Schistosomiasis in Lake Malaŵi Villages
Historically, open shorelines of Lake Malaŵi were free from schistosome, Schistosoma haematobium, transmission, but this changed in the mid-1980s, possibly as a result of over-fishing reducing density of molluscivore fishes. Very little information is available on schistosome infections among people in lake-shore communities and therefore we decided to summarise data collected from 1998 to 2007. Detailed knowledge of the transmission patterns is essential to design a holistic approach to schistosomiasis control involving the public health, fisheries and tourism sectors. On Nankumba Peninsula, in the southern part of the lake, inhabitants of villages located along the shores of Lake Malaŵi have higher prevalence of S. haematobium infection than those living in inland villages. Overall prevalence (all age classes combined) of urinary schistosomiasis in 1998/1999 ranged from 10.2% to 26.4% in inland villages and from 21.0% to 72.7% in lakeshore villages; for school children prevalence of infection ranged from 15.3% to 57.1% in inland schools and from 56.2% to 94.0% in lakeshore schools. Inhabitants on the islands, Chizumulu and Likoma, also have lower prevalence of infection than those living in lakeshore villages on Nankumba Peninsula. This increased prevalence in lakeshore villages is not necessarily linked to transmission taking place in the lake itself, but could also be due to the presence of more numerous typical inland transmission sites (e.g., streams, ponds) being close to the lake. Temporal data witness of intense transmission in some lakeshore villages with 30–40% of children cleared from infection becoming reinfected 12 months later (also lakeshore village). The level of S. mansoni infection is low in the lakeshore communities. Findings are discussed in relation to fishing in the lake.
KeywordsSchistosomiasis Over-fishing S. haematobium Lake Malaŵi
We are grateful to all the people who assisted in the field work. Also we would like to thank various institutions with the Government of Malawi for assistance and facilitation of the project. The BCP studies were supported by the Danish International Development Assistance, the Danish Bilharziasis Laboratory and the GoM/Danida/DBL Bilharzia Control Project in Malawi and the other studies by the NSF/NIH joint programme in ecology of infectious diseases (DEB-0224958).
- Beadle LC (1974) The Inland Waters of Tropical Africa. An Introduction to Tropical Limnology. Longman Group Ltd. 365 ppGoogle Scholar
- Bloch P, Madsen H, Furu P, Makaula P, Magnussen P (2001) Intersectoral collaboration on schistosomiasis control in lakeshore communities on Nankumba Peninsula, Mangochi district, Malaŵi. In: Proceedings of Workshop on Medical and Veterinary Malacology in Africa, Madsen, H, Appleton CC and Chimbari M (editors), Harare, Zimbabwe, November 8–12, 1999, Danish Bilharziasis Laboratory, pp 21–31Google Scholar
- Brown DS (1994) Freshwater Snails of Africa and Their Medical Importance. 2nd edition. Taylor and Francis, LondonGoogle Scholar
- Centers for Disease Control (1993). Schistosomiasis in US Peace Corps volunteers—Malaŵi, 1992. Morbidity and Mortality Weekly Report 42:564–570Google Scholar
- Hilbe JM (2008) Negative Binomial Regression. Cambridge University Press, CambridgeGoogle Scholar
- Hosmer DW, Lemeshow S (1989) Applied Logistic Regression. John Wiley and Sons, New YorkGoogle Scholar
- Louda SM, Gray WN, McKaye KR, Mhone OJ (1983) Distribution of gastropod genera over a vertical depth gradient at Cape Maclear, Lake Malaŵi. The Veliger 25:387–392Google Scholar
- Madsen H, Bloch P, Kristensen TK, Furu P (2001) Bulinus nyassanus is intermediate host for Schistosoma haematobium in Lake Malaŵi. Annals of Tropical Medicine and Hygiene 95:353–360Google Scholar
- Mandahl-Barth G (1972) The freshwater mollusca of Lake Malaŵi. Revue de zoologie et de botanique Africaines 86:257–289Google Scholar
- Phiri H, Bloch P, Madsen H, Dudley C (2001) Distribution and population dynamics of Bulinus globosus and B. nyassanus on Nankumba Peninsula, Mangochi District, Malaŵi. Preliminary findings. In: Proceedings of Workshop on Medical and Veterinary Malacology in Africa, Madsen, H, Appleton CC and Chimbari M (editors), Harare, Zimbabwe, November 8–12, 1999, Danish Bilharziasis Laboratory, pp 273–286Google Scholar
- Plouvier S, Leroy JC, Colette J (1975) A propos d’une technique simple de filtration des urines dans le diagnostic de la bilharziose urinaire en enquete de masse. Medecine Tropicale 35:229–230Google Scholar
- Wright CA, Klein J, Eccles DH (1967) Endemic species of Bulinus in Lake Malaŵi. Journal of Zoology, London 151:199–209Google Scholar