underscores the importance of reassessing endemicity and implementing targeted interventions in areas with uncertain LF transmission.