Zambia finds remedy for insecticide resistant mosquitoes

Kapembwa Simbao

Violet Mengo

AfricaSTI, Lusaka

A new study conducted in Lusaka, the Copperbelt and other areas that are endemic to malaria in Zambia has identified an insecticide described as effective for Indoor Residual Spraying (IRS) against insecticide resistant Anopheles gambiae s.s (Diptera: Culicidae).

The researchers said the product has high acceptability due to low adverse effects and inherent cosmetic values concluding that it was a good candidate for use for insecticide resistance management in Zambia.

Emmaunel Chanda, the study principal investigator and an Entomologist with the Ministry of Health (MoH) said the insecticide with the brand name Vectron 20WP kills the mosquitoes in large numbers and remains effective on the walls for some time after spraying.

The persistence of biological efficacy studies and social acceptability studies were done in Bauleni compound in Lusaka while the susceptibility studies in Chipulukusu and Mushili on the Copper belt province and lasted eight months

Over 200 houses were sprayed and 16 households were involved in the persistence of biological efficacy study that lasted for 8 months.

“Over 90 percent of the people whose houses were sprayed indicated no skin irritation resulting from the spray of the insecticide, because of its odourless nature the majority like the insecticide for use indoors,” he said.

Chanda said the insecticide gave a 100 percent residual efficacy up to the fourth month.

“The results give hope for an effective insecticide in light of the limited number of classes of insecticides available for malaria vector control,” Chanda said.

So far there are only 12 registered insecticides for Indoor Residual Spraying (IRS) and 6 for Insecticide Treated Nets (ITNs), many of which have shown less killing effect on major malaria transmitting mosquitoes due to insecticide resistance development over a period of time.

Mulakwa Kamuliwo, deputy director of Public Health and Research for Malaria at the Zambia Ministry of Health explained that the development of insecticide resistance is a great challenge for malaria control and he hopes the new insecticide would help in the management of insecticide resistance in malaria transmitting mosquitoes in Zambia.

Indoor Residual Spraying is the application of a liquid insecticide with long-lasting residual properties which dries to form a crystalline deposit on the sprayed surface.

A lethal dose of the insecticide is absorbed by insects that come into contact with the surface.The insecticide is applied to the indoor resting places of malaria vectors.

IRS is meant to ensure a reduction in malaria transmission in operational settings, by reducing mosquito daily survival rate thus cutting transmission and reducing the density of adult Anopheles mosquitoes.

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Posted by AfricaSTI on September 12, 2011. Filed under Health. You can follow any responses to this entry through the RSS 2.0. You can leave a response or trackback to this entry