Medical Definition of Chagas disease
Chagas disease: An infection caused by the parasite Trypanosoma cruzi. Also called American trypanosomiasis. Transmitted by reduviid bugs, or kissing bugs, that live in cracks and holes of substandard housing primarily found in South and Central America. These insects become infected after biting an animal or person who already has Chagas disease. Infection is spread to humans when an infected bug deposits feces on a person's skin, usually while the person is sleeping at night. The person often accidently rubs the feces into the bite wound, an open cut, the eyes, or mouth. Infected mothers can pass infection to their baby during pregnancy, at delivery, or while breastfeeding.
Chagas disease primarily affects low income people living in rural areas. Many people get the infection during childhood. The early stage of infection (acute Chagas disease) usually is not severe, but sometimes it can cause death, particularly in infants. However, in about one-third of those who get the infection, chronic symptoms develop after 10-20 years. For these persons who develop chronic symptoms, the average life expectancy decreases by an average of 9 years. There are three stages of infection with Chagas disease;
- Acute: Acute symptoms only occur in about 1% of cases. Most people infected do not seek medical attention. The most recognized symptom of acute Chagas infection is the Romaña's sign, or swelling of the eye on one side of the face, usually at the bite wound or where feces were rubbed into the eye. Other symptoms are usually not specific for Chagas infection. These symptoms may include fatigue, fever, enlarged liver or spleen, and swollen lymph glands. Sometimes, a rash, loss of appetite, diarrhea, and vomiting occur. In infants and in very young children with acute Chagas disease, swelling of the brain can develop in acute Chagas disease, and this can cause death. In general, symptoms last for 4-8 weeks and then they go away, even without treatment.
- Indeterminate: Eight to 10 weeks after infection, the indeterminate stage begins. During this stage, people do not have symptoms.
- Chronic: Ten to 20 years after infection, people may develop the most serious symptoms of Chagas disease. Cardiac problems, including an enlarged heart, altered heart rate or rhythm, heart failure, or cardiac arrest are symptoms of chronic disease. Chagas disease can also lead to enlargement of parts of the digestive tract, which result in severe constipation or problems with swallowing. In persons who are immune compromised, including persons with HIV/AIDS, Chagas disease can be severe. Not everyone develops the chronic symptoms of Chagas disease.
The incubation period (from contact with the parasite to symptoms) ranges from a few days to weeks. Most people do not have symptoms until the chronic stage of infection, 10-20 years after first being infected.
Chagas disease can be transmitted by blood transfusion or organ transplant. In fact, transmission through blood transfusion is now the second main route of infection. In some but not all countries in South and Central America, 100% of blood donors are screened. Infection rates among blood recipients vary from 0.1- 4.2% in Argentina, Brazil, Chile and Uruguay, and can be up to 24.4% in Bolivia. Economic hardship in Latin America has stimulated migration of rural people to urban areas, increasing the possibility of acquiring the infection by blood transfusion in cities. The problem has extended to developed countries because of the increase in population migrations. The infectivity risk, defined as the likelihood of being infected when receiving an infected transfusion unit, has been estimated as 20%.
Medication for Chagas disease is usually effective when given during the acute stage of infection. Once the disease has progressed to later stages, medication may be less effective. In the chronic stage, treatment involves managing symptoms associated with the disease. There is neither a vaccine nor recommended drug available to prevent Chagas disease.
Chagas disease is locally transmitted in Argentina, Belize, Bolivia, Brazil, Chile, Colombia, Costa Rica, Ecuador, El Salvador, French Guiana, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Suriname, Uruguay, and Venezuela. Those people who sleep in poorly constructed houses found in the rural areas of the above-mentioned countries are at elevated risk of infection. Houses constructed from mud, adobe, or thatch present the greatest risk. Travelers planning to stay in hotels, resorts, or other well-constructed housing facilities are NOT at high risk for contracting Chagas disease from reduviid bugs.
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