Vector incrimination studies of lymphatic filariasis in rural areas of endemic Datia district of Madhya Pradesh, India

Background Lymphatic filariasis is a neglected tropical disease caused by infections from Wuchereria bancrofti, Brugia malayi or Brugia timori. These infections are spread by mosquito species such as Culex, Anopheles, Aedes and Mansonia. With >50 million cases in 44 countries, it is the most important parasitic disease next to malaria. India initiated a mass drug administration (MDA) program in 2004 and a gradual reduction was seen in the cases; however, few pockets continue to record new cases. We conducted this study in Datia district of Madhya Pradesh, known to be endemic for filariasis, to understand the ongoing transmission and vector incrimination. Methods Mosquitoes were collected from rural and urban localities of Datia district. Mosquitoes were identified, segregated and pooled. The pools were tested for the presence of W. bancrofti using molecular tools. The polymerase chain reaction (PCR) products were sequenced for confirmation of results. Results Of 974 tested female mosquitoes, 45.8% were Culex quinquefasciatus and 50.8% were Anopheles subpictus. The mosquitoes were segregated in 55 pools; 8 (14.54%) pools were found positive for W. bancrofti by real-time PCR. All the positive pools were of C. quinquefasciatus and the species-specific pool positivity rate was 24.24%. All the positive pools were from Sarsai village. The sequencing results confirmed the presence of W. bancrofti. Conclusions This study confirms ongoing transmission of W. bancrofti and C. quinquefasciatus as the vector species in the rural parts of district. The intervention protocols such as MDA and vector control activities need to be strengthened in rural parts of endemic districts to halt the transmission.