All-cause mortality among young children in western Kenya. VI: the Asembo Bay Cohort Project

Entire expressed peripheral blood transcriptome in pediatric severe malarial anemia

This study on severe malarial anemia (SMA: Hb < 6.0 g/dL), a leading global cause of childhood morbidity and mortality, compares the entire expressed whole blood host transcriptome between Kenyan children (3-48 mos.) with non-SMA (Hb ≥ 6.0 g/dL, n = 39) and SMA (n = 18). Differential expression analyses reveal 1403 up-regulated and 279 down-regulated transcripts in SMA, signifying impairments in host inflammasome activation, cell death, and innate immune and cellular stress responses. Immune cell profiling shows decreased memory responses, antigen presentation, and immediate pathogen clearance, suggesting an immature/improperly regulated immune response in SMA. Module repertoire analysis of blood-specific gene signatures identifies up-regulation of erythroid genes, enhanced neutrophil activation, and impaired inflammatory responses in SMA. Enrichment analyses converge on disruptions in cellular homeostasis and regulatory pathways for the ubiquitin-proteasome system, autophagy, and heme metabolism. Pathway analyses highlight activation in response to hypoxic conditions [Hypoxia Inducible Factor (HIF)-1 target and Reactive Oxygen Species (ROS) signaling] as a central theme in SMA. These signaling pathways are also top-ranking in protein abundance measures and a Ugandan SMA cohort with available transcriptomic data. Targeted RNA-Seq validation shows strong concordance with our entire expressed transcriptome data. These findings identify key molecular themes in SMA pathogenesis, offering potential targets for new malaria therapies.

Entire Expressed Peripheral Blood Transcriptome in Pediatric Severe Malarial Anemia

This study on severe malarial anemia (SMA: Hb < 6.0 g/dL), a leading global cause of childhood morbidity and mortality, analyzed the entire expressed transcriptome in whole blood from children with non-SMA (Hb ≥ 6.0 g/dL, n = 41) and SMA (n = 25). Analyses revealed 3,420 up-regulated and 3,442 down-regulated transcripts, signifying impairments in host inflammasome activation, cell death, innate immune responses, and cellular stress responses in SMA. Immune cell profiling showed a decreased antigenic and immune priming response in children with SMA, favoring polarization toward cellular proliferation and repair. Enrichment analysis further identified altered neutrophil and autophagy-related processes, consistent with neutrophil degranulation and altered ubiquitination and proteasome degradation. Pathway analyses highlighted SMA-related alterations in cellular homeostasis, signaling, response to environmental cues, and cellular and immune stress responses. Validation with a qRT-PCR array showed strong concordance with the sequencing data. These findings identify key molecular themes in SMA pathogenesis, providing potential targets for new malaria therapies.

Genetic variation in CSF2 (5q31.1) is associated with longitudinal susceptibility to pediatric malaria, severe malarial anemia, and all-cause mortality in a high-burden malaria and HIV region of Kenya

Plasmodium falciparum infections remain among the leading causes of morbidity and mortality in holoendemic transmission areas. Located within region 5q31.1, the colony-stimulating factor 2 gene (CSF2) encodes granulocyte–macrophage colony-stimulating factor (GM-CSF), a hematopoietic growth factor that mediates host immune responses. Since the effect of CSF2 variation on malaria pathogenesis remains unreported, we investigated the impact of two genetic variants in the 5q31.1 gene region flanking CSF2:g-7032 G > A (rs168681:G > A) and CSF2:g.64544T > C (rs246835:T > C) on the rate and timing of malaria and severe malarial anemia (SMA, Hb < 5.0 g/dL) episodes over 36 months of follow-up. Children (n = 1654, aged 2–70 months) were recruited from a holoendemic P. falciparum transmission area of western Kenya. Decreased incidence rate ratio (IRR) for malaria was conferred by inheritance of the CSF2:g.64544 TC genotype (P = 0.0277) and CSF2 AC/GC diplotype (P = 0.0015). Increased IRR for malaria was observed in carriers of the CSF2 AT/GC diplotype (P = 0.0237), while the inheritance of the CSF2 AT haplotype increased the IRR for SMA (P = 0.0166). A model estimating the longitudinal risk of malaria showed decreased hazard rates among CSF2 AC haplotype carriers (P = 0.0045). Investigation of all-cause mortality revealed that inheritance of the GA genotype at CSF2:g-7032 increased the risk of mortality (P = 0.0315). Higher risk of SMA and all-cause mortality were observed in younger children (P < 0.0001 and P = 0.0015), HIV-1(+) individuals (P < 0.0001 and P < 0.0001), and carriers of HbSS (P = 0.0342 and P = 0.0019). Results from this holoendemic P. falciparum area show that variation in gene region 5q31.1 influences susceptibility to malaria, SMA, and mortality, as does age, HIV-1 status, and inheritance of HbSS.

Cyclooxygenase-2 haplotypes influence the longitudinal risk of malaria and severe malarial anemia in Kenyan children from a holoendemic transmission region

Cyclooxygenase-2 [(COX-2) or prostaglandin endoperoxide H2 synthase-2 (PTGS-2)] induces the production of prostaglandins as part of the host-immune response to infections. Although a number of studies have demonstrated the effects of COX-2 promoter variants on autoimmune and inflammatory diseases, their role in malaria remains undefined. As such, we investigated the relationship between four COX-2 promoter variants (COX-2 -512 C > T, -608 T > C, -765 G > C, and -1195 A > G) and susceptibility to malaria and severe malarial anemia (SMA) upon enrollment and longitudinally over a 36-month follow-up period. All-cause mortality was also explored. The investigation was carried out in children (n = 1081, age; 2-70 months) residing in a holoendemic Plasmodium falciparum transmission region of western Kenya. At enrollment, genotypes/haplotypes (controlling for anemia-promoting covariates) did not reveal any strong effects on susceptibility to either malaria or SMA. Longitudinal analyses showed decreased malaria episodes in children who inherited the -608 CC mutant allele (RR = 0.746, P = 1.811 × 10-4) and -512C/-608T/-765G/-1195G (CTGG) haplotype (RR = 0.856, P = 0.011), and increased risk in TTCA haplotype carriers (RR = 1.115, P = 0.026). Over the follow-up period, inheritance of the rare TTCG haplotype was associated with enhanced susceptibility to both malaria (RR = 1.608, P = 0.016) and SMA (RR = 5.714, P = 0.004), while carriage of the rare TTGG haplotype increased the risk of malaria (RR = 1.755, P = 0.007), SMA (RR = 8.706, P = 3.97 × 10-4), and all-cause mortality (HR = 110.000, P = 0.001). Collectively, these results show that SNP variations in the COX-2 promoter, and their inherited combinations, are associated with the longitudinal risk of malaria, SMA, and all-cause mortality among children living in a high transmission area for P. falciparum.

Reduced Parasite Burden in Children with Falciparum Malaria and Bacteremia Coinfections: Role of Mediators of Inflammation

Bacteremia and malaria coinfection is a common and life-threatening condition in children residing in sub-Saharan Africa. We previously showed that coinfection with Gram negative (G[-]) enteric Bacilli and Plasmodium falciparum (Pf[+]) was associated with reduced high-density parasitemia (HDP, >10,000 parasites/μL), enhanced respiratory distress, and severe anemia. Since inflammatory mediators are largely unexplored in such coinfections, circulating cytokines were determined in four groups of children (n = 206, aged <3 yrs): healthy; Pf[+] alone; G[-] coinfected; and G[+] coinfected. Staphylococcus aureus and non-Typhi Salmonella were the most frequently isolated G[+] and G[-] organisms, respectively. Coinfected children, particularly those with G[-] pathogens, had lower parasite burden (peripheral and geometric mean parasitemia and HDP). In addition, both coinfected groups had increased IL-4, IL-5, IL-7, IL-12, IL-15, IL-17, IFN-γ, and IFN-α and decreased TNF-α relative to malaria alone. Children with G[-] coinfection had higher IL-1β and IL-1Ra and lower IL-10 than the Pf[+] group and higher IFN-γ than the G[+] group. To determine how the immune response to malaria regulates parasitemia, cytokine production was investigated with a multiple mediation model. Cytokines with the greatest mediational impact on parasitemia were IL-4, IL-10, IL-12, and IFN-γ. Results here suggest that enhanced immune activation, especially in G[-] coinfected children, acts to reduce malaria parasite burden.

Prospects and Pitfalls of Pregnancy-Associated Malaria Vaccination Based on the Natural Immune Response to Plasmodium falciparum VAR2CSA-Expressing Parasites

Pregnancy-associated malaria, a manifestation of severe malaria, is the cause of up to 200,000 infant deaths a year, through the effects of placental insufficiency leading to growth restriction and preterm delivery. Development of a vaccine is one strategy for control. Plasmodium falciparum-infected red blood cells accumulate in the placenta through specific binding of pregnancy-associated parasite variants that express the VAR2CSA antigen to chondroitin sulphate A on the surface of syncytiotrophoblast cells. Parasite accumulation, accompanied by an inflammatory infiltrate, disrupts the cytokine balance of pregnancy with the potential to cause placental damage and compromise foetal growth. Multigravid women develop immunity towards VAR2CSA-expressing parasites in a gravidity-dependent manner which prevents unfavourable pregnancy outcomes. Although current vaccine design, targeting VAR2CSA antigens, has succeeded in inducing antibodies artificially, this candidate may not provide protection during the first trimester and may only protect those women living in areas endemic for malaria. It is concluded that while insufficient information about placental-parasite interactions is presently available to produce an effective vaccine, incremental progress is being made towards achieving this goal.

A reversal in reductions of child mortality in western Kenya, 2003-2009

We report and explore changes in child mortality in a rural area of Kenya during 2003-2009, when major public health interventions were scaled-up. Mortality ratios and rates were calculated by using the Kenya Medical Research Institute/Centers for Disease Control and Prevention Demographic Surveillance System. Inpatient and outpatient morbidity and mortality, and verbal autopsy data were analyzed. Mortality ratios for children less than five years of age decreased from 241 to 137 deaths/1,000 live-births in 2003 and 2007 respectively. In 2008, they increased to 212 deaths/1,000 live-births. Mortality remained elevated during the first 8 months of 2009 compared with 2006 and 2007. Malaria and/or anemia accounted for the greatest increases in child mortality. Stock-outs of essential antimalarial drugs during a time of increased malaria transmission and disruption of services during civil unrest may have contributed to increased mortality in 2008-2009. To maintain gains in child survival, implementation of good policies and effective interventions must be complemented by reliable supply and access to clinical services and essential drugs.

Impact of implementation of free high-quality health care on health facility attendance by sick children in rural western Kenya

OBJECTIVES

To explore whether implementation of free high-quality care as part of research programmes resulted in greater health facility attendance by sick children.

METHODS

As part of the Intermittent Preventive Treatment for Malaria in Infants (IPTi), begun in 2004, and population-based infectious disease surveillance (PBIDS), begun in 2005 in Asembo, rural western Kenya, free high-quality care was offered to infants and persons of all ages, respectively, at one Asembo facility, Lwak Hospital. We compared rates of sick-child visits by children <10 years to all seven Asembo clinics before and after implementation of free high-quality care in 10 intervention villages closest to Lwak Hospital and 8 nearby comparison villages not participating in the studies. Incidence rates and rate ratios for sick-child visits were compared between intervention and comparison villages by time period using Poisson regression.

RESULTS

After IPTi began, the rate of sick-child visits for infants, the study's target group, in intervention villages increased by 191% (95% CI 75-384) more than in comparison villages, but did not increase significantly more in older children. After PBIDS began, the rate of sick-child visits in intervention villages increased by 267% (95% CI 76-661) more than that in comparison villages for all children <10 years. The greatest increases in visit rates in intervention villages occurred 3-6 months after the intervention started. Visits for cough showed greater increases than visits for fever or diarrhoea.

CONCLUSIONS

Implementation of free high-quality care increased healthcare use by sick children. Cost and quality of care are potentially modifiable barriers to improving access to care in rural Africa.

The burden of common infectious disease syndromes at the clinic and household level from population-based surveillance in rural and urban Kenya

BACKGROUND

Characterizing infectious disease burden in Africa is important for prioritizing and targeting limited resources for curative and preventive services and monitoring the impact of interventions.

METHODS

From June 1, 2006 to May 31, 2008, we estimated rates of acute lower respiratory tract illness (ALRI), diarrhea and acute febrile illness (AFI) among >50,000 persons participating in population-based surveillance in impoverished, rural western Kenya (Asembo) and an informal settlement in Nairobi, Kenya (Kibera). Field workers visited households every two weeks, collecting recent illness information and performing limited exams. Participants could access free high-quality care in a designated referral clinic in each site. Incidence and longitudinal prevalence were calculated and compared using Poisson regression.

RESULTS

INCIDENCE RATES RESULTING IN CLINIC VISITATION WERE THE FOLLOWING: ALRI--0.36 and 0.51 episodes per year for children <5 years and 0.067 and 0.026 for persons ≥ 5 years in Asembo and Kibera, respectively; diarrhea--0.40 and 0.71 episodes per year for children <5 years and 0.09 and 0.062 for persons ≥ 5 years in Asembo and Kibera, respectively; AFI--0.17 and 0.09 episodes per year for children <5 years and 0.03 and 0.015 for persons ≥ 5 years in Asembo and Kibera, respectively. Annually, based on household visits, children <5 years in Asembo and Kibera had 60 and 27 cough days, 10 and 8 diarrhea days, and 37 and 11 fever days, respectively. Household-based rates were higher than clinic rates for diarrhea and AFI, this difference being several-fold greater in the rural than urban site.

CONCLUSIONS

Individuals in poor Kenyan communities still suffer from a high burden of infectious diseases, which likely hampers their development. Urban slum and rural disease incidence and clinic utilization are sufficiently disparate in Africa to warrant data from both settings for estimating burden and focusing interventions.

Geospatial distribution and determinants of child mortality in rural western Kenya 2002-2005

OBJECTIVE

To describe local geospatial variation and geospatial risk factors for child mortality in rural western Kenya.

METHODS

We calculated under-5 mortality rates (U5MR) in 217 villages in a Health and Demographic Surveillance System (HDSS) area in western Kenya from 1 May 2002 through 31 December 2005. U5MRs by village were mapped. Geographical positioning system coordinates of residences at the time of death and distances to nearby locations were calculated. Multivariable Poisson regression accounting for clustering at the compound level was used to evaluate the association of geospatial factors and mortality for infants and children aged 1-4 years.

RESULTS

Among 54 057 children, the overall U5MR was 56.5 per 1000 person-years and varied by village from 21 to 177 per 1000 person-years. High mortality villages occurred in clusters by location and remained in the highest mortality quintile over several years. In multivariable analysis, controlling for maternal age and education as well as household crowding, higher infant mortality was associated with living closer to streams and further from public transport roads. For children 1-4 years, living at middle elevations (1280-1332 metres), living within lower population densities areas, and living in the northern section of the HDSS were associated with higher mortality.

CONCLUSIONS

Childhood mortality was significantly higher in some villages. Several geospatial factors were associated with mortality, which might indicate variability in access to health care or exposure and transmission of infectious diseases. These results are useful in prioritising areas for further study and implementing directed public health interventions.

Cohort trial reveals community impact of insecticide-treated nets on malariometric indices in urban Ghana

The efficacy of insecticide-treated nets (ITNs) in prevention of malaria and anaemia has been shown in rural settings, but their impact in urban settings is unknown. We carried out an ITN intervention in two communities in urban Accra, Ghana, where local malaria transmission is known to occur. There was evidence for a mass or community effect, despite ITN use by fewer than 35% of households. Children living within 300 m of a household with an ITN had higher haemoglobin concentrations (0.5g/dl higher, P=0.011) and less anaemia (odds ratio 2.21, 95% CI 1.08-4.52, P=0.031 at month 6), than children living more than 300 m away from a household with an ITN, although malaria parasitaemias were similar. With urban populations growing rapidly across Africa, this study shows that ITNs will be an effective tool to assist African countries to achieve their Millennium Development Goals in urban settings. [Registered trial number ISRCTN42261314; http://www.controlled-trials.com/ISRCTN42261314].

Trends observed during a decade of paediatric sick visits to peripheral health facilities in rural western Kenya, 1997-2006

OBJECTIVES

To assess whether longitudinal surveillance in peripheral health facilities could document trends in disease burden, healthcare practice and utilization resulting from large-scale public health interventions made in the decade 1997-2006.

METHODS

Data were collected from sick child visits (SCVs) among children <5 years attending 14 outpatient facilities in Asembo, rural western Kenya, during 1997-2006. Changes in proportions, and counts and rates were evaluated using chi-square and Poisson regression respectively.

RESULTS

During the decade, 64 394 SCVs were made, yielding an average rate of 0.70 SCVs per child-year. The annual number of SCVs stayed constant during 1997-2003, then increased by 74% between 2003 and 2006 (P < 0.01). The time between symptom onset and SCV shortened from 5.6 days in 1997 to 4.4 days in 2006 (P < 0.01). Malaria and upper respiratory tract infection (URTI) were most commonly diagnosed (69% and 36% of SCVs respectively). Between 2003 and 2006, the proportion of SCVs with a malaria diagnosis fell from 77% to 48%, although the rate of malaria SCVs did not. URTI visits increased in 2004-2006. The most frequently prescribed antimalarials changed three times, lagging 1-2 years behind changes in national policy. Treatment of pneumonia with antibiotics varied by year, ranging from 19% to 89%.

CONCLUSION

Surveillance of paediatric SCVs at peripheral health facilities was useful in documenting the timing and penetration of changes in national policies and clinical patterns of drug use for common infections. The surveillance data suggested that improved access to care, rather than disease burden changes, likely led to greater healthcare utilization after 2003.

Malaria's indirect contribution to all-cause mortality in the Andaman Islands during the colonial era

Malaria has a substantial secondary effect on other causes of mortality. From the 19th century, malaria epidemics in the Andaman Islands' penal colony were initiated by the brackish swamp-breeding malaria vector Anopheles sundaicus and fuelled by the importation of new prisoners. Malaria was a major determinant of the highly variable all-cause mortality rate (correlation coefficient r(2)=0.60, n=68, p<0.0001) from 1872 to 1939. Directly attributed malaria mortality based on post-mortem examinations rarely exceeded one-fifth of total mortality. Infectious diseases such as pneumonia, tuberculosis, dysentery, and diarrhoea, which combined with malaria made up the majority of all-cause mortality, were positively correlated with malaria incidence over several decades. Deaths secondary to malaria (indirect malaria mortality) were at least as great as mortality directly attributed to malaria infections.

Relationship of measles vaccination with anaemia and malaria in western Kenya

OBJECTIVE

Mild viral illness, including that following immunization with live attenuated measles virus (LAMV), has been associated with transient decreases in haemoglobin (Hb) and cellular immune response that may persist for several weeks. In areas of intense malaria transmission, such as western Kenya, infants experience a progressive drop in Hb until age 9-10 months and one-third may have Hb < 8 g/dl. These children may be at risk of developing severe anaemia with further haematological insult. The objective of this paper was to determine if immunization with LAMV was associated with increased risk of transient anaemia and malaria infection.

METHODS

Data from previous cross-sectional surveys (n = 5970) and one cohort study (n = 546) conducted among pre-school children were analyzed retrospectively.

RESULTS

Measles vaccination coverage between 12 and 23 months of age ranged from 44.8% to 62.7%. Hb concentrations in children aged 6-23 months with documented measles immunization within the previous 14 or 30 days (n = 103) were similar to those with no history of measles immunization in the previous 90 days (n = 996); mean differences [95% confidence interval (CI)] by 30 days were: in cross-sectional surveys, -0.49 g/dl (-1.12, 0.14); in the cohort study, -0.032 g/dl (-0.52, 0.46). Similarly, the risk of malaria parasitemia or severe to moderate anaemia did not differ.

CONCLUSION

These data do not suggest that the transient decrease in Hb and cellular immune response after immunization with LAMV results in clinically significant changes in the risk of subsequent severe to moderate anaemia or malaria in young children living in malaria-endemic regions.

Prevalence and severity of malnutrition and age at menarche; cross-sectional studies in adolescent schoolgirls in western Kenya

OBJECTIVE

Nutritional status is an important marker of overall health and linear growth retardation has serious long-term physiological and economic consequences. Approximately 35 and 29% of preschool children in sub-Saharan Africa are stunted and underweight, respectively. There is relatively little information available about the nutritional status in adolescents, the age group with the highest growth velocity after infancy. We conducted a series of cross-sectional surveys to determine the prevalence and main risk groups for malnutrition and to describe the associations between age, sexual maturation and nutritional status in adolescent schoolgirls in western Kenya.

DESIGN

Three cross-sectional surveys; one in Mumias, using random sampling in all schools, and two surveys in Asembo, using a multi-stage random sample design.

SETTING

Public primary schools in two different rural malaria endemic areas in western Kenya with high levels of malnutrition in preschool children.

SUBJECTS

In all, 928 randomly selected adolescent schoolgirls aged 12-18 y.

RESULTS

Overall prevalence of stunting and thinness was 12.1 and 15.6%, respectively. Of the total, 2% were severely stunted. Menarche and start of puberty were delayed by approximately 1.5-2 y compared to a US reference population. The prevalence of stunting and thinness decreased with age and mean height for age z-scores converged towards the median of the US reference curve. Girls who had not yet started menstruating were more likely to be stunted than the girls of the same age who were post-menarche.

CONCLUSIONS

Stunting and thinness are common in young adolescent schoolgirls in these poor rural settings in western Kenya, but the prevalence decreases with age, providing observational support that children catch up on incomplete growth attained earlier in life due to a maturational delay of 1.5-2 y allowing prolonged growth.

Daily iron supplementation is more efficacious than twice weekly iron supplementation for the treatment of childhood anemia in western Kenya

A recent meta-analysis of 14 clinical trials indicated that daily compared with intermittent iron supplementation resulted in significantly greater hematological improvement in pregnant women. No such definitive beneficial effect was demonstrated in preschool children. We compared the efficacy of daily and twice weekly iron supplementation for 6 wk under supervised and unsupervised conditions in the treatment of mild and moderate anemia [hemoglobin (Hb) 50-109 g/L] in children aged 2-59 mo living in a malaria-endemic area of western Kenya. The study was a cluster-randomized trial using a factorial design; participants were aware of the treatment assigned. All children (n = 1049) were administered a single dose of sulfadoxine-pyrimethamine at enrollment followed by 6 wk of daily supervised iron supplementation [3-6 mg/(kg.d)], twice weekly supervised iron supplementation [6-12 mg/(kg.wk)], daily unsupervised iron supplementation, or twice weekly unsupervised iron supplementation. In the supervised groups, Hb concentrations at 6 and 12 wk (6 wk postsupplementation) were significantly higher in children given iron daily rather than twice weekly [mean (95% CI) difference at 6-wk: 4.2 g/L (2.1, 6.4); 12-wk: 4.4 g/L (1.8, 7.0)]. Among the unsupervised groups, Hb concentrations were not different at 6 wk [mean (95% CI) difference: 0.86 g/L (-1.4, 3.1)], but significantly higher at 12 wk for those assigned daily iron [mean (95% CI) difference: 3.4 g/L (0.79, 6.0), P = 0.02]. In this malarious area and after initial antimalarial treatment, 6 wk of daily iron supplementation results in better hematological responses than twice weekly iron supplementation in the treatment of anemia in preschool children, regardless of whether adherence can be ensured.

Prevalence and severity of anemia and iron deficiency: cross-sectional studies in adolescent schoolgirls in western Kenya

OBJECTIVE

Anemia is a major public health concern in preschool children and pregnant women in the developing world. While many studies have examined these two at-risk groups, there is a paucity of data on anemia in adolescents living in developing countries in the complex ecologic context of poverty, parasitism, and malnutrition. We evaluated the prevalence, severity, and risk factors of anemia in adolescent schoolgirls in an area with intense malaria transmission in western Kenya.

DESIGN

Two cross-sectional surveys were conducted, using a multistage random sample design.

SETTING

Public primary schools in an area with intense malaria transmission in western Kenya.

SUBJECTS

A total of 648 randomly selected adolescent schoolgirls aged 12-18 y.

RESULTS

The prevalence of anemia (Hb <120 g/l) was 21.1%; only one girl had an Hb less than 70 g/l. Ferritin levels were available from a subsample of 206 girls. The prevalence of iron deficiency (ferritin <12 microg/l) was 19.8, and 30.4% of anemic girls were iron deficient. Malaria and schistosomiasis were the main risk factors for anemia in younger girls (12-13 y), while menstruation was the principal risk factor in older girls (14-18 y).

CONCLUSIONS

Iron deficiency and anemia in school-attending girls in western Kenya were more prevalent than in developed countries, but considerably less prevalent than in preschool children and pregnant women from the same study area. Our findings are consistent with other recent school-based surveys from western Kenya, but not with recent community- and school-based cross-sectional surveys from other parts of sub-Saharan Africa. It deserves further study to determine if adolescent girls not attending school are at higher risk of anemia.

Antibodies that inhibit Plasmodium falciparum adhesion to chondroitin sulfate A are associated with increased birth weight and the gestational age of newborns

Antibodies that inhibit Plasmodium falciparum adhesion to the placental receptor chondroitin sulfate A are associated with a reduced risk of placental malaria, but whether these antibodies lead to improved pregnancy outcomes is unknown. We measured antiadhesion antibody levels in parturient women in western Kenya, where malaria transmission is intense. Secundigravid women with antiadhesion activity in their plasma delivered babies that were on average 398 g heavier (P = 0.019) and 2 weeks more mature (P = 0.002) than babies delivered to secundigravidas without antiadhesion activity. Our findings support the development of antiadhesion vaccines to prevent poor fetal outcomes due to pregnancy malaria.

Health and nutritional status of orphans <6 years old cared for by relatives in western Kenya

One of the consequences of the HIV/AIDS epidemic in sub-Saharan Africa is the increase in the number of orphans, estimated to have reached 6-11% of children <15 years old in 2000. Orphans who stay in their communities may be at increased risk for poor health due to reduced circumstances and loss of parental care. We have used data from a population-based study in rural western Kenya to compare basic health and nutritional indicators between non-orphaned children <6 years old and children who lost either or both of their parents. In June 2000, all children <6 years old who had been recruited for a cross-sectional survey in 60 villages of Rarieda Division, western Kenya, in June 1999 were invited to return for a follow-up survey. Basic demographic characteristics, including the vital status of the child's parents, and health histories were requested from all 1190 participants of the follow-up survey, along with a finger-prick blood sample for determination of malaria parasite status and haemoglobin (Hb) levels. Height-for-age (H/A) and weight-for-height (W/H) Z-scores were also calculated from anthropometric measurements. Overall, 7.9% of the children had lost one or both their parents (6.4% had lost their father, 0.8% had lost their mother and 0.7% had lost both parents). While there was no difference between orphans and non-orphans regarding most of the key health indicators (prevalence of fever and malaria parasitaemia, history of illness, Hb levels, H/A Z scores), W/H Z-scores in orphans were almost 0.3 standard deviations lower than those of non-orphans. This association was more pronounced among paternal orphans and those who had lost a parent more than 1 year ago. These results suggest that the health status of surviving orphans living in their community is similar to that of the non-orphan population, but longitudinal cohort studies should be conducted to determine better the overall impact of orphanhood on child health.

Protective effects of the sickle cell gene against malaria morbidity and mortality

The high frequency of the sickle-cell haemoglobin (HbS) gene in malaria endemic regions is believed to be due to a heterozygote (HbAS) advantage against fatal malaria. Data to prospectively confirm the protection associated with HbAS against mortality are lacking. We show that HbAS provides significant protection against all-cause mortality, severe malarial anaemia, and high-density parasitaemia. This significant reduction in mortality was detected between the ages of 2 and 16 months, the highest risk period for severe malarial anaemia in this area. These data are important in understanding the role of malaria in the selection and maintenance of the sickle cell gene.