Reactions 659 - 12 Jul 1997

ADRs associated with ivermectinuse in areas endemic for Loa loaPatients who live in an area where Loa loa is endemic

are at risk for serious neurological reactions toivermectin when they are treated for onchocercias,according to the results of a study conducted inCameroon. The patients involved in the study lived in anarea where 40–90% of the residents were infected withOnchocerca volvulus and 10–33% were infected withLoa loa.

In the study, 17 877 patients were monitored for 1week after they were treated with ivermectin 150 µg/kg.Since previous studies have shown cases of ivermectin-induced encephalopathy in patients with a high L. loamicrofilaraemia, pretreatment capillary blood smearswere taken from 5550 patients aged ≥ 15 years.

Serious non-neurological reactions were observed in20 patients (incidence rate 11.2 per 10 000; 95% CI6.8–17.3); these reactions occurred within 5 days ofstarting treatment in all but 1 patient. In addition, 2patients experienced serious neurological reactions(incidence rate 1.1 per 10 000). Both these patientsdeveloped consciousness disorders 3–4 days aftertreatment and subsequently became comatose for 2–3days. They improved with symptomatic treatment andtheir symptoms resolved after 1 month. Theirpretreatment L. loa microfilarial counts were 152 940and 50 520 mf/ml, respectively.

Analysis of the 5550 patients whose pretreatmentmicrofilial load was ascertained, showed that the relativerisk for developing a marked or serious reaction toivermectin was significantly higher when the L. loamicrofilarial load was > 8100 mf/ml. The study authorsconclude that in areas where L. loa and O. volvulus areendemic, the intensity of infection with L. loamicrofilariae should be assessed before ivermectintherapy is administered for onchocerciasis and patientswho are at risk for serious reactions identified.Gardon J, et al. Serious reactions after mass treatment of onchocerciasis withivermectin in an area endemic for Loa loa infection. Lancet 350: 18-22, 5 Jul1997 800546463

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Reactions 12 Jul 1997 No. 6590114-9954/10/0659-0001/$14.95 Adis © 2010 Springer International Publishing AG. All rights reserved