Biomedical subjects

Dianne J Terlouw

Publications and source records attributed to Dianne J Terlouw.

At least 19 recordsLinked to original sources

PubMed2006

Burden of malaria at community level in children less than 5 years of age in Togo.

A community-based baseline cross-sectional survey was conducted in three districts in Togo in September 2004 as part of a multidisciplinary evaluation of the impact of the Togo National Integrated Child Health Campaign. During this campaign, long-lasting-insecticide-treated bed nets (LLITNs) were distributed to households with children between 9 months and 5 years of age throughout the country in December 2004. The pre-intervention survey provided baseline malaria and anemia prevalence in children < 5 years of age during peak malaria transmission. Of 2,532 enrolled children from 1,740 households, 62.2% (1,352/2,172) were parasitemic and 84.4% (2,129/2,524) were anemic (hemoglobin < 11 g/dL). Moderate-to-severe anemia (< 8.0 g/dL) was found in 21.7% (543/2,524), with a peak prevalence in children 6-17 months of age and was strongly correlated with parasitemia (OR = 2.3, 95% CI: 1.8-2.5). Net ownership (mainly untreated) was 225/2,532 (8.9%). Subsequent nation-wide introduction of LLITNs and the introduction of artemisinin-based combination therapy have the potential to markedly reduce this burden of malaria.

Anemia↗

PubMed2005

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.

Anemia↗

PubMed2005

Factors associated with hemoglobin concentrations in pre-school children in Western Kenya: cross-sectional studies.

In sub-Saharan Africa, the etiology of anemia in early childhood is complex and multifactorial. Three community-based cross-sectional surveys were used to determine the prevalence and severity of anemia. Regression methods were used to compare mean hemoglobin (Hb) concentrations across covariate levels to identify children at risk of low Hb levels in an area with intense malaria transmission. In a random sample of 2,774 children < 36 months old, the prevalence of anemia (Hb < 11g/dL) was 76.1% and 71%, respectively, in villages without and with insecticide-treated bed nets (ITNs); severe-moderate anemia (Hb < 7 g/dL) was observed in 11% (non-ITN) and 8.3% (ITN). The prevalence of anemia, high-density malaria parasitemia (21.7%), microcytosis (34.9%), underweight (21.9%), and diarrhea (54.8%) increased rapidly from age three months onwards and remained high until 35 months of age. Multivariate analyses showed that family size, history of fever, pale body, general body weakness, diarrhea, soil-eating, concurrent fever, stunting, and malaria parasitemia were associated with mean Hb levels. Prevention of severe anemia should start early in infancy and include a combination of micronutrient supplementation, malaria control, and possibly interventions against diarrheal illness.

Anemia↗

PubMed2005

Malaria and nutritional status among pre-school children: results from cross-sectional surveys in western Kenya.

Protein-energy malnutrition (PEM) affects millions of children in the developing world. The relationship between malaria and PEM is controversial. The goal of this study was to evaluate whether undernutrition is associated with increased or decreased malaria attributable morbidity. Three cross-sectional surveys were conducted using insecticide-treated bed nets (ITNs) among children aged 0-36 months living in an area with intense malaria transmission. Data were collected on nutritional status, recent history of clinical illness, socioeconomic status, current malaria infection status, and hemoglobin. In multivariate models, stunted children had more malaria parasitemia (odds ratio [OR] 1.98, P < 0.0001), high-density parasitemia (OR 1.84; P < 0.0001), clinical malaria (OR 1.77; P < 0.06), and severe malarial anemia (OR 2.65; P < 0.0001) than nonstunted children. The association was evident in children with mild-to-moderate (-3 < height-for-age Z-score [HAZ] < -2) and severe stunting (HAZ < -3). The cross-sectional nature of the study limits the interpretation of causality, but the data provide further observational support that the presence of undernutrition, in particular chronic undernutrition, places children at higher, not lower risk of malaria-related morbidity.

Bedding and Linens↗

PubMed2004

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.

CONTEXT: 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. OBJECTIVES: 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. DESIGN AND SETTING: 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). PARTICIPANTS: 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). MAIN OUTCOME MEASURES: 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.

Animals↗

PubMed2004

Relation between the response to iron supplementation and sickle cell hemoglobin phenotype in preschool children in western Kenya.

BACKGROUND: Iron supplementation has been associated with greater susceptibility to malaria and lower hematologic responses in pregnant Gambian women with sickle cell trait (HbAS) than in similar women with the normal (HbAA) phenotype. It is not known whether a similar interaction exists in children. OBJECTIVE: Our aim was to determine the influence of the HbAS phenotype on hematologic responses and malaria after iron supplementation in anemic (hemoglobin: 70-109 g/L) children aged 2-35 mo. DESIGN: We conducted a double-blind, randomized, placebo-controlled trial (HbAS, n = 115; HbAA, n = 408) of intermittent preventive treatment with sulfadoxine pyrimethamine (IPT-SP) at 4 and 8 wk and daily supervised iron for 12 wk. RESULTS: The mean difference in hemoglobin concentrations at 12 wk between children assigned iron and placebo iron, after adjustment for the effect of IPT-SP, was 9.1 g/L (95% CI: 6.4, 11.8) and 8.2 g/L (4.0, 12.4) in HbAA and HbAS children, respectively (P for interaction = 0.68). Although malaria parasitemia and clinical malaria occurred more often in HbAS children in the iron group than in those in the placebo iron group, this difference was not significant; incidence rate ratios were 1.23 (95% CI: 0.64, 2.34) and 1.41 (0.39, 5.00), respectively. The corresponding incidence rate ratios in HbAA children in the same groups were 1.07 (95% CI: 0.77, 1.48) and 0.59 (0.35, 1.01), respectively. The corresponding interactions between the effects of iron and hemoglobin phenotype were not significant. CONCLUSIONS: There was no evidence for a clinically relevant modification by the hemoglobin S phenotype of the effects of iron supplementation in the treatment of mild anemia. The benefits of iron supplementation are likely to outweigh possible risks associated with malaria in children with the HbAA or HbAS phenotype.

Anemia↗

PubMed2003

Treatment history and treatment dose are important determinants of sulfadoxine-pyrimethamine efficacy in children with uncomplicated malaria in Western Kenya.

This study retrospectively studied amendable determinants of sulfadoxine-pyrimethamine (SP) efficacy involving 2869 treatments among 1072 Kenyan children <5 years old who had uncomplicated malaria. The dose was based on age: one-quarter tablet was given to infants <1 year old, one-half tablet was given to 1-3-year-old children, and a full tablet was given to 4-year-old children. Only 23.5% received the internationally recommended target dose of 25/1.25 mg of SP per kg of body weight. SP intake in the previous 15-35 days (adjusted relative risk, 1.67; 95% confidence interval, 1.35-2.07) and low SP dose (<27.5/1.375 mg/kg) (adjusted relative risk, 1.58; 95% confidence interval, 1.17-2.13) explained 38% of parasitological treatment failures by day 7. Patients with recent SP intake are likely to have recrudescent infections and may need close follow-up if treated with SP or alternative treatment. Applying our weight-for-age data to 31 existing age-based SP dose recommendations predicted that 22 of them would result in underdosing of >25% of children <5 years. Many age-based dose recommendations need urgent revision, because SP is increasingly used as first-line treatment in sub-Saharan Africa.

Age Factors↗

PubMed2003

Sulfadoxine-pyrimethamine in treatment of malaria in Western Kenya: increasing resistance and underdosing.

Between 1993 and 1999, we monitored the efficacy of sulfadoxine-pyrimethamine in 1175 children aged <24 months receiving 2789 treatments for falciparum malaria in western Kenya using a widely deployed age-based dose regimen: infants, 125 plus 6.25 mg (sulfadoxine plus pyrimethamine); children aged 12 to 23 months; 250 plus 12.5 mg. Cumulative treatment failure by day 7, defined as early clinical failure by day 3 or presence of parasitemia on day 7, increased from 18% in 1993 to 1994 to 22% in 1997 to 1998 (P-trend test = 0.20). Based on body weight, the median dose received was 20 plus 1.00 mg/kg, and 73% of the treatments were given at lower than the recommended target dose of 25 plus 1.25 mg/kg. Underdosing accounted for 26% of cumulative treatment failures. After the dose was increased in 1998 (median, 36 plus 1.8 mg/kg), only 4.2% of patients received less than 25 plus 1.25 mg/kg and there was no association with treatment failure. However, the proportion of cumulative treatment failure continued to increase to 27% by 1999 (P-trend test = 0.03). These results raise concern about the longevity of sulfadoxine-pyrimethamine in these settings. Underdosing may have contributed to the rate at which sulfadoxine-pyrimethamine resistance developed in this area. Treatment guidelines should ensure that adequate doses are given from the initial deployment of antimalarials onward.

Anti-Infective Agents↗

PubMed2003

Association of interferon-gamma responses to pre-erythrocytic stage vaccine candidate antigens of Plasmodium falciparum in young Kenyan children with improved hemoglobin levels: XV. Asembo Bay Cohort Project.

Previous studies in animal models have revealed an association between interferon-gamma (IFN-gamma), produced by CD8+ T cells and irradiated sporozoite-induced sterile immunity. To determine whether IFN-gamma can serve as a marker of pre-erythrocytic protective immunity in individuals naturally exposed to malaria, we characterized IFN-gamma and lymphocyte proliferative responses to previously defined CD8+ cytotoxic T lymphocyte (CTL) epitopes from six pre-erythrocytic stage antigens in 107 children six months to two years old from a community-based birth cohort in western Kenya. We found that IFN-gamma positive responders had higher hemoglobin (Hb) levels and significantly reduced prevalence of severe malarial anemia one month after the test compared with IFN-gamma non-responders, suggesting that IFN-gamma immune responses to these pre-erythrocytic antigens were associated with protection against malarial anemia. Children who responded by lymphocyte proliferation had a significantly longer time to first documented malaria parasitemia after birth; however, there was no correlation between the presence of lymphocyte proliferative response and higher Hb levels. We propose that IFN-gamma production could be used as a potential marker of protective immunity against malaria associated anemia in young children living in malaria holoendemic areas.

Anemia↗

PubMed2003

The efficacy of permethrin-treated bed nets on child mortality and morbidity in western Kenya I. Development of infrastructure and description of study site.

Randomized controlled trials in sub-Saharan Africa have shown that permethrin-treated bed nets and curtains reduce all-cause child mortality by 15-33% in areas with low or high but seasonal malaria transmission. This report describes the study site for a community-based, group-randomized, controlled trial in an area of high and year-round malaria transmission in western Kenya. We outline the development of the human and physical infrastructure required to conduct this trial and discuss some of the difficulties encountered and lessons learned in conducting it.

Bedding and Linens↗

PubMed2003

The efficacy of permethrin-treated bed nets on child mortality and morbidity in western Kenya II. Study design and methods.

This paper describes the study design and methods used in a large community-based, group-randomized, 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. Methodologic difficulties encountered in such large-scale field trials are discussed.

Bedding and Linens↗

PubMed2003

Reduction of malaria during pregnancy by permethrin-treated bed nets in an area of intense perennial malaria transmission in western Kenya.

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 randomized 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.

Adult↗

PubMed2003

Effects of permethrin-treated bed nets on immunity to malaria in western Kenya I. Antibody responses in pregnant women and cord blood in an area of intense malaria transmission.

As part of a community-based group-randomized trial on the impact of permethrin-treated bed nets (ITNs) on malaria in pregnancy in a holoendemic area of western Kenya, we assessed their effects on antibody responses to Plasmodium falciparum pre-erythrocytic antigens (recombinant circumsporozoite protein [CSP] and peptides complimentary to the repeat region of the liver stage antigen-1 [LSA-1]) and blood stage antigen (recombinant C-terminal domain of the merozoite surface protein-1 [MSP-1(19) kD]) in paired maternal/cord plasma samples obtained from 296 deliveries (157 from ITN villages and 139 control villages). Levels of total IgG and IgG subclasses 1-3 to LSA-1 and total IgG and IgG3 to MSP-1 were lower, whereas those of total IgG to CSP were significantly higher in women from ITN villages than those from control villages. In cord plasma, levels of total IgG and IgG2 to LSA-1 and IgG3 to MSP-1 were lower in ITN villages than in control villages, but antibody responses to CSP were similar. Our results suggest that the use of ITNs decreases antibody responses to LSA-1 and MSP-1 antigens in pregnant women with associated reductions in levels of the same antibodies in cord blood. In contrast, ITN use was found to be associated with increased antibody responses to CSP in pregnant women, but had no effect on antibody levels to CSP in cord blood.

Animals↗

PubMed2003

Impact of permethrin-treated bed nets on malaria, anemia, and growth in infants in an area of intense perennial malaria transmission in western Kenya.

As part of a community-based, group-randomized, controlled trial of insecticide-treated bed nets (ITNs) in an area with intense malaria transmission in western Kenya, a birth cohort (n = 833) was followed monthly until the age of 24 months to determine the potential beneficial and adverse effects of reduced malaria exposure during pregnancy and infancy. Malaria transmission and morbidity were comparable pre-intervention. The ITNs reduced malaria attack rates (force of infection) in infancy by 74%, and delayed the median time-to-first parasitemia (4.5 to 10.7 months; P < 0.0001). The incidence of both clinical malaria and moderate-severe anemia (hemoglobin level <7 g/dL) were reduced by 60% (P < 0.001 for both). Protective efficacy was greatest in infants less than three months old and similar in older infants and one-year-old children. Efficacy was lowest in the dry season. Infants from ITN villages experienced better height and weight gain. In areas of intense perennial malaria transmission, ITNs substantially reduce exposure to malaria and subsequent malaria-associated morbidity in children less than 24 months old. Reduced malaria exposure during infancy did not result, with continued ITN use, in increased malaria morbidity in one-year-old children.

Age Factors↗

PubMed2003

Impact of permethrin-treated bed nets on growth, nutritional status, and body composition of primary school children in western Kenya.

Insecticide-treated bed nets (ITNs) have been demonstrated to reduce morbidity and mortality in children less than five years of age. They have also been shown to improve the nutritional status of these children, but little is known about their impact on the nutritional status of school-age children. We evaluated the impact of ITNs on growth, nutritional status, and body composition of primary schoolchildren less than 13 years of age living in an area of intense perennial malaria transmission in western Kenya. The ITNs did not have a significant impact on linear growth or summary measures of protein-energy malnutrition in this age group. This lack of efficacy most likely relates to the reduced burden of malaria in this age group in a setting of stable transmission pressure. Use of ITNs was associated with a change in body composition with an increase in percent lean body mass (1.2%; P = 0.04). This may be consequent to reduced exposure to malaria with subsequent reduced elaboration of pro-inflammatory cytokines known to promote muscle wasting.

Bedding and Linens↗

PubMed2003

Prevalence and severity of malnutrition in pre-school children in a rural area of western Kenya.

We determined the nutritional status of children less than five years of age in an area in rural western Kenya with intense malaria transmission, a high prevalence of severe anemia and human immunodeficiency virus, and high infant and under-five mortality (176/1,000 and 259/1,000). No information is available on the prevalence of malnutrition in this area. Three cross-sectional surveys were conducted between 1996 and 1998 to monitor the effect of insecticide-treated bed nets on child morbidity. Anthropometric indices are presented for 2,103 children collected prior to and during intervention (controls only). The prevalence of stunting (Z-scores for height-for-age [HAZ] <-2), wasting (Z-scores for weight-for-height [WHZ] <-2) and being underweight (Z-scores for weight-for-age [WAZ] <-2) was 30%, 4%, and 20%, respectively. This was severe (Z-score <-3) in 12% (stunting), 1% (wasting), and 5% (underweight) of the children. Few children less than three months of age were malnourished (<2%), but height-for-age and weight-forage deficits increased rapidly in children 3-18 months of age, and were greatest in children 18-23 months old (44% stunted and 34% underweight). While the mean HAZ and WAZ stabilized from 24 months of age onwards, they still remained substantially below the reference median with no evidence of catch-up growth. Malnutrition is likely to interact with infectious diseases, placing children 3-24 months of age at high risk of premature death in this area.

Age Factors↗

PubMed2003

Impact of permethrin-treated bed nets on malaria and all-cause morbidity in young children in an area of intense perennial malaria transmission in western Kenya: cross-sectional survey.

Information on the impact of insecticide (permethrin)-treated bed nets (ITNs) from randomized controlled trials in areas of intense perennial malaria transmission is limited. As part of a large-scale, community-based, group-randomized controlled trial of the effect of ITNs on childhood mortality in a holoendemic area in western Kenya, we conducted three cross-sectional surveys in 60 villages to assess the impact of ITNs on morbidity in 1,890 children less than three years old. Children in ITN and control villages were comparable pre-intervention, but after the introduction of ITNs, children in intervention villages were less likely to have recently experienced illness requiring treatment (protective efficacy [95% confidence intervals] = 15% [1-26%]), have an enlarged spleen (32% [20-43%]), be parasitemic (19% [11-27%]), have clinical malaria (44% [6-66%]), have moderately severe anemia (hemoglobin level < 7.0 g/dL; 39% [18-54%]), or have a pruritic body rash, presumably from reduced nuisance insect bites (38% [24-50%]). Use of ITNs was also associated with significantly higher mean weight-for-age Z-scores and mid-upper arm circumferences. There was no evidence, however, that ITNs reduced the risk of helminth infections, diarrhea, or upper or lower respiratory tract infections. The ITNs substantially reduced malaria-associated morbidity and improved weight gain in young children in this area of intense perennial malaria transmission.

Bedding and Linens↗

PubMed2003

Effects of permethrin-treated bed nets on immunity to malaria in western Kenya II. Antibody responses in young children in an area of intense malaria transmission.

As part of a large community-based trial on the impact of insecticide (permethrin)-treated bed nets (ITNs) on childhood morbidity and mortality in an area of intense perennial malaria transmission in western Kenya, we assessed the effects of ITNs on malaria-specific humoral responses in young children. The IgG responses to Plasmodium falciparum pre-erythrocytic antigens circumsporozoite protein (CSP) and liver stage antigen-1 (LSA-1) and the blood stage antigen merozoite surface protein-1 (MSP-1(19) kD) in children less than three years old were investigated during a series of cross-sectional surveys. At 14 and 22 months after the introduction of ITNs, the frequencies and levels of IgG to CSP and LSA-1 were significantly lower in children from ITN villages than in children from control villages (P < 0.001). In contrast, the prevalence of IgG to MSP-1 was significantly higher in children from ITN villages at 14 months (P = 0.0069), but not at 22 months. Our results show that decreased exposure by ITNs reduces IgG responses to pre-erythrocytic antigens, but there was no evidence that two years of ITN use compromises IgG responses to blood stage antigens in these young children in this malaria holoendemic area.

Antibodies, Protozoan↗