Changes in human ecology and behavior in relation to the emergence of diarrheal diseases, including cholera.

Abstract

Human po s throughout the world can be found in diverse codis. A proportion of the population of developing countries lves in deprived conditions characterized by r a housing, lack of piped water and sanitation, and widespread fecal contamition of the environment. Enteric infections, particularly due to bacterial pathogens, are readily trnsitted under these drcumstances. In contrast, the majority of nhbitats of idurilized countries live in a sanitary environment that generally discourages the transmission of enterc pathogens, particularly bacteria. In both these ecologic niches, i human ecology and behavior are leading to the emergence of certain enteric infections. Relevant factors in developing areas indude urbanization (leading to periurban slums), diminished breastfeeding, and political upheaval that results in population migrations. In indus d areas, large-scale food production (e.g., enormous poultry farms), distribution, and rtailing (e.g., fast-food chains) create opportunities where widespread and extensive outbreaks of food-borne enteric infection can ensue if a breakdown in food hygiene occurs.In a broad sense, one can divide the world into two distinct ecologies with respect to the occurrence of enteric diseases, with a developing country ecology at one extreme and an industrialized world ecology at the other. Between these extremes, one encounters gradations and exceptions. In each ofthese settings, changes in human ecology and behavior are having an impact on enteric infections. In developing areas, some of the sweeping changes in demographics and population distribution that are underway are creating environments of amplified transmission of enteric pathogens or are attenuating the protective features ofsome traditional practices. In industrialized areas, the changes underway to meet the ever-increasing demands of consumption-based economies are creating opportunities for the importation of pathogens that improvements in infrastructure were believed to have eliminated. Finally, even the gains in infrastructure and commercialization of food production, food distribution, and food retailing, with all oftheir positive impact on health, have by their very nature created environments in which we have seen the emergence of enteric pathogens.Developing World Ecology

Toward a Systems Approach to Enteric Pathogen Transmission: From Individual Independence to Community Interdependence

“…Levine & Levine (88) noted that one of the main changes in human ecology in the developed world has been a shift in the production, distribution, and retailing of food. This shift has resulted in the growth of large-scale industrial agriculture characterized by huge centralized farms, as well as large-scale food service such as fast-food chains, creating a possibility for widely disseminated outbreaks if breakdowns in food hygiene occur.…”

“…Several of the few studies that did focus on these multiple pathways fit the Levine & Levine (88) concept that there are developing world ecological niches in the developed world, such as daycare centers, where risks are elevated (47). Another such location was agricultural camps, with studies emphasizing availability of water for hygiene (64) and need for increased quality of water and sanitation measures (6).…”

Shigella and enteroinvasive Escherichia coli

“…Certain populations, however, may be predisposed to infection and disease due to the nature of transmission of the organisms. In the US, outbreaks of shigellosis and other diarrheal diseases are increasing in day care centers as more single-parent and two parent working families turn to these facilities to care for their children (Levine and Levine, 1994;Arvelo et al, 2009). Over-crowding, poor sanitation, substandard hygiene and unsafe water supplies are conditions that contribute to outbreaks of shigellosis in these areas.…”

Converging paradigms for environmental health theory and practice.

“…These composite approaches recognize the importance of intergenerational and interregional issues when health effects of ecosystem change are displaced in time and space (Aron and Patz 2001; Hales et al 1997). Third, ecosystem principles provide core resources for understanding and responding to complex environment, health, and sustainability challenges-through concepts such as systems interactions, ecological hierarchies, ecosystem services, and the mutually constitutive relations within and among biotic and abiotic influences on health (Kay et al 1999;Levine and Levine 1994;McMichael et al 1999;Pimentel et al 2000; WaltnerToews and Wall 1997).…”

“…By focusing on human-environment interrelationships within ecosystems, human ecology highlights direct and indirect health impacts caused by unhealthy trajectories of development, anthropogenic ecosystem change, and related social inequities (Follér 2001;Levine and Levine 1994;Marten 2001). Foci on "health" are not always explicit, but human ecology is based on the premise that developmental processes and human health gains are entirely dependent on ecosystem services (Costanza et al 1997;Daily 1997).…”