New diagnostic techniques for Chagas disease

Although over 100 years have passed since its discovery, Chagas disease continues to be a serious poverty-related health problem and the main cause of myocarditis in endemic regions.

The development of accurate diagnostic tools and indirect markers of treatment response are among the priorities of researchers working in the fight against Chagas disease. One possible solution lies in DNA amplification methods, which have been proposed as highly sensitive and specific laboratory tools for detecting T. cruzi infection in a range of clinical settings. In certain parts of the world, the spread of Chagas disease has been controlled by blood transfusion testing and vector-control programmes, but mother-to-child (vertical) transmission is responsible for many of the new cases, and this is increasingly the case in urban areas and non-endemic countries due to population movements. Routine testing for congenital Chagas disease consists of direct parasite visualisation at birth, but such tests have a low sensitivity (approximately 50% when conducted by expert examiners). Serologic tests are of no value in children younger than 9 months due to the effects of circulating maternal antibodies. The long-term monitoring required to confirm infection in children is a major obstacle, particularly in resource-poor settings, where many of the children who leave the maternity ward undiagnosed are lost to follow-up. PCR (polymerase chain reaction) and LAMP (loop-mediated isothermal amplification) are two DNA amplification techniques currently being validated for the early diagnosis of congenital Chagas disease in peripheral blood samples from newborns.

These techniques are also gaining popularity for monitoring the disease in patients with compromised immune systems due to organ transplant or HIV coinfection, as thanks to their high sensitivity, molecular diagnostic methods can detect disease reactivation prior to the onset of symptoms.

We can expect that these methods will be incorporated into clinical practice in the near future, just as has occurred with other infectious diseases such as tuberculosis, HIV/AIDS, and viral hepatitis.