Illustration of the life cycle of the parasitic roundworm Angiostrongylus cantonensis, also known as the rat lungworm. The adult form of the worm is found in rodents. Parasitic eggs hatch in the rodent's lungs and are passed in the faeces as larvae. The larvae are consumed by a gastropod intermediate host, where they mature and reach the infective stage. If the infected gastropod is consumed by a rodent, the life cycle is completed. Alternatively, the infected larvae can be consumed by a human, either through direct consumption of the gastropod, or by consumption of larvae on contaminated produce. Once consumed by a human, the larvae migrate to the brain, or occasionally the eyes or lungs, but does not reach reproductive maturity. The parasites die over time inducing mild symptoms such as headaches, nausea and vomiting. Sometimes the infection can cause a rare form of meningitis (eosinophilic meningitis). Treatment with anti-parasitics is not usually needed.