Performance of case definitions used for influenza surveillance among hospitalized patients in a rural area of India.

OBJECTIVE: To assess case definitions for influenza in a rural community in India. METHODS: Residents of the study area who were hospitalized for any acute medical condition for at least one night between May 2009 and April 2011 were enrolled. Respiratory specimens were collected and tested for influenza viruses in a reverse-transcription polymerase chain reaction (PCR). The PCR results were taken as the "gold standard" in evaluating the performance of several case definitions. FINDINGS: Of the 3179 patients included in the final analysis, 21% (665) were PCR-positive for influenza virus, 96% reported fever and 4% reported shortness of breath. The World Health Organization (WHO) case definition for severe acute respiratory illness had a sensitivity of 11% among patients aged < 5 years and of 3% among older patients. When shortness of breath was excluded from the definition, sensitivities increased (to 69% and 70%, respectively) and corresponding specificities of 43% and 53% were recorded. Among patients aged ≥ 5 years, WHO's definition of a case of influenza-like illness had a sensitivity of 70% and a specificity of 53%. The addition of "cough and reported or measured fever" increased sensitivity to 80% but decreased specificity to 42%. CONCLUSION: The inclusion of shortness of breath in WHO's case definition for severe acute respiratory illness may grossly underestimate the burden posed by influenza in hospitals. The exclusion of shortness of breath from this definition or, alternatively, the inclusion of "cough and measured or reported fever" may improve estimates of the burden.

Burden of seasonal and pandemic influenza-associated hospitalization during and after 2009 A(H1N1)pdm09 pandemic in a rural community in India.

BACKGROUND: Influenza is vaccine-preventable; however, the burden of severe influenza in India remains unknown. We conducted a population-based study to estimate the incidence of laboratory confirmed influenza-associated hospitalizations in a rural community in western India. METHODS: We conducted active surveillance for hospitalized patients with acute medical illnesses or acute chronic disease exacerbations in Pune during pandemic and post pandemic periods (May 2009-April 2011). Nasal and throat swabs were tested for influenza viruses. A community health utilization survey estimated the proportion of residents hospitalized with respiratory illness at non-study facilities and was used to adjust incidence estimates from facility-based surveillance. RESULTS: Among 9,426 hospitalizations, 3,391 (36%) patients were enrolled; 665 of 3,179 (20.9%) tested positive for influenza. Of 665 influenza positives, 340 (51%) were pandemic A(H1N1)pdm09 and 327 (49%) were seasonal, including A/H3 (16%), A/H1 (3%) and influenza B (30%). The proportion of patients with influenza peaked during August 2009 (39%) and 2010 (42%). The adjusted annual incidence of influenza hospitalizations was 46.8/10,000 during pandemic and 40.5/10,000 during post-pandemic period with comparable incidence of A(H1N1)pdm09 during both periods (18.8 and 20.3, respectively). The incidence of both pH1N1 and seasonal hospitalized influenza disease was highest in the 5-29 year olds. CONCLUSIONS: We document the previously unrecognized burden of influenza hospitalization in a rural community following the emergence of influenza A(H1N1)pdm09 viruses in India. During peak periods of influenza activity circulation i.e during the monsoon period, 20% of all hospital admissions in the community had influenza positivity. These findings can inform development of influenza prevention and control strategies in India.

The short-term association of temperature and rainfall with mortality in Vadu Health and Demographic Surveillance System: a population level time series analysis.

BACKGROUND: Research in mainly developed countries has shown that some changes in weather are associated with increased mortality. However, due to the lack of accessible data, few studies have examined such effects of weather on mortality, particularly in rural regions in developing countries. OBJECTIVE: In this study, we aimed to investigate the relationship between temperature and rainfall with daily mortality in rural India. DESIGN: Daily mortality data were obtained from the Health and Demographic Surveillance System (HDSS) in Vadu, India. Daily mean temperature and rainfall data were obtained from a regional meteorological center, India Meteorological Department (IMD), Pune. A Poisson regression model was established over the study period (January 2003-May 2010) to assess the short-term relationship between weather variables and total mortality, adjusting for time trends and stratifying by both age and sex. RESULT: Mortality was found to be significantly associated with daily ambient temperatures and rainfall, after controlling for seasonality and long-term time trends. Children aged 5 years or below appear particularly susceptible to the effects of warm and cold temperatures and heavy rainfall. The population aged 20-59 years appeared to face increased mortality on hot days. Most age groups were found to have increased mortality rates 7-13 days after rainfall events. This association was particularly evident in women. CONCLUSION: We found the level of mortality in Vadu HDSS in rural India to be highly affected by both high and low temperatures and rainfall events, with time lags of up to 2 weeks. These results suggest that weather-related mortality may be a public health problem in rural India today. Furthermore, as changes in local climate occur, adaptation measures should be considered to mitigate the potentially negative impacts on public health in these rural communities.

Does self-rated health predict death in adults aged 50 years and above in India? Evidence from a rural population under health and demographic surveillance.

BACKGROUND: The Study on Global Ageing and Adult Health (SAGE) aims to improve empirical understanding of health and well-being of adults in developing countries. We examine the role of self-rated health (SRH) in predicting mortality and assess how socio-demographic and other disability measures influence this association. METHODS: In 2007, a shortened SAGE questionnaire was administered to 5087 adults aged ≥50 years under the Health Demographic Surveillance System in rural Pune district, India. Respondents rated their own health with a single global question on SRH. Disability and well-being were assessed using the WHO Disability Assessment Schedule Index, Health State Score and quality-of-life score. Respondents were followed up every 6 months till June 2011. Any change in spousal support, migration or death during follow-up was updated in the SAGE dataset. RESULTS: In all, 410 respondents (8%) died in the 3-year follow-up period. Mortality risk was higher with bad/very bad SRH [hazard ratio (HR) in men: 3.06, 95% confidence interval (CI): 1.93-4.87; HR in women: 1.64, 95% CI: 0.94-2.86], independent of age, disability and other covariates. Disability measure (WHO Disability Assessment Schedule Index) and absence of spousal support were also associated with increased mortality risk. CONCLUSION: Our findings confirm an association between bad/very bad SRH and mortality for men, independent of age, socio-demographic factors and other disability measures, in a rural Indian population. This association loses significance in women when adjusted for disability. Our study highlights the strength of nesting cross-sectional surveys within the context of the Health Demographic Surveillance System in studying the role of SRH and mortality.