Introductory Chapter: Chagas Disease – A Multidisciplinary Old Public Health Problem

1. Introduction: state of art

Chagas disease and its etiological agent the protozoan Trypanosoma cruzi (Figure 1) still represents an important barrier to the public health strategies, especially in Latin America, even after more than 110 years of its discovery. Tropical neglected diseases including Chagas disease have been mainly associated with low-income populations in endemic countries, but due to the globalization nowadays, an intense migratory flux is established to well-developed countries in Europe and North America, among other continents, many cases related to blood transmission (congenital, transfusional, and transplant routes) have been notified [1, 2]. It looks incredible that neglected illnesses still present unacceptable and frightening morbimortality rates in the twenty-first century. In order to change the scenario, private and special public health authorities must work together, giving the veritable attention to these diseases, what would culminate in a reduction in the number of deaths [3].

Figure 1.

Countless bloodstream trypomastigotes of the protozoan parasite Trypanosoma cruzi. Micrograph produced by Drs. Helene Barbosa and RubemMenna-Barreto in Jeol JSM6390LV scanning electron microscope located in Plataforma de MicroscopiaEletrônica Rudolf Barth (Instituto Oswaldo Cruz, Fiocruz). Bar: 10 μm.

2. The disease

Epidemiological data from World Health Organization point to 21 Latin American countries endemic of Chagas disease, estimated 6 to 7 million infected people, and 75 million under risk of infection worldwide. This illness possesses two clinical phases: acute and chronic. Patent parasitemia and intense tissue inflammation are the characteristics of acute phase, usually oligosymptomatic [4]. After few months, chronic phase starts in an indeterminate form without any clinical signs or symptoms. Almost 70% of infected individuals will not progress to the symptomatic chronic stage, remaining in this phase for the rest of their lives. The most frequent clinical manifestation observed in chronic phase is cardiac dysfunction, more severe when compared to the other cardiomyopathies, the main cause of mortality in chronic patients. Heart complications are directly associated with the high socioeconomic impact, generating expenditure in the range of billions of dollars annually, as well as the loss of productivity of affected individuals. To avoid mortality and excessive financial expense, more studies about biomarkers for early prognosis should be incited. More groups should develop applicable research focused in this area [5].

3. The treatment: past, present, and future

On the other hand, the treatment of Chagas disease is restricted to the use of two nitroderivatives called benznidazole and nifurtimox developed more than half century ago, presenting its effectiveness is controversial, especially in the chronic phase. Undesirable side effects together with limited efficacy among different parasite stocks justify the intense and continuous efforts to find alternative anti-T. cruzi compounds; however, few drugs have reached the stage of clinical trials up to now [6]. The better understanding of cellular, molecular, and biochemical mechanisms involved in the infection of vertebrate hosts, as well as essential processes in the parasite, can provide subsidies that direct for the development of more effective drugs, and which have fewer adverse effects. It is important to encourage projects and research lines in this direction.

Another no less important point is the use of non-pharmacological approaches in the patients. As an example, it is well known that physical training improves the immune response against many kinds of infections in heart tissue. Once that the worsening of the cardiac alterations in Chagas disease has been related to the prooxidant and immunological responses triggered by the parasite, strategies that promote exacerbation of anti-inflammatory and antioxidant machinery produce protective effects against tissue injury. Recently, our group described the anti-fibrotic effect of the physical exercise in indeterminate stage model in mice, suggesting that regular physical training in indeterminate individuals could partial attenuate the progression of the cardiac lesion [7]. However, further studies analyzing the correlation physical exercise and progression of heart dysfunction must be performed in near future to answer this open question. The search of alternative approaches must be stimulated, once the chronic patients today cannot wait for the development of new drugs.