Self-feedbacks determine the sustainability of human interventions in eco-social complex systems: Impacts on biodiversity and ecosystem health.

Several administrative polices have been implemented in order to reduce the negative impacts of fishing on natural ecosystems. Four eco-social models with different levels of complexity were constructed, which represent the seaweed harvest in central-northern Chile under two different regimes, Management and Exploitation Areas for Benthic Resources (MAEBRs) and Open Access Areas (OAAs). The dynamics of both regimes were analyzed using the following theoretical frameworks: (1) Loop Analysis, which allows the local stability or sustainability of the models and scenarios to be assessed; and (2) Hessian´s optimization procedure of a global fishery function (GFF) that represents each dynamics of each harvest. The results suggest that the current fishing dynamics in MAEBRs are not sustainable unless the market demand presents some type of control (i.e. taxes). Further, the results indicated that if the demand changes to a self-negative feedback (self-control) in MAEBRs, the stability is increased and, simultaneously, a relative maximum for the GFF is reached. Contrarily, the sustainability of the model/system representing the harvest (principally by cutting plants) in OAAs is not reached. The implementation of an "ecological" tax for intensive artisanal fisheries with low operational cost is proposed. The network analysis developed here is proposed as a general strategy for studying the effects of human interventions in marine coastal ecosystems under transient (short-term) dynamics.

Ethnic density and mortality: aboriginal population health in Taiwan.

BACKGROUND: Ethnic density (the proportion of ethnic minority populations in a geographic area) has emerged as an important factor determining population health. By examining the relationship between mortality rates and the proportion of aboriginal population in Taiwan, this ecological approach highlights the pressing need to understand why aboriginal health remains relatively disadvantaged affecting the population as a whole, especially given the provision of universal health coverage. METHODS: Using combined data from various government departments in Taiwan, we first compare overall mortality rates between aboriginal people and the general population in Taiwan's 21 administrative locations during the years 2010 and 2011. Then we describe the associations between ethnic density and the relative risk of 40 different causes of death. RESULTS: Aboriginal people in Taiwan on average have higher overall mortality rates than the general population. The proportion of aboriginal population is associated with a higher risk of death for overall mortality, homicide, vehicle crashes, tuberculosis, and several alcohol-related diseases such as peptic ulcer, chronic liver disease, and cirrhosis. These affect the health of the general population in counties where aborigines are abundant. CONCLUSION: The proportion of aboriginal population may play an essential role in determining Taiwan's population health. When universal health coverage is in place, the root causes (for example, alcoholism, culture, and socioeconomic disadvantages) of health disparities between aboriginal populations and general populations need to be addressed.

Application of loop analysis for evaluation of malaria control interventions.

BACKGROUND: Despite continuous efforts and recent rapid expansion in the financing and implementation of malaria control interventions, malaria still remains one of the most devastating global health issues. Even in countries that have been successful in reducing the incidence of malaria, malaria control is becoming more challenging because of the changing epidemiology of malaria and waning community participation in control interventions. In order to improve the effectiveness of interventions and to promote community understanding of the necessity of continued control efforts, there is an urgent need to develop new methodologies that examine the mechanisms by which community-based malaria interventions could reduce local malaria incidence. METHODS: This study demonstrated how the impact of community-based malaria control interventions on malaria incidence can be examined in complex systems by qualitative analysis combined with an extensive review of literature. First, sign digraphs were developed through loop analysis to analyse seven interventions: source reduction, insecticide/larvicide use, biological control, treatment with anti-malarials, insecticide-treated mosquito net/long-lasting insecticidal net, non-chemical personal protection measures, and educational intervention. Then, for each intervention, the sign digraphs and literature review were combined to analyse a variety of pathways through which the intervention can influence local malaria incidence as well as interactions between variables involved in the system. Through loop analysis it is possible to see whether increases in one variable qualitatively increases or decreases other variables or leaves them unchanged and the net effect of multiple, interacting variables. RESULTS: Qualitative analysis, specifically loop analysis, can be a useful tool to examine the impact of community-based malaria control interventions. Without relying on numerical data, the analysis was able to describe pathways through which each intervention could influence malaria incidence on the basis of the qualitative patterns of the interactions between variables in complex systems. This methodology is generalizable to various disease control interventions at different levels, and can be utilized by a variety of stakeholders such as researchers, community leaders and policy makers to better plan and evaluate their community-based disease control interventions.

Social and land use composition determinants of health: variability in health indicators.

Previous studies have shown that a community's socioeconomic status has a significant impact on its residents' health, and that vulnerability in deprived populations expresses itself as variability in health outcomes. The current study adds to this ecological research approach the notion that underlying community vulnerabilities are also related to the physical environment and population growth of a locality. The paper explores the variability in various health indicators in 252 localities in Israel as a function of the localities' socioeconomic status, population growth, and land use composition measures. The results indicate that a locality's socioeconomic status and its land use composition are both strongly associated with various health outcomes and their variability. These findings are of particular interest in light of the fact that the results were obtained from a country with a universal healthcare system.

One foot in, one foot out.

As radical health professionals, we have the triple identity of workers, of activists, and of intellectuals that creates the cauldron in which we live contradictory lives. We share the concerns of other workers for salaries, job security, health and safety at work, and work load. But like teachers and unlike most other workers we are not completely alienated from our work and have a stake in the outcomes of our labors that we are not always free to express or act on. As professionals, we share with our colleagues the intellectual curiosity about the origins of new infectious diseases, how racism exhausts the adrenals, or the egg-laying behavior of mosquitoes in polluted environments but may be in conflict with them around the need for universal free health care, or distorted priority given to molecular approaches to disease. We are partisans in institutions that feign neutrality. As activists, we are unwilling to accept the boundaries of "professionalism" and both learn from and offer our understanding to our communities of struggle. These three moments of our lives sometimes conflict but are also mutually enriching. There is no single formula for navigating this turbulent habitat but there is an array of options for avoiding burn-out and enjoying a life that is politically productive, intellectually challenging, and with lovely people.

Ecology of vector mosquitoes in Sri Lanka--suggestions for future mosquito control in rice ecosystems.

Mosquito-borne diseases are a major public health threat in Asia. To explore effective mosquito control strategies in rice ecosystems from the ecological point of view, we carried out ecological analyses of vector mosquitoes in Sri Lanka. During the 18-month study period, 14 Anopheles, 11 Culex, 5 Aedes, 2 Mansonia, and 1 Armigeres species were collected, most of which are disease vectors for malaria, filariasis, Japanese encephalitis, or dengue in Sri Lanka and elsewhere in Asia. The density and occurrence of Anopheles and Culex species were the highest in seepage pools and paddy fields, where the majority of niche overlaps between larval mosquito and aquatic insect species were observed. All 7 aquatic insect species, which are larval mosquito predators, overlapped their niche with both Anopheles and Culex larvae. This suggests that conserving these aquatic insect species could be effective in controlling mosquito vectors in the study site. Correlations between several climatic factors and mosquito density were also analyzed, and weather conditions, including higher temperature, lower relative humidity, and higher wind velocity, were found to affect mosquito oviposition, propagation, and survival. These findings deepen our understanding of mosquito ecology and will strengthen future mosquito control strategies in rice ecosystems in Asia.

Coronary heart disease (CHD)--one or several diseases? Changes in the prevalence and features of CHD.

In retrospect, mortality from coronary heart disease (CHD) in the 20th century followed an epidemic pattern: mortality rates increased dramatically from 1920 until about 1960, remained roughly constant for almost a decade, and have been decreasing since the late 1960s. CHD has traditionally been conceived of as a single disease with multifactorial causality. We suggest instead that CHD cases may comprise at least two distinct populations: those associated with hypercholesterolemia, and those associated with insulin resistance. The epidemic of CHD was due primarily to changes in the incidence of the hypercholesterolemia subgroup. We propose that young adults who survived the 1918 influenza pandemic were rendered vulnerable to lipid-associated CHD and coronary thrombosis upon reinfection with influenza later in life. This vulnerability may be due to autoimmune disruption of low-density lipoprotein-receptor interactions. Historical events may affect the health of populations by affecting the susceptibility of populations to chronic diseases such as CHD. The life experiences of individuals are known to influence their susceptibility to infectious diseases; we suggest that life experiences may also influence individual susceptibility to chronic diseases.

Blood pressure and hypertension in an American colony (Puerto Rico) and on the USA mainland compared, 1886-1930.

We compare blood pressure and hypertension between adult men on the USA mainland and in Puerto Rico born during 1886-1930 to test hypotheses about the link between cardiovascular health and large socioeconomic and political changes in society: (a) 8853 men surveyed in Puerto Rico in 1965 and (b) 1449 non-Hispanic White men surveyed on the mainland during 1971-1975. Systolic and diastolic blood pressure and hypertension were regressed separately on demographic and socioeconomic variables and cardiovascular risk factors. Mainland men not taking anti-hypertensive medication showed statistically significant improvements in systolic blood pressure and hypertension at the beginning of the century and men in Puerto Rico showed improvements in diastolic blood pressure but only during the last two quinquenniums. An average man born on the mainland during the last birth quinquennium (1926-1930) had 7.4-8.7 mmHg lower systolic blood pressure and was 61% less likely to have systolic hypertension than one born before 1901. On average Puerto Rican men born during 1921-1925 had approximately 1.7 mmHg lower diastolic blood pressure than men born before 1901. Analyses of secular trends in cardiovascular health complements analyses of secular trends in anthropometric indicators and together provide a fuller view of the changing health status of a population.

Impact of deforestation and agricultural development on anopheline ecology and malaria epidemiology.

To clarify mechanisms linking deforestation, anopheline ecology, and malaria epidemiology, this study draws together 60 examples of changes in anopheline ecology and malaria incidence as a consequence of deforestation and agricultural development. The deforestation projects were classified based on subsequent land use and were reviewed in terms of their impact on anopheline density and malaria incidence. To further examine different anopheline responses to land transformation, two major ecological characteristics of 31 anopheline species were tested for their associations with changes in their densities and malaria incidence. Although niche width of anopheline species was not associated with density changes, sun preference was significantly associated with an increase in density. This study suggests the possibility of predicting potential impacts of future deforestation on vector density by using information on types of planned agricultural development and the ecology of local anopheline species.

Adult male height in an American colony: Puerto Rico and the USA mainland compared, 1886-1955.

The links between adult height and socioeconomic-political marginality are controversial. We test hypotheses by comparing secular trends between two groups of USA adult male citizens born during 1886-1930: (a) 9805 men surveyed in Puerto Rico during 1965 and (b) 3064 non-Hispanic Whites surveyed on the mainland during 1971-1975. Puerto Rico provides an apt case study because it is the oldest colony in the world and was the poorest region of the USA during the 20th century. During the period considered the average adult man in Puerto Rico was 164.8 cm tall, 8.3 cm shorter than the average adult man on the mainland (173.1cm). Both groups experienced secular improvements in height, with men on the mainland having higher rates than men in Puerto Rico. In neither case were results statistically significant. The modest changes in Puerto Rico likely reflect the offsetting role of improved health and a stagnant rural economy during the first half of the 20th century.

Impact of education on knowledge, agricultural practices, and community actions for mosquito control and mosquito-borne disease prevention in rice ecosystems in Sri Lanka.

Mosquito-borne diseases are a major public health threat in Sri Lanka. A 20-week pilot education program to improve community knowledge and mosquito control with participatory and non-chemical approaches was developed, implemented, and evaluated using pre-educational and post-educational surveys in two intervention and two comparison villages. Correlates of baseline knowledge were sex, number of family members, ratio of family members with malaria history, school education level, and availability of electricity at the residence. Participation in the educational program led to improved knowledge of mosquito ecology and disease epidemiology, changes in agricultural practices, and an increase in environmentally sound measures for mosquito control and disease prevention. The variety of actions at the post-educational stage were determined by improved knowledge, but not by sociodemographic characteristics. Such community-based educational interventions are effective in increasing understanding and active involvement in mosquito control and disease prevention in rice ecosystems regardless of sociodemographic characteristics.

Community-based rice ecosystem management for suppressing vector anophelines in Sri Lanka.

Sri Lanka is one of the Asian countries most affected by mosquito-borne diseases, especially malaria. This 18-month study assessed the effectiveness of a new community-based ecosystem management programme to control mosquito vectors in the country's rice ecosystem. Farmers in a malaria-prone village were educated and motivated to engage in source reduction as well as measures to restore and maximise rice ecosystem functions. Over the course of the programme, the impact of farmers' ecosystem management on local mosquito ecology was also examined. Although little impact was detected on Culex and Aedes densities, adult Anopheles density was significantly suppressed in the southwest monsoon season. Rice farmers who manage their ecosystems can reduce the burden of Anopheles mosquitoes, interrupt malaria transmission and prevent the destruction of ecosystems.

Life expectancy change in perturbed communities: derivation and qualitative analysis.

Pollution, loss of habitat, and climate change are introducing dramatic perturbations to natural communities and affecting public health. Populations in perturbed communities can change dynamically, in both abundance and age structure. While analysis of the community matrix can predict changes in population abundance arising from a sustained or press perturbation, perturbations also have the potential to modify life expectancy, which adds yet another means to falsify experimental hypotheses and to monitor management interventions in natural systems. In some instances, an input to a community will produce no change in the abundance of a population but create a major shift in its mean age. We present an analysis of change in both abundance and life expectancy, leading to a formal quantitative assessment as well as qualitative predictions, and illustrate the usefulness of the technique through general examples relating to vector-borne disease and fisheries.

Whose scientific method? Scientific methods for a complex world.

Critics of the precautionary principle assail it for calling for action before science establishes unquestionably that a substance causes harm. They claim theirs is the viewpoint of the "scientific method." But the conflict is not between science and antiscience but rather between different pathways for science and technology; between a commodified science-for-profit and a gentle science for humane goals; between the sciences of the smallest parts and the sciences of dynamic wholes. This article addresses the social construction of scientific production and the pattern of strengths and weaknesses to which it leads. The author offers proposals for a more holistic, integral approach to understanding and addressing environmental issues.

Variability and vulnerability at the ecological level: implications for understanding the social determinants of health.

OBJECTIVES: We examined variability in disease rates to gain understanding of the complex interactions between contextual socioeconomic factors and health. METHODS: We compared mortality rates between New York and California counties in the lowest and highest quartiles of socioeconomic status (SES), assessed rate variability between counties for various outcomes, and examined correlations between outcomes' sensitivity to SES and their variability. RESULTS: Outcomes with mortality rates that differed most by county SES were among those whose variability across counties was high (e.g., AIDS, homicide, cirrhosis). Lower-SES counties manifested greater variability among outcome measures. CONCLUSIONS: Differences in health outcome variability reflect differences in SES impact on health. Health variability at the ecological level might reflect the impact of stressors on vulnerable populations.

Qualitative analysis of the all-cause black-white mortality crossover.

To date, despite decades of investigations and the relative abundance of mortality data, our understanding of the phenomenon of 'mortality crossover' remains inadequate. We propose a methodology for transforming mortality data from the 'age-domain' to the 'time-domain'. We then introduce a model of selection partially offset by mobility, to simulate the dynamics of vulnerability in a population cohort that is heterogeneous in health and death. Using our model of vulnerability simulating the dynamics of mortality in the time-domain, we compare the mortality experience of the Black and White populations of the United States, identify the significance of selection and mobility as potential factors producing the crossover phenomenon, and make diagnostic use of them.