Distribution

Biomphalaria:

  • tolerate a wide range of climatic conditions, including a large variety of different freshwater habitats
  • survive best in sub-tropical and tropical climates, as recruitment of juveniles is believed to be reduced below about 13°C

Potential impact of climate change

Since 13°C is lower than the minimum reproductive temperature of the schistosome parasites carried by the snail, Biomphalaria are found in a number of places where the parasites cannot multiply. Climate change could therefore allow schistosomiasis to spread into previously unaffected regions.

Widespread and spreading

Within the tropics and the sub-tropics, Biomphalaria are found generally wherever there is enough freshwater for survival. They have spread across 5 continents.

From their origin in South America, they radiated:

  • northwards into Central and North America and the Caribbean
  • eastwards across the Atlantic and into Africa where they dominate the continent, being found:
    • as far north as Egypt
    • as far south as South Africa
    • east from Senegal until Somalia

Populations of Biomphalaria are also found in the Middle East. 

More recently, populations have been described from Hong Kong and Hungary. These are probably human-influenced introductions, through laboratory escapes in the former case, and agricultural trading in the latter.

Geographical range of B. choanomphala

Despite the wide geographical range of the genus, B. choanomphala is only found in East Africa, in a few of the region's Great Lakes:

  • Lake Victoria
  • Lake Kyoga
  • potentially Lake Albert

Taxonomic confusion has made it difficult to establish its exact range, but functionally it is known to be the most important species for the transmission of schistosomiasis in Lake Victoria, and probably in Lake Kyoga as well.

  • Biomphalaria snail on a rock
    Habitat

    Learn about the habitat preferences of B. choanomphala and its adaptability.

  • A typical transmission site of intestinal schistosomiasis on Lake Victoria
    Population biology

    Learn about Museum research into the population dynamics of B. choanomphala in Lake Victoria. Our scientists hope to uncover whether human interference with the lake's biota caused the snail's population to expand rapidly and led to an associated increased risk of schistosomiasis transmission in the region.