Changes

*''Lymnaea'' is found in muddy areas (but not on highly acidic soils)

*''Lymnaea'' is found in muddy areas (but not on highly acidic soils)

*habitats may be permanent (dry summer) or temporary (wet summer).

*habitats may be permanent (dry summer) or temporary (wet summer).

=== Epidemiology ===

=== Epidemiology ===

In temperate areas, there are two superimposed epidemiological cycles, known as the summer and winter infections of the snail. On mainland Britain, the summer cycle predominates as a high proportion of snails perish during the winter, but very occasionally, weather sequences allow the winter cycle to affect the pattern of disease. On the west coast of Ireland, the winter cycle of events determines the timing of clinical outbreaks.

In temperate areas, there are two superimposed epidemiological cycles, known as the summer and winter infections of the snail. On mainland Britain, the summer cycle predominates as a high proportion of snails perish during the winter, but very occasionally, weather sequences allow the winter cycle to affect the pattern of disease. On the west coast of Ireland, the winter cycle of events determines the timing of clinical outbreaks.

=== Summer Infection of the Snail ===

=== Summer Infection of the Snail ===