Sensitivity of the nested-polymerase chain reaction (PCR) assay for Brugia malayi and significance of 'free' DNA in PCR-based assays

Int J Parasitol. 2000 Oct;30(11):1177-9. doi: 10.1016/s0020-7519(00)00104-1.


The blood filtration method was used as the gold standard to determine the detection level of simple blood-spot sampling and nested-polymerase chain reaction (PCR) for Brugia malayi. Of 100 samples, 48 were filtration-positive. Of these, 26 had microfilaria counts that were low enough (<1-29 microfilariae/ml) to accurately assess the limit of detection by nested-PCR. Nested-PCR consistently detected B. malayi DNA in samples with > or = 10 microfilariae/ml. Post-filtration, microfilaria-depleted, blood-spots from microfilaria-positive samples were screened by nested-PCR and B. malayi specific 'free' DNA was detected in 51.7% of these samples. There was no evidence for 'free' DNA in microfilaria-negative individuals from this endemic community.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Brugia malayi / genetics
  • Brugia malayi / isolation & purification*
  • DNA, Helminth / blood*
  • Filariasis / blood
  • Filariasis / diagnosis*
  • Humans
  • Microfilariae / isolation & purification
  • Parasitemia
  • Polymerase Chain Reaction
  • Sensitivity and Specificity


  • DNA, Helminth