Influenza and other infections: surveillance and long-term health effects

Thesis (Sc.D.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.Annual influenza epidemics and occasional pandemics cause substantial morbidity and mortality. New surveillance methods are constantly under consideration, though some aspects of influenza natural history and epidemiology are not well understood. While the short-term health consequences of many infectious diseases, including influenza, are well established, the long-term effects are only recently being examined. This dissertation evaluates questions relevant to influenza surveillance and epidemiology, and to the association between prenatal and childhood infections and certain adult health outcomes. The first two studies relate to influenza in Massachusetts. In Study 1, clinical laboratory data were used to estimate the amount of influenza-like illness (ILI) hospital discharges and emergency department (ED) visits associated with influenza and respiratory syncytial virus (RSV). The percent of ILI associated with influenza and RSV varied by season, from 0.18% to 2.5% and 0.04% to 0.21%, respectively, for discharges and from 1.4% to 2.3% and 0.08% to 0.68%, respectively, for ED visits. Study 2 examined racial/ethnic disparities in ILI hospital visits during the first wave of the 2009 H1N1 pandemic. We found that blacks and Hispanics had higher age-adjusted rates of ED visits, observation stays, and discharges compared to whites. Studies 3 and 4 were both set in Denmark. Study 3 evaluated the association between prenatal and childhood hospitalized infections and adult obesity among a cohort of 17,456 male military conscripts. For prenatal and early childhood infections, the adjusted odds ratios were 1.34 (95% CI: 0.82, 2.19) and 1.21 (95% CI: 1.01, 1.44), respectively. Study 4 assessed whether prenatal exposure to the 1918, 1957, or 1968 influenza pandemics was associated with increased rates of acute myocardial infarction or stroke. Overall, there was no evidence of an association between prenatal influenza and the outcomes. In summary, we observed that in Massachusetts, a small proportion of ILI discharges and ED visits are associated with influenza and RSV, and that there were racial/ethnic disparities in H1N1 morbidity in three hospital databases. In Denmark, we found evidence that prenatal and childhood infections are associated with adult obesity, but prenatal influenza exposure does not appear to be associated with cardiovascular events