Efficacy of niclosamide as a potential antipenetrant (TAP) against cercariae of Schistosoma mansoni monkeys

Abstract

A 1% (W/V) formulation of Niclosamide (2', 5-Dichloro-4-nitrosalicylanilide) (TAP) was tested on Cebus apella monkeys as a topical prophylactic against schistosomiasis mansoni. Two experiments were conducted using the same formulation. In the first experiment, the TAP provided complete protection against schistosomiasis for 3 days. Of the 4 monkeys treated with TAP 7 days before exposure to Schistosoma mansoni cercariae, 2 were completely protected. The remaining 2 monkeys of the 7 day treatment group had a 78% or greater reduction in adult worm burdens when compared to the placebo treated monkeys. The second experiment was designed to determine the time between day 3 and 7 when the TAP no longer provided complete protection. However, all of the TAP treated monkeys in this experiment were completely protected, even the monkeys treated 7 days earlier. In both experiments, all monkeys used as infection controls and those receiving only the placebo became infected and showed typical experimental schistosomiasis. These results demonstrate that the TAP could provide fast acting, short-term protection to people who must enter cercariae infested water.

Cream formulations protecting against cercarial dermatitis by Trichobilharzia

“…Our results confirm earlier findings: a 1% niclosamide-based lotion guarantees a high level of cercarial impairment and significantly reduces the likelihood of infection (Bruce et al 1992;Abu-Elyazeed et al 1993).…”

New Tools for the Schistosomiasis Elimination Toolbox: Barriers and Opportunities for Development of a Topical Cercarial Anti-Penetrant

“…Although 1 percent niclosamide-based lotion was shown to provide a high level of cercarial impairment that significantly reduced the likelihood of infection in a controlled laboratory setting (Bruce et al, 1992;Abu-Elyazeed, Podgore, Mansour, & Kilpatrick, 1993;Wulff, Haeberlein, & Haas, 2007), a subsequent population-based study suggested that a 1 percent niclosamide lotion self-applied to the limbs and torso twice a week failed to prevent S. haematobium reinfection among Egyptian farmers (Podgore et al, 1994). The conflicting results from the populationbased study may have been influenced by variation in skin coverage among study participants when applying the compound, including differences in the frequency of application and techniques used to rub the lotion on the skin.…”