The evolving needs of vector-borne disease surveillance across the world

Discussion

More than half of the world’s population is at risk of deadly and debilitating vector-borne diseases. These include neglected tropical diseases (NTDs) currently targeted for elimination such as lymphatic filariasis, onchocerciasis, leishmaniasis, human African trypanosomiasis and Chagas disease. They also include emerging threats which require active surveillance and rapid response such as the arboviral diseases Zika, dengue and chikungunya. Both eliminable and emerging vector-borne diseases require new, sustainable and low cost approaches to improve surveillance in order to protect vulnerable populations. Xenomonitoring, the detection of pathogen DNA in its arthropod vector, can be used to indirectly assess the presence of a pathogen in a community. This presents a less invasive alternative which could be used as a first alert tool to trigger further testing and treatment or vector control. Xenomonitoring could also be used as a tool to assess interruption of transmission of a pathogen following, for example, a disease elimination programme as in the case of LF. We have developed a new approach to molecular xenomonitoring which allows us to detect a range of pathogens from the excreta of potentially exposed mosquitoes. The vector excreta surveillance system enables nearly unlimited pool sizes, can be integrated with existing mosquito collections and can be used to detect pathogens in non-vectors. We present results using malaria, filariasis and trypanosomes and discuss application to viral pathogens. We are also developing field friendly approaches to the extraction, amplification and detection of parasite DNA from mosquitoes or excreta.