Aelurostrongylus abstrusus is the scientific name of the cat lung worm. This is an indirect lifecyle, involving two intermediate hosts, and a definitive host. The female is ovo-viviparous, and passes L1 within the host faeces. The L1 then infect the molluscs, and later develop into L2, then infective L3. The paratenic host ingests the molluscs.
The cat, acting as the definitive host then ingests the L3, and becomes infected with the parasite. The larvae then travel to the lungs via the lymphatic system or the bloodstream. These can be seen as nodules on the lungs. They then hatch out, and are coughed up and swallowed. The parasite enters the alimentary tract, and is passed out in the faeces. The parasite affects pulmonary parenchyma and causes aelurostrongylosis.