Collective rationality

The majority of people infected with T. cruzi show some sign or symptom at the time of infection and in a small number of cases acute Chagas disease can be fatal. But for the majority, the symptoms go unnoticed for years and those infected experience no further problems. It is estimated that approximately 70 per cent of these people live with the parasite without their health being affected. Nevertheless, in the chronic phase of the disease 30 per cent will develop problems in their heart, gastrointestinal tract and central nervous system that cause irreversible damage. There are currently only two medicines to combat Chagas disease, both of which were developed more than 35 years ago and in investigations not specifi cally aimed at Chagas disease. Neither of these drugs can be used in pregnant women but the success rate reaches almost 100 per cent in newborns and infants. However, in older children, adolescents and adults, treatment is only 60–70 per cent effective and can have multiple side effects and, therefore, has to be taken under medical supervision. This means having a weekly checkup with a trained healthcare worker. But, as the side effects are more common in older patients, many doctors have been reluctant to use the drugs in adults, although it has now been shown that the adverse effects can be manageable. With the limited resources available in rural areas of Latin America to treat Chagas disease, medical teams are often unable to diagnose and treat the disease. New diagnostic tests, better medicines and cure tests urgently need to be developed to deal with this illness, say MSF. Currently, MSF uses a rapid diagnostic test to detect cases. But, following WHO recommendations, all positive tests need to be confi rmed with two conventional laboratory serological assays. If there is any discrepancy between the two tests, a third laboratory test must be used to obtain a reliable result. In areas such as rural Bolivia, where the incidence of the disease is high, the ideal would be to have a highly sensitive and specifi c rapid diagnostic test which would reveal whether the patient was infected or not in a short space of time and would not require specialised laboratories. MSF says the Drugs for Neglected Diseases initiative (DNDi), of which it is a founder member, is working on possible alternative treatments to the two currently available. But these are a …