American trypanosomiasis, later called Chagas disease after Brazilian researcher Carlos Chagas, who discovered it, is a relevant disease caused by infection by the hemoflagellate parasitic protozoa Trypanosoma cruzi. The parasite is transmitted by triatomine bugs, which serve as vectors. The most significant modes of transmission of Chagas disease are still vectorial, whether through the lesion that results from the bite or through the ocular or oral mucosa. However, transfusional and congenital transmission are also epidemiologically relevant.
In the 1980’s, several authors estimated that the disease affected about 18-20 million individuals in endemic areas in Latin America.
Recent data from the World Health Organization, released after a meeting of specialists in Argentina in 2005, indicated the existence of 16-18 million people infected by T. cruzi. However, in a recent publication Dias Scielo estimated this number to range from 12 to 14 million people in Latin America alone; contaminated individuals have also been found in European and in North American countries, most of the times a result of migration as these infected individuals moved from their countries in search of better life conditions. These figures show the inexistence of a recent epidemiological survey and indicate, as pointed out by the WHO, the still current need to know the prevalence and the incidence of the disease. In any case, figures illustrate the social importance of Chagas diasease 100 years after it was discovered.
In Brazil, acute cases of Chagas disease must be reported, according to Decree 5 of 21 February 2006 of the Secretary’s Office of Health Surveillance of the Ministry of Health.
Due to the recent outbreaks of acute infection byT. cruzi, especially through oral contamination, after a meeting of specialists and scientists in 2005 the Secretary’s Office of Health Surveillance of the Ministry of Health launched the Brazilian Consensus on Chagas disease. Official information provided by the Brazilian Ministry of Health regarding different aspects of Chagas disease can be consulted on the Health Portal of the Ministry of Health.
Although initiatives by the WHO and by Latin American governments have led to the control of the vectorial transmission of the disease in different endemic areas by its main vector, Triatoma infestans, the inexistence of a vaccine and of an effective treatment, especially for patients with the chronic form of the disease, is still a challenge that needs to be faced. One of the current challenges in the treatment of patients infectd by T. cruzi is the identification of clinical and laboratory markers that indicate risk or prognosis for the development of arrhythmias, cardiac failure and death for a person with Chagas.
The diagnosis of acute, chronic or congenital infection uses parasitological, serological and molecular methods. After infection, most individuals go through an asymptomatic acute phase. Years or even decades after the acute phase of the infection, about 40% of patients develop symptomatic forms of the chronic phase of the disease.
The pathology is mainly characterized by its cardiac form, with dilated cardiomyopathy associated to myocarditis, fibrosis and cardiac dysfunction. About 10% of infected individuals develop the gastrointestinal form, which may result in megacolon and/or megaesophagus, frequently associated to the cardiac form, making up the mixed chronic form.
In this book, we revisited the history of the discovery of this disease and of the main findings that followed it regarding the parasite, its vectors, the disease itself and its diagnosis and treatment, as well as relevant points in scientific research. We will be bringing reflections on the concepts of health and disease, as well as educational tools, targeting the population at risk of infection. The book uses scientific language and yet it is accessible to students and non-academic people who are interested in the subject.