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

The study was conducted in Ramnaickapalayam, Chinnallapuram, Kaspa and Vasanthapuram, four geographically adjacent, semi-urban slums located in the western outskirts of Vellore, Tamil Nadu, India, with a population of about 40,000, comprising of approximately 50% Hindu, 45% Muslim and 5% Christian households. A large proportion of households use firewood as their primary cooking fuel. “Beedi-work” (manual production of indigenous tobacco-based cigarette-like products) is the predominant occupation, followed by unskilled labor. The majority of household incomes depend on daily-wage earners, who do not have the benefit of a regular salary and other benefits such as pension or health insurance. The residents receive piped drinking water, supplied by the local municipality intermittently (at intervals of 2–28 days), which they collect and store in multiple wide-mouthed containers and mostly consume without further treatment [10]. During times of water scarcity, bore-wells located at different parts of the study area and water supplied by the Vellore Municipal Corporation through tank trucks serve as an alternative source of drinking water.

A government urban health centre (UHC), providing free health care to the residents, is located within the study area; and a government teaching hospital is located approximately five km away. Numerous private facilities, clinics, nursing homes or hospitals and traditional medicine and faith healers are also located in close proximity. The Christian Medical College (CMC), Vellore, a not-for-profit organization and its two outreach units – the Community Health and Development (CHAD) and the Low Cost Effective Care Unit (LCECU), are located within a few kilometers of the study area.

The UHC records document a birth rate of 15.3 live births per 1000 population per year and an infant mortality rate of 18.2 deaths per 1000 live-births per year for the years 2008–2011. As per the sample registration survey conducted by the Government of India, the birth and infant mortality rates for urban Tamil Nadu for the year 2010 is 15.8 live births per 1000 population and 22 deaths per 1000 live-births respectively [11].

A quasi-experimental (non-randomized) study was conducted to determine whether or not a protected water supply could prevent or delay cryptosporidial infections in children under the age of two years. Children were recruited at birth or while they were still being exclusively breast-fed, and their families received either bottled (protected) or municipal (unprotected) drinking water based on their area of residence. The water availability and consumption patterns were, however, similar among residents living in each of these areas, as was the degree of environmental contamination.

The bottled drinking water was obtained from a commercial provider in 20-liter Polyethylene terephthalate (PET) bottles. It is sourced from an underground aquifer and purified by reverse osmosis followed by ultraviolet irradiation and ozonization. The commercial provider follows quality control procedures to ensure that the physical, chemical and microbiological properties of the bottled water meet the specifications of the Bureau of Indian Standards (http://​www.​bis.​org.​in/​cert/​REQUIREMENTSIS14​543.​htm) (personal communication from the commercial bottled water provider). Prior to start of the study, multiple water samples from the same bottled water provider were independently tested using standard techniques [12], and were found to be free of microbial contamination (presumptive and fecal coliforms).

Supply of bottled water commenced at least one week prior to the scheduled weaning date of the enrolled child or, in case of unscheduled weaning, as soon as the field team became aware of the event. For the purpose of this study, a child was considered to be weaned if he/she were given anything to eat or drink other than breast-milk, including water. Sufficient water was provided for the drinking water needs of the entire household, with households encouraged to call if a replacement was needed ahead of the biweekly scheduled delivery.

Prior to enrollment, a door-to-door survey of houses in the study area was conducted to identify families with women in late pregnancy or with children who were being exclusively breast-fed. Those families intending to stay in the area for at least two years were approached by the field staff for consent and recruitment. Children with gross congenital anomalies or with birth weight <1500 gm were excluded. The study was approved by the Institutional Review Boards at the Christian Medical College, Vellore, India, and the Tufts Medical Center and Tufts University Health Sciences Campus, Boston, USA. Recruitment was consecutive and followed written informed consent by parents or legal guardians of the eligible children. Each child was followed up until he/she attained the age of two years. The study commenced in September 2008 and ended in April 2011.

Soon after recruitment, field workers visited the house to obtain baseline demographic details and information on water usage and storage, toileting and animal contact. Socio-economic status (SES) of the participating families was also ascertained using a modified version of the Kuppuswamy scale as described previously in the same locality [9]. This composite SES scale takes into account the educational and occupational level of the family, house ownership, total number of rooms in the house (excluding kitchen and bathroom), and household possessions. Based on the above parameters, families received a score ranging from 0–5. A score of <2 denoted low SES.

Household hygiene was measured using a structured questionnaire covering the aspects of water, food and personal hygiene, which has previously been validated and used in the same community [9, 10]. For this analysis, the hygiene measurement of each child closest to their time of weaning was used. Based on responses to the questionnaire a scoring system was developed and the households were assigned a hygiene score ranging from 0–18. Families whose scores were at or above the upper tertile (≥12) were considered as those with good household hygiene.

Every week, the field staff visited the study household and interviewed the caregiver about diarrhea, vomiting, fever, cold/cough or any other illness experienced by the child during each day since the last visit, using a structured questionnaire. They also enquired about diarrheal and other illnesses in the family, and were trained to use standard definitions to identify common morbidities.

A physician-run clinic was also set up within the study area to provide basic health care to all children under the age of five years in the locality. Primary caregivers were encouraged to bring their sick children to the clinic, and those requiring hospitalization or specialized care were referred to the secondary (CHAD) or tertiary care hospital (CMC), as deemed necessary by the study physician. A record of all such visits was maintained by the field staff. If a child was taken to any other health-care facility for treatment, the physician recorded-diagnosis in the prescription or discharge summary, if available, was obtained by the field staff during their weekly home visits.

Monthly anthropometric (weight and length/height) measurements were also recorded for all study children. Malnutrition in children was assessed by computing the height-for age (HAZ), weight-for-height (WHZ) and weight-for-age (WAZ) z-scores, using the 2006 WHO child growth standards as the reference population [13]. Based on their z-scores, children were classified as stunted (HAZ<−2 SD), wasted (WHZ<−2 SD), underweight (WAZ<−2 SD) or normal. Any child who was found to be either wasted or underweight was further classified as undernourished. A child was considered to be early and persistently stunted if the HAZ score was <−2 SD at 6 months and remained so at 12, 18 and 24 months of age. Similarly, children who were either wasted (WHZ <−2 SD) or underweight (WAZ <−2 SD) at 6, 12, 18 and 24 months were classified as early and persistently undernourished.

The morbidity experiences of each child, as reported by the primary caregiver or obtained from the discharge summary during the weekly visits were classified into five broad categories - respiratory, gastrointestinal (GI), skin, other infections and non-infectious morbidities. GI illness was defined as diarrhea (3 or more loose watery stools over a 24 h period [14]) or vomiting lasting for more than 24 h. Respiratory illnesses were classified as either upper (URI) or lower respiratory tract infections (LRI). LRI included bronchitis or pneumonia as diagnosed by a physician, whereas URI included cough, cold and runny nose with and without concomitant symptoms. For URIs without any concomitant symptom, only those lasting for five or more days were considered for analysis. Skin lesions consisted mostly of rashes, but also included a wide variety of other conditions such as vesicles, pustules, cysts, ulcerations and excoriations. Other infections included infections of the eyes, ears or any other localized infection with or without fever. Non-infectious morbidities included non-specific swellings, surgical conditions such as hernia and phimosis, congenital diseases, injuries, insect bites and accidents. For GI morbidities, a new episode was defined as illness occurring at least 48 h after resolution of the previous episode. For all other illnesses, this time was taken as 72 h.

Data were entered in duplicate using the Epi-Info 2002 (CDC, Atlanta, GA, USA) software and analyzed using STATA 10.1 for Windows (StataCorp, College Station, TX, USA) software. Comparison of baseline differences between the bottled and municipal water cohorts was done using χ ² test or Fisher’s exact test for categorical variables and using two-tailed t-tests or Wilcoxon rank sum tests for continuous variables, depending on the distribution of data. Incidence rates were calculated as the number of episodes divided by the child-years of follow-up. The total person-time at risk was calculated as total days under surveillance minus days of missing surveillance data (if ≥1 week). In order to account for multiple failures in a child, Poisson survival models with robust standard errors were fitted to calculate the incidence rates for different disease conditions.

Of the 176 children enrolled into the study, 160 (90.9%) completed the two-year follow-up. The baseline socio-demographic characteristics of children who were lost to follow-up did not differ significantly from those who remained in the study until the end of follow-up (Table 1). The primary reason for loss to follow-up was migration out of the study area. There was no significant difference in the number of children lost to follow-up between those using bottled or municipal water (P=0.340). Children who dropped out, remained in the study for a median (IQR) period of 14.4 (5.7-17.4) months. The cohort recruitment and follow-up is outlined in Figure 1.

Overall, children were born mostly into nuclear (83, 47.2%) or extended (75, 42.6%) families. The median (IQR) family size was 5 (4–7) members. The mean (SD) age of the mother at the time of birth of the child was 24.1 (3.4) years, and they had completed a median (IQR) of 8 (5–10) years of schooling. The majority of the children were Hindus (97, 55.1%), or Muslims (70, 39.8%), with only a small proportion of children (9, 5.1%) belonging to Christian households. Approximately two-thirds (117, 66.5%) of the children belonged to families classified as low socio-economic status. Firewood was the predominant cooking fuel for about half (90, 51.1%) of the recruited families.

More than half of the children were males (95, 54%) and over two-thirds (119, 67.6%) had older siblings. The median age at introduction of supplementary feeding was 4.6 (3.5-5.7) months. For the 167 (94.9%) children for whom birth weight data was available, mean (SD) weight at birth was 2.9 (0.5) kg, with 20 (12%) children classified as low birth weight (<2.5 kg).

Comparison of baseline characteristics between the bottled and municipal water cohorts (Table 2) revealed certain baseline differences. For example, children provided bottled water weaned earlier and had a smaller family size. Also, a greater proportion of families in the bottled water cohort belonged to the Hindu religion and had poorer household hygiene. On the other hand, significantly more families in the municipal water cohort used firewood as their primary cooking fuel. Compared to those in the municipal water cohort, mothers as well as the head of the households of children in the bottled water cohort had higher levels of education.

Complete anthropometric data were available for 161 (91.5%) of the 176 children under observation. Figure 2 (A and B) presents the proportion (with 95% CI) of stunted and undernourished (wasted and/or underweight) children at the four different time points (6, 12, 18 and 24 months of age). Stunting was observed to increase progressively from 14.9% at 6 months to 30.4% at 24 months (Figure 2A). On the other hand, prevalence of undernutrition showed an increasing trend between 6 to 18 months of age, decreasing thereafter at 24 months (Figure 2B). The proportions of stunted and undernourished children were comparable between the bottled and municipal water cohorts at each of the four time points.

Twelve (7.5%) children were found to have early and persistent stunting, whereas 21 (13%) were persistently undernourished. Seventy (40.5%) and 85 (52.8%) children were found to be stunted and undernourished respectively in at least one of the four observations. A total of 101 (62.7%) children experienced one or more growth failures (stunted/wasted/underweight) during their follow-up period. When the nutritional parameters were compared between male and female children, no gender differences in the prevalence of either stunting or undernourishment was noticed at any of the four time points.

Children had more illnesses during infancy (13.8 episodes/child-year) than during the subsequent year (11.0 episodes/child-year), irrespective of whether they belonged to the municipal (14.2 vs. 11.6 episodes/child-year) or bottled water (13.5 vs. 10.4 episodes/child-year) cohort (Table 3).

Respiratory morbidity was the most common (Figure 3), comprising 60.2% of all reported morbidities. The incidence (95% CI) of respiratory morbidities was calculated at 7.5 (7.2-7.9) episodes/child-year. Children in the municipal water cohort reported significantly more respiratory morbidities (8.3 episodes/child-year) than those in the bottled water cohort (6.8 episodes/child-year, P<0.001). This difference persisted even after adjusting for the effect of potential confounding variables (Table 4). Almost all respiratory morbidities (98%) were URIs. The median (IQR) duration of an episode of respiratory illness was 10 (6–21) days, since all uncomplicated URIs of less than 5 days were excluded. On an average, children had an additional 3 episodes of respiratory illness in infancy than during the subsequent year. This trend was similar in children who received bottled and municipal water (Table 3).

GI morbidities accounted for 26.8% of all reported illnesses (Figure 3), with an incidence (95% CI) of 3.4 (3.0-3.8) episodes of GI illness/child-year. The majority of GI morbidities (807 episodes, 76.7%) were diarrheal episodes (with or without vomiting), followed by vomiting without diarrhea (243 episodes, 23.1%). The overall diarrheal incidence (95% CI) was 2.6 (2.3-2.9) episodes/child-year, whereas that of vomiting was 0.77 (0.63-0.97) episodes/child-year of follow-up.

The incidence of GI morbidities decreased from 4.0 episodes/child-year during infancy to 2.6 episodes/child-year during the second year of their life. No difference in the incidence of GI morbidities was noticed between children in the bottled and municipal drinking water cohorts (3.5 episodes/child-year vs. 3.2 episodes/child-year, P=0.549), even after adjusting for potential confounders (Table 4). The median (IQR) duration of an episode of GI morbidity was 3 (2–4) days.

Incidences of other illnesses ranged from 0.83-0.37 episodes/child-year and were equally distributed between the bottled and municipal water cohorts except for non-infectious morbidities, which was found to be significantly higher during infancy among children using bottled water (0.21 episodes/child-year vs. 0.07 episodes/child year, P=0.038). However, this difference was not statistically significant in the adjusted analysis (Table 4). In general, the incidence of skin, and other infectious and non-infectious diseases were higher among children during the second year of their life (Table 3). No deaths were reported among the study children.

A large proportion of morbidities (2789/3932, 70.9%) resulted in clinic or hospital outpatient visits. Among all morbidities reported, healthcare (clinic visit and/or hospitalization) was sought more frequently for respiratory illnesses (2077/2366, 87.8%), followed by gastrointestinal (557/1052, 52.9%) and non-infectious (56/117, 47.9%) morbidities (Table 3). Overall, 2.2% (86/3932) of all morbidities required hospitalization, at a rate of 0.3 (0.2-0.4) hospitalizations/child-year. A greater proportion of gastrointestinal (29/1052, 2.8%) and other infectious diseases (6/135, 4.4%) required hospitalization than respiratory (45/2366, 1.9%), skin (5/262, 1.9%) and non-infectious (1/117, 0.8%) diseases.