Epidemiology of hepatitis E virus in the United States: results from the Third National Health and Nutrition Examination Survey, 1988-1994

A niche for infectious disease in environmental health: rethinking the toxicological paradigm

OBJECTIVE

In this review we highlight the need to expand the scope of environmental health research, which now focuses largely on the study of toxicants, to incorporate infectious agents. We provide evidence that environmental health research would be strengthened through finding common ground with the tools and approaches of infectious disease research.

DATA SOURCES AND EXTRACTION

We conducted a literature review for examples of interactions between toxic agents and infectious diseases, as well as the role of these interactions as risk factors in classic "environmental" diseases. We investigated existing funding sources and research mandates in the United States from the National Science Foundation and the National Institutes of Health, particularly the National Institute of Environmental Health Sciences.

DATA SYNTHESIS

We adapted the toxicological paradigm to guide reintegration of infectious disease into environmental health research and to identify common ground between these two fields as well as opportunities for improving public health through interdisciplinary research.

CONCLUSIONS

Environmental health encompasses complex disease processes, many of which involve interactions among multiple risk factors, including toxicant exposures, pathogens, and susceptibility. Funding and program mandates for environmental health studies should be expanded to include pathogens in order to capture the true scope of these overlapping risks, thus creating more effective research investments with greater relevance to the complexity of real-world exposures and multifactorial health outcomes. We propose a new model that integrates the toxicology and infectious disease paradigms to facilitate improved collaboration and communication by providing a framework for interdisciplinary research. Pathogens should be part of environmental health research planning and funding allocation, as well as applications such as surveillance and policy development.

Living with companion animals, physical activity and mortality in a U.S. national cohort

Living with a canine companion is postulated to increase physical activity. We test the hypotheses that adults living with a canine companion have a higher level of physical activity and reduced mortality risk compared to those not living with a companion animal. A U.S. national health survey with longitudinal mortality follow-up studied 11,394 American men and women aged 40 years and over examined in 1988–1994 followed an average 8.5 years. Measurements at baseline included self-reported companion animals in the household, socio-demographics, health status, physical and biochemical measurements. Outcome measures were leisure-time physical activity (LTPA), and death from all causes. Death during follow-up occurred in 3,187 persons. In bivariate cross-sectional analyses living with a dog was associated with more frequent LTPA and higher survival. In proportional hazards regression analysis, no significant interaction of age, gender or ethnicity with animals was found. After adjusting for confounding by baseline socio-demographics and health status at ages 40+, the hazards ratio (95% confidence limits) for living with a canine companion compared to no animals was 1.21(1.04–1.41, p < 0.001). After also controlling for health behaviors, blood pressure and body mass, C-reactive protein and HDL-cholesterol, the HR was 1.19 (0.97–1.47, NS). In a nationwide cohort of American adults, analyses demonstrated no lower risk of death independent of confounders among those living with canine or feline companions, despite positive association of canine companions with LTPA.

Much meat, much malady: changing perceptions of the epidemiology of hepatitis E

Hepatitis E, which is caused by hepatitis E virus (HEV), may now be considered a zoonosis as well as an anthroponosis. Pigs, boars and deer have been identified as reservoirs, and their flesh and entrails--as meat and offal--as vehicles of HEV transmission. Shellfish also act as vehicles. Dietary, gastronomic and culinary preferences influence how extensively HEV conveyed by these vehicles can be inactivated before their ingestion by the host. Another route of infection is paved by HEV that is enterically shed by humans and by live animals into the environment. Although anthroponotic transmission of HEV is primarily environmental, zoonotic transmission may proceed along both foodborne and environmental routes.