Indoor residual spraying (IRS) is considered an effective means of mosquito (vector) control. IRS involves spraying internal walls and ceilings of dwellings using insecticides with residual action (i.e. insecticides that remain on the surface for a long time). The effectiveness of this control method depends to a large extent on the vector’s sensitivity to the insecticide used and how much they like to rest indoors. Most vectors in Africa do prefer to rest indoors.
Spraying needs to take place before the malaria transmission season.
The parasite in the blood takes about 12 days at 25oC (or longer in cooler environments) to
develop before it is ready to be transmitted by the mosquito. During this period, the mosquito has to feed about 4-6 times. There is a high probability that the mosquito will rest on a sprayed wall during this time; if it dies then the parasite will not have been transmitted.
Spraying needs to take place before the malaria transmission season.
The parasite in the blood takes about 12 days at 25oC (or longer in cooler environments) to
develop before it is ready to be transmitted by the mosquito. During this period, the mosquito has to feed about 4-6 times. There is a high probability that the mosquito will rest on a sprayed wall during this time; if it dies then the parasite will not have been transmitted.