Geographical distribution and habitats of the freshwater snail Bulinus reticulatus and its susceptibility to Schistosoma haematobium miracidia under experimental conditions

Abstract

A brief account is given of the geographical distribution and habitats of Bulinus reticulatus as reflected by the 278 samples currently on record in the database of the National Freshwater Snail Collection, Potchefstroom University. The  susceptibility of field specimens and their F1 generation offspring to miracidia of Schistosoma haematobium (urinary bilharzia parasite) under experimental conditions was also investigated. The records show that B. reticulatus is well represented only in a central area in South Africa. However, as it is a specialized inhabitant of ephemeral, seasonal habitats and might not be active for more than a few months each year, it may not be found unless searched for specifically. It could therefore be more widespread than indicated by its scattered records at present. The samples on record were collected mainly in streams and in habitats with seasonal water and either sandy or muddy substrata. Although infection rates of 40% and 75% were recorded for the parental specimens and their F1 generation, respectively, it is concluded that B. reticulatus would probably not play a major role in the transmission of urinary bilharzia under natural conditions on account of the relatively short lifespan and shedding period of infected snails, and the nature of their habitats.

Key words: geographical distribution, habitat preferences, experimental infection, epidemiology of schistosomiasis, Bulinus reticulatus