A Five-Year Study of the Epidemiology of Fascioliasis in the North, East and West of Scotland

Abstract

Observations made over a period of five years, of the epidemiology of fascioliasis in the North, West and East of Scotland using snail sampling and tracer lamb techniques, are presented and compared with the results of previous investigations in Scotland. Two periods of snail and pasture infections occurred. An early lower spring infection and a higher summer infection. Levels varied and were dependent upon the occurrence of suitable temperature and moisture conditions. Previous observations on the epidemiology in the West were confirmed and a similar epidemiological pattern was observed in the North, although in the latter area there was evidence to indicate the occurrence of a higher spring/summer pasture infection. Significant snail mortalities were observed, in adult over-wintering snails during the spring and early summer, following dry spells in the spring generation during the summer months, and in this latter generation again in the autumn. The investigations failed to confirm the presence of a significant winter carry-over infection in any of the areas studied. The epidemiology in the East was similar to that in the West although snail development was observed to occur later in some years. High densities of snails were observed on many habitats in some years in the East although snail infections were few or absent in this area. It is suggested that fluke eggs may be a significant limiting factor in the epidemiology of fascioliasis in certain ecological conditions.