Last revised by Yuranga Weerakkody on 19 Jan 2020

Paragonimiasis is a disease caused by several species of the trematode genus Paragonimus. 

More than 50 different species of Paragonimus have been described in Asia, Africa, and the Americas and of those nine species infecting humans. The most important species is Paragonimus Westermani, which is distributed worldwide. Paragonimus heterotremus, P. siamensis and P. skrjabini are distributed in Asia. Paragonimus kellicotti is endemic in North America, P. mexicanus in Latin America, and P. africanus and P. uterobilateralis in Africa1 .

Paragonimiasis Infections can occur after ingesting undercooked freshwater crayfish, crabs, or shrimp that are infected with encysted larvae 1. After penetration of the intestinal wall, juvenile worms (metacercariae) enter the inner wall of the abdominal cavity, these worms penetrate the diaphragm and then move to the lung parenchyma.

The primary habitat of adult Paragonimus is the lung, and the most severe complication is secondary to the erratic migration of paragonimiasis to the brain. 2

Pulmonary paragonimiasis is the most common manifestation of the disease and usually presents one to twenty-seven months after infection. Patients generally present with chronic productive cough, hemoptysis, and chest pain. 3

During the migration process, other parts of the body can be involved, such as the brain, skin, abdomen, heart, breast, intraspinal, and subcutaneous tissues.

Cerebral paragonimiasis symptoms usually present after the onset of pulmonary symptoms and can include headaches, seizures, blurred visions, and gait disturbance, or even paralysis.1-3

Diagnosis of paragonimiasis requires the finding of eggs in the sputum, feces, pleural, brain, effusion, cerebrospinal fluid, or other liquids. Ziehl-Neelsen staining can also be used for detection in the sputum as is done for tuberculosis. 1

In sectioned surgical or biopsy specimens of extrapulmonary infections, juvenile or adult worms are also frequently detected.  

ELISA testing should confirm the diagnosis.

DNA probes, PCR, and PCR-based restriction fragment length polymorphism (PCR-RFLP) analysis have been developed. 1-4

Praziquantel is the treatment for human paragonimiasis, 25 mg/kg three times daily for 2–3 days is the recommended dose and achieves 100% efficiency.  4

Triclabendazole is a new drug for the treatment of paragonimiasis, but its efficacy is to be determined. 1

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