paragonimíase

Paragonimiasis is a parasitic disease caused by trematode worms of the genus *Paragonimus*, primarily affecting humans and other mammals. The most common species responsible for human infection is *Paragonimus westermani*, though other species such as *P. mexicanus* and *P. kellicotti* can also cause illness. The parasite is classified as a lung fluke due to its preference for residing in the lungs, though it can also infect other organs, including the brain, liver, and peritoneal cavity.

Transmission occurs through the ingestion of raw or undercooked freshwater crabs or crayfish that harbor the metacercariae, the infective larval stage of the parasite. Once ingested, the metacercariae excyst in the gastrointestinal tract, penetrate the intestinal wall, and migrate through the body to the lungs, where they mature into adult flukes. The entire life cycle typically spans several months, with humans serving as a dead-end host, meaning the parasite cannot complete its life cycle without an intermediate host (such as a freshwater snail) and a definitive host (such as a crab or crayfish).

Symptoms of paragonimiasis often resemble those of tuberculosis or other respiratory infections, including chronic coughing, chest pain, hemoptysis (coughing up blood), and shortness of breath. In advanced cases, the parasite may cause pleural effusion (fluid accumulation around the lungs), bronchiectasis (permanent dilation of the bronchi), or even neurological symptoms if the parasite migrates to the brain. Diagnosis typically involves a combination of clinical evaluation, imaging studies (such as chest X-rays or CT scans), and laboratory tests, including stool or sputum analysis to detect parasite eggs or serological tests to detect antibodies against the parasite.

Treatment primarily involves the use of antiparasitic drugs, such as praziquantel or bithionol, which are effective in killing the adult flukes. Prevention focuses on avoiding consumption of raw or improperly cooked freshwater crustaceans, as well as improving sanitation and public health measures in endemic regions. Paragonimiasis is most commonly found in East and Southeast Asia, Africa, and parts of South America, where the parasite’s intermediate and definitive hosts are prevalent. Proper diagnosis and treatment are essential to prevent complications and reduce the spread of the disease.