Biomphalaria alexandrina

Biomphalaria alexandrina

Biomphalaria alexandrina is a species of freshwater snail, an aquatic gastropod mollusk in the family Planorbidae, the ram's horn snails. This species is of significant medical importance as it serves as an intermediate host for the parasitic flatworm Schistosoma mansoni, which causes schistosomiasis in humans.

Description

Biomphalaria alexandrina is characterized by its planispiral shell, which is typically brownish in color and can reach up to 12 mm in diameter. The shell is thin and fragile, with a depressed spire and a wide aperture. The body of the snail is soft and greyish, with tentacles and a foot used for locomotion.

Distribution

This species is predominantly found in freshwater habitats across the Nile Delta and other parts of North Africa. It thrives in slow-moving or stagnant waters such as ponds, lakes, and irrigation canals.

Life Cycle

The life cycle of Biomphalaria alexandrina involves both sexual and asexual reproduction. The snails are hermaphroditic, possessing both male and female reproductive organs, which allows them to self-fertilize or cross-fertilize with other snails. Eggs are laid in gelatinous masses on submerged surfaces, and hatch into juvenile snails after a few weeks.

Medical Importance

Biomphalaria alexandrina is a crucial vector in the transmission of Schistosoma mansoni. The parasite's larvae, known as miracidia, penetrate the snail's tissues and develop into cercariae, which are released into the water. Humans become infected when they come into contact with contaminated water, as the cercariae can penetrate the skin.

Control Measures

Controlling the population of Biomphalaria alexandrina is essential in reducing the incidence of schistosomiasis. Methods include environmental management to reduce snail habitats, chemical molluscicides, and biological control using natural predators or competitors.

Also see

• Schistosomiasis
• Schistosoma mansoni
• Planorbidae
• Intermediate host