Positive phototropism is accelerated in Biomphalaria glabrata snails by infection with Schistosoma mansoni.

Parasite-induced behavioral changes in their hosts favor to complete the lifecycle of parasites. Schistosome infection is also known to cause physiological changes in infected freshwater snail intermediate hosts. Here, we report, a novel phenomenon in which Schistosoma mansoni, a highly debilitating worm affecting millions of people worldwide, alters the phototropic behavior of Biomphalaria glabrata, the vector snail. S. mansoni-infection enhanced positive phototropism of vector snails and infected snails spent significantly more time in light. Possibly, these behavioral changes help the parasite to be released efficiently from the infected intermediate hosts, and to infect mammalian hosts.