Seasonality in the transmission of schistosomiasis and in populations of its snail intermediate hosts in and around a sugar irrigation scheme at Richard Toll, Senegal


Sturrock, RF; Diaw, OT; Talla, I; Niang, M; Piau, JP; Capron, A; (2001) Seasonality in the transmission of schistosomiasis and in populations of its snail intermediate hosts in and around a sugar irrigation scheme at Richard Toll, Senegal. Parasitology, 123 Suppl. S77-89. ISSN 0031-1820

[img]
Preview
Text - Published Version
License:

Download (388kB) | Preview

Abstract

Irrigation for intensive sugar cultivation started in the early 1980s at Richard Toll, some 100 km from the mouth of the Senegal River. Infections with Schistosoma mansoni were first seen in late 1988. This study records quantitative snail surveys for over 3 years from 1992 at sites representing different habitats in and around the irrigation scheme. Populations of both Biomphalaria pfeifferi (the intermediate host of S. mansoni) and Bulinus spp. (mainly B. truncatus, the local host of S. boris) peaked in late 'spring' or early 'summer', depending on the habitat, and then remained low until the following spring', B. pfeifferi favoured smaller, man-made habitats with most transmission between May and August each year. The less abundant Bulinus spp. favoured larger natural and man-made habitats with most S. bovis transmission between April and July. S. mansoni infections were more, but S. bovis infections were less abundant than other trematodes in their respective snail hosts. Ecological changes in the early 1980s due to sugar irrigation pre-dated similar, more widespread changes in the late 1980s when the completion of dams across the Senegal River prevented seasonal rain fed floods and sea water intrusion. S. mansoni has since spread rapidly around Richard Toll. The incompatibility of the local S. haematobium strains with the dominant bulinid snails has so far prevented an epidemic of urinary schistosomiasis at Richard Toll, but the invasion of similar downstream habitats by susceptible B. globosus is worrying. The principal control measure, chemotherapy, given in the 'winter' would minimise the rate of reinfection. It could be reinforced by judicious mollusciciding within the sugar irrigation scheme but not elsewhere.

Item Type: Article
Keywords: Animal, Biomphalaria/growth & development/*parasitology, Bulinus/growth & development/*parasitology, Ecology, Female, Human, Male, Schistosoma mansoni/*growth & development, Schistosomiasis mansoni/epidemiology/*transmission, Seasons, Senegal/epidemiology, Support, Non-U.S. Gov't, Water/parasitology, Animal, Biomphalaria, growth & development, parasitology, Bulinus, growth & development, parasitology, Ecology, Female, Human, Male, Schistosoma mansoni, growth & development, Schistosomiasis mansoni, epidemiology, transmission, Seasons, Senegal, epidemiology, Support, Non-U.S. Gov't, Water, parasitology
Faculty and Department: Faculty of Infectious and Tropical Diseases > Dept of Disease Control
PubMed ID: 11769294
Web of Science ID: 173291200007
URI: http://researchonline.lshtm.ac.uk/id/eprint/16273

Statistics


Download activity - last 12 months
Downloads since deposit
305Downloads
459Hits
Accesses by country - last 12 months
Accesses by referrer - last 12 months
Additional statistics for this record are available via IRStats2

Actions (login required)

Edit Item Edit Item