Chagas disease is named after the Brazilian physician Carlos Chagas, who discovered the disease in 1909. It is caused by the parasite Trypanosoma cruzi, which is transmitted to animals and people by insect vectors and is found only in the Americas (mainly, in rural areas of Latin America where poverty is widespread). Chagas disease (T. cruzi infection) is also referred to as American trypanosomiasis.
In the United States, Chagas disease is considered one of the neglected parasitic infections (NPI), a group of five parasitic diseases that have been targeted by CDC for public health action.
Chagas disease, or American trypanosomiasis, is caused by the parasite Trypanosoma cruzi. Infection is most commonly acquired through contact with the feces of an infected triatomine bug (or "kissing bug"), a blood-sucking insect that feeds on humans and animals.
Infection can also occur from:
- mother-to-baby (congenital),
- contaminated blood products (transfusions),
- an organ transplanted from an infected donor,
- laboratory accident, or
- contaminated food or drink (rare)
Chagas disease has an acute and a chronic phase. If untreated, infection is lifelong.
Acute Chagas disease occurs immediately after infection, may last up to a few weeks or months, and parasites may be found in the circulating blood. Infection may be mild or asymptomatic. There may be fever or swelling around the site of inoculation (where the parasite entered into the skin or mucous membrane). Rarely, acute infection may result in severe inflammation of the heart muscle or the brain and lining around the brain.
|Romaña's sign, the swelling of the child's eyelid, is a marker of acute Chagas disease. The swelling is due to bug feces being accidentally rubbed into the eye, or because the bite wound was on the same side of the child's face as the swelling. Photo courtesy of WHO/TDR.|
Following the acute phase, most infected people enter into a prolonged asymptomatic form of disease (called "chronic indeterminate") during which few or no parasites are found in the blood. During this time, most people are unaware of their infection. Many people may remain asymptomatic for life and never develop Chagas-related symptoms. However, an estimated 20 - 30% of infected people will develop debilitating and sometimes life-threatening medical problems over the course of their lives.
Complications of chronic Chagas disease may include:
- heart rhythm abnormalities that can cause sudden death;
- a dilated heart that doesn’t pump blood well;
- a dilated esophagus or colon, leading to difficulties with eating or passing stool.
In people who have suppressed immune systems (for example, due to AIDS or chemotherapy), Chagas disease can reactivate with parasites found in the circulating blood. This occurrence can potentially cause severe disease.
The diagnosis of Chagas disease can be made by observation of the parasite in a blood smear by microscopic examination. A thick and thin blood smear are made and stained for visualization of parasites. However, a blood smear works well only in the acute phase of infection when parasites are seen circulating in blood.
Diagnosis of chronic Chagas disease is made after consideration of the patient's clinical findings, as well as by the likelihood of being infected, such as having lived in an endemic country. Diagnosis is generally made by testing with at least two different serologic tests.
Treatment for Chagas disease is recommended for all people diagnosed with an acute infection, congenital infection, and for those with suppressed immune systems, and for all children with chronic infection. Adults with chronic infection may also benefit from treatment.
For cardiac or gastrointestinal problems resulting from Chagas disease, symptomatic treatment may be helpful. Patients should consult with their primary health care provider. Some patients may be referred to a specialist, such as a cardiologist, gastroenterologist, or infectious disease specialist.
In the U.S., medication for Chagas is available only through CDC. Your health care provider can talk with CDC staff about whether and how you should be treated.
In endemic areas of Mexico, Central America, and South America improved housing and spraying insecticide inside housing to eliminate triatomine bugs has significantly decreased the spread of Chagas disease. Further, screening of blood donations for Chagas is another important public health tool in helping to prevent transfusion-acquired disease. Early detection and treatment of new cases, including mother-to-baby (congenital) cases, will also help reduce the burden of disease.
In the United States and in other regions where Chagas disease is now found but is not endemic, control strategies are focused on preventing transmission from blood transfusion, organ transplantation, and mother-to-baby.