Chagas disease, caused by the protozoan parasite, Trypanosoma cruzi, is the most important vector-borne disease in Latin America. It is transmitted to humans by triatomine bugs. Despite an ongoing eradication campaign, transmission persists in many areas, particulary in the Gran Chaco region of Argentina where Triatoma infestans is the main vector. The long-term goal of our project is to understand and model the reinfestation processes of human dwellings and peridomestic structures by T. infestans and the transmission of T. cruzi to humans.

Causes

Chagas disease is caused by a parasite. It is common in Latin America but not in the United States. Infected blood-sucking bugs, sometimes called kissing bugs, spread it. When an infected bug bites you, usually on your face, it leaves behind infected waste. You can get the infection if you rub it in your eyes or nose, the bite wound or a cut. The disease can also spread through contaminated food, a blood transfusion, a donated organ or from mother to baby during pregnancy.

Factors depending on parasites (eg, size of the inoculum, repeated inoculations) and individual host differences (immunological or nutritional status) likely contribute to the diversity of clinical forms of Chagas disease.The occurrence of cardiopathy and digestive forms of Chagas disease has been associated with some HLA haplotypes.

Patients may develop heart failure. Swallowing difficulties may be the first symptom of digestive disturbances and may lead to malnutrition. Patients who have parasitic infection of the colon may experience abdominal pain and constipation. Death is usually caused by heart disease.

Symptoms

Chief symptoms of Chagas' disease include constipation, malaise or a feeling of always being tired, the inability to swallow, fever, and varying degrees of discomfort and/or abdominal pain.

Myocarditis (pictured to the right) is an inflammation of the heart muscle, frequently associated with the acute stage of the disease, which usually returns to normal without treatment. After an asymptomatic period of up to 10-13 years, chronic Chagas heart disease, characterized by fibrosis of myocardial fibres, is seen in a high percentage of the carriers of Trypanosoma cruzi infection.

A few people (about 1% of cases) have symptoms soon after infection. The most recognized acute symptom is 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 tiredness, fever, enlarged liver or spleen, swollen lymph glands, and sometimes a rash, loss of appetite, diarrhea, and vomiting. Infants and very young children can get an often-fatal swelling of the brain.

Treatment

Antiparasitic treatment is most effective early in the course of infection but is not limited to cases in the acute phase. In the United States, this type of treatment is available through CDC. Your health care provider can talk with CDC staff about whether and how you should be treated. Most people do not need to be hospitalized during treatment.

Symptomatic treatment may help people who have cardiac or intestinal problems from Chagas disease. For example, pacemakers and medications for irregular heartbeats may be life saving for some patients with chronic cardiac disease.