The challenges of Chagas disease

12 Jul 2010

Paul Chinnock

Source: PLoS Neglected Tropical Diseases (see original article or PDF)

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Citation: Lannes-Vieira J, de Araújo-Jorge TC, Soeiro MdNC, Gadelha P, Corrêa-Oliveira R (2010) The Centennial of the Discovery of Chagas Disease: Facing the Current Challenges. PLoS Negl Trop Dis 4(6): e645.

2010 Lannes-Vieira et al.

An estimated 8–15 million people, in the 15 Latin American countries afflicted by Chagas disease, are infected with the parasite Trypanosoma cruzi. Every year, over 40,000 are infected through vector transmission and there are 14,000 cases of congenital infection. Over one per cent of the blood in blood banks in these countries is also infected. The most serious and frequent manifestation of the chronic disease is Chagas disease cardiopathy, the leading cause of infectious myocarditis worldwide. Some 20–40% of infected individuals develop this condition 10–30 years after they have become infected.

An article by scientists at the Fundação Oswaldo Cruz, Rio de Janeiro, Brazil looks at the current challenges posed by the disease, 101 years after the publication of research by Carlos Chagas, in which the great Brazilian scientist described the disease, the organism responsible and its means of transmission [1].

The scientific challenges include the lack of a vaccine, the need for more effective treatment, the difficulties of surveillance, finding ways to measure disease progression in infected individuals, and the need to know more about the biology and behaviour of the triatomine bugs that transmit the disease.

However, these are not the only issues; Chagas disease mainly affects the poor and socially marginalized, and its social determinants cannot be neglected. They include poor housing and working conditions, low salaries and malnutrition.

The authors report some favourable developments in recent years. These include large-scale vector control programmes in parts of Central America and the Amazon that have led to reductions in disease control and mortality. However, more such programmes are needed and there is a need for integration of vector control and patient treatment activities, which are generally run as separate, vertical programmes.

Although many hopes have been pinned on the development of a vaccine, these have yet to be realised. The authors say it is still unclear whether a prophylactic vaccine will have a place in Chagas disease control or whether all that we can realistically expect is a vaccine that would delay disease progression in those who are already infected.

Currently there are only five clinical trials in progress for Chagas disease treatment. The authors describe this as “negligence” on the part of the pharmaceutical industry. They also note the importance of the contributions to Chagas research and control now being made by the Drugs for Neglected Diseases initiative (DNDi) and Médicins Sans Frontières (MSF).

Of particular interest is the BENEFIT study which is looking at the use of benznidazole (one of two drugs used in the treatment of the acute infection) in chronic cases of the disease. The investigation of combination therapies may also lead to improvements in treatment. Better diagnostic tests and the development of biomarkers indicative of treatment efficacy and cure are also on the list of challenges.

To improve the care of patients, the authors identify four priorities:

holistic care of the patients beyond solely conventional therapy
innovation on drugs or combined therapies that provide a shorter treatment course with fewer side effects, and on paediatric formulations
new tools to follow up treatment efficacy during the chronic phase
new biomarkers to identify cure and assist with stratification and prognosis of risk factors.

Other challenges in Chagas disease control are:

sustainable and integrated surveillance strategies and identification of priority areas for immediate intervention
provision of adequate, universal, integral, and holistic care to patients, with access to available and new therapies

improvement of diagnostic and prognostic markers for disease progress, aiming for more rational interventions
guaranteed access to information, education, and social organisations for Chagas disease patients and their families
creation of more organized, integrated, and collaborative networks between researchers, physicians, patients, and policy makers.

However, Carlos Chagas himself described “the construction of decent housing, compatible with a healthy way of life” as “the most necessary element” in control of the disease. This remains true 101 years on.

Reference

Chagas CRJ das (1909). Nova tripanosomiase humana. Estudos sobre a morfolojia e o ciclo evolutivo do Schizotrypanum cruzi n.g., n.sp., ajente etiolojico de nova entidade morbida do homem. Mem Inst Oswaldo Cruz 1: 159-218. Available from: http://www.scielo.br/pdf/mioc/v1n2/tomo01%28f2%29_159-218.pdf