In Brazil, an estimated four million people suffer from chronic Chagas; 600,000 people have developed heart or gastrointestinal complications; and each year 5,000 people succumb to the disease. In absolute values, the number of deaths caused by Chagas disease in Brazil is on a par with those caused by tuberculosis, and is ten times higher than the combined number of fatalities resulting from schistosomiasis (a parasitic disease caused by trematode flatworms of the genus Schistosoma), malaria, leprosy, and leishmaniasis. The disease mainly affects people between 30 and 60 years of age. Because this is the working population, the loss of earnings and the inability to work have a major social and economic impact. Moreover, the disease afflicts mostly the poor and, given its serious impact, leads to a vicious circle in which poverty is perpetuated and aggravated.

The discovery and the consequences
In the early 20th century, Carlos Chagas travelled inland to Minas Gerais in Brazil. Chagas had been appointed by Oswaldo Cruz, then director of the Federal Department of Public Health, to carry out an investigation into an outbreak of malaria that was jeopardising the completion of the national central railway extension. The investigation resulted in the identification of a new vector, a blood-sucking bug commonly known as the “kissing bug”, a new species of parasite, Trypanosoma cruzi, named after Oswaldo Cruz, as well as the finding of a new disease, called after the discoverer himself. Carlos Chagas announced the triple discovery in 1909. This was an unprecedented breakthrough in the history of medicine, encompassing the whole cycle of the disease: etiologic agent, insect vector, and human infection. Oswaldo Cruz described it as follows: “The discovery of this disease is the most beautiful illustration of the power of logic at the service of science. Never before, in the field of biological research, has such a fully researched and brilliant discovery been made in such a short time and, what is more, by a single researcher.” The scientific discovery bolstered the country’s international prestige, and among other acknowledgments from national and international institutions, Carlos Chagas was nominated for the Nobel Prize twice – in 1913 and 1921.
The magnitude of Carlos Chagas’ discovery can be appreciated in light of the success achieved in the interruption of the transmission of Chagas disease through vector control. In 2006, Brazil was certified by WHO as having interrupted the transmission of the disease by Triatoma infestans, the main Chagas vector in the country. Other challenges, however, still need to be addressed: ensuring the sustainability of the vector control, to prevent transmission by other insects or mechanisms (e.g. via dietary exposure), and making quality care available to millions of patients suffering from both, acute and chronic Chagas disease.

Major challenges ahead to tackle a complex disease
To prevent and identify acute infection, it is still necessary to improve diagnostic tools, test drug combinations, and gain a better understanding of patients’ responses to treatment protocols. Rapid and low-cost tests are essential to ensure proper care is given to chronic patients, for whom it is necessary to define reliable markers to monitor disease evolution and manifestation. The relationship between the immune system and the nutritional profile of patients also requires further investigation and clarification, especially in terms of ingestion of selenium and vitamins.
One important epidemiological challenge is the emergence of the disease in the Amazon – and as in the rest of country, it is necessary to improve the tools for monitoring and controlling vectors in wild environments and habitats. In the past century, little progress has been made in terms of specific awareness-raising activities to address the challenges of this national disease. Overall, there is a lack of initiatives and resources targeting the population at risk, health and education professionals, and patients. Yet undoubtedly the biggest gap concerns the development of new drugs. Brazil remains as committed to playing a responsible and leading role as Carlos Chagas and his collaborators did in the first decade of the 20th century.