What is rat lung worm? Rat lung worm or Angiostrongylus catonensis is a parasite that mainly lives in rodents such as rats and can infect snails and slugs that come into contact with infected rat faeces. People can be infected when they eat an infected snail or slug. How is it treated? Most people with symptoms recover fully without treatment over days, weeks or months. However in my case the infection caused severe meningitis that required specialist treatment. The infection is occasionally fatal. There is no vaccine and no preventative treatment is recommended for exposed people. It took nearaly 10 years to be well again from the rat lung worm infestation I had.