Paragonimus westermani

Paragonimus westermani is the causative agent of Oriental lung fluke infection or Paragonimiasis. There are various other species of Paragonimus that can infect man. Pergonimus kellicotti, or the North American lung fluke, is an important cause of Paragonimiasis in the United States.

Disease / Pathology

Paragonimus westermani produces pulmonary type symptoms that can mimic those of tuberculosis. Hemoptysis is a key symptom.

Location in the Host

Paragonimus westermani is found encapsulated in the parenchyma of the lung.

Geographic Distribution

Paragonimus westermani is found throughout Asia. Paragonimus kellicotti is known as the North American lung fluke but is also found in Southeast Asia and China.

Life Cycle

Paragonimus westermani infections are acquired by the ingestion of undercooked or raw, crabs and crayfish.

Morphology & Diagnosis

Paragonimus westermani eggs detected in the feces or sputum during an ova & parasite examination are diagnostic. Eggs are shed in low numbers and therefore detection is difficult without repeated specimen collected for analysis. Eggs are also sometimes confused with those of Diphylobothrium latum (the broad fish tapeworm). Diphylobothrium latum eggs are smaller in size and have a distinctive abopercular knob at the posterior end of the egg.

Paragonimus westermani eggs are large, measuring 80-120u in length and 45-70u wide. Those of Diphylobothrium latum are 58-75u in length by 40-50u wide.


Adult Paragonimus westermani fluke
Photo by W. Vientos
Paragonimus westermani egg