Mollusca - Human Interaction - Uses By Humans - Pests

Pests

Schistosomiasis (also known as bilharzia, bilharziosis or snail fever) is transmitted to humans via water snail hosts, and affects about 200 million people. A few species of snails and slugs are serious agricultural pests; in addition, accidental or deliberate introduction of various snail species into new territory has resulted in serious damage to some natural ecosystems.

Schistosomiasis is "second only to malaria as the most devastating parasitic disease in tropical countries. An estimated 200 million people in 74 countries are infected with the disease — 100 million in Africa alone." The parasite has 13 known species, of which two infect humans. The parasite itself is not a mollusc, but all the species have freshwater snails as intermediate hosts.

Some species of molluscs, particularly certain snails and slugs, can be serious crop pests, and when introduced into new environments, can unbalance local ecosystems. One such pest, the giant African snail Achatina fulica, has been introduced to many parts of Asia, as well as to many islands in the Indian Ocean and Pacific Ocean. In the 1990s, this species reached the West Indies. Attempts to control it by introducing the predatory snail Euglandina rosea proved disastrous, as the predator ignored Achatina fulica and went on to extirpate several native snail species, instead.

Despite its name, Molluscum contagiosum is a viral disease, and is unrelated to molluscs.