Infant morbidity in an Indian slum birth cohort

Occupational health hazards of bidi workers and their families in India: a scoping review

BACKGROUND

Bidi workers and their families are exposed to harmful substances during bidi rolling, thereby jeopardising their health. We aimed to assess existing evidence on health conditions of bidi workers and their families in India.

METHODS

We searched nine databases and relevant websites, and conducted citation screening to identify primary studies assessing occupational health hazards of bidi workers and their families. Two authors independently conducted screening and data extraction. We synthesised the findings narratively in a structured fashion.

RESULTS

We found 3842 studies, out of which 95 studies met our eligibility criteria. High prevalence of disease conditions across all organ systems of the body was reported in bidi workers. Studies on female bidi workers showed decreased fertility (n=2), increased frequency of miscarriages (n=1) and higher risk of cervical cancer (n=1). Pregnant bidi workers were at an increased risk of anaemia and pregnancy-induced hypertension (n=2), higher frequency of neonatal deaths (n=1), stillbirths (n=1) and premature births (n=1) in comparison with non-bidi workers. Babies born to bidi workers reported low birth weight (n=5). Evidence from cohort studies suggests causal nature of the exposure to the disease condition.

CONCLUSION

Our review shows that bidi rolling leads to numerous occupational health hazards in bidi workers and their family members. It is essential to provide alternative livelihoods, and safe and protective working environment, and cover bidi workers under various social security provisions to alleviate the deleterious effect of bidi making at home. It is also important to shift bidi making away from home and strengthen existing regulations and promulgation of new provisions, including India's Occupational Safety, Health, and Working Conditions Code 2020.

Study of factors leading to treatment delay in new sputum positive pulmonary tuberculosis patients and its impact on sputum conversion

Our study was done to identify patient or health system related delay in diagnosis of treatment naïve sputum positive PTB patients and its impact on sputum conversion at 2 months. A total of 280 patients were enrolled and followed up for 2 months following which repeat sputum examination was done. Detailed clinical history was taken with emphasis on duration of symptoms, day of presentation, diagnosis and starting of therapy. The median(range) of delay in treatment initiation was 15 (0-82) days, most commonly because of delay due to the health system. Patients with positive sputum at the end of two months had significantly higher delay in treatment initiation (p < 0.05). Being remote (>5 km) from a health provider, being an unskilled labourer, and visiting a private practitioner were associated with delay in diagnosis. Eradication of tuberculosis in India requires training of health professionals, intersectoral cooperation and better public outreach.

Secular Growth Trends in Early Childhood—Evidence from Two Low-Income Birth Cohorts Recruited over a Decade in Vellore, India

Stunting and extreme poverty are considered significant risk factors impacting child development in low-and-middle-income countries. We used two birth cohorts recruited 8–9 years apart in urban low-income (slum) settings in Vellore, south India and analyzed secular growth trends and their predictors. In the rotavirus cohort recruited between 2002 and 2003, 373 children completed the 3-year follow-up. “The Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development” (MAL-ED) cohort recruited between 2010 and 2012 had 215 children completing follow-up. The MAL-ED cohort had better socio-economic status (SES) markers and mothers were better educated compared with the previous cohort. Children in the MAL-ED cohort had less stunting at 1, 2, and 3 years of age. The linear mixed effects model evaluating linear growth during the first 3 years of age showed that low birth weight and being a female child were associated with stunting in both cohorts. There was no association between SES and stunting in the rotavirus cohort, whereas SES was associated with linear growth in the MAL-ED cohort. Future studies could incorporate nutritional and nonnutritional interventions in vulnerable populations to evaluate their effect on birth weight as well as early childhood stunting.

Functional principal component analysis for identifying the child growth pattern using longitudinal birth cohort data

Background

Longitudinal studies are important to understand patterns of growth in children and limited in India. It is important to identify an approach for characterising growth trajectories to distinguish between children who have healthy growth and those growth is poor. Many statistical approaches are available to assess the longitudinal growth data and which are difficult to recognize the pattern. In this research study, we employed functional principal component analysis (FPCA) as a statistical method to find the pattern of growth data. The purpose of this study is to describe the longitudinal child growth trajectory pattern under 3 years of age using functional principal component method.

Methods

Children born between March 2002 and August 2003 (n = 290) were followed until their third birthday in three neighbouring slums in Vellore, South India. Field workers visited homes to collect details of morbidity twice a week. Height and weight were measured monthly from 1 month of age in a study-run clinic. Longitudinal child growth trajectory pattern were extracted using Functional Principal Component analysis using B-spline basis functions with smoothing parameters. Functional linear model was used to assess the factors association with the growth functions.

Results

We have obtained four FPCs explained by 86.5, 3.9, 3.1 and 2.2% of the variation respectively for the height functions. For height, 38% of the children’s had poor growth trajectories. Similarly, three FPCs explained 76.2, 8.8, and 4.7% respectively for the weight functions and 44% of the children’s had poor growth in their weight trajectories. Results show that gender, socio-economic status, parent’s education, breast feeding, and gravida are associated and, influence the growth pattern in children.

Conclusions

The FPC approach deals with subjects’ dynamics of growth and not with specific values at given times. FPC could be a better alternate approach for both dimension reduction and pattern detection. FPC may be used to offer greater insight for classification.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-022-01566-0.

A scientometric analysis of birth cohorts in South Asia: Way forward for Pakistan

The present study aims to: a) systematically map the of birth cohort studies from the South Asian region b) examine the major research foci and landmark contributions from these cohorts using reproducible scientometric techniques and c) offer recommendations on establishing new birth cohorts in Pakistan, building upon the strengths, weaknesses and gaps of previous cohorts. Bibliographic records for a total of 260 articles, published during through December 2018, were retrieved from the Web of Science (core database). All data were analysed using Microsoft Excel (2013), Web of Science platform and CiteSpace. A series of network analysis were then run for each time-period using the link reduction method and pathfinder network scaling. The co-cited articles were clustered into their homogeneous research clusters. The clusters were named using the Latent Semantic Indexing (LSI) method that utilized author keywords as source of names for these clusters. The scientometric analyses of original research output from these birth cohorts also paint a pessimistic landscape in Pakistan- where Pakistani sites for birth cohorts contributed only 31 publications; a majority of these utilized the MAL-ED birth cohort data. A majority of original studies were published from birth cohorts in India (156), Bangladesh (63), and Nepal (15). Out of these contributions, 31 studies reported data from multiple countries. The three major birth cohorts include prospective and multi-country MAL-ED birth cohort and The Pakistan Early Childhood Development Scale Up Trial, and a retrospective Maternal and infant nutrition intervention cohort. In addition to these, a few small-scale birth cohorts reported findings pertaining to neonatal sepsis, intrauterine growth retardation and its effects on linear growth of children and environmental enteropathy.

Immune predictors of oral poliovirus vaccine immunogenicity among infants in South India

Identification of the causes of poor oral vaccine immunogenicity in low-income countries might lead to more effective vaccines. We measured mucosal and systemic immune parameters at the time of vaccination with oral poliovirus vaccine (OPV) in 292 Indian infants aged 6-11 months, including plasma cytokines, leukocyte counts, fecal biomarkers of environmental enteropathy and peripheral blood T-cell phenotype, focused on gut-homing regulatory CD4+ populations. We did not find a distinct immune phenotype associated with OPV immunogenicity, although viral pathogens were more prevalent in stool at the time of immunization among infants who failed to seroconvert (63.9% vs. 45.6%, p = 0.002). Using a machine-learning approach, we could predict seroconversion a priori using immune parameters and infection status with a median 58% accuracy (cross-validation IQR: 50-69%) compared with 50% expected by chance. Better identification of immune predictors of OPV immunogenicity is likely to require sampling of mucosal tissue and improved oral poliovirus infection models.

Why do participants drop-out: findings from a prospective pediatric cohort for fever surveillance established at Vellore, southern India

BACKGROUND

Cohort studies are pivotal in understanding the natural history, and to thereby determine the incidence of a disease. The conduct of large-scale community-based cohort studies is challenging with reference to money, manpower and time. Further, attrition inherent to cohort studies can affect the power, and thereby the study's validity. Our objective was to estimate the percentage of participant withdrawal and to subsequently understand reasons for the same in the Vellore Typhoid Surveillance (VTS) cohort.

METHODS

VTS study, a prospective community-based pediatric cohort, was established in a semi-urban settlement of Vellore to estimate the incidence rate of typhoid fever. An active weekly surveillance identified children with fever, and blood cultures were performed for fevers of ≥3 days. Reasons for participant drop-out in the cohort were documented. Nine focus group discussions (FGD), each with 5 to 7 parents/primary caregivers of former as well current participants were conducted separately, to understand reasons for consent withdrawal as well as the good aspects of the study that the current participants perceived. A descriptive, as well as an interpretative account of the themes that emerged from the FGDs were done.

RESULTS

Of the 5639 children in the VTS cohort, 404 (7.2%) withdrew consent during the 12-month surveillance. Of these, 50% dropped out due to migration from study area; 18.1% as their parents were unhappy with the blood draws for blood culture; and 14.4% did not clearly put forth the reason for consent withdrawal. Being from an orthodox background, high socio-economic status and joint family were associated with a decision to drop-out. Frequent and voluminous blood draws, male field research assistants (FRA) making weekly home-visits, the perception that inquiring about fever made their child fall sick, and that the study clinic did not initiate antibiotics immediately, were the important themes that emerged from the FGDs conducted among drop-outs.

CONCLUSION

Our study showed that specific beliefs and behaviours within the community influenced the drop-out rate of the VTS cohort. Background characteristics and perceptions that exist, along with attrition data from previous cohort studies in the specific community are important to be considered while implementing large-scale cohort studies.

Risk factors for diarrhoea and malnutrition among children under the age of 5 years in the Tigray Region of Northern Ethiopia

BACKGROUND

Diarrhoea and malnutrition are the leading cause of morbidity and mortality among children in areas with poor access to clean water, improved sanitation, and with low socioeconomic status. This study was designed to determine the prevalence of diarrhoea, malnutrition and risk factors among children aged 6-59 months in the Tigray Region of Northern Ethiopia.

METHODS

A community based cross-sectional study design was conducted from June to August 2017 to assess the magnitude and factors associated with diarrhoea and malnutrition among children. A standardized questionnaire was used to collect data on diarrhoea, environmental, demographic and behavioural factors from 610 mother-child pairs. Anthropometric measurements were collected from the children. SPSS ver.21 statistical software was used for analysis. Factors associated with diarrhoea and nutritional status were identified using bivariate and multivariate logistic regression. A p-value ≤ 0.05 was considered statistically significant.

RESULTS

Of the 610 children monitored in this study, the incidence of diarrhoea among 6-59 month-old children in the two weeks preceding the day of the interview day was 27.2% (95% CI: 23.6-31%). Specifically, 35.9%, 9.7%, and 1.8% had 1-2, 3-4 and 5-6 times of diarrhoea episodes in a one year of time, respectively. The prevalence of stunting, underweight, wasting, and acute under-nutrition were 36.1% (95% CI: 31-38.6%), 37% (95% CI: 32-39.6%), 7.9% (95% CI: 5.5-9.7%), and 5.4% (95% CI: 3.8-7.4%), respectively. In a multivariate logistic regression analysis, type of drinking water source [AOR = 3.69; 95% CI: 2.03-6.71], mothers not hand washing at critical times [AOR = 15.42; 95% CI: 2.02-117.78], improper solid waste disposal [AOR = 12.81; 95% CI: 2.50-65.62], and child age (36-47 months) [AOR = 2.57; 95% CI: 1.45-4.55] were found to be predictors of diarrhoea. Being within the age range of 12-23 months was a predictor for wasting [AOR = 4.38; 95% CI: 1.61-11.90] and being underweight [AOR = 4.4; 95% CI: 1.7-11.2]. Similarly, the age range of 36-47 months was associated with wasting [AOR = 2.3; 95% CI: 1.45-3.85] and stunting [AOR = 1.7; 95% CI: 1.03-2.67]. Family size (less than 4) [AOR = 0.56; 95% CI: 0.368-0.959] was inversely associated for wasting.

CONCLUSIONS

Our study revealed that the problem of diarrhoea and malnutrition amongst 6-59 months children in the study area was significant. Access to clean water was the main problem in the study area. Hence, improving access to clean water and providing health education to mothers on personal and environmental hygiene, and proper waste disposal could improve diarrhoea in the study area. Intervention on children's nutrition should also be implemented to minimize the problem of malnutrition.

Legal Status and Deprivation in Urban Slums over Two Decades

In India, 59% of urban slums are "non-notified" or lack legal recognition by the government. We use data on 2,901 slums from four waves of the National Sample Survey spanning nearly 20 years to assess the relationship between a slum's legal status and the severity of deprivation in access to basic services, including piped water, latrines, and electricity. Our analysis reveals a progressive reduction in deprivation the longer that a slum has been notified. These findings suggest that legally recognizing non-notified slums and targeting government aid to these settlements may be crucial for improving health outcomes and diminishing urban disparities.

Brief Report: Estimating Differences and Ratios in Median Times to Event

Time differences and time ratios are often more interpretable estimates of effect than hazard ratios for time-to-event data, especially for common outcomes. We developed a SAS macro for estimating time differences and time ratios between baseline-fixed binary exposure groups based on inverse probability-weighted Kaplan-Meier curves. The macro uses pooled logistic regression to calculate inverse probability of censoring and exposure weights, draws Kaplan-Meier curves based on the weighted data, and estimates the time difference and time ratio at a user-defined survival proportion. The macro also calculates the risk difference and risk ratio at a user-specified time. Confidence intervals are constructed by bootstrap. We provide an example assessing the effect of exclusive breastfeeding during diarrhea on the incidence of subsequent diarrhea in children followed from birth to 3 years in Vellore, India. The SAS macro provided here should facilitate the wider reporting of time differences and time ratios.

Estimating the incidence of rotavirus infection in children from India and Malawi from serial anti-rotavirus IgA titres

Accurate estimates of rotavirus incidence in infants are crucial given disparities in rotavirus vaccine effectiveness from low-income settings. Sero-surveys are a pragmatic means of estimating incidence however serological data is prone to misclassification. This study used mixture models to estimate incidence of rotavirus infection from anti-rotavirus immunoglobulin A (IgA) titres in infants from Vellore, India, and Karonga, Malawi. IgA titres were measured using serum samples collected at 6 month intervals for 36 months from 373 infants from Vellore and 12 months from 66 infants from Karonga. Mixture models (two component Gaussian mixture distributions) were fit to the difference in titres between time points to estimate risk of sero-positivity and derive incidence estimates. A peak incidence of 1.05(95% confidence interval [CI]: 0.64, 1.64) infections per child-year was observed in the first 6 months of life in Vellore. This declined incrementally with each subsequent time interval. Contrastingly in Karonga incidence was greatest in the second 6 months of life (1.41 infections per child year [95% CI: 0.79, 2.29]). This study demonstrates that infants from Vellore experience peak rotavirus incidence earlier than those from Karonga. Identifying such differences in transmission patterns is important in informing vaccine strategy, particularly where vaccine effectiveness is modest.

The Influence of Household- and Community-Level Sanitation and Fecal Sludge Management on Urban Fecal Contamination in Households and Drains and Enteric Infection in Children

Urban sanitation necessitates management of fecal sludge inside and outside the household. This study examined associations between household sanitation, fecal contamination, and enteric infection in two low-income neighborhoods in Vellore, India. Surveys and spatial analysis assessed the presence and clustering of toilets and fecal sludge management (FSM) practices in 200 households. Fecal contamination was measured in environmental samples from 50 households and household drains. Enteric infection was assessed from stool specimens from children under 5 years of age in these households. The two neighborhoods differed significantly in toilet coverage (78% versus 33%) and spatial clustering. Overall, 49% of toilets discharged directly into open drains (“poor FSM”). Children in households with poor FSM had 3.78 times higher prevalence of enteric infection when compared with children in other households, even those without toilets. In the neighborhood with high coverage of household toilets, children in households with poor FSM had 10 times higher prevalence of enteric infection than other children in the neighborhood and drains in poor FSM clusters who had significantly higher concentrations of genogroup II norovirus. Conversely, children in households with a toilet that contained excreta in a tank onsite had 55% lower prevalence of enteric infection compared with the rest of the study area. Notably, households with a toilet in the neighborhood with low toilet coverage had more fecal contamination on floors where children played compared with those without a toilet. Overall, both toilet coverage levels and FSM were associated with environmental fecal contamination and, subsequently, enteric infection prevalence in this urban setting.

Exclusive breastfeeding practices among mothers in urban slum settlements: pooled analysis from three prospective birth cohort studies in South India

BACKGROUND

The World Health Organization (WHO) recommends six months of exclusive breastfeeding. Despite documented health, social and economic benefits, the practice of exclusive breastfeeding is quite low and information on influencing factors is limited especially from slum settlements. Our goal is to assess the prevalence and evaluate factors associated with early cessation of exclusive breastfeeding in the first six months of life among mothers in urban slums of Vellore, Southern India.

METHODS

We pooled data from three similar birth cohort studies (n = 1088) conducted between 2002 and 2009. Breastfeeding information was obtained soon after birth and then from follow-up home visits conducted once every two weeks by the field workers. Multivariable Cox regression analyses were used to assess factors associated with early cessation of exclusive breastfeeding.

RESULTS

The prevalence of exclusive breastfeeding for the first six months was 11.4%, based on prospective data since birth. Results from multivariable analyses revealed maternal education (Adjusted Hazard Ratio [AHR] 1.18 , 95% CI 1.03, 1.35), pucca type of house (AHR 1.25 , 95% CI 1.10, 1.43), two or more number of children in the family (AHR 1.26 , 95% CI 1.10, 1.43), joint family structure (AHR 1.20 , 95% CI 1.02, 1.40) and birth during summer (AHR 1.16, 95% CI 1.01, 1.31) were associated with early cessation of exclusive breastfeeding in the first six months.

CONCLUSIONS

Our results indicate that exclusive breastfeeding rates are well below the recommended levels. Educational interventions providing comprehensive breastfeeding information to mothers and their families can be evaluated to assess its effect on improving infant feeding practices.

Rotavirus and other Diarrheal Disease in a Birth Cohort from Southern Indian Community

OBJECTIVE

To describe the incidence, severity and etiology of diarrheal disease in infants and young children residing in an urban slum community in Southern India.

SETTING

Three contiguous urban slums in Vellore, Tamil Nadu.

PARTICIPANTS

452 children participating in a birth cohort study on diarrheal disease; 373 completed three years of follow-up.

OUTCOME MEASURES

Diarrheal incidence (obtained by twice-weekly home visits) and severity (assessed by the Vesikari scoring system), and etiological agents associated with diarrhea (through examination of stool specimens by bacteriologic culture, rotavirus enzyme immunoassay, PCR for norovirus and microscopy for parasites).

RESULTS

A total of 1856 diarrheal episodes were reported in 373 children. The overall incidence rate of diarrhea was 1.66 episodes per child year for three years, with 2.76 episodes per child year in infancy. The incidence peaked during the months of July and August. Severe diarrhea formed 8% of the total episodes. Rotavirus was the most common pathogen detected, being identified in 18% of episodes. Good hygiene status resulted in 33% protection against moderate-to-severe diarrhea.

CONCLUSIONS

This study highlights the burden of diarrheal disease and the important etiological agents of childhood diarrhea in Southern India. Promotion of hygienic behavior through health education may help reduce diarrheal incidence in this and similar communities.

MG, Henry A, Deosaran JD, Muliyil J, Kang G. Measuring Poverty in Southern India: A Comparison of Socio-Economic Scales Evaluated against Childhood Stunting

INTRODUCTION

Socioeconomic status (SES) scales measure poverty, wealth and economic inequality in a population to guide appropriate economic and public health policies. Measurement of poverty and comparison of material deprivation across nations is a challenge. This study compared four SES scales which have been used locally and internationally and evaluated them against childhood stunting, used as an indicator of chronic deprivation, in urban southern India.

METHODS

A door-to-door survey collected information on socio-demographic indicators such as education, occupation, assets, income and living conditions in a semi-urban slum area in Vellore, Tamil Nadu in southern India. A total of 7925 households were categorized by four SES scales-Kuppuswamy scale, Below Poverty Line scale (BPL), the modified Kuppuswamy scale, and the multidimensional poverty index (MDPI) and the level of agreement compared between scales. Logistic regression was used to test the association of SES scales with stunting.

FINDINGS

The Kuppuswamy, BPL, MDPI and modified Kuppuswamy scales classified 7.1%, 1%, 5.5%, and 55.3% of families as low SES respectively, indicating conservative estimation of low SES by the BPL and MDPI scales in comparison with the modified Kuppuswamy scale, which had the highest sensitivity (89%). Children from low SES classified by all scales had higher odds of stunting, but the level of agreement between scales was very poor ranging from 1%-15%.

CONCLUSION

There is great non-uniformity between existing SES scales and cautious interpretation of SES scales is needed in the context of social, cultural, and economic realities.

Norovirus Gastroenteritis in a Birth Cohort in Southern India

BACKGROUND

Noroviruses are an important cause of gastroenteritis but little is known about disease and re-infection rates in community settings in Asia.

METHODS

Disease, re-infection rates, strain prevalence and genetic susceptibility to noroviruses were investigated in a birth cohort of 373 Indian children followed up for three years. Stool samples from 1856 diarrheal episodes and 147 vomiting only episodes were screened for norovirus by RT-PCR. Norovirus positivity was correlated with clinical data, secretor status and ABO blood group.

RESULTS

Of 1856 diarrheal episodes, 207 (11.2%) were associated with norovirus, of which 49(2.6%) were norovirus GI, 150(8.1%) norovirus GII, and 8 (0.4%) were mixed infections with both norovirus GI and GII. Of the 147 vomiting only episodes, 30 (20.4%) were positive for norovirus in stool, of which 7 (4.8%) were norovirus GI and 23 (15.6%) GII. At least a third of the children developed norovirus associated diarrhea, with the first episode at a median age of 5 and 8 months for norovirus GI and GII, respectively. Norovirus GI.3 and GII.4 were the predominant genotypes (40.3% and 53.0%) with strain diversity and change in the predominant sub-cluster over time observed among GII viruses. A second episode of norovirus gastroenteritis was documented in 44/174 (25.3%) ever-infected children. Children with the G428A homozygous mutation for inactivation of the FUT2 enzyme (se428se428) were at a significantly lower risk (48/190) of infection with norovirus (p = 0.01).

CONCLUSIONS

This is the first report of norovirus documenting disease, re-infection and genetic susceptibility in an Asian birth cohort. The high incidence and apparent lack of genogroupII specific immunity indicate the need for careful studies on further characterization of strains, asymptomatic infection and shedding and immune response to further our understanding of norovirus infection and disease.

Burden of acute infections (except respiratory and diarrheal) and its risk factors among under-five children in India: A systematic review and meta-analysis

CONTEXT

Acute infections of eyes, ears, skin, and others are a common cause of morbidity in under-five children. The overall burden of other infections and their risk factors is not known.

EVIDENCE ACQUISITION

Available literature was searched comprehensively using PubMed for acute infections (except acute respiratory and diarrheal diseases) using the relevant medical subject heading terms. Extracted articles were independently reviewed against inclusion/exclusion criteria and rated for quality. 10 articles were abstracted and reviewed to identify the reported prevalence and risk factors for acute infections among children.

RESULTS

The pooled prevalence of infections (not including acute respiratory and diarrhea) between 2002 and 2013 was 18.42 (95% confidence interval: 9.30-30.62), with reported range of 3.7-50.8%. The significantly positively associated factors reported in single studies were young age of the child, malnutrition, poor breastfeeding, low socio-economic status, animal rearing near household and mothers' illiteracy for independent morbidities.

CONCLUSION

The evidence on risk factors including breastfeeding, vaccination, age, and sex that predispose under-five Indian children to different infections is inconclusive. There is a need to conduct more studies on acute infections other than acute respiratory and diarrhea, to establish their determinants in Indian children.

Epidemiology of acute respiratory infections in children - preliminary results of a cohort in a rural north Indian community

BACKGROUND

Despite acute respiratory infections being a major cause of death among children in developing countries including India, there is a lack of community-based studies that document its burden and aetiology.

METHODS

A dynamic cohort of children aged 0-10 years was established in four villages in a north Indian state of Haryana from August 2012 onwards. Trained health workers conducted weekly home visits to screen children for acute respiratory infection (ARI) defined as one of the following: cough, sore throat, nasal congestion, earache/discharge, or breathing difficulty. Nurses clinically assessed these children to grade disease severity based on standard age-specific guidelines into acute upper or lower respiratory infection (AURI or ALRI) and collected nasal/throat swabs for pathogen testing.

RESULTS

Our first year results show that ARI incidence in 0-10 years of age was 5.9 (5.8-6.0) per child-year with minimal gender difference, the ALRI incidence in the under-five age group was higher among boys (0.43; 0.39-0.49) as compared to girls (0.31; 0.26-0.35) per child year. Boys had 2.4 times higher ARI-related hospitalization rate as compared to girls.

CONCLUSION

ARI impose a significant burden on the children of this cohort. This study platform aims to provide better evidence for prevention and control of pneumonia in developing countries.

Prevalence and risk factors of diarrhea morbidity among under-five children in India: A systematic review and meta-analysis

BACKGROUND

Acute diarrhea accounts for a huge burden of infectious diseases in under-five children.

OBJECTIVE

This systematic review was carried out to study the prevalence and associated risk factors of diarrhea among Indian children aged <5 years.

METHODS

Papers were identified by a comprehensive electronic search of relevant medical subject heading (MeSH) terms in PubMed. Identified articles were independently reviewed against inclusion/exclusion criteria and rated for quality. 15 articles were abstracted and reviewed to identify the reported prevalence and risk factors for childhood diarrhea. Meta-analysis was done for calculating the pooled prevalence of diarrhea and point estimates of risk factors using random effects model with use of appropriate population weights, and depicted using forest plot.

RESULTS

The overall prevalence of diarrhea between 2002 and 2013 was 21.70% (95% confidence interval [CI]: 11.24-34.46). The significantly associated risk factors were malnutrition (odds ratio [OR]: 1.73, 95% CI: 1.53-1.96) and anemia (OR: 1.71, 95% CI: 1.29-2.28) in child, and low socioeconomic status (OR: 7.14, 95% CI: 2.19-23.32). Age of the child <24 months, not breastfeeding, mothers' low literacy status and untreated drinking water did not show a significant association. Sex of the child, religion, higher education of mothers, and seasonality were found to be inconsistently associated in single studies.

CONCLUSION

It was concluded that there is sufficient evidence on the association of childhood diarrhea with socio-demographic factors, but evidence on other contributory factors including breastfeeding and vaccination is inconclusive. There is need to conduct more analytical studies on lesser known risk factors of diarrhea to establish their risk factors in Indian children.

Antibiotic treatment of diarrhoea is associated with decreased time to the next diarrhoea episode among young children in Vellore, India

BACKGROUND

Antibiotics are commonly given for the treatment of childhood diarrhoea, but are not indicated in most cases. Antibiotics modify the gastrointestinal microbiota, which may have unanticipated effects on the risk of subsequent diarrhoea.

METHODS

In a prospective observational cohort study, we assessed the effect of caregiver-reported antibiotic treatment for diarrhoea on the timing of a child's next episode among 434 children followed from birth to 3 years of age in Vellore, India. We estimated median time differences and time ratios from inverse probability of exposure-weighted Kaplan-Meier curves for the time to next diarrhoea episode, comparing children who did and did not receive antibiotics for the previous episode.

RESULTS

Study children had more than five diarrhoea episodes on average in the first 3 years of life, and more than a quarter of all episodes were treated with antibiotics. Children who received antibiotics for their first diarrhoea episode had their second episode on average 8 weeks earlier (median time difference: -8, 95% confidence interval: -10, -3) than children who did not receive antibiotics. The effects of antibiotics on subsequent diarrhoea were greatest at earlier episodes and younger ages, and cefixime had a slightly larger effect compared with cotrimoxazole.

CONCLUSIONS

Antibiotic treatment of diarrhoea was associated with reduced time to a subsequent diarrhoea episode, especially among younger infants. Whereas rational use of antibiotics has been advocated to reduce antimicrobial resistance in populations, we show that overuse of antibiotics may also have a direct adverse effect on individual patients.

Rotavirus infections in a community based cohort in Vellore, India

INTRODUCTION

The burden of infection in communities determines the spread of rotavirus infection and disease in susceptible populations. This study reports rotavirus infection and disease in a community based birth cohort in Vellore.

METHODS

Bimonthly surveillance and diarrheal stool were collected from 452 children enrolled at birth, of whom 373 completed three years of follow up. Samples were screened for rotavirus by an ELISA and genotyped by reverse transcription polymerase chain reaction for VP7 and VP4 genes. Rotavirus incidence rates were calculated using Poisson regression equations. Risk factors associated with symptomatic and asymptomatic rotavirus infections were compared using multiple logistic regression.

RESULTS

A total of 1149 episodes of rotavirus infections occurred in 94.4% children in the cohort. Incidence of rotavirus infection was 1.04 (0.97-1.1) per child-year with 0.75 asymptomatic and 0.29 symptomatic infections per child-year. About 18% of the children were infected in the first month, mainly with the G10P[11] strain. Rotavirus infections were more prevalent during October-March, but seasonality was not as marked in rotavirus disease. Rotavirus was associated with 15.1% of mild diarrhea, 38.9% of moderate/severe diarrhea and 66.7% of very severe diarrhea. Four common G types - G1 (26.8%), G2 (16%), G10 (11.2%) and G9 (9.6%) were seen, with high rates of mixed infections and untypable samples. Male gender, presence of siblings and low maternal education were associated with rotavirus disease.

CONCLUSION

This study demonstrates that rotavirus is the most common cause of gastroenteritis in the community, and indicates that since rotavirus caused the greatest proportion of moderate and severe disease, targeted interventions such as vaccines are needed for rotavirus, in addition to health education, sanitation and appropriate treatment to decrease diarrheal disease in communities.

Environmental predictors of diarrhoeal infection for rural and urban communities in south India in children and adults

Diarrhoeal diseases are major causes of morbidity and mortality in developing countries. This longitudinal study aimed to identify controllable environmental drivers of intestinal infections amidst a highly contaminated drinking water supply in urban slums and villages of Vellore, Tamil Nadu in southern India. Three hundred households with children (<5 years) residing in two semi-urban slums and three villages were visited weekly for 12-18 months to monitor gastrointestinal morbidity. Households were surveyed at baseline to obtain information on environmental and behavioural factors relevant to diarrhoea. There were 258 diarrhoeal episodes during the follow-up period, resulting in an overall incidence rate of 0·12 episodes/person-year. Incidence and longitudinal prevalence rates of diarrhoea were twofold higher in the slums compared to rural communities (P < 0·0002). Regardless of study site, diarrhoeal incidence was highest in infants (<1 year) at 1·07 episodes/person-year, and decreased gradually with increasing age. Increasing diarrhoeal rates were associated with presence of children (<5 years), domesticated animals and low socioeconomic status. In rural communities, open-field defecation was associated with diarrhoea in young children. This study demonstrates the contribution of site-specific environmental and behavioural factors in influencing endemic rates of urban and rural diarrhoea in a region with highly contaminated drinking water.

Risk factors for cryptosporidiosis among children in a semi urban slum in southern India: a nested case-control study

The risk factors for acquisition of cryptosporidial infection in resource-poor settings are poorly understood. A nested case-control study was conducted to assess factors associated with childhood cryptosporidiosis (detected by stool polymerase chain reaction) in an endemic, Indian slum community using data from two community-based studies with 580 children followed prospectively until their second birthday. Factors were assessed for overall cryptosporidiosis (N = 406), and for multiple (N = 208), asymptomatic (N = 243), and symptomatic (N = 163) infections, respectively. Presence of older siblings (odds ratio [OR] = 1.88, P = 0.002) and stunting at 6 months of age (OR = 1.74, P = 0.019) were important risk factors for childhood cryptosporidiosis. Always boiling drinking water before consumption, the use of a toilet by all members of the family, and maternal age ≥ 23 years were protective. These results provide insights into acquisition of childhood cryptosporidiosis in settings with poor environmental sanitation, contaminated public water supply systems, and close human-animal contact. Disease control strategies will require a multifaceted approach.

Association of serum antibodies with protection against rotavirus infection and disease in South Indian children

Serum antibodies play an important role in natural protection from rotavirus infection and disease, but conflicting estimates of association have emerged from epidemiological studies in different geographical settings. In this study, we aim to assess the relationship between pre-existing serum immunoglobulin (Ig)G and IgA titers with protection against rotavirus infection and disease in a birth cohort of Indian children. Children were recruited at birth and followed up for 36 months. Stool samples were collected every 2 weeks and during episodes of diarrhea and serum samples were obtained at least every 6 months. The incidence rate of rotavirus infection and diarrhea was 0.9 (95% CI: 0.88, 0.99) and 0.2 (95% CI: 0.19, 0.25) episodes per child year, respectively. The risk of rotavirus infection and diarrhea decreased with age, while antibody titers (IgG and IgA) increased with age. After adjusting for age and number of previous infections, higher levels of IgG and IgA were independently associated with reduced risk of rotavirus infection. However, we did not find a clear association of IgG or IgA with rotavirus diarrhea risk or a threshold level of protection. The study supports a correlation of serum antibodies in reducing the risk of rotavirus infections, however the potential of serum antibody titer as a correlate of protection is not clear for children in lower income settings.

Burden of diarrhea, hospitalization and mortality due to cryptosporidial infections in Indian children

BACKGROUND

Cryptosporidium spp. is a common, but under-reported cause of childhood diarrhea throughout the world, especially in developing countries. A comprehensive estimate of the burden of cryptosporidiosis in resource-poor settings is not available.

METHODOLOGY/PRINCIPAL FINDINGS

We used published and unpublished studies to estimate the burden of diarrhea, hospitalization and mortality due to cryptosporidial infections in Indian children. Our estimates suggest that annually, one in every 6-11 children <2 years of age will have an episode of cryptosporidial diarrhea, 1 in every 169-633 children will be hospitalized and 1 in every 2890-7247 children will die due to cryptosporidiosis. Since there are approximately 42 million children <2 years of age in India, it is estimated that Cryptosporidium results in 3.9-7.1 million diarrheal episodes, 66.4-249.0 thousand hospitalizations, and 5.8-14.6 thousand deaths each year.

CONCLUSIONS/SIGNIFICANCE

The findings of this study suggest a high burden of cryptosporidiosis among children <2 years of age in India and makes a compelling case for further research on transmission and prevention modalities of Cryptosporidium spp. in India and other developing countries.

The first 1000 days of life: prenatal and postnatal risk factors for morbidity and growth in a birth cohort in southern India

OBJECTIVE

To estimate the burden and assess prenatal and postnatal determinants of illnesses experienced by children residing in a semiurban slum, during the first 1000 days of life.

DESIGN

Community-based birth cohort

SETTING

Southern India

PARTICIPANTS

Four hundred and ninety-seven children of 561 pregnant women recruited and followed for 2 years with surveillance and anthropometry.

MAIN OUTCOME MEASURE

Incidence rates of illness; rates of clinic visits and hospitalisations; factors associated with low birth weight, various illnesses and growth.

RESULTS

Data on 10 377.7 child-months of follow-up estimated an average rate of 14.8 illnesses/child-year. Gastrointestinal and respiratory illnesses were 20.6% and 47.8% of the total disease burden, respectively. The hospitalisation rate reduced from 46/100 child-years during infancy to 19/100 child-years in the second year. Anaemia during pregnancy (OR=2.3, 95% CI=1.08 to 5.18), less than four antenatal visits (OR=6.8, 95% CI=2.1 to 22.5) and preterm birth (OR=3.3, 95% CI=1.1 to 9.7) were independent prenatal risk factors for low birth weight. Female gender (HR=0.88, 95% CI=0.79 to 0.99) and 6 months of exclusive breast feeding (HR=0.76, 95% CI=0.66 to 0.88) offered protection against all morbidity. Average monthly height and weight gain were lower in female child and children exclusively breast fed for 6 months.

CONCLUSIONS

The high morbidity in Indian slum children in the first 1000 days of life was mainly due to prenatal factors and gastrointestinal and respiratory illness. Policymakers need disease prevalence and pathways to target high-risk groups with appropriate interventions in the community.

Acute respiratory infections among under-5 children in India: A situational analysis

Acute respiratory infections (ARIs) are the leading cause of death among children less than 5 years in India. Emergence of newer pathogenic organisms, reemergence of disease previously controlled, wide spread antibiotic resistance, and suboptimal immunization coverage even after many innovative efforts are major factors responsible for high incidence of ARI. Drastic reduction in the burden of ARI by low-cost interventions such as hand washing, breast feeding, availability of rapid and feasible array of diagnostics, and introduction of pentavalent vaccine under National Immunization Schedule which are ongoing are necessary for reduction of ARI.

Factors associated with morbidities among infants in three sub centre areas of belgaum district of South India: a longitudinal study

Background:

Health status of infants is a sensitive indicator of development and factors influencing it need to be better understood.

Objectives:

This study was conducted to search for factors associated with morbidity among infants and to find out their influence on weight gain during infancy.

Materials and Methods:

This longitudinal study was undertaken in south India from November 2004 till April 2006. A birth cohort of all children born during first 6 months of the study period were assessed at enrollment and followed up monthly till they attained 1 year of age.

Results:

Incidence of morbidity among infants was found to be least among those exclusively breast fed (EBF) for 6 months and most when EBF for less than 6 months (P = 0.045). It was also more when infants were weaned with a combination of animal milk, formula milk, semi-solids and solid diet and least when weaned only with semi-solids and solids (P = 0.018). Diarrheal episodes were more in infants who were bottle-fed (P < 0.001). Weight gain between 6^th and 12^th month of infancy was found to be significantly affected by various morbidities (P = 0.001). Incidence of morbidities was less among preterm babies and more among partially immunized (P < 0.001) babies with birth order ≥ 3 (P = 0.012), babies of mothers with low socio-economic and educational status. Delayed milestones during infancy was seen more in babies with history of birth asphyxia (P = 0.018).

Conclusion:

Several factors influenced incidence of morbidities and these morbidities had a negative effect on weight gain. Hence these factors need to be addressed to promote better child health.

Rotavirus seasonality and age effects in a birth cohort study of southern India

INTRODUCTION

Understanding the temporal patterns in disease occurrence is valuable for formulating effective disease preventive programs. Cohort studies present a unique opportunity to explore complex interactions associated with emergence of seasonal patterns of infectious diseases.

METHODS

We used data from 452 children participating in a birth cohort study to assess the seasonal patterns of rotavirus diarrhea by creating a weekly time series of rotavirus incidence and fitting a Poisson harmonic regression with biannual peaks. Age and cohort effects were adjusted for by including the weekly counts of number of children in the study and the median age of cohort in a given week. Weekly average temperature, humidity and an interaction term to reflect the joint effect of temperature and humidity were included to consider the effects of meteorological variables.

RESULTS

In the overall rotavirus time series, two significant peaks within a single year were observed--one in winter and the other in summer. The effect of age was found to be the most significant contributor for rotavirus incidence, showing a strong negative association. Seasonality remained a significant factor, even after adjusting for meteorological parameters, and the age and cohort effects.

CONCLUSIONS

The methodology for assessing seasonality in cohort studies is not yet developed. This is the first attempt to explore seasonal patterns in a cohort study with a dynamic denominator and rapidly changing immune response on individual and group levels, and provides a highly promising approach for a better understanding of the seasonal patterns of infectious diseases, tracking emergence of pathogenic strains and evaluating the efficacy of intervention programs.

Nature, prevalence and risk factors of alcohol use in an urban slum of Southern India

BACKGROUND

There is a paucity of data on the use of alcohol in urban slums of southern India.

METHODS

We screened 2811 men for alcohol use via a household-level census in an urban slum in Vellore, Tamil Nadu, and interviewed 220 age- and area-matched pairs of men drinkers and non-drinkers to examine factors associated with alcohol use. Alcohol Use Disorder Identification Test (AUDIT), a standard instrument, was used to assess risk levels of drinking of 354 drinkers. Prevalence rates were calculated using age- adjusted direct standardization. Odds ratios (ORs) of drinking status and higher-risk drinking were calculated using conditional logistic regression and ordinal logistic regression, respectively.

RESULTS

Among all men, we estimated that 46.1% consumed alcohol and 31.4% were hazardous drinkers (19% increased-risk, 7.7% high-risk and 4.7% dependent drinkers). Factors associated with alcohol use were: manual labour occupations (OR 2.08); presence of a common mental disorder (OR 1.50) and smoking (OR 2.08); while Muslim religion was protective (OR 0.43). Factors associated with higher-risk alcohol use were: being reported as a non-drinker during the census (OR 3.96); presence of a common mental disorder (OR 3.83); smoking (OR 1.78); drinking before legal age of 21 years (OR 2.71); spending more than `100 per day on alcohol (OR 6.17); and mainly drinking Indian-made foreign liquor (OR 5.45).

CONCLUSION

High prevalence of hazardous drinking and the factors associated with it suggest the need for population- wide interventions and further investigations to effectively reduce hazardous alcohol use and its harmful effects.

Rotavirus shedding in symptomatic and asymptomatic children using reverse transcription-quantitative PCR

Reverse transcription-real-time polymerase chain reaction (RT-qPCR) for the VP6 gene was used to study group A rotavirus shedding in children with symptomatic and asymptomatic rotavirus infection. Sequential stool samples (n = 345) from 10 children with rotavirus associated diarrhea and from five children (n = 161) with asymptomatic rotavirus infection were collected over a period of 2 months. A RT-qPCR assay on the samples using a rotavirus VP6 plasmid standard demonstrated high reproducibility, with an inter-assay coefficient of variation (CV) of 1.40-2.97% and an intra-assay CV of 0.03-3.03%. The median duration of shedding was longer in children with diarrhea compared to asymptomatic children (24 days vs. 18 days; P = 0.066). The median quantitation cycle (C(q)) at presentation in symptomatic children was 17.21 compared to 30.98 in asymptomatic children (P = 0.086). The temporal pattern in symptomatic children consisted of a high initial viral shedding coinciding with the duration of diarrhea, followed by a rapid fall, and then a small increase in secondary shedding 21 days later. Compared to children with rotavirus diarrhea, those with asymptomatic infection shed lower quantities of virus throughout the observation period. No difference was noted between the G and P genotypes of samples collected at onset of infection and during the shedding period. Shedding was intermittent in a subset of children in both groups. RT-qPCR is a useful method to characterize shedding patterns.

Exposure to human and bovine noroviruses in a birth cohort in southern India from 2002 to 2006

Human and bovine norovirus virus-like particles were used to evaluate antibodies in Indian children at ages 6 and 36 months and their mothers. Antibodies to genogroup II viruses were acquired early and were more prevalent than antibodies to genogroup I. Low levels of IgG antibodies against bovine noroviruses indicate possible zoonotic transmission.

Burden of childhood diseases and malnutrition in a semi-urban slum in southern India

Background

India has seen rapid unorganized urbanization in the past few decades. However, the burden of childhood diseases and malnutrition in such populations is difficult to quantify. The morbidity experience of children living in semi-urban slums of a southern Indian city is described.

Methods

A total of 176 children were recruited pre-weaning from four geographically adjacent, semi-urban slums located in the western outskirts of Vellore, Tamil Nadu for a study on water safety and enteric infections and received either bottled or municipal drinking water based on their area of residence. Children were visited weekly at home and had anthropometry measured monthly until their second birthday.

Results

A total of 3932 episodes of illness were recorded during the follow-up period, resulting in an incidence of 12.5 illnesses/child-year, with more illness during infancy than in the second year of life. Respiratory, mostly upper respiratory infections, and gastrointestinal illnesses were most common. Approximately one-third of children were stunted at two years of age, and two-thirds had at least one episode of growth failure during the two years of follow up. No differences in morbidity were seen between children who received bottled and municipal water.

Conclusions

Our study found a high burden of childhood diseases and malnutrition among urban slum dwellers in southern India. Frequent illnesses may adversely impact children’s health and development, besides placing an additional burden on families who need to seek healthcare and find resources to manage illness.

Risk factors for upper respiratory infection in the first year of life in a birth cohort

OBJECTIVES

Despite being one of the commonest causes of morbidity among infants, there are no reliable data on the incidence and risk factors of upper respiratory infection among Indian infants. Accordingly, we aimed to study the incidence and age related prevalence, socio-demographic risk factors and association between upper respiratory infection and nasopharyngeal colonization with Streptococcus pneumoniae in the first year of life among rural Indian infants.

METHODS

A birth cohort of 210 babies was evaluated monthly with nasopharyngeal swabbing to note the frequency of upper respiratory infection and carriage rate with S. pneumoniae. Data on 11 potential risk factors were noted and subjected to statistical analysis.

RESULTS

Upper respiratory infection episodes commenced within a few weeks of life and increased in frequency with age, peaking at 72% in the 9th month. There were 747 episodes of upper respiratory infection overall (6.1 episodes per child-year follow up). The prevalence was maximum in the winter months (65%). There were 3 significant risk factors for upper respiratory infection in the first year of life, i.e., winter season (OR=1.86; 95% CI=1.4-3.5), nasopharyngeal colonization with S. pneumoniae (OR=1.34; 95% CI=1.1-1.7) and parental occupation (OR=1.37; 95% CI=1.1-1.8). The OR were adjusted for other covariates like sex of the child, parents' education, type of house, birth weight, number of family members, passive smoking, use of firewood for cooking and water source.

CONCLUSIONS

Seasonal predilection in winter, nasopharyngeal colonization with S. pneumoniae and parental occupation (poor socioeconomic status) are the most important risk factors for upper respiratory infection among rural Indian infants.

Wasting is associated with stunting in early childhood

The longitudinal relationship between stunting and wasting in children is poorly characterized. Instances of wasting or poor weight gain may precede linear growth retardation. We analyzed longitudinal anthropometric data for 1599 children from 8 cohort studies to determine the effect of wasting [weight-for-length Z-score (WLZ) < -2] and variability in WLZ in the first 17 mo on length-for-age Z-score (LAZ) at 18-24 mo of age. In addition, we considered the effects of change in WLZ during the previous 6-mo period on length at 18 and 24 mo. Wasting at 6-11 or 12-17 mo was associated with decreased LAZ; however, children who experienced wasting only at 0-5 mo did not suffer any long-term growth deficits compared with children with no wasting during any period. Children with greater WLZ variability (≥0.5 SD) in the first 17 mo of life were shorter [LAZ = -0.51 SD (95% CI: -0.67, -0.36 SD)] at 18-24 mo of age than children with WLZ variability <0.5. Change in WLZ in the previous 6-mo period was directly associated with greater attained length at 18 mo [0.33 cm (95% CI: 0.11, 0.54 cm)] and 24 mo [0.72 cm (95% CI: 0.52, 0.92 cm)]. Children with wasting, highly variable WLZ, or negative changes in WLZ are at a higher risk for linear growth retardation, although instances of wasting may not be the primary cause of stunting in developing countries.

Serum IgG responses and seroconversion patterns to Cryptosporidium gp15 among children in a birth cohort in south India

The correlates of protective immunity to cryptosporidiosis are not well understood. This study was conducted to assess the effect of maternal serum IgG against Cryptosporidium gp15 on responses to this antigen in children with (cases) and without (controls) PCR-confirmed cryptosporidial diarrhea. Maternal sera (n = 129) and sera from cases (n = 39) and controls (n = 90) collected at 3.5, 9, and 24 months of age were tested for serum IgG against Cryptosporidium gp15 by enzyme-linked immunosorbent assay (ELISA). Seroconversion patterns were evaluated by estimating probabilities of seroconversion along three time points based on the transition pathways by using a first-order Markov chain process and empirical Bayesian estimates. There was no difference in serum IgG levels or seropositivity rates to gp15 between cases and controls across all time points in children or in IgG levels to this antigen between mothers of cases and controls. The most common transition pathway can be described as a seronegative child at 3.5 months who seroconverts at 9 months and remains seropositive at 24 months. This pattern remained stable irrespective of the serological status of the mother or the case or control status of the child. Children were most likely to be exposed to Cryptosporidium for the first time between the ages of 3 and 9 months, and most of the children seroconverted by 24 months. The high degree of seroconversion among control children is suggestive of high rates of asymptomatic transmission in this region.

Pneumonia in South-East Asia Region: public health perspective

Globally, pneumonia is the leading cause of death in young children and burden of disease is disproportionately high in South-East Asia Region of WHO. This review article presents the current status of pneumonia disease burden, risk factors and the ability of health infrastructure to deal with the situation. Literature survey was done for the last 20 years and data from country offices were also collected. The estimated incidence of pneumonia in under five children is 0.36 episodes per child, per year. Risk factors are malnutrition (40% in India), Indoor air pollution, non-breast feeding, chronic obstructive pulmonary disease, etc. Strengthening of health care delivery system for early detection and treatment and as well as minimization of preventable risk factors can avert a large proportion of death due to pneumonia.

Analysis of human immune responses in quasi-experimental settings: tutorial in biostatistics

BACKGROUND

Human immunology is a growing field of research in which experimental, clinical, and analytical methods of many life science disciplines are utilized. Classic epidemiological study designs, including observational longitudinal birth cohort studies, offer strong potential for gaining new knowledge and insights into immune response to pathogens in humans. However, rigorous discussion of methodological issues related to designs and statistical analysis that are appropriate for longitudinal studies is lacking.

METHODS

In this communication we address key questions of quality and validity of traditional and recently developed statistical tools applied to measures of immune responses. For this purpose we use data on humoral immune response (IR) associated with the first cryptosporidial diarrhea in a birth cohort of children residing in an urban slum in south India. The main objective is to detect the difference and derive inferences for a change in IR measured at two time points, before (pre) and after (post) an event of interest. We illustrate the use and interpretation of analytical and data visualization techniques including generalized linear and additive models, data-driven smoothing, and combinations of box-, scatter-, and needle-plots.

RESULTS

We provide step-by-step instructions for conducting a thorough and relatively simple analytical investigation, describe the challenges and pitfalls, and offer practical solutions for comprehensive examination of data. We illustrate how the assumption of time irrelevance can be handled in a study with a pre-post design. We demonstrate how one can study the dynamics of IR in humans by considering the timing of response following an event of interest and seasonal fluctuation of exposure by proper alignment of time of measurements. This alignment of calendar time of measurements and a child's age at the event of interest allows us to explore interactions between IR, seasonal exposures and age at first infection.

CONCLUSIONS

The use of traditional statistical techniques to analyze immunological data derived from observational human studies can result in loss of important information. Detailed analysis using well-tailored techniques allows the depiction of new features of immune response to a pathogen in longitudinal studies in humans. The proposed staged approach has prominent implications for future study designs and analyses.

Astrovirus MLB1 is not associated with diarrhea in a cohort of Indian children

Astroviruses are a known cause of human diarrhea. Recently the highly divergent astrovirus MLB1 (MLB1) was identified in a stool sample from a patient with diarrhea. It has subsequently been detected in stool from individuals with and without diarrhea. To determine whether MLB1 is associated with diarrhea, we conducted a case control study of MLB1. In parallel, the prevalence of the classic human astroviruses (HAstVs) was also determined in the same case control cohort. 400 cases and 400 paired controls from a longitudinal birth cohort in Vellore, India were analyzed by RT-PCR. While HAstVs were associated with diarrhea (p = 0.029) in this cohort, MLB1 was not; 14 of the controls and 4 cases were positive for MLB1. Furthermore, MLB1 viral load did not differ significantly between the cases and controls. The role of MLB1 in human health still remains unknown and future studies are needed.

Effect of cryptosporidial and giardial diarrhoea on social maturity, intelligence and physical growth in children in a semi-urban slum in south India

BACKGROUND

Early childhood diarrhoea is a major cause of infant morbidity and mortality in developing countries. Recurrent and persistent diarrhoea affect growth and cognition in children as young as 6 years.

OBJECTIVES

To evaluate the effect of early childhood cryptosporidial and giardial diarrhoea on growth and development in children in a semi-urban slum in India. This is the first report of such assessment at 3 years of age.

METHODS

This study was undertaken on 116 children who were part of an ongoing birth cohort study (n=452) of rotaviral and cryptosporidial diarrhoea between June and December 2005. Social quotients (SQ) assessed by the Vineland Social Maturity Scale, intelligence quotients (IQ) assessed by the Seguin Form Board Test, physical growth parameters and sociodemographic data in 84 children with a history of cryptosporidial or giardial diarrhoea were compared with those of 32 without diarrhoea.

RESULTS

Children with a past history of giardial diarrhoea showed a trend towards lower SQ (p=0.09) and had significantly lower IQ (p=0.04) and increased wasting (p=0.04). Cryptosporidial diarrhoea was not associated with poor IQ, SQ or physical growth.

CONCLUSION

This study demonstrates the long-term effect of protozoan diarrhoea, especially that caused by giardia, on both intelligence and physical growth in Indian children as early as 3 years of age and re-inforces the need for early detection and prevention of early childhood protozoan diarrhoea.

Vulnerability of newborns to environmental factors: findings from community based surveillance data in Bangladesh

Infection is the major cause of neonatal deaths. Home born newborns in rural Bangladeshi communities are exposed to environmental factors increasing their vulnerability to a number of disease agents that may compromise their health. The current analysis was conducted to assess the association of very severe disease (VSD) in newborns in rural communities with temperature, rainfall, and humidity. A total of 12,836 newborns from rural Sylhet and Mirzapur communities were assessed by trained community health workers using a sign based algorithm. Records of temperature, humidity, and rainfall were collected from the nearest meteorological stations. Associations between VSD and environmental factors were estimated. Incidence of VSD was found to be associated with higher temperatures (odds ratios: 1.14, 95% CI: 1.08 to 1.21 in Sylhet and 1.06, 95% CI: 1.04 to 1.07 in Mirzapur) and heat humidity index (odds ratios: 1.06, 95% CI: 1.04 to 1.08 in Sylhet and, 1.03, 95% CI: 1.01 to 1.04 in Mirzapur). Four months (June–September) in Sylhet, and six months in Mirzapur (April–September) had higher odds ratios of incidence of VSD as compared to the remainder of the year (odds ratios: 1.72, 95% CI: 1.32 to 2.23 in Sylhet and, 1.62, 95% CI: 1.33 to 1.96 in Mirzapur). Prevention of VSD in neonates can be enhanced if these interactions are considered in health intervention strategies.

Protective effect of natural rotavirus infection in an Indian birth cohort

BACKGROUND

More than 500,000 deaths are attributed to rotavirus gastroenteritis annually worldwide, with the highest mortality in India. Two successive, naturally occurring rotavirus infections have been shown to confer complete protection against moderate or severe gastroenteritis during subsequent infections in a birth cohort in Mexico. We studied the protective effect of rotavirus infection on subsequent infection and disease in a birth cohort in India (where the efficacy of oral vaccines in general has been lower than expected).

METHODS

We recruited children at birth in urban slums in Vellore; they were followed for 3 years after birth, with home visits twice weekly. Stool samples were collected every 2 weeks, as well as on alternate days during diarrheal episodes, and were tested by means of enzyme-linked immunosorbent assay and polymerase-chain-reaction assay. Serum samples were obtained every 6 months and evaluated for seroconversion, defined as an increase in the IgG antibody level by a factor of 4 or in the IgA antibody level by a factor of 3.

RESULTS

Of 452 recruited children, 373 completed 3 years of follow-up. Rotavirus infection generally occurred early in life, with 56% of children infected by 6 months of age. Levels of reinfection were high, with only approximately 30% of all infections identified being primary. Protection against moderate or severe disease increased with the order of infection but was only 79% after three infections. With G1P[8], the most common viral strain, there was no evidence of homotypic protection.

CONCLUSIONS

Early infection and frequent reinfection in a locale with high viral diversity resulted in lower protection than has been reported elsewhere, providing a possible explanation why rotavirus vaccines have had lower-than-expected efficacy in Asia and Africa. (Funded by the Wellcome Trust.).

Systematic review of birth cohort studies in South East Asia and Eastern Mediterranean regions

BACKGROUND

Few longitudinal studies of children have taken place in the developing world, despite child mortality being concentrated there. This review summarises the methodologies and main outcomes of longitudinal studies of pre-school children (0 to 59 months) in the World Health Organization's South East Asia (SEA) and Eastern Mediterranean (EM) Regions.

METHODS

A systematic search of literature using pre-defined criteria revealed 7863 papers. After application of quality criteria, 120 studies were selected for analysis.

RESULTS

The search revealed 83 studies in the SEA region and 37 in the EM region, of which 92 were community-based and 8 facility-based. Objectives were diverse but topics included growth (n = 49 studies), mortality (n = 28), nutrition (n = 24), and infectious diseases (n = 33). Only 12 studies focused on non-communicable diseases. Duration ranged from 7 to 384 months. Measurements included anthropometric (n = 56 studies), socioeconomic (n = 50) and biological sampling (n = 25), but only one study was DNA-based.

CONCLUSION

Biobanks have emerged as the most successful approach to generating knowledge about disease causes and mechanisms. Little of this is possible to undertake in the in SEA or EM regions, however. Further longitudinal studies of young children with DNA sampling should be set up to better understand determinants of diseases in low-income countries.

Dissemination of NDM-1 positive bacteria in the New Delhi environment and its implications for human health: an environmental point prevalence study

BACKGROUND

Not all patients infected with NDM-1-positive bacteria have a history of hospital admission in India, and extended-spectrum β-lactamases are known to be circulating in the Indian community. We therefore measured the prevalence of the NDM-1 gene in drinking water and seepage samples in New Delhi.

METHODS

Swabs absorbing about 100 μL of seepage water (ie, water pools in streets or rivulets) and 15 mL samples of public tap water were collected from sites within a 12 km radius of central New Delhi, with each site photographed and documented. Samples were transported to the UK and tested for the presence of the NDM-1 gene, bla(NDM-1), by PCR and DNA probing. As a control group, 100 μL sewage effluent samples were taken from the Cardiff Wastewater Treatment Works, Tremorfa, Wales. Bacteria from all samples were recovered and examined for bla(NDM-1) by PCR and sequencing. We identified NDM-1-positive isolates, undertook susceptibility testing, and, where appropriate, typed the isolates. We undertook Inc typing on bla(NDM-1)-positive plasmids. Transconjugants were created to assess plasmid transfer frequency and its relation to temperature.

FINDINGS

From Sept 26 to Oct 10, 2010, 171 seepage samples and 50 tap water samples from New Delhi and 70 sewage effluent samples from Cardiff Wastewater Treatment Works were collected. We detected bla(NDM-1) in two of 50 drinking-water samples and 51 of 171 seepage samples from New Delhi; the gene was not found in any sample from Cardiff. Bacteria with bla(NDM-1) were grown from 12 of 171 seepage samples and two of 50 water samples, and included 11 species in which NDM-1 has not previously been reported, including Shigella boydii and Vibrio cholerae. Carriage by enterobacteria, aeromonads, and V cholera was stable, generally transmissible, and associated with resistance patterns typical for NDM-1; carriage by non-fermenters was unstable in many cases and not associated with typical resistance. 20 strains of bacteria were found in the samples, 12 of which carried bla(NDM-1) on plasmids, which ranged in size from 140 to 400 kb. Isolates of Aeromonas caviae and V cholerae carried bla(NDM-1) on chromosomes. Conjugative transfer was more common at 30°C than at 25°C or 37°C.

INTERPRETATION

The presence of NDM-1 β-lactamase-producing bacteria in environmental samples in New Delhi has important implications for people living in the city who are reliant on public water and sanitation facilities. International surveillance of resistance, incorporating environmental sampling as well as examination of clinical isolates, needs to be established as a priority.

FUNDING

European Union.

Symptomatic and asymptomatic Cryptosporidium infections in children in a semi-urban slum community in southern India

Cryptosporidium is a leading cause of childhood diarrhea in developing countries. We investigated symptomatic and asymptomatic cryptosporidiosis in 20 children less than two years of age in a semi-urban slum in southern India. All surveillance (conducted every two weeks) and diarrheal samples from 20 children (n = 1,036) with cryptosporidial diarrhea previously identified by stool microscopy were tested by polymerase chain reaction-restriction fragment length polymorphism for species and subgenotype determination. Thirty-five episodes of cryptosporidiosis were identified in 20 children, of which 25 were diarrheal. Fifteen episodes were associated with prolonged oocyst shedding. Multiple episodes of cryptosporidiosis occurred in 40% of the children. Most infections were with C. hominis, subtype Ia. Children with multiple infections had significantly lower weight-for-age and height-for-age Z scores at 24 months but had scores comparable with children with a single episode by 36 months. Multiple symptomatic Cryptosporidium infections associated with prolonged oocyst shedding occur frequently in this disease-endemic area and may contribute to the long-term effects of cryptosporidiosis on physical growth in these children.

Burden of illness in the first 3 years of life in an Indian slum

The morbidity and mortality in a cohort of 452 children followed up from birth up to 3 years of age, in an urban slum in India, is described. These children were recruited and followed from March 2002 to September 2006. A prospective morbidity survey was established. There were 1162 child-years of follow-up. The average morbidity rate was 11.26 episodes/child-year. Respiratory infections caused 58.3 and diarrheal disease 18.4% of the illnesses. Respiratory illnesses resulted in 48, 67.5 and 50 days of illnesses, and there were 3.6, 1.64 and 1.16 diarrheal episodes per child in the 3 years, respectively. There were five deaths in the cohort in the 3 years of follow-up. Of the 77 drop-outs 44 were contacted for mortality data. The morbidity in the area is high, comparable to other studies. The mortality is low, and is attributed to the facilitated access to care.

Chronic growth faltering amongst a birth cohort of Indian children begins prior to weaning and is highly prevalent at three years of age

BACKGROUND

Poor growth of children in developing countries is a major public health problem associated with mortality, morbidity and developmental delay. We describe growth up to three years of age and investigate factors related to stunting (low height-for-age) at three years of age in a birth cohort from an urban slum.

METHODS

452 children born between March 2002 and August 2003 were followed until their third birthday in three neighbouring slums in Vellore, South India. Field workers visited homes to collect details of morbidity twice a week. Height and weight were measured monthly from one month of age in a study-run clinic. For analysis, standardised z-scores were generated using the 2006 WHO child growth standards. Risk factors for stunting at three years of age were analysed in logistic regression models. A sensitivity analysis was conducted to examine the effect of missing values.

RESULTS

At age three years, of 186 boys and 187 girls still under follow-up, 109 (66%, 95% Confidence interval 58-73%) boys and 93 (56%, 95% CI 49-64%) girls were stunted, 14 (8%, 95% CI 4-13%) boys and 12 (7%, 95% CI 3-11%) girls were wasted (low weight-for-height) and 72 (43%, 95% CI 36-51) boys and 66 (39%, 95% CI 31-47%) girls were underweight (low weight-for-age). In total 224/331 (68%) children at three years had at least one growth deficiency (were stunted and/or underweight and/or wasted); even as early as one month of age 186/377 (49%) children had at least one growth deficiency. Factors associated with stunting at three years were birth weight less than 2.5 kg (OR 3.63, 95% CI 1.36-9.70) 'beedi-making' (manual production of cigarettes for a daily wage) in the household (OR 1.74, 95% CI 1.05-2.86), maternal height less than 150 cm (OR 2.02, 95% CI 1.12-3.62), being stunted, wasted or underweight at six months of age (OR 1.75, 95% CI 1.05-2.93) and having at least one older sibling (OR 2.00, 95% CI 1.14-3.51).

CONCLUSION

A high proportion of urban slum dwelling children had poor growth throughout the first three years of life. Interventions are needed urgently during pregnancy, early breastfeeding and weaning in this population.