Household pit latrines as a potential source of the fly Musca sorbens– a one year longitudinal study from The Gambia

Abstract

Summaryobjectives To assess whether the trachoma vector Musca sorbens was breeding in household latrines in a trachoma-endemic part of The Gambia.methods Longitudinal study of flies emerging from 16 sentinel household latrines selected at random from a list of all latrines present in four Gambian villages. Latrines were surveyed and fly traps were set over the drop hole for 24 h once per month for a year.results All the sentinel latrines were of the 'Gambian improved household latrine' design, which has a cement slab but is not ventilated or fly-proofed. The latrines were all in regular use by a family, mean number of users per latrine 14. conclusions Gambian improved household pit latrines cannot be considered a source of the trachoma vector M. sorbens, and the promotion of pit latrines as a method to reduce M. sorbens is warranted. A large number of C. albiceps were caught emerging from the latrines, but this species is not considered to be of medical importance.

Chrysomya putoria, a Putative Vector of Diarrheal Diseases

“…The first, and only, previous record of C. putoria in The Gambia was from one ‘modern’ lavatory in Sukuta, on the coast, in July 1952 [30]. The adults of C. putoria are morphologically similar to C. albiceps , and we think that recent descriptions of C. albiceps emerging from pit latrines in The Gambia [12] are likely to be mistaken; meaning C. putoria is the dominant fly in the country, not C. albiceps . Chrysomya putoria are known to breed in wet feces and can liquefy large fecal masses [31], which help break down feces and increase the longevity of latrines.…”

“…It was found to be the major fly species in a variety of latrine types in Botswana and Tanzania [11]. In The Gambia, an average pit latrine produces over 100,000 flies each year [12]. Of these flies, 97.8% were identified as Chrysomya spp.…”

Integrated Mapping of Yaws and Trachoma in the Five Northern-Most Provinces of Vanuatu

“…M . sorbens preferentially breeds on human faeces left lying on the soil, with faeces in pit latrines of any kind, including “unimproved” latrines, not constituting a site for oviposition [32,33]. In our data, poor latrine access may simply be a surrogate for deprivation overall, with its associated limitations in economic and educational opportunities.…”

Risk Factors for Active Trachoma and Ocular Chlamydia trachomatis Infection in Treatment-Naïve Trachoma-Hyperendemic Communities of the Bijagós Archipelago, Guinea Bissau

“…The presence of flies on faces has been well-documented as a risk factor for active trachoma in some environments [8], [29], [45] and there is evidence that the eye-seeking flies Musca sorbens (and possibly other domestic muscidae) are passive vectors in C. trachomatis transmission [45]–[48]. One study that examined fly density around used household pit latrines in The Gambia found that the majority of flies emerging from the latrine were Chrysomya albiceps , rather than M. sorbens [47]. We do not have data on the species of flies around pit latrines in Bijagós communities, however it is possible that there is ovipositioning by M. sorbens in or around latrines in these communities.…”