An AIIMS-CDC Surveillance platform at Ballabgarh for Acute Respiratory Tract Infections (SuBhARTI) has been established to study the epidemiology of Acute Respiratory Infections in a rural north Indian community.

Acute respiratory infections (ARI) are a major burden to child health in developing countries like India [1, 2]. ARI, mainly of lower respiratory tract, are the leading cause of death among children under five years of age in such countries [3-5], resulting in nearly 1.9 million childhood deaths per year, of which 20 % are estimated to occur in India [6, 7]. Worldwide, about 85–88 % of ARI episodes are Acute Upper Respiratory Infections (AURI) while the remaining are Acute Lower Respiratory Infections (ALRI) [8–10]. In the most recent estimate of ALRI associated mortality in India, pneumonia was held responsible for 369,000 deaths (28 % of all deaths) among those 1–59 months, making it the single most important killer in this age group [11]. ARIs also impose a significant economic burden on health systems and individual families in developing countries. We recently estimated that among children aged < 5 years, the median direct cost of ARI was US$135 in private and US$54 in public institutions [12].

Studies from Bangladesh and Pakistan, estimate the average cost of treatment for a single episode of pneumonia as US$ 13 for outpatient care and US$ 71 to US$235 for severe hospitalized pneumonia. It was also estimated that 75 % of the families spent more than half of their total monthly expenditure on hospitalization [13, 14].

This burden of respiratory infections, both globally and in India, can be reduced by many proven effective strategies. The Global Action Plan for Prevention and Control of Pneumonia (GAPP) prioritizes them as case management, vaccination, prevention and management of HIV infection, improvement of nutrition and breastfeeding, reduction of low birth weight, and control of indoor air pollution [15]. Identification of risk factors and etiological agents of pneumonia were among the top ten research priorities by an Expert Group on Childhood Pneumonia in 2011 [16].

A recent systematic review for advocacy and action on pneumonia in India identified the lack of evidence on epidemiology and etiology of pneumonia as important barriers to effective planning and implementation of preventive measures [17]. A meta-analysis of ARI among under-five children based on 12 Indian studies conducted since 1994, estimated incidence rates between 2.4 to 7.4 episodes per child per year and also highlighted the lack of community-based studies on etiology of ARI from India [18]. The few existing studies on etiology of pneumonia have all been hospital based [19, 20].

In order to fill these evidence gaps in the epidemiology of community-acquired ARI in India, we established community-based surveillance among a cohort of rural children up to 10 years of age, with a plan to extend this cohort to a vaccine-testing platform. We chose to include a cohort until 10 years of age, as there is very little information on ARIs in the 5–10 year age group. This paper describes this on-going surveillance platform and presents the preliminary findings from its first year of data collection.

The study is funded by a co-operative agreement between the United States Centers for Disease Control and Prevention (CDC) and the All India Institute of Medical Sciences (AIIMS), New Delhi. The Institutional Ethics Committee of the AIIMS, New Delhi approved the study, with an institutional reliance by the US CDC Institutional Review Board. A written informed consent was obtained from the either parent of the children for children under 7 years of age and from both parents and children for children aged 7 or more years.

The study area consists of four villages, Sunped, Sagarpur, Deegh and Khandawali in the rural Ballabgarh Block of Faridabad district, in the north Indian state of Haryana. The villages are situated approximately 40 km south of New Delhi. (Figure 1) In this region, there are three seasons: winter (October to February), summer (March to June) and monsoon (July to September). These communities are typically agrarian with creeping urbanization from the nearby Ballabgarh town. The study villages are served by the Mohna Primary Health Centre (Sunped, Sagarpur and Deegh) and Panheda Khurd PHC (Khandawali), located at a distance of about 15 to 20 Km. Ballabgarh town is about 5 km away and has a secondary level government health facility as well as a multitude of private health facilities. In each village, Auxiliary Nurse Midwives (ANM) provide primary medical facilities such as immunization and maternal care.Fig. 1

Map of the study area

In the study villages, ground water is the predominant source of drinking water (61.8 %); about a quarter of households practice open defecation, two-thirds (69.1 %) use bio-fuels for cooking and 61 % have a tobacco smoker in the house. On average each house had 1.75 children below 10 years of age (Table 2).Table 2

Household characteristics of houses in Surveillance platform at Ballabgarh for Acute Respiratory Tract Infections SuBhARTI cohort, 2012–13 (n = 2292)

At the start of surveillance on 13th August 2012, there were 2859 children (refusal rate of 2.4 %) enrolled in the cohort, by the end of first year a total of 3192 children had been enrolled in the cohort with 2884 still remaining in the cohort at the end of year 1 (Fig. 3). 182 children reached 10 years of age; none withdrew consent; 105 children migrated out of the study area and 21 died during this period. During the one-year period, 259 newborns and 74 immigrated children were added to the cohort. Those children who were enrolled in the study but followed up for less than four weeks (n = 15) and those without complete information (n = 3) were excluded, leaving 3174 children for this analysis.Fig 3

Flow chart of enrollment and follow-up of the cohort

Although there are some smaller cohort studies and a few cross-sectional studies in India, this is the first large-scale and comprehensive study of community-based ARI with more than 3000 children under surveillance [25–31]. Our preliminary results are similar to other studies among under-five children who have reported an incidence of pneumonia between 0.25 to 0.50 episodes per child per year in the South-Asia region [17, 32]. The sex differentials in hospitalization due to ARI in South—Asia has been commented by Nair et al. previously as well [33].

To the best of our knowledge, this is the first study to provide community-based ARI incidence among 5–10 year olds in India. Our sample size was calculated to establish a minimum expected agent-specific incidence of 0.035 episodes per child per year (10 % of 0.35 pneumonia incidence) with a relative precision of 20 and 95 % confidence. Our clinical definition of ARI was broad as compared to studies identified in reviews of ARI both in India and else where in under-five children which might have resulted in a slight overestimate of AURI and potentially could include non-infectious causes of cough as well [18, 34, 35]. However, this was not the case with ALRI as trained nurses, who were closely monitored by physicians, used standard classification guidelines for ALRI ascertainment. The continuous nature of the weekly surveillance platform minimized the possibility of missing ARI episodes regardless of duration, as long as the child was present in the study area. The rigorous quality control measures and the continuity of data collection irrespective of holidays add to the credibility and robustness of our estimates.

The weaknesses in this study include the classification of ARI as AURI and ALRI was determined by clinical assessments and did not include auscultation or radiology and could have resulted in some misclassification. Due to the time lag between birth and enrolment, surveillance was missed in the early neonatal period. It is possible that repeated contacts with the family members might have resulted in overestimation of ARI due to reporting of mild symptoms that would have otherwise been unnoticed. The rigorous surveillance could also have resulted in early recognition and treatment seeking, preventing progression of AURI to ALRI, potentially leading to an underestimation of ALRI in the community. While it is difficult to decide an appropriate recall period and most studies have used a two week recall period, we feel that weekly surveillance represents the best trade-off between missing due to recall and development of fatigue due to repeated visits [36, 37].

The cohort established as a part of this collaboration will provide critical information on respiratory infections epidemiology in rural India. The preliminary results show that ARI impose a significant burden on the children of this cohort. Further analysis of the data would help us elucidate the risk factors, social inequities related to this disease. We have just initiated a vaccine trial using live attenuated influenza vaccine and social contact mixing studies in the established cohort to generate more evidence on transmission dynamics and prevention of respiratory infection in this population.