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Stephan Bachenheimer, World Bank
The paper, ‘Quantifying anti-trypanosomal treatment effects in chronic indeterminate Chagas disease: a secondary analysis of individual patient data from two proof of concept trials’, has been published in Lancet Microbe.
Chagas disease is a disease of poverty in Latin America and is caused by the parasite Trypanosoma cruzi. The disease is primarily transmitted by Triatominae (‘kissing bugs’) or from infected mothers to children. Individuals can be infected without symptoms for multiple decades. If left untreated, chronic infection can cause irreversible, life-threatening damage to the heart and other vital organs. Daily treatment morning and evening for 8 weeks (112 doses) with either benznidazole or nifurtimox is recommended in chronic infection to prevent the long-term clinical consequences. However, very few individuals living with the infection are given antiparasitic treatment (<1%). This is partly because of limited access to diagnosis, but also because both drugs are poorly tolerated, particularly by adults. Many people stop treatment after only two or three weeks because of the side effects.
The new study used individual participant data (IPD) from 441 patients enrolled into two randomised clinical trials conducted in Bolivia. In chronic Chagas disease it is difficult to assess cure, because parasite densities in blood are very low and seroconversion can take years. By combining the data from these two studies and using a novel probabilistic model, taking into account how the samples were collected over time after treatment, the researchers showed that it was possible to get more accurate estimates of cure. In particular this showed that weekly treatment was as good as daily treatment (8x more drug).
Read the full story on the Centre for Tropical Medicine and Global Health website.