Central Data Catalog

Health and demographic surveillance system (HDSS) is a population-based health and vital event registration system that collects and monitors demographic and health events information in a geographically defined population at regular intervals (1). HDSS is usually comprised of a large team of qualified professionals and volunteers involved in large-scale data collection, monitoring, analysis, and report generation in a specific population for a long period of time. HDSS sites, because of their reliable information, can help policy makers to prioritize health issues and accordingly allocate resources more efficiently. It can act as a platform for intervention studies and provides feedback on programs’ effectiveness, which consequently helps in improving policies (2). INDEPTH is a global network of HDSS sites comprising of 42 member centers, which observe through 47 HDSS field sites (http://www.indepth-network.org/). These sites monitor life events of over three million individuals in 18 low and middle-income countries from Africa, Asia, and Oceania (3). Unlike cohort studies, HDSS follows the entire population in a defined geographic area for an ongoing period of time. During its initial census, HDSS registers all households and individuals who are then followed by frequent documentation of events such as births, deaths, marriages, and migrations in subsequent census rounds. Furthermore, information pertaining to health, social, and economic aspects of the population under surveillance is also collected, which eventually serves as a comprehensive metadata for any study on human populations. As a result, HDSS provides a platform for various research activities and offers a ready-made sampling frame for tracking the population. Apart from demographic information, any other information relevant to the particular study can be easily augmented and linked with other datasets in HDSS program (4).

We are increasingly able to understand that microbes contribute in many aspects of human health and physiology. Many intrinsic and extrinsic factors like mode of birth, infant feeding patterns, antibiotic usage, sanitary habits, age, genetics, diet, geography, socioeconomic status, and disease condition have been shown to alter the microbiome, which in turn affects human health (5–9). Extensive studies have been conducted across the globe focusing on the influence of microbiome in chronic diseases like asthma, chronic obstructive pulmonary disease (COPD), inflammatory bowel disease, obesity, diabetes, and cardiovascular diseases (10–15). Apart from genetics, many environmental factors are known to be associated with these diseases (16). Based on recent studies of the microbiome, it is clear that a robust research framework accompanied by a collection of comprehensive metadata is essential in building our knowledge of this tripartite relationship between humans, environment, and the microbes.

Asthma and COPD are common chronic airway diseases with high prevalence and mortality rates across the world (17, 18). Although several studies have linked various factors such as genetic predisposition, smoking, air pollution, and occupational exposures to these diseases; microbes are also known to play a vital role (19–22). In the past decade, the discovery of the human respiratory tract microbiome has steered growing number of studies to understand the role of the microbiome in asthma and COPD (23). Understanding why and how these diseases develop and progress over time requires long-term follow-up. Many cohorts have been established worldwide, such as ECLIPSE, CanCOLD, Birmingham, MicroCOPD (24–27). Although advancements have been made regarding descriptions of the main characteristics of chronic airway diseases, much is still to be explored about the factors associated with changes in the microbiome and the relevance of these changes in host-specific pathogenesis of the disease (23).

In this review, we discuss microbiome studies on chronic airway diseases like asthma and COPD to understand how HDSS can aid in human microbiome research. In addition to this, we also highlight opportunities and limitations in human microbiome research and also show how HDSS can benefit this field in future.