MOLECULAR XENOMONITORING OF FILARIAL INFECTION IN MALAYSIAN MOSQUITOES UNDER THE NATIONAL PROGRAM FOR ELIMINATION OF LYMPHATIC FILARIASIS

The Deputy Director General of Health initiated the Malaysian National Programme for the Elimination of Lymphatic Filariasis, which aims to obtain nationwide entomological data as a criterion of confirming interruption of trans - mission by mosquitoes, from year 2009. Since then, nationwide entomological surveillance was conducted to eliminate LF in 2018. Molecular xenomonitoring is a promising tool for detecting pools of mosquito samples for the presence of microfilarial DNA in a mosquito population even in minute quantity. This study aimed to determine the possibility of local transmission of lymphatic filariasis by detecting the filarial DNA in field-caught mosquitoes using duplex polymerase chain reaction techniques. Mosquito samples collected from 21 endemic implementation units (red IUs) from 5 endemic states (Kedah, Pahang, Perak, Sabah, and Terengganu) and 6 non-endemic (green IUs) from 2 non-endemic states (Malacca and Selangor), were sorted and labeled. A total of 668 pools of mosquitoes were obtained from a total of 4,738 mosquitoes comprising 21 species from 6 genera. Filarial DNA was extracted from the mosquito samples, PCR amplified and electrophoresed for the specific bands of Brugia malayi and / or Wuchereria bancrofti at 322 bp and 188 bp, respectively, together with negative control of laboratory-bred Aedes togoi. The results confirmed that none of the mosquito samples were infected with B. malayi and / or W. bancrofti. We concluded that there was no evidence of active transmission of microfilariae by the vector population from the study areas.