What Is Chagas Disease?

Medically Reviewed by Nayana Ambardekar, MD on April 09, 2024
3 min read

Chagas disease isn’t well-known in America, but it’s been around for thousands of years. A parasite called Trypanosoma cruzi (T. cruzi) causes it.

The disease infects up to 8 million people, mostly in Latin America. The CDC estimates that about 300,000 people in the U.S. have the disease, most of them contracting it in Latin America. 

T. cruzi isn’t passed from person to person like a cold or flu.

Instead, the parasite is spread by triatomine bugs, also known as “kissing bugs.” They’re called that because they often bite people on the thin skin around the eyes or mouth, usually while the person is asleep. (The bites are fairly painless and probably wouldn’t wake someone up.)

But the bug’s bite isn’t what causes the infection -- it’s their poop. If a bug bites an infected animal or person, it becomes a carrier of T. cruzi, which is passed through its feces. The next time the bug feeds on a person, it leaves droppings on them, which can enter that person’s body through their eyes, nose, mouth, or the wound from the bite itself.

Although people mainly get infected from triatomine bugs, the parasite can be passed a few other ways:

  • A blood transfusion or organ transplant from an infected person.
  • Eating uncooked food that’s been contaminated with the parasite, or eating undercooked meat from an infected animal.
  • An infected pregnant mother can transmit the disease to their baby in the womb.

In November 2014, a study from the University of Pennsylvania School of Medicine found that bed bugs can carry T. cruzi. It’s not clear whether these bugs are likely to pass the parasite to people, though.

Chagas disease has two phases. During the first (or acute) phase, symptoms are usually mild. They might include:

  • Fever, fatigue, or other flu-like symptoms
  • A rash
  • A sore where the parasite has entered the body
  • Vomiting, diarrhea, or loss of appetite
  • Swollen eyelids, if the parasite has entered through the eyes (known as Romaña’s sign)

These early symptoms -- if they happen at all -- usually fade on their own in a few weeks or months. The only people in real danger are young children or people with already weakened immune systems.

While the symptoms may go away, the parasite remains in the body. It can stay dormant for years or even decades.

If the disease enters its second (or chronic) phase, it can cause serious heart and intestinal problems, including:

Chagas disease is easiest to treat during the first phase. But the lack of symptoms can make it tough to spot early on.

If you think you have it, your doctor can give you blood tests. If they show you're infected, you’ll need an EKG and other heart tests to check for any heart problems.

Two drugs can treat the disease: benznidazole (Alunbrig) and nifurtimox (Lampit), which kill the parasite. They work well if taken soon after infection. The longer someone's had Chagas disease, the less likely the drugs are to work. Pregnant women can’t take them, but infected newborns can.

If you’re in the U.S., the only way to get the drugs is through the CDC, since they’re not approved by the FDA. The drugs must be taken for up to 2 months. They can cause serious side effects, especially in older people.

There is no vaccine. The best way to prevent it is by avoiding triatomine bugs. They tend to live in homes made from mud, adobe, straw, and palm thatch, according to the CDC. If you’re traveling in Latin America, it’s best to stay out of these types of dwellings. You can also protect yourself by using nets to cover your bed while sleeping.

Since 2007, blood banks in the U.S. have begun screening for Chagas, so there's no longer any chance of infection from the blood supply in America.