PCR- elisa for the detection of Brugia malayi infection using finger-prick blood

A polymerase chain reaction assay based on the enzyme-linked immunosorbent assay (PCR- elisa) has been developed to detect Brugia malayi infection in an area of low endemicity in Malaysia. Blood samples from 239 subjects were tested: 192 amicrofilaraemic individuals, 14 microfilaraemic persons and 3 chronic elephantiasis cases from endemic areas and 30 city-dwellers (non-endemic controls). PCR products were examined by elisa and Southern hybridization. In the PCR- elisa, digoxigenin-labelled PCR products were hybridized to a biotin-labelled probe. This was followed by incubation in streptavidin-coated microtitre wells and detection using anti-digoxigenin-peroxidase and ABTS TM [2,2′-azinobis(3-ethylbenzthiazoline-6-sulphonic acid)]. All microfilaraemic samples were positive by PCR- elisa and Southern hybridization and all samples from non-endemic subjects and chronic elephantiasis patients were negative. The PCR- elisa detected 12 times as many B. malayi infections as did thick blood film examination. Nineteen of the 194 samples from the endemic area gave positive results by both PCR- elisa and Southern hybridization, and an additional 5 samples were positive by PCR- elisa only. The PCR- elisa was specific and sensitive, detected more infections, and was more reproducible than Southern hybridization.