October 2000. Palau asked if members had any experience or knowledge of using malathion inside houses to reduce the chances of mosquitoes spreading dengue.
The unanimous response was it would not be members’ choice! It smells, probably does not last long and a synthetic pyrethroid, such a permethrin, would be a far better choice. Vietnam reported that malathion had been used in the past (0.1-1.5% Malathion 50 e.c.), but today cypermethrin is used. Doses are 50-70 mg a.i./m2.
It was also pointed out that the inside of aircraft are regularly sprayed with permethrin against the risk of spread of vector-borne diseases. Permethrin is used as a water-based emulsion at a rate of 0.2 g per m2. Carpets in aircraft receive a heavier treatment.
Permethrin is also used to treat the interiors of huts, tents, insect netting and bedding. It has been a valuable option in Africa, especially against mosquitoes. The treatment can be quite persistent. In a trial in Pakistan, it was found that the interior of a tent treated with permethrin was still toxic to mosquitoes after 6 months. Aircraft cabins are sprayed with 2% d-phenothrin. ICON (lambda cyhalothrin) is recommend by the WHO as an indoor spray against malaria and dengue vectored mosquitoes.
In the event, a epidemic of dengue occurred in Palau in 2000, and the synthetic pyrethroid, Resmethrin, was sprayed on several schools. It was intended to distribute Bacillus thuringiensis var. israelensis to households.