Chagas disease (American trypanosomiasis)

Epidemiology

An estimated 8 million people are infected with Trypanosoma cruzi worldwide, mainly in Latin America where Chagas disease remains one of the biggest public health problems, causing incapacity in infected individuals and more than 10 000 deaths per year.

In the past two decades, Chagas disease has spread to more uninfected regions compared with its evolution since over 9 000 years ago.

Infection caused by T. cruzi existed among wild animals but later spread to domestic animals and human beings, with relative intensification noted at the beginning of the 20th century.

For many decades Chagas disease was a strictly rural disease. However socio-economic changes, rural exodus, deforestation and urbanisation have transformed the epidemiological profile of the disease, rendering it to a more urban/peri-urban phenomenon.

Furthermore, age of infection may also vary - in areas with domiciliary vector transmission, children aged <5 years are more often found to be infected. In areas without domiciliary transmission, the infection is detected at older ages and is usually related to agricultural, fishing or hunting activities providing greater exposure to sylvatic vectors. In general, there is no gender predominance in Chagas disease, but local variations exist according to exposure to different routes of transmission.

Situation in non-endemic countries

In the last decades, infection has been increasingly detected in countries where Chagas disease is non-endemic.

The presence of Chagas disease outside Latin America is due to population mobility, mostly migration, but cases of infection have been reported among travellers returning from Latin America and even in adopted children.

Subsequent (autochthonous) transmission arises mainly from blood transfusion, congenital means and transplantation routes.

HIV-T. cruzi co-infection

Over the past 30 years, the rapid worldwide spread of HIV, in combination with the changing epidemiology of T. cruzi has led to the emergence of T.cruzi/HIV co-infections.

Diagnosis of T. cruzi infection in HIV positive individuals is particularly difficult. When Chagas disease reactivates, especially in a HIV patient, it behaves like a separate disease with acute features such as severe neurological symptoms.

This can lead to misdiagnosis with other infections, the most common differential diagnosis observed being toxoplasmosis. Furthermore, traditional serological diagnostic tests for Chagas are found to be weaker and less sensitive, as HIV-positive patients are less likely to build a strong antibody response against the infection.

The spread of HIV pandemic has not only modified the pathological spectrum of Chagas but also its epidemiology. From the 1980s, when the first case of HIV/T. cruzi co-infection was described to today, cases have been reported in 9 countries (click here to access the world map and list of references for the coinfection cases).