Chagas disease

About six to seven million people worldwide, mostly in Latin America, are estimated to be infected with Trypanosoma cruzi, the parasite that causes Chagas disease (WHO data from 2021). Chagas disease is found mainly in endemic areas of 21 Latin American countries. Chagas disease was once entirely confined to rural areas but in the last decades, due to population movements, most infected people live in urban settings and the disease has spread to other continents. The burden of disease is due to its chronic progression with people still suffering years later after initial infection.

The following are standard case definitions to allow national health authorities to interpret data in an international context. However, during an outbreak case definitions may be adapted to the local context and the Red Cross Red Crescent should use those agreed/established by national health authorities. NB: Consider that during community-based surveillance, volunteers should use broad (simplified) case definitions (referred to as community case definitions) to recognize most or all possible cases, provide relevant risk communication and appropriate actions and encourage them to seek care. Other actors such as healthcare workers or investigators studying the cause of a disease, on the other hand, can use more specific case definitions that may require laboratory confirmation.

Any individual who, as a result of a screening programme or of testing as a possible case, was positive for antibodies against T. cruzi in two serological assays.

WHO case definition source of information: https://www.who.int/news-room/fact-sheets/detail/chagas-disease-(american-trypanosomiasis)

Significant increase above historical averages in endemic countries.

A single case of disease as a result of local transmission in non-endemic countries.

• People living in rural areas, in poor conditions in Latin America.
• Pregnancy in a Chagas disease outbreak area is a risk for congenital transmission to the newborn.
• Consumption of food contaminated with T. cruzi.
• Blood transfusion and organ transplantation without correct blood screening.
• Outbreaks of the disease are of particular concern when they occur in overcrowded settings.
• No proper sanitation and hygiene measures.
• Migrants are at increased risk to become infected.

Attack rates will vary from one outbreak to another. In case of an outbreak, consult the latest information provided by health authorities.

It can be below 10 per cent or up to 100 per cent in some epidemics.

• People who have suppressed immune systems (for example, due to HIV or chemotherapy).
• People with chronic diseases such as renal disease, cancer, chronic lung or liver disease and diabetes.

Trypanosoma cruzi (T. cruzi). It is a parasite.

Vector: Triatomine bugs carry T. cruzi.

Wild animals (e.g. armadillos, raccoons, opossums and rodents), domestic animals, humans.

The large reservoir of T. cruzi parasites in wild animals of the Americas means that the parasite cannot be eradicated.

• Vector-borne: T. cruzi parasites are mainly transmitted by contact with faeces/urine of infected blood-sucking triatomine bugs. They usually bite an exposed area of the skin such as the face, and the bug defecates close to the bite. The parasites enter the body when the person instinctively smears the bug faeces or urine into the bite, the eyes, the mouth, or into any skin break. Normally the bugs hide during the day and become active at night when they feed on animal and human blood.
• Vehicle-borne transmission: less often, T. cruzi can be transmitted by the consumption of food contaminated with T. cruzi; blood transfusion from infected donors; organ transplants using organs from infected donors; and laboratory accidents.
• Congenital transmission: from an infected mother to child transmission during pregnancy or childbirth.

7—14 days.

Reservoirs of T. cruzi are infectious for humans as long as the parasite is present in the faeces/urine of infected bugs.

• The initial acute phase lasts for about two months after infection. During this phase, in most cases symptoms are absent, or mild and unspecific. In less than 50 per cent of people bitten by a triatomine bug, characteristic first visible signs can be a skin lesion or a purplish swelling of the lids of one eye. Additionally, they can present with fever, headache, enlarged lymph glands, pallor, muscle pain, difficulty in breathing, swelling, and abdominal or chest pain.
• During the chronic phase, the parasites are hidden mainly in the heart and digestive muscles. Up to 30 per cent of patients suffer from cardiac disorders and up to 10 per cent suffer from digestive (typically enlargement of the oesophagus or colon), neurological or mixed alterations. In later years the infection can lead to sudden death due to cardiac arrhythmias or progressive heart failure caused by the destruction of the heart muscle and its nervous system.

Non-Chagas cardiomyopathy and diseases of digestive system, typhoid fever, visceral leishmaniasis and some congenital infections.

• The diagnosis of acute Chagas disease can be made by observation of the parasite in a blood smear by microscopic examination.
• In the chronic phase, the parasite is difficult to detect and antibodies, which are produced by the body to fight the disease, can be tested in the blood.
• Because no test is sufficiently accurate to work as a stand-alone, two or three different tests must be used.

Please refer to the appropriate local or international guidelines for clinical management. All clinical management including the administration of any treatment should be conducted by health professionals.

• Chagas disease can be treated with antibiotics. The treatment periods, however, are long (60—90 days) and the treatment has serious side effects. If given soon after infection, antibiotics are almost 100 per cent effective in curing the disease (if given at the onset of the acute phase including the cases of congenital transmission). The efficacy diminishes the longer a person has been infected. Infected adults with no symptoms should be offered treatment as well to prevent or curb disease progression.
• In chronic patients, antiparasitic treatment can potentially prevent disease progression and prevent congenital transmission.
• There is no vaccine for Chagas disease.

None. A person who has had Chagas disease and has been cured can be re-infected through any of the routes of transmission.