Sustainability of reductions in malaria transmission and infant mortality in western Kenya with use of insecticide-treated bednets: 4 to 6 years of follow-up.
BACKGROUND
Insecticide-treated bednets reduce malaria transmission and child morbidity and mortality in short-term trials, but this impact may not be sustainable. Previous investigators have suggested that bednet use might paradoxically increase mortality in older children through delayed acquisition of immunity to malaria.


OBJECTIVE
To determine whether adherence to and public health benefits of insecticide-treated bednets can be sustained over time and whether bednet use during infancy increases all-cause mortality rates in older children in an area of intense perennial malaria transmission.


METHODS
A community randomized controlled trial in western Kenya (phase 1: January 1997 to February 2000) followed by continued surveillance of adherence, entomologic parameters, morbidity indicators, and all-cause mortality (phase 2: April 1999 to February 2002), and extended demographic monitoring (January to December 2002).


METHODS
A total of 130,000 residents of 221 villages in Asembo and Gem were randomized to receive insecticide-treated bednets at the start of phase 1 (111 villages) or phase 2 (110 villages).


METHODS
Proportion of children younger than 5 years using insecticide-treated bednets, mean number of Anopheles mosquitoes per house, and all-cause mortality rates.


RESULTS
Adherence to bednet use in children younger than 5 years increased from 65.9% in phase 1 to 82.5% in phase 2 (P<.001). After 3 to 4 years of bednet use, the mean number of Anopheles mosquitoes per house in the study area was 77% lower than in a neighboring area without bednets (risk ratio, 0.23; 95% confidence interval [CI], 0.15-0.35). All-cause mortality rates in infants aged 1 to 11 months were significantly reduced in intervention villages during phase 1 (hazard ratio [HR], 0.78; 95% CI, 0.67-0.90); low rates were maintained during phase 2. Mortality rates did not differ during 2002 (after up to 6 years of bednet use) between children from former intervention and former control households born during phase 1 (HR, 1.01; 95% CI, 0.86-1.19).


CONCLUSIONS
The public health benefits of insecticide-treated bednets were sustained for up to 6 years. There is no evidence that bednet use from birth increases all-cause mortality in older children in an area of intense perennial transmission of malaria.
Lindblade
Kim A
KA
Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, Ga 30333, USA. klindblade@kisian.mimcom.net
Eisele
Thomas P
TP
Gimnig
John E
JE
Alaii
Jane A
JA
Odhiambo
Frank
F
ter Kuile
Feiko O
FO
Hawley
William A
WA
Wannemuehler
Kathleen A
KA
Phillips-Howard
Penelope A
PA
Rosen
Daniel H
DH
Nahlen
Bernard L
BL
Terlouw
Dianne J
DJ
Adazu
Kubaje
K
Vulule
John M
JM
Slutsker
Laurence
L
D000818:Animals; D000852:Anopheles; D001512:Bedding and Linens; D002675:Child, Preschool; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D007306:Insecticides; D007630:Kenya / Q000453:epidemiology; D008288:Malaria / Q000453:epidemiology / Q000517:prevention & control* / Q000635:transmission; D009017:Morbidity
D007306:Insecticides