Parasitic Infections: What they are, and why you should know.

Article parasitic infections

Parasites might seem like something found in a Sci-fi thriller but they’re very real and often dangerous. They’re called parasitic infections, or parasitic diseases and the U.S. Centers for Disease Control and Prevention (CDC) has listed five types Americans should know about. All are caused by parasites – living things that use the human body as their source of food and shelter.2

“Parasitic infections affect millions around the world causing seizures, blindness, infertility, heart failure, and even death," said Dr. Tom Frieden, director of the CDC. “They're more common in the U.S. than people realize and yet there is so much we don't know about them.”

The CDC reports many parasitic infections can be treated. Better still, most can be prevented. The problem is, people and doctors don’t know enough about them to recognize them, or treat them properly.2

Where they come from

The National Institutes of Health said parasites can be picked up from food, water, bug bites, or sexual contact. Parasites can be as tiny as just one cell, or they can be worms big enough to see without a microscope. Many parasitic infections cause gastrointestinal symptoms (diarrhea, vomiting, nausea, etc.).1

The CDC’s five “most wanted” parasitic diseases

1. Chagas disease can be spread in many ways. Its original source is a parasite carried by a bloodsucking insect called a “kissing bug.” The Chagas parasite is called Trypanosoma cruzi. The CDC says more than 300,000 Americans are infected, and more than 300 babies are born with it each year.

Chagas disease is usually spread through contaminated blood transfusions, organ transplants, lab accidents, or by pregnant mothers to the babies they’re carrying. Chagas disease is a major problem in Mexico and Latin America. The CDC says as many as eight million people may be infected in that region.3

2. Cysticercosis is caused by larval cysts from tapeworms in brain, muscle, or other tissue. It’s a major cause of adult-onset seizures in most low-income countries.

Latin America, Asia, and Africa or places with poor sanitation and free-ranging pigs with access to human feces are the highest-risk areas. However, people who live with someone who’s traveled to those places are at risk, too. This is why the CDC is concerned about cysticercosis in the U.S. If an infected person does not wash his or her hands, he or she might accidentally contaminate food with tapeworm eggs while preparing it for others.4

3. Toxocariasis comes from the larvae of two roundworms: Toxocara canis from dogs, and Toxocara cati from cats. Infected dogs and cats shed Toxocara eggs in their feces into say, flowerbeds, gardens, or yards. In two to four weeks, Toxocara larvae develop and eggs become infectious. Because dogs, cats, and people often live together, there may be large numbers of infected eggs in the environment.

Once in the body, the Toxocara eggs hatch and roundworm larvae can travel in the bloodstream to different parts of the body. This includes the liver, heart, lungs, brain, muscles, or eyes. While most infected people don’t show symptoms, fever, coughing, an inflamed liver, or eye problems are possible.5

4. Toxoplasmosis is a top cause of death by foodborne illness. More than 60 million people in America carry the Toxoplasma parasite. Few have symptoms because their immune systems protect them from the parasite. But others suffer flu-like symptoms, painful or swollen lymph nodes, and muscle aches or pains that last longer than a month.6

People are usually infected with toxoplasmosis in one of three ways: foodborne, animal-to-human (zoonotic), and mother-to-child (congenital).7

5. Trichomoniasis is a very common sexually transmitted disease (STD). An estimated 3.7 million people have it. It’s also thought of as the most common curable STD. But trichomoniasis is hard to spot: only about 30 percent of infected men and women have any symptoms. It’s more common in women, and most common in older women.

Without treatment, trichomoniasis can increase the chances of getting or spreading other STDs. Also, pregnant women with trichomoniasis can deliver early or low- birth-weight babies.8

Avoiding parasitic infections

Healthline recommends these ways to protect yourself from parasitic infections:

  • - Drink clean, bottled water when traveling.
  • - If you are pregnant, stay away from cat litter and feces.
  • - Practice safe sex.
  • - Wash your hands often, especially after contact with contaminated food, water, and feces.
  • - Cook food to recommended temperatures and practice good hygiene.
  • - Avoid swallowing water in lakes, streams, or ponds.9


1 The National Library of Medicine, 2014:
2 U.S. Department of Health and Human Services, 2014

Centers for Disease Control and Prevention, 2013:

9 Healthline, 2013: