Detection of Brugia malayi in laboratory and wild-caught Mansonioides mosquitoes (Diptera : Culicidae) using Hha IPCR assay

An Hha 1 based polymerase chain reaction (PCR) assay developed for the dete ction of Brugia malayi, the causative agent of Brugian lymphatic filariasis , was evaluated for its sensitivity in the laboratory and for its usefulnes s in measuring changes in transmission of the disease in the field. Laborat ory studies showed that the new assay was highly sensitive in comparison wi th the standard dissection and microscopy technique. The assay can detect a s little as 4 pg of parasite DNA or a single microfilaria in pools of up to 100 mosquitoes. The optimum pool size for convenience was found to be 50 m osquitoes per pool. The efficacy of PCR assay was evaluated in filariasis c ontrol programmes in operation in endemic areas of Kerala State, South Indi a. The infection rates obtained by the Hha I PCR assay and the conventional dissection and microscopy technique were 1.2% and 1.7% respectively in ope rational areas and 8.3% and 4.4% respectively, in check areas, which were n ot significantly different (P < 0.05). Thus, the Hha I PCR assay was found to be as sensitive as the conventional technique and hence it can be used a s a new epidemiological tool for assessing parasite infection in field-coll ected mosquitoes.