Lung fluke

Lung fluke is a common name for several species of trematodes (parasitic flatworms) of the family Paragonimidae. The most well-known species is Paragonimus westermani, which is a significant cause of parasitic infection in humans, leading to a disease known as paragonimiasis.

Life Cycle

The life cycle of the lung fluke involves several stages and multiple hosts. The adult fluke resides in the lungs of a definitive host, such as a human or other mammal. The fluke produces eggs which are coughed up and swallowed by the host, then excreted in the feces. If these eggs reach fresh water, they hatch into free-swimming larvae called miracidia. These miracidia infect a suitable snail intermediate host, where they develop into another larval stage, the cercaria. The cercariae leave the snail and encyst on the surface of fresh water crustaceans, such as crabs or crayfish, becoming metacercariae. When the definitive host consumes undercooked or raw infected crustaceans, the metacercariae excyst in the intestine, penetrate the intestinal wall, and migrate to the lungs, where they mature into adult flukes.

Symptoms and Treatment

Infection with lung flukes can cause a variety of symptoms, including cough, chest pain, and fever. In severe cases, it can lead to pulmonary disease and other complications. Diagnosis is typically made by identifying fluke eggs in stool or sputum samples. Treatment usually involves the use of antiparasitic drugs, such as praziquantel.

Epidemiology

Lung fluke infections are most common in East Asia and South America, where consumption of raw or undercooked crustaceans is common. However, cases have been reported worldwide.

Prevention

Prevention of lung fluke infection primarily involves proper cooking of crustaceans to kill any encysted metacercariae. Public health measures to improve sanitation and educate at-risk populations can also help reduce the incidence of infection.