Bulinus

Bulinus is a genus of freshwater, air-breathing snails in the family Planorbidae, commonly referred to as ram’s horn snails. Members of this genus have flat, planispiral shells that are typically small to medium in size and often brownish in color. As pulmonate snails, they breathe air using a pallial lung, and they inhabit still or slow-moving freshwater habitats such as ponds, lakes, marshes, and vegetated sides of rivers.

Geographic distribution of Bulinus is centered in Africa, with extensions into parts of Europe, the Middle East, and adjacent regions. Within these areas, Bulinus species occupy a range of aquatic environments, from calm margins to shallow, sunlit waters, where they feed primarily on algae and detritus. Their populations can be influenced by water quality, vegetation, and seasonal fluctuations.

Bulinus species are of particular medical and veterinary importance because several act as intermediate hosts for the trematode Schistosoma haematobium, the parasite responsible for urogenital schistosomiasis in humans. In the snail, miracidia from the parasite develop into sporocysts and produce cercariae, which are released into the water and can penetrate human skin during contact, continuing the parasite’s lifecycle. Control of Bulinus populations—through environmental management or molluscicides—forms part of strategies to reduce transmission in endemic areas.

Key species include Bulinus truncatus, Bulinus globosus, Bulinus nasutus, and Bulinus africanus, among others. Taxonomically, the genus is distinguished by its planispiral shell morphology and freshwater pulmonate physiology, and accurate identification often relies on a combination of morphological and, where available, molecular methods.