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Dr. Ajay Mohan (AIIMS)MBBS

October 28, 2020

October 28, 2020


Paragonimiasis is a flatworm infection in the lungs. This infection can last for years. These parasitic worms—also called flukes or lung flukes—may infect the human lungs when a person consumes undercooked crayfish or crab infested with it. The illness resembles stomach flu and pneumonia. In rare cases, the parasite may travel to the central nervous system, making the condition even more serious. Continue reading to find out more about paragonimiasis, its symptoms, causes and treatment.

Symptoms of paragonimiasis

It is common for paragonimiasis to be asymptomatic. For those who show symptoms, the symptoms only begin 2-15 days after the initial infection. The symptoms largely depend upon the location of the worms in the body. They may include:

In around 25% of people with paragonimiasis, the worms end up infecting the brain. The following signs may be indicative of the same:

Causes of paragonimiasis

The cause of paragonimiasis is infection with a flatworm, a parasitic worm that is also known as fluke. Seafood such as crab or crayfish may contain immature flukes.

When these foods aren’t cooked properly and consumed while undercooked, it is highly likely the person consuming them will get paragonimiasis.

These worms enter the body upon being swallowed. They then grow and mature inside the host’s body. With time, these flatworms spread across the body through the intestines. If they end up entering the lungs by perforating the diaphragm, the worms can survive for years.

Diagnosis of paragonimiaisis

Paragonimiasis is a difficult condition to diagnose, as its symptoms overlap with those of many other diseases and are mild in nature. Usually, the patient has to go through multiple tests before paragonimiasis can be confirmed.

To make a diagnosis, your doctor will ask you questions about the pattern in which the symptoms appeared and if you ate crab or crayfish recently. Following this, a physical examination is likely to be done. The doctor will check for any tenderness in the belly. Abnormal breath sounds and tenderness of the belly or chest may indicate the need for more tests.

  • If a blood test is ordered and there are a large number of specific white blood cells, it may be an indication of the parasitic infection.
  • Imaging tests such as CT scans, chest X-rays and MRI can be used to obtain high definition visuals, especially in cases where paragonimiasis has reached the brain or liver.
  • The most definitive diagnostic tool at our disposal is sputum microscopy. If paragonimus eggs are detected in the sputum under a microscope, paragonimiasis is confirmed.
  • Fluke eggs may also be present in stool samples.

Paragonimiasis treatment

In most cases, paragonimiasis is curable with oral medication. The doctor usually prescribes antiparasitic medicines such as Triclabendazole or Praziquantel which are both approved for treatment.

If the condition has turned severe and the presence of flatworms is confirmed in diagnostic tests, the treatment plan is likely to be more complex. With paragonimiasis in the brain, there is a huge chance of brain swelling or cysts. Drugs such as anti-seizure meds may be prescribed. The healthcare professional may also recommend surgery.


  1. Muneo Yokogawa, Editor(s): Ben Dawes, Paragonimus and Paragonimiasis Advances in Parasitology, Academic Press, Volume 3, 1965, Pages 99-158,
  2. Jennifer Keiser, Dirk Engels, Gottfried Büscher & Jürg Utzinger (2005) Triclabendazole for the treament of fascioliasis and paragonimiasis, Expert Opinion on Investigational Drugs, 14:12, 1513-1526,
  3. S H Cha, K H Chang, S Y Cho, M H Han, Y Kong, D C Suh, C G Choi, H K Kang and M S Kim Cerebral paragonimiasis in early active stage: CT and MR features American Journal of Roentgenology. 1994;162: 141-145
  4. Fukumi Nakamura-Uchiyam, N. Onah, Yukifumi Nawa, Clinical Features of Paragonimiasis Cases Recently Found in Japan: Parasite-Specific Immunoglobulin M and G Antibody Classes, Clinical Infectious Diseases, Volume 32, Issue 12, 15 June 2001, Pages e171–e175

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