Utility of PCR in Chagas Disease

In chronic T. cruzi infection, PCR is used as a research tool, but is not generally a useful diagnostic test. In the chronic phase, patients have low circulating parasite loads, so PCR is positive in some patients, but the sensitivity is relatively low and highly variable.

PCR assays provide the most sensitive diagnostic tool to:

• Diagnose acute phase and early congenital Chagas disease
• Monitor for acute T. cruzi infection in the recipient of an infected organ or after accidental exposure
• Monitor for reactivation in the immunosuppressed T. cruzi-infected host
  • In these patients, a positive result on conventional PCR does not prove reactivation
  • However, quantitative (real time) PCR assays showing rising copy numbers provide a sensitive indicator of reactivation

Gel electrophoresis showing T. cruzi DNA fragments by PCR from blood. Image courtesy of Laboratory of Infectious Diseases, Universidad Peruana Cayetano Heredia, Lima, Peru