Field efficacy and persistence of long-lasting insecticidal nets (LNs) and long-lasting - insecticidal Hammock Nets (LLIHN) in comparison with conventional insecticide treated mosquito nets (ITN) under the containment of artemisinin tolerant malaria paras

Abstract

The area along the Thai-Cambodia border is considered an epicenter of anti-malarial drug

resistance. Recently. parasite resistance to artemisinin-based therapies has been reported in the area. The artemisinin resistance containment project was initiated in November 2008, with the aims to limit resistant parasites and eliminate malaria in this region. A core method to prevent the spread of drug-tolerant strains of malaria through intensive vector control measures and individual prevention was to distribute long-lasting insecticide-treated nets (LNs) to resident population and long-lasting insecticidal hammock nets (LLIHN) for mobile and migrant populations and forest-goers with in all endemic villages in 7 provinces along Thai-Cambodia border. The efficacy of these measures against primary vector, Anopheles minimus, in this area is unknown. The objective of this study was to compare the bioefficacy of long-lasting insecticidal nets and conventional nets under field conditions in two forest villages.

           The study was carried out in a malaria - endemic area, the households in Baan-Wang-Kraprae of village no. 2, and Khlong-Kachay. Tab-Sai Subdistrict of Pong Num Ron District, Chanthaburi Province. LNs and LLIHN (Permanet") and conventional ITN (K-O-Tab) were distributed to the households. WHO standard procedures for cone bioassay tests were conducted with the bed net samples collected from the households that the net were using. Anopheles minimus used in this study were colonized at the Bureau of Vector Borne Diseases.

           Results of the study showed that both LNs and LLIHN. Permanet nets are highly effective in killing anopheline mosquitoes. The efficacy offered >80% mortality on Anopheles minimus over the entire 5 years period of field evaluation. Moreover the efficacy of LLIHN was higher than that of LNs. But conventional ITN (K-O-Tab) offered less than 80% mortality within 12 months.