Disease ecology, health and the environment: a framework to account for ecological and socio-economic drivers in the control of neglected tropical diseases.

Reducing the burden of neglected tropical diseases (NTDs) is one of the key strategic targets advanced by the Sustainable Development Goals. Despite the unprecedented effort deployed for NTD elimination in the past decade, their control, mainly through drug administration, remains particularly challenging: persistent poverty and repeated exposure to pathogens embedded in the environment limit the efficacy of strategies focused exclusively on human treatment or medical care. Here, we present a simple modelling framework to illustrate the relative role of ecological and socio-economic drivers of environmentally transmitted parasites and pathogens. Through the analysis of system dynamics, we show that periodic drug treatments that lead to the elimination of directly transmitted diseases may fail to do so in the case of human pathogens with an environmental reservoir. Control of environmentally transmitted diseases can be more effective when human treatment is complemented with interventions targeting the environmental reservoir of the pathogen. We present mechanisms through which the environment can influence the dynamics of poverty via disease feedbacks. For illustration, we present the case studies of Buruli ulcer and schistosomiasis, two devastating waterborne NTDs for which control is particularly challenging.This article is part of the themed issue 'Conservation, biodiversity and infectious disease: scientific evidence and policy implications'.

Ecology. The value of nature and the nature of value.

Ecosystems are capital assets: When properly managed, they yield a flow of vital goods and services. Relative to other forms of capital, however, ecosystems are poorly understood, scarcely monitored, and--in many important cases--undergoing rapid degradation. The process of economic valuation could greatly improve stewardship. This potential is now being realized with innovative financial instruments and institutional arrangements.

Economic incentives for rain forest conservation across scales.

Globally, tropical deforestation releases 20 to 30% of anthropogenic greenhouse gases. Conserving forests could reduce emissions, but the cost-effectiveness of this mechanism for mitigation depends on the associated opportunity costs. We estimated these costs from local, national, and global perspectives using a case study from Madagascar. Conservation generated significant benefits over logging and agriculture locally and globally. Nationally, however, financial benefits from industrial logging were larger than conservation benefits. Such differing economic signals across scales may exacerbate tropical deforestation. The Kyoto Protocol could potentially overcome this obstacle to conservation by creating markets for protection of tropical forests to mitigate climate change.

The fertility plateau in Costa Rica: a review of causes and remedies.

PIP: Costa Rica achieved a substantial reduction in its overall fertility rate in a very short period of time. The halving of the fertility rate which occurred in less than ten years in Costa Rica transpired over the course of 100 years in France and 170 in Sweden. The level of contraceptive use in Costa Rica is twice that in other Central American nations. The authors summarize the recent demographic history of Costa Rica and review factors influencing its remarkable fertility decline. They then discuss possible explanations for the ensuing fertility plateau and conclude by suggesting strategies for affecting a further decrease in fertility rates. With regard to the reasons for the fertility plateau, cultural factors, socioeconomic factors, declining government commitment and family planning services, education, and the Church are considered. To reduce the level of fertility even further, the authors recommend that the government adopt a clear population policy which could serve as a basis for other changes such as increased support of family planning programs, improvements in the educational system, increased women's status and employment opportunities, and extensive education in schools and through the mass media on the socioeconomic and environmental effects of overpopulation. It is important to increase Costa Ricans' understanding of the negative impacts of continued population growth and the role of individual family planning decisions in that growth.^ieng