The Gut Microbiome of the Snails Lissachatina fulica and Parmarion martensi, Infected and Uninfected by the Rat Lungworm, Angiostrongylus cantonensis

This project focused on a parasite, the rat lungworm (Angiostrongylus cantonensis), and its intermediate snail hosts (rats are the definitive hosts in which the worms reproduce). This parasite is important because it is the main etiological agent causing human eosinophilic meningitis. The intermediate hosts are important because people are infected by the parasite when they consume infected hosts, deliberately or inadvertently. Once consumed, the parasites eventually reach the brain, where they remain, feeding and moving until they die. This can lead to a wide range of signs and symptoms resulting from the neurological damage and inflammation the worms cause; in severe cases it may lead to coma and death. The bacterial microbiota in the gut of the snail host may be important in influencing the likelihood of infection of the host by the parasite. Therefore the goal of this project was to characterize the gut microbiome of two snail species, Lissachatina fulica and Parmarion martensi, to determine whether their microbiomes differed and whether being infected by A. cantonensis led to a change in their microbiomes. The snails were collected in Heeia, island of Oahu, Hawaii. Molecular screening for A. cantonensis infection permitted selection of 20 infected and 17 uninfected L. fulica and 13 infected and 20 uninfected P. martensi for analysis. High throughput sequencing of the gut microbiomes of these snails identified four dominant bacterial phyla: Proteobacteria, Tenericutes, Firmicutes, and Bacteroidetes. However, there were significant differences between the microbiomes of the two snail species and between infected and uninfected individuals. The significance of this project is two-fold. First it has shed light on the gut microbiomes of snails and how biotic interactions may impact them. Second, by increasing current knowledge about the impact of this parasite on its host it may lead to novel methods to hinder the ability of the parasite to effectively complete its life cycle and thereby decrease the number of accidental human infections