Paragonimiasis

What is paragonimiasis?

Paragonimiasis (pronounced “pare-uh-gone-uh-MY-uh-sis”) is a parasitic infection with any of several species of Paragonimus flukes, a type of flatworm. You get it from eating raw, undercooked or pickled crab or crayfish.

Paragonimus usually infects your lungs, but it can also infect other organs, like your skin (cutaneous paragonimiasis) and your brain (cerebral paragonimiasis). Symptoms like coughing up blood, chest pain and weight loss can easily be confused with symptoms of tuberculosis (TB) or lung cancer.

Where is Paragonimus found?

Species of Paragonimus exist in many parts of the world, including parts of the U.S. and Canada. But most cases of paragonimiasis are reported in areas of Asia, Africa and Latin America.

What are the symptoms of paragonimiasis?

Symptoms of paragonimiasis usually affect your lungs, but you might also experience digestive or abdominal symptoms first. They can start two to eight weeks after eating something contaminated.

Symptoms of paragonimiasis include:

• Fever.
• Chest pain.
• Fatigue.
• Cough. This might be a dry cough at first and progress to producing rusty-colored or blood-tinged mucus.
• Unintended weight loss.
• Diarrhea.
• Abdominal pain.
• Bumps under the skin of your abdomen (belly). These may hurt to touch and they might gradually move upward toward your chest.

Cerebral paragonimiasis symptoms

If you have a Paragonimus infection in your nervous system (your brain, spine and nerves), symptoms could include:

• Seizures.
• Headache.
• Double vision, blurred vision or other issues seeing.
• Confusion.
• Vomiting.
• Neck stiffness.
• Muscle weakness.

What causes paragonimiasis?

Parasitic flatworms, called fluke, of the genus (group) Paragonimus cause paragonimiasis. You get it from eating raw or partially cooked crabs or crayfish. Cysts containing larvae (young fluke) can contaminate crabs or crayfish or their juices. The larvae come out of the cysts in your small intestine and move to your lungs.

Your immune system reacts to the worms in your lungs — now adults — by forming hard pockets (cysts) around them. These pockets can break open and leak blood, pus and fluke eggs into your lungs. This often causes a secondary bacterial infection.

Is paragonimiasis contagious?

No, paragonimiasis isn’t contagious — you can’t get it from other people.

What are the complications of paragonimiasis?

Complications of paragonimiasis usually involve your lungs. They include:

• Pneumonia.
• Bronchiectasis.
• Lung abscess (an area of pus and dead tissue).
• Pleural effusion.
• Empyema.

How is paragonimiasis diagnosed?

A healthcare provider diagnoses paragonimiasis by looking for parasite eggs in:

• Sputum (mucus coughed up from your lungs).
• Poop (stool).
• Fluid from around your lungs.
• Skin or other tissue samples.

They’ll also use imaging to look at your lungs or other affected organs. Depending on your symptoms, they also might test your blood or cerebrospinal fluid for antibodies to the fluke.

Tests and procedures

Your provider might perform or order the following tests and procedures:

• Blood tests.
• Chest X-ray.
• CT scan.
• MRI.
• Bronchoscopy.
• Skin biopsy.

How is paragonimiasis treated?

Healthcare providers use antiparasitic medications (praziquantel or triclabendazole) to treat paragonimiasis. If you have cerebral paragonimiasis, they may also treat you with corticosteroids to reduce inflammation in your brain and spinal cord. Rarely, you might need surgery to remove cysts.

Is paragonimiasis curable?

Yes, paragonimiasis is curable. Studies from Japan suggest that praziquantel cures 86% to 100% of Paragonimus infections.

Can you prevent paragonimiasis?

You can prevent paragonimiasis by not eating preparations of crab and crayfish that might be contaminated with Paragonimus. Preparations to avoid include:

• Raw or undercooked crab.
• Pickled crab.
• Salted crab.
• “Drunken” crab (dipped or marinated in wine).
• Crab juice.

What can I expect if I have paragonimiasis?

If you have paragonimiasis, you can expect a short course of oral antiparasitic medications, usually only one to three days. If the medication doesn’t completely get rid of all of the flukes, sometimes, your symptoms will come back and you’ll need to be treated again.

What’s the mortality rate of paragonimiasis?

If not treated, cerebral paragonimiasis is fatal in 5% of cases.

When should I see my healthcare provider?

Contact a healthcare provider if you have symptoms of paragonimiasis. Let them know if you could have eaten undercooked crab or crayfish. It can take anywhere from two weeks to two months to develop symptoms.

When should I go to the ER?

Go to the emergency room if you have any symptoms of serious illness, including:

• High fever (above 103 degrees Fahrenheit or 40 degrees Celsius).
• Chest pain.
• Coughing up blood.
• Seizures.
• Confusion or altered mental state.

What questions should I ask my doctor?

It might be helpful to ask a healthcare provider:

• When can I expect to feel better?
• How do I take this medication?
• What severe symptoms should I look out for?
• When should I follow up with you?

A note from Cleveland Clinic

A “fluke” is usually something that you don’t expect to happen. It’s safe to say that none of us expect a literal parasitic fluke to find its way into our lungs. Fortunately, avoiding certain preparations of crab and crayfish is an easy way to prevent paragonimiasis. If you have symptoms of paragonimiasis, see a healthcare provider right away. Treatment is very effective and can prevent the infection from spreading and causing serious damage.