Detecting Toxoplasma gondii in the giant African snail (Lissachatina fulica) in Oʻahu, Hawaiʻi

Abstract

Toxoplasmosis is one of the most common parasitic foodborne diseases in the world and has severe negative impacts on humans and causes mortality in several wildlife species. Felids are the only definitive host of the disease-causing agent, Toxoplasma gondii, and once infected, shed millions of oocysts through their feces. Several mechanical vectors can disperse these oocysts, but it is unknown if invasive land snails can act as mechanical vectors. My goal was to demonstrate if T. gondii DNA and intact T. gondii oocysts can be detected in Lissachatina fulica feces to determine if L. fulica can act as a mechanical vector for T. gondii. To complete this goal, I fed 500 deactivated T. gondii oocysts to four Lissachatina fulica and used conventional PCR to detect the presence/absence of T. gondii DNA in the resulting feces. I used genetic sequencing to confirm positive samples and light microscopy to detect full T. gondii oocysts. The first fecal sample of each snail tested positive through conventional PCR and and successfully sequenced for T. gondii DNA. Oocysts were not found for any of the samples. However, successfully detecting T. gondii DNA in the fecal samples makes L. fulica a potential candidate for a biosentinel of T. gondii contamination. This would involve removing the destructive L. fulica from the environment, which would be helpful to several countries where L. fulica is invasive. L. fulica as a biosentinel could also be a solution to the difficulty of detecting T. gondii in environmental samples.