Occurrence of Onchocerciasis infection after decades of mass drug administration in the Western North Region of Ghana: The case of Sefwi Akontombra district

Abstract

Background Onchocerciasis is the world’s second leading cause of infectious blindness and a major public health problem in many parts of the world, including Ghana, with severe impact on the skin also. Mass drug administration (MDA) with ivermectin began in the Sefwi Akontombra district of the Western North Region of Ghana in 1994. The aim of this cross-sectional study was to evaluate the impact of about three decades of MDA on onchocerciasis and its clinical manifestations by investigating the current nodule and microfilaria (MF) prevalence in the Sefwi Akontombra district using established protocols. Methodology This cross-sectional study had participants examined for signs of dermal/skin onchocerciasis and palpated, and those with ≥ 1 palpable sub-cutaneous nodule had skin snips taken from the left and right iliac crests for later parasitological (microfilariae) assessment. Logistic regression models were used to identify independent predictive and risk factors significantly associated with nodule and MF prevalence. Results A total of 1980 participants from 25 communities in three sub-districts were recruited. Compliance to the MDA intervention in the district was 93.7%. The study recorded Onchocerca nodule prevalence of 35.4% (N = 701), out of which 31.5% (N = 221) were MF positives, with district community microfilariae load (CMFL) and geometric mean intensity of 0.25 MF/ss and 0.26 MF/ss respectively. Adawu, the central community among the 25 surveyed recorded the highest CMFL (0.77 MF/ss)— with 14 communities being hypoendemic and 11, mesoendemic for the onchocerciasis infection. The overall estimated district onchocerciasis MF prevalence was 11.2%, making the district hypoendemic. Of the 17 participants who presented with dermal symptoms, acute papular onchodermatitis (41.2%) was the most prevalent. Age, ivermectin intake and gender were the independent predictive factors significantly associated (p < 0.05) with onchocerciasis in the district. Conclusion Despite decades of ivermectin administration in the district, the MF prevalence in the district was > the 1% threshold required for elimination. As the focus of the Ghana Onchocerciasis Control Programme has changed from control to elimination, MDA should be intensified in areas with MF prevalence > 1%. Though the district’s CMFL was far below the 5.0 MF/ss public health problem threshold, macrofilaricidal drugs should be explored to complement the microfilaricidal ivermectin.