Use of PCR in the field.

Polymerase chain reaction (PCR) represents a powerful new technology with a variety of field applications. While most of these are still experimental, implementation of PCR-based detection of Onchocerca volvulus in black flies, and subspecific differentiation strongly suggest that potential problems can be overcome. Because of high sensitivity and specificity, PCR provides in some cases the only means to address central parasitological questions, and may well become the 'gold standard' by which other diagnostic techniques are measured. In spite of these advantages, routine implementation of PCR,at present,requires transportation of samples to a central facility for processing, and personnel whose technical competence is high. In addition, reagents are expensive. Robert Barker here weighs up these considerations with regard to the potential utility of PCR assays for some applications.