Parasitic Infections

Parasites are organisms that live in or on another organism, called the host. The parasites can be microscopic or large enough to see with the naked eye, and they survive by feeding from the host. They can also spread parasitic infections, which can lead to sepsis.

Sepsis, which was often called blood poisoning, is the body’s life-threatening response to infection. Sepsis kills and disables millions and requires early suspicion and rapid treatment for survival.

Sepsis is and septic shock can result from an infection anywhere in the body, such as pneumonia, influenza, or urinary tract infections. Worldwide, one-third of people who develop sepsis die. Many who do survive are left with life-changing effects, such as post-traumatic stress disorder (PTSD), chronic pain and fatigue, organ dysfunction (organs don’t work properly), and/or amputations.

Examples of parasitic infections

Some people think of parasitic infections, like malaria, as occurring only in developing countries or in tropical areas, but parasitic infections exist in North America as well. The most common ones found in North America include Giardia infections (through contaminated water) and toxoplasmosis (spread by cats).

Others include:

  • E.vermicularis, or pinworm
  • Trypanosoma cruzi, the cause of Chagas disease.
  • Echinococcosis, another tapeworm, passed through dogs and sheep
  • Cysticercosis, or tapeworm.
  • Toxocariasis, or roundworm.
  • Trichomoniasis, a sexually transmitted infection.
  • Amebiasis

What are the symptoms of parasitic infections?

The symptoms of parasitic infections depend on the parasite. Here are a few examples:

Giardia infection (giardiasis) infection can cause symptoms such as diarrhea, abdominal cramping and bloating, gas, nausea, fatigue, and weight loss. Not everyone with the infection shows symptoms though, and they may pass the infection on to others unknowingly.

Chagas disease: Most people who contract Chagas disease may not have symptoms for the first few weeks or months. If they do, they may experience mild swelling at the infection site, low fever, body aches and pains, skin rash, headache, nausea and vomiting, diarrhea, and swollen glands, among other symptoms. The infection then moves into the chronic phase. This is when signs and symptoms may start for those who did not have any during the acute phase. They may include an irregular heartbeat, congestive heart failure, swollen esophagus that makes it hard to swallow, and abdominal pain or constipation. The infection could also cause a cardiac arrest.

Tapeworm: Symptoms of tapeworm may not be noticed right away, beginning only about 8 weeks after the tapeworms have developed in the intestine. The symptoms may be mild and non-specific, including nausea, diarrhea, constipation, and abdominal pain. Untreated tapeworms can live for years, and can lead to malnutrition. Long-term complications could include headaches, blindness, and seizures.

How are parasitic infections diagnosed and treated?

The treatment for parasitic infections depends on the type of infection and how far the infection has progressed. Blood tests can show the presence of parasites such as those that cause Chagas disease and samples of stool (from bowel movements) can show the presence of parasites that infect the intestines.

Giardia infections: The infection usually clears up on its own within a few weeks. If the infection is severe or does not clear up, your doctor may prescribe a medication like metronidazole (Flagyl), tinidazole (Tindamax) or nitazoxanide (Alinia).

Chagas disease: Antiparasitic medications benznidazole and nifurtimox will kill the parasites, but other treatments to manage the complications like heart irregularities may be needed.

Tapeworm: The most commonly used medications to kill tapeworms are praziquantel (Biltricide), albendazole (Albenza), and nitazoxanide (Alinia). However, if the infection has progressed and become more invasive, you may need treatment with anti-inflammatory medications, anti-seizure medications, a shunt to drain fluid from your brain, or surgery to remove cysts caused by the tapeworm.

Roundworm: There are several types of roundworm so treatment varies according to the infection. The most commonly used medications for roundworm include medendazole (Vermox), albdendazole (Albenza) and ivermectin (Stromectol). Surgery could be required to remove the worm if there is a bowel obstruction.


Most parasitic infections enter the body through your mouth, either in food or drink, or by contamination – touching your face with contaminated hands.

  • When working around animals or where there may be animal feces, including gardens, wear gloves and wash hands thoroughly when your task is completed.
  • When traveling or in an area where food or water may be contaminated, drink only from bottles that were sealed. Ice cubes may not have been made with clean water, so avoid adding ice to your drinks. And eat only thoroughly cooked foods. Fruit with peels that have been washed with clean water may be safe to eat.
  • Malaria may be prevented by taking medications before, during, and after a trip to places known to have the infection. Speak with your doctor before you leave about malaria prevention.
  • Swim in chlorinated pools when possible. Avoid rivers, lakes, or streams that may have sewage.

If you suspect sepsis, call 9-1-1 or go to a hospital and tell your medical professional, “I AM CONCERNED ABOUT SEPSIS.” 

Would you like to share your story about sepsis or read about others who have had sepsis? Please visit Faces of Sepsis, where you will find hundreds of stories from survivors and tributes to those who died from sepsis.

Suggested Citation: Sepsis Alliance. Sepsis and Parasitic Infections. 2023.

Updated May 3, 2023.

Read Personal Stories of Sepsis and Parasitic Infections

Mansi Sharma


It was the September of 2018. Just like any other 17 year old young girl who finished high school, I had my dream to become a doctor, for which we have an entrance exam in my country. I was preparing for that when I suffered from Dengue. (Sepsis and Parasitic Infections) It left me extremely weak. The excruciating pain, dizziness, confusion lasted for around fifteen days, after which my platelet count started improving. It was September 26th, my birthday, when all went downhill again. The body temperature raised to 104 degrees, and I wasn’t able to breathe, or even sit ... Read Full Story

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Parasitic Infections

Parasites are organisms that live in or on another organism, called the host. The parasites can be microscopic or large enough to see with the naked eye, and they survive by feeding from the host. They can also spread parasitic infections, which can lead to sepsis.