Chagas Disease (American trypanosomiasis)

Page originally published 04/05/2024. Last updated 05/08/2024.

T. cruzi

Chagas disease, also known as American trypanosomiasis, is a vector-borne disease caused by the parasite Trypanosoma cruzi (T. cruzi). T. cruzi is spread to animals and people by insect vectors called triatomine bugs.

Chagas disease is endemic in 21 countries across Latin America, mainly in rural areas, but due to population movements from rural to urban areas, the geographic distribution has changed. Cases of Chagas disease have been found in other regions around the world including the U.S. 

How is Chagas Disease Transmitted (Spread)?

triatomine map

The parasite and the bug that carries it are not new to the U.S. and can be found in 30 states, however it is not considered endemic due to having less evidence of local transmission of the disease. Chagas disease is a reportable disease in 8 U.S. states (Texas, Arkansas, Tennessee, Arizona, Louisiana, Mississippi, Utah, Washington), and was previously reportable in Massachusetts. Within California, Chagas disease has been reportable in Los Angeles County, since 2019, and is newly reportable in San Diego County as of 2024. It is estimated that 300,000 individuals are living with Chagas disease in the United States. It is believed most transmission occurs in countries where Chagas disease is endemic.

Chagas disease infects people through the bite of a specific type of bug or vector. The bug vectors are called triatomine (tri-atomine) bugs, which are mostly active at night. These bugs are also known as “kissing bugs” or “conenose bugs.” Once the bugs are infected, they pass T. cruzi by biting people’s faces or body when they are sleeping at night. After they bite and ingest blood, they defecate (poop) on the person.

Someone cannot get infected from the bite of a kissing bug. Chagas disease spread only occurs when the feces from an infected bug comes into contact with the bite wound, mucous membranes, or breaks in the skin. The person may scratch or rub the feces into the bite wound, eyes, or mouth.

Chagas disease can also spread through:

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  • Mother-to-baby (congenital),
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  • Contaminated blood products (transfusions),
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  • Organ transplantation from an infected donor,
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  • Eating uncooked food that is contaminated with feces from infected kissing bugs, and/or
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  • Accidental laboratory exposure. 

Chagas disease is not transmitted from person-to-person through contact with infected people or animals.

What are Kissing Bugs?


Most kissing bugs are found in Texas, New Mexico, and Arizona. Also, these bugs can be found throughout most of California in natural areas, including rural foothills and mountainous areas.

  • The Triatoma protracta kissing bug species is most commonly found in California.
  • 28% of these bugs located in Southern California are infected with T. cruzi. This species differs from other kissing bugs because it bites and defecates separately, decreasing the chances for local transmission to occur.
  • Adult kissing bugs can fly and are attracted to light, especially on warm nights, and can get into homes through cracks or holes in infrastructure or through open windows or doors. 
kissing bug

There are 11 different kinds of kissing bugs in the U.S., but the most common kinds are about 1-inch long with dark red stripes, or yellow-orange stripes. Some, especially those found in California, may have a single, light-brown band around the outer edge of the body.

  • The bugs have a long, cone-shaped head with a dark brown or black body.
  • Their legs are all thin and long.
  • Young kissing bugs, called nymphs, look similar in appearance to adults but they are smaller and do not have wings.

Do not touch a kissing bug with your bare hands! Use a glove or plastic bag to catch the bug so you do not touch the bug directly to avoid exposure to possible parasitic infection of Chagas disease.

Please see below section, “What Should I Do if I think I Have Chagas Disease,” to learn more about ways to safely collect a kissing bug if a possible kissing bug is found.

What are the Symptoms of Chagas Disease?

There are two phases of Chagas disease: acute and chronic. Most people with acute infection have no symptoms (asymptomatic) and if left untreated, they will progress to chronic infection.

Acute phase: Lasts for the first few weeks or months of infection. A person may have no symptoms (asymptomatic) or mild ones that usually resolve on their own such as:

  • Swelling at the infection site;
  • Fever;
  • Fatigue;
  • Rash;
  • Body aches;
  • Eyelid swelling;
  • Headache;
  • Loss of appetite;
  • Nausea, diarrhea, or vomiting;
  • Swollen glands; and/or
  • Enlargement of liver or spleen. 
romana sign

Romaña’s sign, the swelling of the child’s eyelid, is a marker of acute Chagas disease. Swelling is due to T. cruzi infecting the eyelid when bug feces are accidentally rubbed into the eye, or because the bite wound was on the same side of the child’s face as the swelling.

Chronic phase: Can last for decades or be lifelong. It may not occur for 10 to 20 years after initial infection. Most people have no symptoms and remain asymptomatic, but less than half (20-30%) of infected people develop severe and sometimes life-threatening medical problems, which may include:

  • Cardiac complications: irregular heartbeat, heart failure, sudden cardiac arrest.
  • Gastrointestinal complications: enlarged esophagus or colon, difficulty eating or pooping, stomach pain.

How is Chagas Disease Diagnosed?

Chagas disease is diagnosed using blood tests. If Chagas disease is suspected, a doctor will consider the following factors:

  • Overall health and medical history,
  • Signs and symptoms, and
  • Travel history.

If Chagas disease is diagnosed, the doctor may recommend cardiac function tests including:

  • Echocardiogram,
  • Electrocardiogram (EKG, ECG), and/or
  • X-ray or CT scan of the abdomen or chest. 

For information specific to healthcare providers about diagnosing Chagas disease, please visit Chagas Information for Healthcare Professionals.

How is Chagas Disease Treated?

Treatment for Chagas disease can be life-saving and occur in either the acute or chronic phase. This includes:

  • Antiparasitic treatment to kill the parasite, and
  • Symptomatic treatment to manage the signs and symptoms of infection.
  • Most people do not need to be hospitalized during treatment.

For information specific to healthcare providers about treating Chagas disease, please visit Chagas Information for Healthcare Professionals.

How Can Chagas Disease be Prevented?

Currently, there is no vaccine, or drugs, available to prevent Chagas disease spread. If you plan on traveling to Chagas endemic areas, it is important to take the following precautions:

  • Sleep indoors, in well-constructed facilities.
    • In areas where the T. cruzi parasite is present, improved housing and spraying insecticide inside housing to eliminate the bugs has decreased the spread of Chagas disease.
  • Avoid sleeping in adobe, mud, or thatch housing in endemic areas.
  • Spray infested areas with long-lasting insecticides.
  • Use bed nets treated with long-lasting insecticides.
  • Wear protective clothing.
  • Apply insect repellent to exposed skin day and night.
  • Follow food and beverage precautions.
  • Avoid consuming salads, uncooked vegetables, unpeeled fruits, and unpasteurized fruit juices.

Keeping Kissing Bugs Away from Your Home

  • Use weather stripping and caulking to close cracks and crevices.
  • Seal openings where bugs can get in.
  • Fix structural problems that allow entry.
  • Screen all windows and vents.
  • Insect-proof pet entrances.
  • Keep lights off at night by doors, windows and on patios when not needed.
  • Remove rodent nests, including wood rat middens, that are close to your home.
  • Remove firewood piles and debris.
  • Check beds at night and shake out bedding.
  • Keep beds a few inches away from the wall.

What Should I Do if I Think I Have Chagas Disease?

If You Have Been Bitten by a Kissing Bug:

  • Wash the bite area with soap and water or disinfect it with an over-the-counter medicated cream.
  • Most bug bites occur in the home, often while a person is sleeping.
  • Bites usually occur on areas of the body that are not covered by clothes (face, neck, arms, and shoulders).
  • Bites are painless but may cause redness of the skin, itching, or swelling within 24 to 48 hours.
  • Call your healthcare provider and discuss your concerns. They will examine you and decide if you need the tests to confirm you have Chagas disease. If you do not have a healthcare provider, contact 2-1-1.

If You Find a Kissing Bug:

  • If you think a kissing bug has bitten a person and you are concerned about Chagas disease, have the bug identified. There are many other bugs in California that look like kissing bugs.
  • If you have the bug, or photo of the bug, please contact the Epidemiology Unit at (619) 692-8499 for identification.

Safe Kissing Bug Collection

If a kissing bug is requested for species identification, or being submitted for testing, it is important to follow safe collection methods including:

  • Do not handle the kissing bug with bare hands. Make sure to handle gently to avoid crushing the bug.
  • Use a glove or small plastic bag to capture or retrieve the bug.
  • Store the bug in a sealed plastic bag, medicine vial, or other small container.
  • Thoroughly clean all surfaces the kissing bug came in contact with using a 10% bleach and 90% water solution.
  • Wash your hands thoroughly after capturing the bug and disposing of any materials used.
  • Document where the bug was found, date (MM/DD/YYYY) and time (HH:MM AM/PM) it was found, whether or not the bug was alive when it was found, what it was doing when it was found, and any noted human exposure (e.g., bites, crawling on you, etc.). 

Can Animals Get Chagas Disease?

Animals can also be affected by the protozoan parasite that causes Chagas disease in people. Dogs and other animals can be exposed to this disease by eating the triatomine bug, by being exposed to the feces of the bug, or by consuming the meat of an infected animal. 

Dogs can develop lethargy, vomiting, diarrhea, decreased appetite, or sudden death quickly after an exposure. On a long-term basis, dogs can develop heart disease or other problems with their internal organs. Less is known about the affects T. cruzi can have on other species of animals such as wildlife.

A range of antiparasitics have been utilized for treating Chagas disease in dogs during the acute phase of the disease, although there is no consensus on the best treatment method. Treatment is focused on the clinical signs (symptoms) of heart failure in the later stages of disease, similar to people. The same prevention methods mentioned above will also keep your pet safe.


For more information, contact the One Health Epidemiology Program via email at, or call the Epidemiology Unit at (619) 692-8499.