Chasing the kissing bug: new study cracks open the door for improving diagnoses of chagas
New TDR-supported research establishes a crucial first step in opening the way towards more accurate and reliable diagnostic testing for Chagas disease, one of the highest burden diseases of poverty, which affects an estimated 10 million people.
The infection by the protozoan Trypanosoma cruzi can be acquired from blood-sucking triatomine bugs, blood transfusion, transplacental transmission or by the oral contamination foodstuffs by infected triatomine faeces. Chagas is curable if detected soon after infection, but diagnosing the parasitic disease can be difficult. If left untreated, chronically infected people can develop cardiac, digestive, or neurological disorders.
A TDR-facilitated consortium has published in PLoS Neglected Tropical Diseases (January 2011 | Volume 5 | Issue 1 | e931) the results of a multi-country study to develop standards for the best way to administer currently available diagnostics for Chagas. The diagnostic they focused on was the polymerase chain reaction (PCR) test, which is currently the most sensitive tool, has a high variation in accuracy and a lack of international quality controls in diagnostics. The project was coordinated by Alejandro G. Schijman, Ph.D., of the Instituto de Investigaciones en Ingeniería Genética Biología Molecular, Buenos Aires, Argentina.
The study worked with 26 expert laboratories from 16 countries, which evaluated their current PCR procedures against sets of control samples, composed by serial dilutions of T.cruzi DNA from culture stocks belonging to different lineages, human blood spiked with parasite cells and blood samples from Chagas disease patients. A high variability in sensitivities and specificities was found among the 48 reported PCR tests. Out of them, four tests with best performance were selected and further evaluated.
One of the most unique aspects of the study was the fact that participating countries, which are mostly middle and low-income, contributed not only scientific but also financial resources to making it work. This is really a case of countries taking responsibility and action for dealing with their own disease burden, said Dr Janis Lazdins, one of the co-authors of the study who helped develop the project for TDR. It is a model for how to do multi-country collaborative research on limited budgets, he said.
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