A blinded, controlled trial of an ultrasound device as mosquito repellent

Ultrasound emitting devices are used to repel mosquitoes. We tested the repelling properties of a commercially available ultrasound device in a domestic setting in Gabon. Devices emitting three different block frequencies ranging from 3 to 11 kHz were tested in a paired, cross-over blinded and placebo controlled trial during eighteen nights in nine pairs of houses. A total of 7485 mosquitoes (10% Anopheles, 62% Culex, 27% Mansonia and 1% Aedes) were caught, 23 per house per night. There was no significant difference in landing rate between the houses with ultrasound device and the houses with placebo for any species of mosquito. Thus the ultrasound device used was not effective against mosquitoes in this strictly controlled trial.