Insecticide-treated bednets for the prevention of Plasmodium falciparum malaria in Cambodia: a cluster-randomized trial.
OBJECTIVE
To validate and quantify the impact of insecticide-treated bednets (ITN) on malaria morbidity and mortality in Cambodia.


METHODS
A paired, cluster-randomized trial of ITN was conducted in Rattanakiri, North East Cambodia. Thirty-four villages with a total population of 10,726 were randomized to receive deltamethrin-impregnated bednets or to control (no net provision). Cross-sectional surveys measured Plasmodium falciparum prevalence at baseline and 10 months after ITN distribution. Village malaria volunteers in control and intervention villages treated dipstick-positive P. falciparum cases with artesunate and mefloquine. The resulting passive surveillance data were used as an estimate of the incidence of clinical P. falciparum infections.


RESULTS
There was a protective efficacy of 28% in P. falciparum incidence (adjusted rate ratio 0.72, 95% CI 0.47-1.08) and 9% in P. falciparum prevalence (adjusted prevalence ratio 0.91, 95% CI 0.65-1.28) in ITN relative to control villages; however, neither of these estimates reached statistical significance. Individual-level analysis indicated a greater reduction in P. falciparum prevalence among under 5-year-olds (adjusted OR = 0.63, 95% CI 0.26-1.53) compared to older individuals (interaction P = 0.042). The protective efficacy of 35% (95% CI -28, 67%) with respect to clinical P. falciparum incidence in under 5-year-olds was more pronounced than the corresponding estimates for prevalence but was again not significant.


CONCLUSIONS
Lack of statistical significance in the results is likely to be due to a lack of power. The analysis provides further evidence for ITN effectiveness in South East Asia, particularly among individuals under 5 years of age.
Sochantha
T
T
National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia.
Hewitt
S
S
Nguon
C
C
Okell
L
L
Alexander
N
N
Yeung
S
S
Vannara
H
H
Rowland
M
M
Socheat
D
D
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001512:Bedding and Linens; D002160:Cambodia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D007223:Infant; D007306:Insecticides; D016778:Malaria, Falciparum / Q000453:epidemiology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D009570:Nitriles; D011722:Pyrethrins; D012423:Rural Health; D017678:Sex Distribution
D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin