Summary Background The burden of loiasis has received limited attention and loiasis is still considered a benign condition. To assess whether loiasis bears any excess mortality, we did a ...retrospective cohort study in Cameroon. Methods In 2001, 3627 individuals living in 28 villages were examined for Loa loa infection. In 2016, these villages were revisited and the vital status was determined for 3301 individuals (91%). The data were analysed at community level to assess the relation between the level of L loa infection in 2001 and standardised mortality rates (SMRs), and at individual level to assess the excess mortality relative to the 2001 microfilaraemia and to calculate the population-attributable fraction of mortality associated with L loa microfilaraemia. Findings 915 deaths occurred during the follow-up time (mean time of 12·5 years IQR 10·2–14·9) between April, 2001, and March 22, 2016. Crude mortality rate was 20·3 deaths per 1000 person-years. SMRs increased by 4·1% when the proportion of participants infected with greater than 30 000 microfilariae per mL increased by 1% (p=0·030). People aged older than 25 years with greater than 30 000 microfilariae per mL in 2001 died significantly earlier than did amicrofilaraemic people (time ratio 0·67, 95% CI 0·48–0·95, p=0·024). The population-attributable fraction of mortality associated with presence of L loa microfilaraemia was 14·5% (95% CI 6·5–21·8, p=0·001). Interpretation High-grade L loa microfilaraemia is associated with an increased mortality risk, suggesting that loiasis is not a benign condition and merits more attention because of its effect on onchocerciasis and lymphatic control strategies. Loiasis should be considered for inclusion in the WHO's list of neglected tropical diseases. Funding Drugs for Neglected Diseases initiative.
Summary The broad-spectrum antiparasitic drug ivermectin was licensed for use against onchocerciasis in 1987, yet the mechanisms by which it exerts a fast decrease and long-lasting suppression of ...Onchocerca volvulus microfilaridermia, and inhibition of microfilarial release by female worms remain largely unknown. A better understanding of the effects of ivermectin on O volvulus microfilariae and macrofilariae is crucial to improve our ability to predict the long-term effect of treatment. We did a systematic review of individual and population-based ivermectin trials to investigate the temporal dynamics of the drug's microfilaricidal and embryostatic efficacy after administration of a single, standard dose (150 μg/kg). Meta-analyses on data from 26 microfilarial and 15 macrofilarial studies were linked by a mathematical model describing the dynamics of potentially fertile female parasites to skin microfilariae. The model predicts that after treatment, microfilaridermia would be reduced by half after 24 h, by 85% after 72 h, by 94% after 1 week, and by 98–99% after 1–2 months, the latter also corresponding to the time when the fraction of females harbouring live microfilariae is at its lowest (reduced by around 70% from its original value). Our results provide a baseline microfilarial skin repopulation curve against which to compare studies done after long-term treatment.
Summary 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 (8209·0–11 480·0) to 724·4 (340·7–1114·2; p<0·0001), and of T trichiura eggs from 1107·4 (878·5–1336·3) to 366·0 (255·7–476·2; 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. Funding Bill & Melinda Gates Foundation.
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