Chagas disease

The disease is caused by Trypanosoma cruzi, a protozoan parasite. It is named after Brazilian physician and researcher Carlos Chagas, who identified the disease in 1909. The Pan American Health Organization describes it as endemic in 21 countries in the Americas. Although transmission has historically been associated with rural areas and triatomine insects, infection is now reported in countries beyond the traditionally endemic region. The CDC's journal Emerging Infectious Diseases has reported locally acquired human cases in multiple U.S. states, while the extent of U.S. endemicity remains debated. Many infected people do not know they carry the parasite, which can delay diagnosis and care.

In the Americas, a major route involves blood-feeding triatomine bugs, sometimes called kissing bugs. The insects can deposit parasite-containing feces near a bite; scratching may bring the feces through broken skin, while contamination of the eyes or mouth can also transmit infection. The bite itself is not the principal mechanism described in this route. Other recognized routes include transmission from an infected mother to a child during pregnancy or birth, ingestion of contaminated food or drink, infected blood products, organ transplantation and laboratory accidents.

Chagas disease usually has an acute phase followed by a chronic phase. The acute phase begins soon after infection and may cause no noticeable illness or only nonspecific symptoms such as fever and fatigue. A skin lesion near the entry site or swelling around one eye can occur, but neither appears in every case. The chronic phase may last for years or decades without symptoms. In some people, the infection eventually causes heart disease, including rhythm problems or heart failure, or disorders of the digestive tract such as enlargement of the esophagus or colon. The likelihood and form of complications vary, so symptoms alone cannot establish a diagnosis.

Diagnosis relies on clinical and exposure history together with laboratory testing; the tests used depend in part on the stage of infection. The antiparasitic medicines benznidazole and nifurtimox are used to treat Chagas disease. They are most effective when treatment begins early, while decisions for chronic infection take account of the individual and possible benefits and adverse effects. Care may also be needed for heart or digestive complications. There is no vaccine. Prevention combines reducing contact with triatomine bugs through housing improvement and vector control in affected settings with screening of blood and organ donors and detection of congenital infection. Public-health guidance also emphasizes early diagnosis, follow-up and access to care.