Distribution and habitats of Gyraulus connollyi, snail intermediate host of intestinal flukes of the family Echinostomatidae, in South Africa

Abstract

This paper focuses on the geographical distribution and habitats of Gyraulus connollyi, snail intermediate host of intestinal flukes of the family Echinostomatidae as reflected by the 969 collection sites on record in the database of the National Freshwater Snail Collection (NFSC) of South Africa. The presence of this species was reported from 13 different types of water-bodies, however, the highest percentage by far was collected in streams and rivers and in habitats of which the water was described as perennial, clear and fresh. A predominantly stony substratum and the presence of vegetation were also reported for the majority of habitats. The effect size was calculated for each variable to determine its importance for the occurrence of this species. An integrated decision tree constructed from the data indicated that temperature, altitude and type of water-body were the most important of the factors evaluated that could have an effect on the geographical distribution of this species. This was supported by the effect size values calculated for each variable. A temperature index calculated for each species in the database ranked G. connollyi seventh out of 53 due to its association with low temperatures. Although human echinostomosis has not yet been diagnosed in Africa, concern is expressed that G. connollyi is able to serve as first intermediate host in the transmission of echinostomosis.