Xenomonitoring of Culex quinquefasciatus mosquitoes as a guide for detecting the presence or absence of lymphatic filariasis: a preliminary protocol for mosquito sampling.

A protocol for the collection of resting, blood-engorged Culex quinquefasciatus Say and their examination for microfilariae has been developed as a way of detecting whether lymphatic filariasis (LF) occurs in a particular locality. The protocol was first implemented in a pilot study in Trinidad, West Indies. For gathering prevalence data, such xenomonitoring is a suitable alternative to the use of human bait, which is ethically questionable. The resting mosquitoes were collected, either indoors or outdoors, using electrical and mouth aspirators. A 'cocoeya broom', made from a bunch of the midribs of coconut-palm leaves, was found to be useful in flushing out the mosquitoes resting in hard-to-reach areas within bedrooms. The rationale behind the strategy and the five-step methodology, of householder notification, mapping, preparation of equipment, mosquito collecting and laboratory processing, are described. Data from the pilot study indicate that this xenomonitoring protocol may be applicable worldwide, albeit with modifications to take account of variations in the vector species involved and their ecology and resting behaviour.