The polymerase chain reaction (PCR) was used for diagnosing Wuchereria bancrofti infection in a small village in the province of Sorsogon, the Philippines. Of 54 night-time blood samples collected, 4 (7.4%) were found to be microfilaremic as determined by combined direct blood film examination and membrane filtration of blood followed by blood film examination. However, utilization of the SspI PCR assay to detect repeated W. bancrofti DNA sequences in human blood doubled the number of microfilaremic individuals to 8 (13.0%). The results of this survey suggest that utilization of diagnostic tools based on microscopy could underestimate the true prevalence of W. bancrofti in the Philippines.
