Paragonimiasis is a parasitic infection caused commonly by a lung fluke called the Paragonimus westermani. However, there are ten or so Paragonimus species known to infect humans, but only 8 of these can cause significant health issues in humans. The usual cause of the infection is eating partially cooked or poorly processed seafood, such as crayfish or crabs. The Paragonimus westermani parasite infects humans’ lungs, and if the parasite makes its way to the central nervous system, more severe cases of paragonimiasis can occur.

It is a common disease in East Asia, and an estimated 22 million people yearly are infected worldwide. Paragonimiasis may persist for up to 20 years.


  • Extrapulmonary – extrapulmonary paragonimiasis happens when the eggs of the Paragonimus flukes or the worms themselves, whether immature or mature, and worms end up in different parts of the body, aside from the lungs. Subcategories from this type include abdominal, cerebral, cardiovascular, and cutaneous forms, and in 50% of extrapulmonary cases, cerebral paragonimiasis is the most frequent. Though not as familiar or routine, other parts of the body under extrapulmonary paragonimiasis include the skin, spleen, testes, eye, liver, kidney, ovaries, and lymph nodes.
  • Pulmonary: Very often, paragonimiasis infections are characterized by pulmonary problems. Other than that, the patient may also experience symptoms such as weight loss and anemia.
  • Pleuropulmonary: This type of paragonimiasis infection is characterized by patients exhibiting signs of pleurisy when the lungs’ protective pleural membranes that also line the chest cavity become infected.


Patients of paragonimiasis tend to have the same symptoms as chronic bronchitis or tuberculosis. Shortness of breath and chest pain are often accompanied by blood-tinged or dark brown sputum containing eggs of an adult Paragonimus westermani fluke.

  • Cough that lasts for more than three weeks
  • Bloody or rust-colored sputum
  • Headaches
  • Diagnosis of tuberculosis but with a negative smear
  • Seizures
  • Ectopic lesions
  • Low-grade fever
  • Abdominal pain
  • Visual impairment


  • Antibody detection – In the United States, the standard diagnostic test for paragonimiasis called the complement fixation (CF) test is frequently used to determine a therapeutic cure. Still, the test is also highly sensitive for the diagnosis of a patient. The detection of the Paragonimus westermani parasite’s antibodies has enabled healthcare professionals to tell apart paragonimiasis from tuberculosis.
  • Concentration techniques – these diagnostic techniques are used for patients with light infections.
  • A biopsy allows for identifying a developing or adult fluke’s species when one is found or recovered and allows for diagnostic confirmation or paragonimiasis.
  • Immunological techniques – used to detect in serum or stool samples the worm-specific antigens or antibodies.
  • Molecular techniques – an example of a polymerase chain reaction, while still in the experimental stages, are being used.
  • Parasitological techniques –  these diagnostic testing techniques can be used only once the Paragonimus flukes started laying eggs in the lungs.


For three days, 25 mg/kg of body weight of praziquantel administered three times a day and 20 mg/kg of triclabendazole conducted on the same day, given in two doses of 10 mg/kg are both recommended medications for treating paragonimiasis by the World Health Organization (WHO), with the latter more preferred for the simplicity of administering it.

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