***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: A group-r and omized controlled trial of insecticide (permethrin)-treated bed nets ( ITNs ) was conducted in an area of high perennial malaria transmission in western Kenya to test the effect of ITNs on  all-cause mortality in children 1 - 59 months of age . Child deaths were monitored over a two-year period by biannual household census in Asembo ( 1997 - 1998 ) and in Gem ( 1998 - 1999 ) . Overall , 1,722 deaths occurred in children 1 - 59 months followed for 35,932 child-years .  Crude mortality rates/1,000  child-years were 51.9 versus 43.9 in control and ITN villages in children 1 - 59 months old . The protective efficacy ( PE ) ( 95 % confidence interval ) adjusted for age , study year , study site , and season was 16 % ( 6 - 25 % ) . Corresponding figures in 1 - 11- and 12 - 59-month-old children in control and ITN villages were 133.3 versus 102.3 , PE = 23 % ( 11 - 34 % ) and 31.1 versus 28.7 , PE = 7 % ( -6 - 19 % ) . The numbers of lives saved/1,000 child-years were 8 , 31 , and 2 for the groups 1 - 59 , 1 - 11 , and 12 - 59 months old , respectively . Stratified analysis by time to insecticide re-treatment showed that the PE of  ITNs  re-treated per study protocol ( every six months ) was 20 % ( 10 - 29 % ) , overall and 26 % ( 12 - 37 % ) and 14 % ( -1 - 26 % ) in 1 - 11- and 12 - 59-month-old children , respectively . ITNs prevent approximately one in four infant deaths in areas of intense perennial malaria transmission , but their efficacy is compromised if re-treatment is delayed beyond six months Spatial analyses of the effect of insecticide (permethrin)-treated bed nets ( ITNs ) on nearby households both with and without ITNs was performed in the context of a large-scale , group-r and omized , controlled mortality trial in Asembo , western Kenya . Results illustrate a protective effect of ITNs on compounds lacking ITNs located within 300 meters of compounds with ITNs for child mortality , moderate anemia , high-density parasitemia , and hemoglobin levels . This community effect on nearby compounds without nets is approximately as strong as the effect observed within villages with ITNs . This implies that in areas with intense malaria transmission with high ITN coverage , the primary effect of insecticide-treated nets is via area-wide effects on the mosquito population and not , as commonly supposed , by simple imposition of a physical barrier protecting individuals from biting . The strength of the community effect depended upon the proportion of nearby compounds with treated nets . To maximize their public health impact , high coverage with treated nets is essential This paper describes the study design and methods used in a large community-based , group-r and omized , controlled trial of  permethrin-treated bed nets ( ITNs ) in an area with intense , perennial malaria transmission in western Kenya conducted between 1996 and 1999 . A multi-disciplinary framework was used to explore the efficacy of ITNs in the reduction of all-cause mortality in children less than five years old , the clinical , entomologic , immunologic , and economic impact of ITNs  , the social and behavioral determinants of ITN use , and the use of a geographic information system to allow for spatial analyses of these outcomes . Method ologic difficulties encountered in such large-scale field trials are discussed New tools to prevent malaria morbidity and mortality are needed to improve child survival in sub-Saharan Africa .  Insecticide treated bednets ( ITBN ) have been shown , in one setting ( The Gambia , West Africa ) , to reduce childhood mortality . To assess the impact of ITBN on child survival under different epidemiological and cultural conditions we conducted a community r and omized , controlled trial of permethrin treated bednets ( 0.5 g/m2 ) among a rural population on the Kenyan Coast . Between 1991 and 1993 continuous community-based demographic surveillance linked to hospital-based in-patient surveillance identified all mortality and severe malaria morbidity events during a 2-year period among a population of over 11000 children under 5 years of age . In July 1993 , 28 r and omly selected communities were issued ITBN , instructed in their use and the nets re-impregnated every 6 months . The remaining 28 communities served as contemporaneous controls for the following 2 years , during which continuous demographic and hospital surveillance was maintained until the end of July 1995 . The introduction of ITBN led to significant reductions in childhood mortality ( PE 33 % , CI 7 - 51 % ) and severe , life-threatening malaria among children aged 1 - 59 months ( PE 44 % , CI 19 - 62 ) . These findings confirm the value of ITBN in improving child survival and provide the first evidence of their specific role in reducing severe morbidity from malaria The effectiveness of insecticide-treated bednets ( ITBN ) in preventing malaria and anaemia among primigravidae living in Kilifi District , Kenya , was assessed by a r and omized controlled trial between September 1994 and November 1995 . All residents within 28 community clusters received ITBN in July 1993 , whilst residents of another 28 clusters served as contemporaneous controls . All resident primigravid women with singleton pregnancies attending antenatal care at Kilifi District Hospital were eligible for recruitment . 503 primigravidae were recruited . 91.4 % were anaemic antenatally ( Hb < 11 g/dl ) : 91.0 % from the intervention arm and 92.0 % from the control arm . Severe anaemia ( Hb < 7 g/dl ) was found among 15.1 % of intervention women and 20.1 % of control women ( P = 0.28 ) . No significant differences were observed in reports of febrile illness or the presence of chloroquine in the serum or peripheral parasitaemia during the third trimester between the two groups . In the women delivering in hospital ( n = 130 ) , there was no association between placental malaria infection and the intervention : 77.4 % of placentas from control women had evidence of past or active infection , compared with 72.0 % of placentas from intervention women ( P = 0.76 ) . Similarly , in the women delivering in hospital , ITBN did not improve birth weight , and there were no differences in perinatal mortality between the two study groups . Despite ITBN having a great impact on paediatric severe malaria and mortality in this transmission setting , there was very little impact of ITBN on the morbidity associated with malaria infection in primigravidae . Alternative strategies are required to tackle this continued public health problem for pregnant women living in endemic areas similar to the Kenyan Coast The impact of insecticide (permethrin)-treated bed nets ( ITNs ) on  malaria in pregnancy was studied in a rural area in western Kenya with intense perennial malaria transmission . All households in 40 of 79 villages were r and omized to receive  ITNs  by January 1997 . The ITNs were distributed in control villages two years later . Complete data on birth outcome were available on 2,754 ( 89.6 % ) of 3,072 deliveries . Women ( n = 780 ) were followed monthly throughout pregnancy in 19 of 79 villages . Among gravidae 1 - 4 , ITNs were associated with reductions of 38 % ( 95 % confidence interval [ CI ] = 17 - 54 % ) in the incidence of malaria parasitemia and 47 % ( 95 % CI = 6 - 71 % ) in the incidence of severe malarial anemia ( hemoglobin level < 8 g/dL with parasitemia ) during pregnancy . At the time of delivery , mean hemoglobin levels were 0.6 g/dL ( 95 % CI = 0.01 - 1.2 g/dL ) higher , the prevalence of placental or maternal malaria was reduced by 35 % ( 95 % CI = 20 - 47 % ) , and the prevalence of low birth weight was reduced by 28 % ( 95 % CI = 2 - 47 % ) in gravidae 1 - 4 from ITN villages . No beneficial impact was observed in gravidae five or higher . In areas of intense perennial malaria transmission , permethrin-treated bed nets reduce the adverse effect of malaria during the first four pregnancies A prospect i ve comparison of the antimalarial efficacy of bed nets was conducted with 341 pregnant women living in a mesoendemic malarious area of the Thai-Burmese border . Women in 3 adjacent study sites were allocated at r and om to receive either a single size permethrin-impregnated bed net ( PIB ) , a non-impregnated bed net ( NIB ) , or to a control group who used either their own family size non-impregnated bed net ( FNIB ) or no net . In one study site , but not the other 2 , PIB significantly reduced parasite densities and , together with FNIB , reduced the incidence of malaria in pregnancy from 56 % to 33 % ( relative risk = 1.67 , confidence interval = 1.07 - 2.61 , P = 0.03 , allowing for parity ) . Anaemia proved a more sensitive marker of bed net antimalarial efficacy than parasite rates . The incidence of anaemia ( haematocrit < 30 % ) at all study sites was significantly lower at delivery in the PIB ( 27 % ) and FNIB groups ( 21 % ) than in the NIB group ( 41 % ) or those using no net ( 56 % ) . This suggests that a significant proportion of the malaria in pregnancy in this mesoendemic area was sub-patent . Both patent Plasmodium falciparum parasitaemia and anaemia were associated with a reduction in birth weight . Infant mortality was high ( 16 % ) and strongly associated with prematurity , low birth weight and maternal anaemia . PIB were well tolerated and had no apparent adverse effect on the pregnancy or infant development . Although the overall effect of bed nets on patent parasitaemia was marginal , they were associated with a significant reduction in maternal malaria-associated anaemia . ( ABSTRACT TRUNCATED AT 250 WORDS A district-wide study was undertaken in a rural population of northern Ghana to identify factors influencing the acceptance and use of insecticide-impregnated bednets ( IIBNs ) . A series of focus group discussion s were conducted during 2 years of implementation of IIBNs to gauge community reactions to the introduction of the nets and a structured question naire was administered to approximately 2000 r and omly selected individuals . Although the IIBNs were accepted and used because they provided protection from mosquito bites , seasonal factors , patterns of use , and questions of cost were key factors likely to influence the dissemination and effectiveness of bednets . Use of the bednets was highly seasonal . Almost all recipients used their IIBNs in the rainy season ( 99 % ) , corresponding to the period of high mosquito density and 20 % used them in the dry seasons , the period of low mosquito density . Mothers with young children were more likely to wash the bednets frequently ( because the children soiled the bednets with faeces and urine ) , result ing in no protection from the insecticide . Provision of wider bednets , or the provision of plastic sheets with the bednets or possible incorporation of the insecticide in washing soaps could improve protection for young children . The success of the promotion of IIBNs in malaria control programmes will depend on the cost of the package and the time of year that it is delivered . Financing mechanisms for individual and village groups are discussed . Social research effectively monitored the intervention in this study , and it should be included as an important component of national malaria control programmes To compare the effects of intermittent treatment with sulfadoxine-pyrimethamine ( SP ) given during the second and third trimester of pregnancy , the use of insecticide-treated nets ( ITN ) , or the combination of both on haemoglobin ( Hb ) levels during pregnancy , a r and omized , placebo-controlled intervention trial was conducted in a malaria-endemic area of western Kenya from July 1997 to September 1999 . Primigravidae and secundigravidae were enrolled into the study and r and omized into 4 intervention groups : ( i ) ITNs and SP , ( ii ) ITNs and placebo SP , ( iii ) SP alone , and ( iv ) placebo SP . All groups were offered case management and iron and folic acid supplementation .  Seven hundred and fifty-two women were followed until delivery ( 53.2 % were primigravidae and 46.8 % secundigravidae ) . Among primigravidae in all the groups there was a significant improvement in Hb levels at delivery ( 107.6 g/L ) compared with recruitment ( 101.9 g/L ) ( P < 0.006 ) with the greatest improvement in the combination ITNs + SP group . The protective efficacy of ITNs + SP on anaemia was 55.8 % ( 95 % CI 30.6 - 71.8 ) , of SP alone 50.9 % ( 95 % CI 22.2 
    Output:
    
AUTHORS ' CONCLUSIONS ITNs have a beneficial impact on pregnancy outcome in malaria-endemic regions of Africa when used by communities or by individual women .