***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: The effect of permethrin-treated wall cloths ( Mbu cloth ) on malaria parasitaemia prevalences and malaria morbidity , was evaluated in a population of over 10,000 for a period of three years in the Marigat area , Baringo District , Kenya . The use of the treated cloth in 2,000 houses result ed in significantly lower rates of malaria parasite prevalences with an overall reduction rate of 73 % ( P < 0.001 ) in the treated area . Control areas had an initial increase in rate of malaria parasite prevalence of 30 % and later a reduction of 31 % . There was a slight reduction in spleen rates in the control and treated areas but it was not significant for either between the surveys or among the villages Abstract Objective : To assess the impact of a social marketing programme for distributing nets treated with insecticide on malarial parasitaemia and anaemia in very young children in an area of high malaria transmission . Design : Community cross sectional study . Annual , cross sectional data were collected at the beginning of the social marketing campaign ( 1997 ) and the subsequent two years . Net ownership and other risk and confounding factors were assessed with a question naire . Blood sample s were taken from the children to assess prevalence of parasitaemia and haemoglobin levels . Setting : 18 villages in the Kilombero and Ulanga districts of southwestern Tanzania . Participants : A r and om sample of children aged under 2 years . Main outcome measures : The presence of any parasitaemia in the peripheral blood sample and the presence of anaemia ( classified as a haemoglobin level of ≤80 g/l ) . Results : Ownership of nets increased rapidly ( treated or not treated nets : from 58 % to 83 % ; treated nets : from 10 % to 61 % ) . The mean haemoglobin level rose from 80 g/l to 89 g/l in the study children in the successive surveys . Overall , the prevalence of anaemia in the study population decreased from 49 % to 26 % in the two years studied . Treated nets had a protective efficacy of 62 % ( 95 % confidence interval 38 % to 77 % ) on the prevalence of parasitaemia and of 63 % ( 27 % to 82 % ) on anaemia . Conclusions : These results show that nets treated with insecticide have a substantial impact on morbidity when distributed in a public health setting Malaria vector mosquitoes belonging to the Anopheles gambiae complex were studied in four hamlets in The Gambia . All inhabitants were given bednets treated either with a placebo ( milk ) in two hamlets or with the pyrethroid insecticide permethrin ( 500 mg/m2 ) in two other hamlets . Malaria transmission occurred mainly during a few weeks of the rainy season , in September and October 1987 . The indoor resting densities of mosquitoes in permethrin-treated hamlets were reduced , and we estimated over 90 % reduction in biting on man by An . gambiae Giles sensu stricto in these hamlets . No mosquitoes were found under permethrin-treated bednets compared with eighty-one recovered from placebo-treated bednets . Mosquitoes exited more readily from rooms where permethrin-treated bednets were used than from rooms with placebo-treated nets . The annual mean probability that a child would receive an infective bite was estimated to be 0.09 in hamlets with insecticide-treated bednets , compared with 1.9 where placebo-treated bednets were used . Permethrin-treated bednets are therefore recommended as a means of effectively reducing the risk of exposure to malaria transmission , particularly in areas of low seasonal transmission BACKGROUND Malaria remains a major cause of mortality and morbidity in Africa . Many approaches to malaria control involve reducing the chances of infection but little is known of the relations between parasite exposure and the development of effective clinical immunity so the long-term effect of such approaches to control on the pattern and frequency of malaria can not be predicted . METHODS We have prospect ively recorded paediatric admissions with severe malaria over three to five years from five discrete communities in The Gambia and Kenya . Demographic analysis of the communities exposed to disease risk allowed the estimation of age-specific rates for severe malaria . Within each community the exposure to Plasmodium falciparum infection was determined through repeated parasitological and serological surveys among children and infants . We used acute respiratory-tract infections ( ARI ) as a comparison . FINDINGS 3556 malaria admissions were recorded for the five sites . Marked differences were observed in age , clinical spectrum and rates of severe malaria between the five sites . Paradoxically , the risks of severe disease in childhood were lowest among population s with the highest transmission intensities , and the highest disease risks were observed among population s exposed to low-to-moderate intensities of transmission . For severe malaria , for example , admission rates ( per 1000 per year ) for children up to their 10th birthday were estimated as 3.9 , 25.8 , 25.9 , 16.7 , and 18.0 in the five communities ; the forces of infection estimated for those communities ( new infections per infant per month ) were 0.001 , 0.034 , 0.050 , 0.093 , and 0.176 , respectively . Similar trends were noted for cerebral malaria and for severe malaria anaemia but not for ARI . Mean age of disease decreased with increasing transmission intensity . INTERPRETATION We propose that a critical determinant of life-time disease risk is the ability to develop clinical immunity early in life during a period when other protective mechanisms may operate . In highly endemic areas measures which reduce parasite transmission , and thus immunity , may lead to a change in both the clinical spectrum of severe disease and the overall burden of severe malaria morbidity The malaria incidence and prevalence rates among children who slept under permethrin-impregnated mosquito nets in four villages near Madang , Papua New Guinea , were compared with the rates among children who slept under unimpregnated nets in four paired control villages . Immediately following a parasitological survey in the eight villages , malaria parasites were cleared from the children with chemotherapy , and the mosquito nets in the four experimental villages were impregnated with permethrin . Follow-up parasitological surveys were performed 4 and 10 weeks later . Sporozoite rates in female mosquitos of the Anopheles punctulatus complex decreased significantly in two of the experimental villages after impregnation . Also , the incidence of Plasmodium falciparum between the 4-week and 10-week surveys was significantly lower among the 0 - 4-year olds in villages with impregnated nets than in those with unimpregnated nets , leading to reduced prevalence of P. falciparum in this age group . Use of permethrin-impregnated nets had no effect on the incidence or prevalence of P. falciparum among 5 - 9-year olds or on that of P. vivax among the 0 - 4- or 5 - 9-year olds 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 The effectiveness of village-wide use of permethrin-impregnated bed nets or eave , window , and door curtains as control measures for Plasmodium falciparum malaria was evaluated during two successive high-transmission seasons in western Kenya . Pairs of villages were assigned to one of three study groups : bed net , curtain , or control . Clinical , parasitologic , and entomologic measures were made from March to July 1990 and again 12 months later . When compared with the controls in 1990 and 1991 , we observed a marked reduction in the incidence of P. falciparum infections in children less than six years old in the bed net villages ( reduced by 40 % and 48 % ) and a smaller but still significant reduction in the curtain villages ( 10 % and 33 % ) . Significant reductions were also seen in the incidence of P. falciparum parasitemias greater than 2,500/mm3 in the bed net group ( reduced by 44 % and 49 % ) and curtain group ( 16 % and 32 % ) . Additionally , we observed significant reductions in the incidence of documented fevers in association with P. falciparum parasitemia in bed net ( reduced by 63 % ) and curtain villages ( 53 % ) when compared with controls . Entomologic inoculation rates in both bed net and control villages decreased by more than 50 % below control values during both high transmission seasons . The results of this study , together with a 1988 study in the same area during the low transmission season , show that bed nets offer greater year-round of protection against P. falciparum infection than curtains . However , during the high transmission season , this technique reduces the frequency of P. falciparum infection rather than preventing it entirely The efficacy of nets treated with lambda-cyhalothrin , a pyrethroid insecticide , on  malaria infection and disease  was assessed for the first time at the community level in Anopheles gambiae pyrethroid resistance areas . The study was carried out in northern Côte d'Ivoire , which is an area of kdr resistance . Four pairs of villages were selected and matched according to demographic , sociological , and ecological criteria . Among each pair , a village was r and omly allocated to receive mosquito nets . More than 80 % of beds were covered with nets treated with lambda-cyhalothrin and retreated after 6 months . In each village , 54 children aged 0 - 59 months were r and omly selected and clinical ly monitored for 8 periods of 7 days throughout the year . Results showed that the efficacy of treated nets was maintained with a reduction of the prevalence of asymptomatic malaria infection by 12 % and an estimated protective efficacy against malaria disease of 56 % 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 
    Output:
    
REVIEW ERS ' CONCLUSIONS ITNs are highly effective in reducing childhood mortality and morbidity from malaria .