Chagas: a growing silent disease with worrying data in Argentina

Chagas disease: in Argentina, data are worrying, with estimates of 1.6 million infected people, 7 million people at risk of becoming infected, and 1300 babies born with the disease every year. Photograph: Fernando Calzada.

Chagas is a disease associated with extreme poverty; it is endemic in 21 countries in Latin America, affecting approximately 8 million people in the world, of which 1.2 million are women of childbearing age. According to the World Health Organization, more than 95 percent of those people are not aware of their condition. In Argentina, data are worrying: with estimates of 1.6 million infected people, 7 million people at risk of becoming infected, and 1300 babies born with the disease every year. DEF spoke with biologist Diego Weinberg about this topic.

-What are the principal modes of transmission?
–While the disease is generally associated with the presence of bugs, vinchucas, at present, and as a result of progress made in vector and transfusion control, mother-to-child is one of the most important transmission routes. In other words, an infected mother can transmit Chagas disease to her child during pregnancy. Transmission is also possible through blood or organ donation, although now this is very unlikely. As a consequence, while there is a clear need for vector control, undoubtedly it is essential to ensure access to diagnosis and treatment of women of childbearing age; this is an important task that is not being performed most appropriately.

-What is the situation in our region?
-Chagas is an endemic disease all throughout our continent. In the case of the North American countries, there is permanent movement of infected people from other Latin American countries; this fact has generated a health problem that will be important in the future, because a person suffering from Chagas disease is likely to have cardiac or gastrointestinal problems that will have to be treated. It is estimated that there are about seven million people infected with Chagas disease in the Americas and the rate of treated people is very low, due to problems related to access to diagnosis and treatment. It should be noted that this is a global problem.

In Argentina, there are more than one million and a half people infected with Chagas disease; they mostly live in big cities: Buenos Aires city, Greater Buenos Aires, Rosario and Córdoba. Photograph: Fernando Calzada.

-Are population movements responsible for the global expansion of the disease?
–In Argentina, there are more than one million and a half people infected with Chagas disease; they mostly live in big cities: Buenos Aires city, Greater Buenos Aires, Rosario and Córdoba. Persisting with the idea that the disease is related to the mud-walled house, the vinchuca and the Chaco woodland is a partial view. It is true that vector transmission is concentrated in certain provinces –Chaco, Santiago del Estero, Formosa, San Juan, Catamarca–, but the people infected with Chagas disease are distributed all across the country and the rest of the world. Migration of Latin American people expanded the disease to another continent, such as the European one, where there are no vincuchas. Therefore, again, the problem is not the vector, but the infected people. I mean, we need to debunk the myths and start to see the real problem: the infected people distributed all throughout Argentina.

VECTOR CONTROL
-There are studies indicating that vinchucas have been considerably reduced in the last 50 years, is that true?
-In South America, the main vector of Trypanosoma cruzi is the vinchuca. In fact, due to the vector control actions and the advance of deforestation, the habitat has been largely reduced. The presence of vinchucha is currently restricted to the Gran Chaco ecoregion, which covers part of Argentina, Bolivia and Paraguay.
-What are the main control actions?
-The national control program has been implemented for more than 60 years now and, although there have been periods of lower or higher activity, the program has been present in all the area of influence. Moreover, there are provincial programs in the endemic areas. Prevention tasks include chemical control of vinchucas through indoor residual spraying, which makes houses refractory to infestation. Thus the aim is to prevent the presence of vinchucas inside the houses. And, by houses, I am referring to all the peridomestic structures, such as storerooms, ovens, cellars surrounding the house.

Chagas is a disease associated with extreme poverty; it is endemic in 21 countries in Latin America, affecting approximately 8 million people in the world, of which 1.2 million are women of childbearing age.Photograph: Fernando Calzada.

-Are there any other actions taken besides vector control?
-Yes. Besides prevention through chemical control, another important line is the training of the population in healthy practices. A clear example is the inconvenience of having domestic animals –dogs, cats, goats, and pigs– living with the people inside the houses.
-Can animals transmit the disease?
–The cycle is as follows: the vinchuca bites warm-blooded animals; thus, domestic mammals may become infected with the parasite and, if that animal is bitten by a vinchuca and this in turn bites a person, it can transmit the disease.
-Can the disease be cured?
-Yes. I think it is important to make it clear, because there is a myth that says the opposite. The disease cure rate is very high up to adolescence; then it starts to decrease. Therefore, it is very unlikely that a woman of childbearing age can be cured; however, treatment of that woman before pregnancy reduces mother-to-child transmission to zero. For this reason, diagnosis and treatment of children at an early age are key. There are drugs that were not developed for this disease, but that have been used for decades. Although there were some problems with dosage –they were considered for adults and chronic Chagas disease–, in the last years, treatment with these drugs has been strongly promoted, and having access to that treatment in the simplest way possible is essential. Chagas disease can be and must be cured.

MAKING THE DISEASE VISIBLE AS A MEANS TO CHANGE HISTORY
-You work at Fundación Mundo Sano, an organization that implements programs related to Chags disease, among others.
-Yes, we work in Añatuya, Santiago del Estero; Clorinda, Formosa; Puerto Iguazú, Misiones; Pampa del Indio, Chaco, and Tartagal, Salta, where we implement programs for vector control focused on the improvement of houses: making houses refractory to vinchucas is a very important advance. For instance, in the rural area of Añatuya we have a program through which, along with communities, we optimize the houses using local elements. The aim is having houses with no cracks, whitewashed, with storage structures and spaces for healthy cooking. I mean, there are some key issues to consider regarding decent housing, like building a latrine and a cistern to try to alleviate the water issue, which is very severe in those places. Regarding the disease, we installed doctor’s offices to attend people, as a way of mitigating the historical deficit of access to diagnosis and treatment. In summary, the programs have three parts: house improvement, community training, and vector control.

In South America, the main vector of Trypanosoma cruzi is the vinchuca. In fact, due to the vector control actions and the advance of deforestation, the habitat has been largely reduced. Photograph: Fernando Calzada.Photograph: Fernando Calzada.

-The Fundación is implementing the campaign “Not a single baby with Chagas disease”, what is it about?
-The aim is that, by 2030, all the babies born with Chagas disease can be treated and cured. Recent studies have shown that mother-to-child transmission can be prevented; hence, the fact that babies continue to be born infected with Chagas disease is very unfair.
-Is there a high percentage of babies born with Chagas disease?
-The transplacental infection rate is estimated to be in the order of four per cent. To give an idea, in Argentina 1300 babies are born with Chagas diseae every year. That is a lot.
-Finally, has the pandemic had any type of impact on Chagas diseae?
-I am a biologist so, it is not for me to give an opinion about the topic; however, I do believe that the pregnancy follow-up schedules may have been less efficient than usual and that Chagas disease may have gone unnoticed. What I do know is that during the pandemic, almost no work has been done by the vector control groups in the endemic provinces; hence, intervention was almost null compared to the annual surveillance of thousands of houses in the country.