Effects of temperature on the life cycle of schistosoma mansoni and its snail intermediate host, biomphalaria glabrata, in laboratory setting

Abstract

The increasing of water temperature due to global warming may impact the life cycle of schistosome as well as its snail intermediate host. This study aimed to investigate the effects of water temperature on reproductive biology and development of Biomphalaria glabrata, cercarial production and infectivity of S. mansoni cercaria in mice. B. glabrata were reared in the aquaria where the water temperatures were at 25, 28, 30 and 32oC. B. glabrata reared at 28 °C gave the highest egg outputs and hatching rate. Survival rate at 25 °C was highest while the growth of snail at 32 °C was significantly higher than the other groups. In terms of cercarial emergence, B. glabrata infected with S. mansoni miracidia reared at 28 °C shedded the highest number of cercariae followed by those reared at 30, 32 and 25 °C. The duration, onset and peak of cercaria shedding and survival of infected snails from each temperature were different. Cercariae shedded from B. glabrata of different temperatures were used to infect the mice by tail exposure. Weekly fecal examination revealed that the mice infected with cercariae shedded from 28 °C group released the S.mansoni eggs one week earlier than the other groups. Adult worm burden of the mice infected with cercariae was highest in 25 oC group followed by 28, 30 and 32 oC groups. Water temperature affects the reproductive biology, development and survival of B.glabrata and also the life cycle of S. mansoni which may alter the pattern of disease transmission in final host and disease control strategy.