Parasitic Infection

Parasitic infections are diseases caused by organisms that live off of another living thing. They can cause fever, fatigue, intestinal symptoms, skin rashes or neurological symptoms. You can get them from contaminated food, water or surfaces, bug bites and eating undercooked meat. Antiparasitic medications treat parasitic infections.


What is a parasitic infection?

Parasitic infections are any illnesses or conditions caused by parasites living and reproducing in your body. Parasites are organisms that need another living thing (a host) to get the nutrients they need to survive.

Parasitic infections often cause intestinal illness, with symptoms like diarrhea and vomiting. But they can also give you itchy skin rashes or infect other parts of your body, like your brain or lungs.


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What are the types of parasitic infection?

There are three main types of parasites that cause infections in humans:

  • Protozoa.
  • Helminths.
  • Ectoparasites.

Protozoal infections

Protozoa are single-celled parasites. They can infect your blood, intestinal tract (gut), brain, skin, eyes and other parts of your body.

Helminth infections

Helminth is a general term for parasitic worms. Scientists further classify them as flukes (trematodes), tapeworms (cestodes), roundworms (nematodes) and thorny-headed worms (acanthocephalans). Both adults and immature (larval) helminths can infect you. Helminths usually infect your intestinal tract, but they can also infect your skin, brain and other tissues.

Ectoparasitic infections

Ectoparasites are insects and arachnids (spider-like bugs) that burrow into your skin and live there. This includes ticks, mites, lice and fleas. They usually don’t infect other parts of your body.

What are the most common parasitic infections?

Millions of people around the world get parasitic infections every year. The most common parasitic infections include:

Other examples of parasitic infections include:


Symptoms and Causes

What are the symptoms of parasitic infections?

Symptoms of parasitic infections depend on where in your body you’re infected. Some common symptoms include:

  • Fever.
  • Muscle aches.
  • Fatigue.
  • Nausea.
  • Vomiting.
  • Diarrhea.

Depending on where you’re infected, you might have:

  • Neurological symptoms, like seizures, severe headache or disorientation.
  • Skin symptoms, like redness, itching, rash or sores.

Sometimes parasitic infections don’t cause any symptoms.

How do you get parasitic infections?

You can get parasitic infections from:

  • Drinking contaminated water or getting it in your mouth.
  • Eating undercooked meats.
  • Eating contaminated foods (like food washed with contaminated water).
  • Mosquito bites, tick bites, fly bites or other bites from insects that carry parasites.
  • Contaminated surfaces.
  • Unprotected sex.
  • Contaminated dirt (soil).

Some parasitic infections can pass from a pregnant person to the fetus.

What are the risk factors for parasitic infections?

Some parasitic infections, like pinworms, are common all over the world. Many other parasitic infections are more common in rural areas of the world without developed sanitation systems. People who are at higher risk for parasitic infections include:


Diagnosis and Tests

How are parasitic infections diagnosed?

Providers diagnose parasitic infections by looking for parasites or signs of parasites (like their eggs) in body fluids or tissues. To test you for parasites, a provider might take samples of your:

A provider may also use other tests, such as X-rays, MRI or CT scans to diagnose a parasitic infection, depending on your symptoms.

How do you know if you have a parasitic infection?

Symptoms of parasitic infections can be similar to many other infectious diseases. The only way to know for sure if you have a parasitic infection is to have a provider evaluate you.

Management and Treatment

How are parasitic infections treated?

Providers use different medications to treat various types of parasitic infections, including:

Sometimes you might need a combination of different medications to cure the infection. Your provider will select a treatment that’s best for the specific type of parasitic infection you have.

How do you get rid of parasites in your body?

Most parasites will only go away with medication or a combination of medications. Providers treat some skin infections, lice and mites with medicated lotions or shampoos.


Can parasitic infections be prevented?

Following a few precautions can reduce your risk of parasitic infections, including:

  • Wash your hands frequently. It’s especially important to wash your hands when preparing food, before eating, after going to the bathroom and after changing diapers.
  • Don’t swim when you have diarrhea. Wait until you haven’t had diarrhea for at least two weeks before swimming in a public pool again.
  • Practice safe food habits. This includes storing food properly, heating meat and poultry to a safe temperature, and washing or peeling fruits and vegetables before eating.
  • Use a condom or dental dam during any kind of sex.
  • Protect yourself from bug bites. Wear protective clothing, use bug spray and sleep under mosquito netting if necessary.
  • Be an informed traveler. Learn about infectious diseases in your destination that you may need to take special precautions against. Some precautions might include taking prophylactic medications (before you get sick) or getting vaccinated.

Outlook / Prognosis

What can I expect if I have a parasitic infection?

What you can expect with a parasitic infection depends on:

  • What kind you have.
  • How severe it is.
  • Whether or not you have a compromised immune system.
  • How well you respond to standard treatments.

Some parasitic infections respond well to medications. But some infections can last for a long time or keep coming back. Ask your healthcare provider what to expect in your specific situation.

Living With

When should I see my healthcare provider?

See your healthcare provider if you have symptoms of a parasitic infection. Let them know if you recently:

  • Traveled.
  • Could have been bitten by a tick, mosquito or other bug, even if you don’t remember being bitten.
  • Swam in water that could have been contaminated.
  • Ate or drank something that could have been contaminated.

When should I go to ER?

Go to the emergency room if you experience any of these symptoms of severe illness:

What questions should I ask my doctor?

It might be helpful to ask your healthcare provider:

  • How did I get this infection?
  • What are my treatment options?
  • Am I contagious?
  • How long until I feel better?
  • How can I take care of myself at home?
  • What new or worsening symptoms should I look out for?
  • When should I follow up with you?

A note from Cleveland Clinic

Parasitic infections affect millions of people around the world. Some people show no signs of these infections, while others develop life-threatening symptoms. Providers can cure most parasitic infections with medication. You can also take precautions to protect yourself against infections, especially when you’re traveling. If you have symptoms of a parasitic infection, talk to a healthcare provider. They can tell you about treatment options and answer any concerns you have.

Medically Reviewed

Last reviewed on 04/07/2023.

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