# Assessment of the efficacy and safety of two albendazole regimens for the treatment of hypermicrofilaraemic loiasis in adults in Woleu-Ntem Province, Gabon: A phase IIb single-blind randomised controlled trial

## TL;DR

A study in Gabon found that a 30-day course of 400 mg albendazole safely and effectively reduces high levels of Loa loa parasites in the blood, potentially making other treatments safer.

## Contribution

Demonstrates that 400 mg albendazole is as effective as 800 mg in reducing microfilaraemia and is better tolerated.

## Key findings

- Both 400 mg and 800 mg albendazole regimens significantly reduced microfilaraemia in hypermicrofilaraemic patients.
- Over 70% of patients treated with albendazole had microfilaraemia below 8,000 mf/mL after 30 days.
- The 400 mg dose was better tolerated and showed no significant difference in efficacy compared to the 800 mg dose.

## Abstract

Loa (L.) loa hypermicrofilaraemia (≥ 8,000 mf/mL) increases the risk of severe adverse events during mass ivermectin administration for onchocerciasis control. Albendazole has been proposed as a potential alternative for reducing microfilaraemia prior to ivermectin administration.

This prospective study was conducted in northern Gabon from November 2021 to April 2022. Individuals infected with L. loa were screened and allocated to three groups: two treatment arms receiving 400 mg or 800 mg of albendazole daily for 30 days among hypermicrofilaraemic participants, and a group with microfilaraemia < 8,000 mf/mL. Clinical symptoms and parasitological data were collected on Days 0, 2, 7, 14, and 30. A total of 70 participants were enrolled: 16 in the 400 mg group, 16 in the 800 mg group, and 38 in the group with microfilaraemia below 8,000 mf/mL. Itching was the most frequently reported adverse event. By Day 30, no participants in the group with microfilaraemia below 8,000 mf/mL presented with clinical symptoms. Microfilaraemia significantly decreased in all groups (p < 0.01). After 30 days, over 70.0% of patients treated with albendazole had microfilaraemia < 8,000 mf/mL. There was no significant difference in efficacy between the two albendazole regimens.

Daily administration of 400 mg albendazole for 30 days effectively reduces microfilarial loads in patients with L. loa hypermicrofilaraemia and is well tolerated and safe. This pre-treatment regimen may reduce the risk of adverse events associated with ivermectin administration. Further research is needed to evaluate the long-term persistence of microfilarial suppression.

Loiasis is a parasitic disease caused by the Loa loa worm and transmitted by the bite of a fly called Chrysops. People living in Central Africa can carry millions of these microscopic worms in their blood. However, treating this disease is complicated: when the number of parasites in the blood is too high, giving the usual treatments (like ivermectin) can lead to dangerous side effects, including coma or even death. This study tested whether albendazole, a common anti-parasitic drug, could safely reduce the number of worms in heavily infected patients in rural Gabon. We compared two doses - 400 mg and 800 mg taken daily for 30 days - and found that both doses were effective in lowering parasite levels below the danger threshold. The lower dose worked just as well and was better tolerated, making it more suitable for use in individual-scale treatment campaigns. Our findings suggest that a 400 mg daily regimen of albendazole may help prepare patients for safer treatment with curative medications and could improve control of this neglected disease in hard-to-reach communities.