Nutrition as an important mediator of the impact of background variables on outcome in middle childhood

Adequate nutrition is fundamental to the development of a child's full potential. However, the extent to which malnutrition affects developmental and cognitive outcomes in the midst of co-occurring risk factors remains largely understudied. We sought to establish if the effects of nutritional status varied according to diverse background characteristics as well as to compare the relative strength of the effects of poor nutritional status on language skills, motor abilities, and cognitive functioning at school age. This cross-sectional study was conducted among school-age boys and girls resident in Kilifi District in Kenya. We hypothesized that the effects of area of residence, school attendance, household wealth, age and gender on child outcomes are experienced directly and indirectly through child nutritional status. The use of structural equation modeling (SEM) allowed the disaggregation of the total effect of the explanatory variables into direct effects (effects that go directly from one variable to another) and indirect effects. Each of the models tested for the four child outcomes had a good fit. However, the effects on verbal memory apart from being weaker than for the other outcomes, were not mediated through nutritional status. School attendance was the most influential predictor of nutritional status and child outcomes. The estimated models demonstrated the continued importance of child nutritional status at school-age

Measurement of expressive vocabulary in school-age children:Development and application of the Kilifi Naming Test (KNT)

The dearth of locally developed measures of language makes it difficult to detect language and communication problems among school-age children in sub-Saharan African settings. We sought to describe variability in vocabulary acquisition as an important element of global cognitive functioning. Our primary aims were to establish the psychometric properties of an expressive vocabulary measure, examine sources of variability, and investigate the measure’s associations with non-verbal reasoning and educational achievement. The study included 308 boys and girls living in a predominantly rural district in Kenya. The developed measure, the Kilifi Naming Test (KNT), had excellent reliability and acceptable convergent validity. However, concurrent validity was not adequately demonstrated. In the final regression model, significant effects of schooling and area of residence were recorded. Contextual factors should be taken into account in the interpretation of test scores. There is need for future studies to explore the concurrent validity of the KNT further

Screening for developmental disabilities in HIV positive and HIV negative children in South Africa: Results from the Asenze Study

Background While neurodevelopmental abnormalities are common in children with HIV infection, their detection can be challenging in settings with limited availability of health professionals. The aim of this study was to assess the ability to identify developmental disability among HIV positive and HIV negative children living in South Africa with an internationally used screen. Methods and findings This analysis uses a sample of 1,330 4–6 year old children and 1,231 of their caregivers in KwaZulu-Natal, South Africa, including administration of the Ten Questions (TQ) screen, a standardized medical history and physical examination conducted by a medical doctor, with hearing and vision screening, psychological assessment for cognition and language delay, and voluntary HIV testing. There was a high prevalence of disability among the sample. Compared to HIV negative children, HIV positive children were more likely to screen positive on at least one TQ item (59.3 vs 42.8%, p = 0.01), be delayed in sitting, standing or walking (OR 3.89, 95% CI = 2.1–7.2) and have difficulty walking or weakness in the arms or legs (OR = 2.7, 95%CI = 0.8–9.37). By medical doctor assessment, HIV positive children were more likely to be diagnosed with gross motor disability (OR = 3.5, 95%CI = 1.3–9.2) and hearing disability (OR = 2.5, 95%CI = 1.2–5.3). By independent psychological assessment, HIV positive children were more likely to have cognitive delay (OR = 2.2, 95%CI = 1.2–3.9) and language delay (OR = 4.3, 95%CI = 2.2–8.4). Among HIV positive children, the sensitivity and specificity of the TQ for serious disability (vs. no disability) was 100% and 51.2%, respectively. Among HIV-negative children, the sensitivity and specificity of the TQ for serious disability (vs. no disability) was 90.2% and 63.9%, respectively. Conclusions In this first report of the use of the TQ screen in the isiZulu language, it was found to have high sensitivity for detecting serious developmental disabilities in children, especially HIV positive children. The performance of the TQ in this sample indicates utility for making best use of limited neurodevelopmental resources by screening HIV positive children

Patterns of geohelminth infection, impact of albendazole treatment and re-infection after treatment in schoolchildren from rural KwaZulu-Natal/South-Africa

BACKGROUND: Geohelminth infection is a major health problem of children from rural areas of developing countries. In an attempt to reduce this burden, the Department of Health of the province of KwaZulu-Natal (KZN) established in 1998 a programme for helminth control that aimed at regularly treating primary school children for schistosomiasis and intestinal helminths. This article describes the baseline situation and the effect of treatment on geohelminth infection in a rural part of the province. METHODS: Grade 3 schoolchildren from Maputaland in northern KZN were examined for infections with hookworm, Ascaris lumbricoides, and Trichuris trichiura, treated twice with 400 mg albendazole and re-examined several times over one year after the first treatment in order to assess the impact of treatment and patterns of infection and re-infection. RESULTS: The hookworm prevalence in the study population (83.2%) was considerably higher than in other parts of the province whereas T. trichiura and especially A. lumbricoides prevalences (57.2 and 19.4%, respectively) were much lower than elsewhere on the KZN coastal plain. Single dose treatment with albendazole was very effective against hookworm and A. lumbricoides with cure rates (CR) of 78.8 and 96.4% and egg reduction rates (ERR) of 93.2 and 97.7%, respectively. It was exceptionally ineffective against T. trichiura (CR = 12.7%, ERR = 24.8%). Re-infection with hookworm and A. lumbricoides over 29 weeks after treatment was considerable but still well below pre-treatment levels. CONCLUSION: High geohelminth prevalences and re-infection rates in the study population confirm the need for regular treatment of primary school children in the area. The low effectiveness of single course albendazole treatment against T. trichiura infection however demands consideration of alternative treatment approaches

Mapping Schistosoma haematobium for Novel Interventions against Female Genital Schistosomiasis and Associated HIV Risk in KwaZulu-Natal, South Africa

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Patterns of Schistosoma haematobium infection, impact of praziquantel treatment and re-infection after treatment in a cohort of schoolchildren from rural KwaZulu-Natal/South Africa

BACKGROUND: Schistosomiasis is one of the major health problems in tropical and sub-tropical countries, with school age children usually being the most affected group. In 1998 the Department of Health of the province of KwaZulu-Natal established a pilot programme for helminth control that aimed at regularly treating primary school children for schistosome and intestinal helminth infections. This article describes the baseline situation and the impact of treatment on S. haematobium infection in a cohort of schoolchildren attending grade 3 in a rural part of the province. METHODS: Primary schoolchildren from Maputaland in northern KwaZulu-Natal were examined for Schistosoma haematobium infection, treated with praziquantel and re-examined four times over one year after treatment in order to assess the impact of treatment and patterns of infection and re-infection. RESULTS: Praziquantel treatment was highly efficacious at three weeks after treatment when judged by egg reduction rate (95.3%) and cure rate of heavy infections (94.1%). The apparent overall cure rate three weeks after treatment (57.9%) was much lower but improved to 80.7% at 41 weeks after treatment. Re-infection with S. haematobium was low and appeared to be limited to the hot and rainy summer. Analysis of only one urine specimen per child considerably underestimated prevalence when compared to the analysis of two specimens, but both approaches provided similar estimates of the proportion of heavy infections and of average infection intensity in the population. CONCLUSION: According to WHO guidelines the high prevalence and intensity of S. haematobium infection necessitate regular treatment of schoolchildren in the area. The seasonal transmission pattern together with the slow pace of re-infection suggest that one treatment per year, applied after the end of summer, is sufficient to keep S. haematobium infection in the area at low levels

Pre-hospital antibiotics in meningococcal disease

Introduction Invasive meningococcal disease is a devastating infection and early treatment is considered critical in reducing the risk of death. To this end, in some countries general practitioners (GPs) are advised to give parenteral (i.e. intramuscular or intravenous) antibiotics when they suspect meningococcal infection, without waiting for a confirmed diagnosis. However, a number of studies reporting results from small case series have failed to demonstrate strong evidence in support of this approach, while two larger observational studies, one from the United Kingdom and one from Denmark, reported an increased likelihood of death in cases given pre-hospital antibiotics. For ethical and practical reasons, a randomised controlled trial of pre-hospital antibiotics is not considered feasible. Aim The primary aim of the current study was to resolve this controversy by estimating the effect of pre-hospital parenteral antibiotics on case fatality risk (CFR) in meningococcal disease. Methods This was an observational study of New Zealand (NZ) meningococcal disease surveillance data for 1995 – 2006 (n=5340). Causal modelling indicated that minimising bias from confounding would be a major challenge of the analysis. Adjusting for multiple confounders in regression analyses resulted in a large number of cases being dropped, mainly because of missing data patterns in the model covariates. This situation led to a decision to impute missing data using chained equations. The validity of the observed estimate of effect was investigated using quantitative bias analysis methods to assess the likely impact of bias from unmeasured confounders and measurement error. These bias analysis techniques were also applied to earlier studies to explore reasons for the contradictory results reported in the literature. Results Among the 3796 patients in the dataset who were seen by a GP before admission the CFR was 2.9%, and pre-hospital antibiotic treatment was associated with a reduced CFR of 1.9% (adjusted and imputed RR 0.54; 95%CI 0.33 – 0.90). No likely sources of bias were identified that would alter the conclusion of a treatment benefit. Conclusions This is the largest reported investigation of pre-hospital antibiotics in meningococcal disease. The large study size improves precision but does not protect against bias, hence the decision to address and quantify bias in a systematic way – which did not substantively alter findings. This approach strengthens the study conclusion that pre-hospital treatment can reduce the risk of death from meningococcal disease. Following on from this investigation, the next steps will be to consider how to translate these findings to clinical and public health practice. Investigations using surveillance data are vulnerable to bias from several sources, such as lack of data on likely confounders. These bias analysis methods could usefully be applied to other public health research questions. A final observation is that this study was made feasible by the fact that in NZ, pre-hospital antibiotic treatment is recorded routinely in surveillance data. There is a need to consider what other information could be collected by the notification system to guide the management of meningococcal disease and related conditions of public health importance

Ecologic covariates of hookworm infection and reinfection in rural Kwazulu-natal/south Africa: a geographic information system-based study.

Information on hookworm infection and re-infection in a cohort of primary school children and interview data on their socioeconomic background and behavior were combined with environmental data using a geographic information system (GIS). Multivariate models served to explore the covariation of environmental and infection patterns adjusted for possible confounders. Our aim was to identify environmental factors that might serve to predict infection and thus guide control efforts when epidemiologic information is insufficient. Furthermore, we wanted to establish whether soil type has a genuine influence on hookworm infection. Prevalence maps and spatial statistics showed considerable spatial clustering of infection in the small ( approximately 28 x 16 km) study area. The multivariate logistic regression models showed strong positive associations of infection at baseline (baseline prevalence = 83.2%) with settlement density (odds ratio [OR] = 1.24, 95% confidence interval [CI] = 1.10-1.38) and vegetation density (OR = 1.66, 95% CI = 1.25-2.22) and a strong negative association with the clay content of the soil (OR = 0.67, 95% CI = 0.62-0.73). Similar but weaker correlations were found after re-infection. Socioeconomic status and behavior did not seem to confound these associations. Spatial analysis of the model residuals suggested that because the models accounted for most of the spatial pattern, the model standard errors were not affected by spatial clustering. Our study shows that the pattern of hookworm infection is strongly influenced by several environmental factors. The GIS-aided prediction of areas in need of treatment is therefore a promising tool to guide control efforts when epidemiologic information is insufficient

Geophagy and its association with geohelminth infection in rural schoolchildren from northern KwaZulu-Natal, South Africa.

The social pattern of geophagy (soil-eating) and its possible role in the transmission of Ascaris lumbricoides, Trichuris trichiura and hookworm were investigated in a rural area of South Africa between March 1998 and July 1999. Schoolchildren (median age = 10.7 years; interquartile range 8.3-14.8 years) were examined for geohelminth infection at baseline and re-examined 3 and 29 weeks after treatment with albendazole. Interviews were conducted with the pupils in order to find out about their socio-economic background and their behaviour regarding geophagy. Soil-eating was less frequent in boys (39%), where it decreased with age, than in girls (53%), where no such age trend was apparent. The habit was more common in children from families of higher socio-economic status. The baseline prevalence of A. lumbricoides infection was higher in pupils who regularly ate soil from termite mounds (28%) when compared with non-geophageous pupils (19%; prevalence ratio (PR) = 1.46; 95% confidence interval (95% CI) 1.04-2.03). In contrast it was markedly lower in the groups who preferred eating tree termite soil (13%; PR = 0.67; 95% CI 0.43-1.04) or soil from other sources (8%; PR = 0.40; 95% CI 0.15-1.04). This pattern was still apparent after adjusting for possible confounders and was also found when analysing A. lumbricoides reinfection. In contrast, differences in prevalence of T. trichiura and hookworm infection between groups with different soil preference were small