Effect of 3 years of biannual mass drug administration with albendazole on lymphatic filariasis and soil-transmitted helminth infections: a community-based study in Republic of the Congo

Background The standard treatment strategy of mass drug administration with ivermectin plus albendazole for lymphatic filariasis cannot be applied in central Africa, because of the risk of serious adverse events in people with high Loa loa microfilaraemia. Thus, alternative strategies are needed. We investigated one such alternative strategy for mass drug administration for elimination of lymphatic filariasis and soil-transmitted helminth infections in Republic of the Congo. Methods In 2012, we started a 3 year community trial of biannual mass administration of albendazole in a village in Republic of the Congo. All volunteering inhabitants aged 2 years or older were offered albendazole (400 mg) every 6 months. Infection with Wuchereria bancrofti was diagnosed with a rapid card immunochromatographic test for antigenaemia. People with antigenaemia were tested for microfilaraemia by night blood smears. Individuals were also tested for soil-transmitted helminth infections (ie, hookworm, Ascaris lumbricoides, Trichuris trichiura) with the Kato-Katz method. Assessment surveys were done at 12, 24, and 36 months. The main outcome measure was change in infection rates from baseline to year 3. Findings Therapeutic coverage was more than 80% in all six rounds of mass administration of albendazole. Between 2012 and 2015, W bancrofti antigenaemia and microfilaraemia rates in the community fell significantly, from 17.3% (95% CI 14.7-20.0) to 4.7% (3.3-6.6; p<0.0001) and from 5.3% (3.9-7.1) to 0.3% (0.1-1.2; p<0.0001), respectively. The geometric mean microfilaria count in microfilaraemic people fell from 199.4 (120.4-330.5) per mL in 2012 to 39.1 (95% CIs not computed) per mL in 2015 (p=0.0095). Hookworm infection was undetectable after 1 year. Between 2012 and 2015, the number of A lumbricoides eggs expelled per g of faeces fell from 9844.6 (82090-11 480.0) to 7244 (3407-11142; p<00001), and of T trichiura eggs from 11074 (878.5-1336.3) to 366.0 (255.7-4762; p<0.0001). Interpretation Our findings strongly support WHO's provisional strategy of biannual mass administration of albendazole to eliminate lymphatic filariasis in areas where loiasis is co-endemic and ivermectin cannot be safely mass administered.