Chagas Disease: 6 Questions and Answers

Chagas disease, a condition commonly contracted as a result of an insect bite, hasn't had nearly as high a profile in the US as other bite-related maladies such as Lyme disease and West Nile virus. That's largely because infection rates are concentrated in Latin America, where most of the seven million to eight million people who have it live. But it's a disease that's gaining attention here, particularly as immigrant populations move north. What is this mysterious ailment, and do you need to be concerned about getting it?

1. Where Do You Get Chagas Disease?

The disease is most commonly contracted through the bite of the triatomine bug, also called the "kissing bug," This is a six-legged bug that's about an inch long and loves to nest in piles of rock, wood, or brush—or inside houses' cracks and holes. You can contract Chagas disease anywhere the triatomine bug is found, which includes the entire southern US; however, since in Latin American countries homes often are not be built to the standards of the typical American home, Chagas disease is much more prevalent there.

Another way to contract Chagas disease is to be born to a woman who has the disease. Although this is far less common than acquiring the disease by bite, transmission does occur in one of every 250 to 500 live births by women with Chagas disease, according to Herbert Tanowitz, MD, a professor of pathology and medicine at Albert Einstein College of Medicine in New York who has been studying Chagas disease for decades.

2. How Exactly is Chagas Disease Transmitted?

According to Christiane Weirauch, an entomologist and associate professor at the University of California, Riverside, people are typically bitten by the bug while they're sleeping. The bug secrets a type of saliva into the skin. The saliva numbs the skin, so people who’ve been bitten normally don't feel anything. The bug may then defecate onto the skin. After a few moments, the numbing saliva wears off, and a person may begin to scratch the area. This can drive the feces into the bite, where it gets into the bloodstream and floods it with parasites. However, the bite alone—without any scratching—may be enough to cause Chagas disease. "Any lesion in the skin could serve as an entry point for the [parasites]," Weirauch explains.

3. Will I know if I Have Chagas Disease?

Not necessarily. "It's not very easy to diagnose, because even in its acute phase it can be asymptomatic," Weirauch explains. The acute phase occurs immediately after being bitten and lasts for about two months, during which time an infected person may feel fine or perhaps experience mild fever or headache. A person may suspect he's been bitten and get a blood test, which will reveal the presence of Chagas parasites.

If a person doesn't realize he or she was bitten and doesn't seek treatment, the disease may progress to a chronic form that may not manifest itself until years or decades later. According to Tanowitz, about 30 percent of people with chronic Chagas disease will go on to have heart problems, including heart failure and arrhythmia (change in heart rhythm). Ten percent will experience damage to their gastrointestinal tract, including megacolon and megaesophagus. Megacolon occurs when part of the colon enlarges and peristalsis—the muscular contractions that push feces through the tract—stops. It often needs to be treated with surgery. Megaesophagus is a similar enlargement of the esophagus that also may require surgery.

4. Can Chagas Disease Be Treated?

Yes. The key, however, is to catch it in its early stages, which can be tricky. The earlier anti-parasitic medication is started, the more effective it is against the disease. The two drugs most commonly used for treatment are nifurtimox and benznidazole. "Although these drugs clear the blood of parasites in the acute [stage], it is unclear if these drugs prevent the progression to chronic disease," Tanowitz explains. The exact mechanism by which the drugs clear the body of parasites is unknown.

Nifurtimox and benznidazole have known side effects and are not approved by the Food and Drug Administration; people who need them must have their physician obtain them from the Centers for Disease Control and Prevention. Younger people are usually given treatment no matter what, but "Once clinical chronic heart disease is apparent, most experts do not treat," Tanowitz says. At that point, the goal is to treat the heart symptoms or perform a transplant if necessary.

5. Can Chagas Disease Be Prevented?

There is no vaccine against Chagas disease, so the best defense is a good offense: Houses should be properly sealed and sprayed with insecticides in affected areas.

6. Should I Worry About Chagas Disease in the US?

While there are about 300,000 people in this country with Chagas disease, the average American probably has a very small chance of contracting it. You can get the disease via donated blood, although all donors in this country are now screened for it. Although uncommon, babies have been known to get the disease through breastfeeding. Another unlikely source of the disease is a donated organ. Finally, there have been isolated cases as well as outbreaks among people who have consumed contaminated food or drink in South America.

Herbert Tanowitz, MD, reviewed this article.


Herbert Tanowitz, MD. Phone conversation and email conversation with source. November 24-December 8, 2014.

Christiane Weirauch, PhD, associate professor at the University of California, Riverside. Phone conversation with source. November 20, 2014.

"Parasites—American Trypanosomiasis (Also Known as Chagas Disease)."Centers for Disease Control and Prevention. Accessed December 4, 2014.

"Parasites—American Trypanosomiasis (Also Known as Chagas Disease): Triatomine Bug FAQs." Centers for Disease Control and Prevention. Accessed December 4, 2014.

"Chagas Disease (American Trypanosomiasis)." World Health Organization. Accessed November 19, 2014.