Malaysian Journal of Microbiology (Jan 2005)

Treatment Follow-up of Brugia malayi Microfilaraemic and Amicrofilaraemic Individuals with Serological Evidence of Active Infection

  • Rahmah, N.,
  • Lim, B. H.,
  • Mehdi, R.,
  • Nazmi, M. N.

Journal volume & issue
Vol. 1, no. 1
pp. 42 – 47

Abstract

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Filariasis caused by Brugia malayi and Brugia timori affects ~13 million Asians. In order to ensure elimination of these infections in the context of the Global Programme for Elimination of Lymphatic Filariasis (GPELF), assays which are more sensitive than night blood examination must be employed. IgG4 assay using BmR1 recombinant antigen has been shown to be highly specific and sensitive for diagnosis of brugian filariasis. To provide further evidence of the diagnostic value of this assay, treatment follow-up study was performed on B. malayi microfilaraemic and amicrofilaraemic individuals who were positive by the BmR1-based IgG4-ELISA. Group 1 comprised 22 treated microfilaraemic individuals; group 2A comprised 13 treated amicrofilaraemic individuals and group 2B (control group) comprised 16 untreated amicrofilaraemic individuals. Group 1 individuals demonstrated decline in IgG4 levels with treatment and all participants were negative by the end of the 21 months study period. Group 2A also demonstrated IgG4 decline to negativity by 21 months, with re-treatment at 12 months performed on 3 individuals. In group 2B untreated individuals, at 21 months seven participants remained IgG4 positive while nine individuals were IgG4 negative, possibly through spontaneous death of adult worms. Significant difference (p=0.008) was observed when proportions between group 2A and group 2B were compared. This study showed decline of filaria-specific IgG4 post-treatment in both microfilaria positive and microfilaria negative individuals. In addition amicrofilaraemic IgG4 positive individuals were shown to be infected as evidenced by the significant difference between treated and untreated groups of individuals. Therefore, this study strengthened the reported findings that IgG4 assay based on BmR1 recombinant antigen is a good diagnostic tool for brugian filariasis.

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