Waning Trends in Prevalence and Intensity of Wuchereria bancrofti Transmission Over Ten Chemotherapy Rounds in Ghana

Ghana’s lymphatic filariasis (LF) elimination was intensified by Global Programme to Eliminate Lymphatic filariasis in 2000. LF transmission was interrupted in some endemic district, yet, persistent in others. This study investigated some characteristics of Wuchereria bancrofti that potentially contribute to persistent LF transmission in Ghana’s endemic districts after prolonged mass chemotherapy (≧15yrs) expected to interrupt transmission. Participants’ finger-prick blood was screened for antigenaemia and positives followed for night blood to detect microfilariae. The antigenaemia/microfilaraemia prevalence, implications of W. bancrofti transmission, and microfilariae clearance using scoring method (SM) were assessed. Exactly 2973 individuals were screened for antigenaemia and 33 found positive. Infected individuals were followed for night blood to detect microfilaraemia in 8 communities from the 4 study districts. The antigenaemia/microfilaraemia prevalence in Antseambua, Asemkow, Badunu, Navio (Sanwu) Central, Atampiisi Bongo, and Balungu Nabiisi were 1.3/0.0, 0.8/0.3, 0.8/0.0, 1.2/0.0, 1.7/0.0, and 3.1/0.9 respectively but none in Ampeasem and Obrayebona. Microfilariae density for thick blood films/Sedgwick counts was relatively higher in Western Region (283.9/410.0) compared to Upper East Region (44.5/25.0). Microfilariae clearance/reinfection was observed (using SM). Currently, prevalence thresholds suggest competent vectors can sustain LF transmission in Ahanta West District (hotspot) and cause possible reinfection/resurgence in Bongo (control district).