Integrative health research (IHR): Ecohealth and One Health

We aim to understand how human health is determined by the inter-linkages between human, animal and environmental health in a socio-ecological context, using the Ecohealth or One Health approach. The context we consider covers environmental pollution, agricultural intensification, urbanization, and environmental sanitation. The primary health issues we focus on are neglected tropical diseases, zoonoses, and chronic diseases.

Water, sanitation and health

Our past research has focused on water, sanitation and health issues in developing countries. We have developed a conceptual framework for integrated health and environmental assessments, combining health status with physical, socioeconomic, and cultural environments to improve health and minimize the environmental impact of environmental sanitation (Figure 1). The assessments provide the basis for the understanding of the key issues important for the improvement of health and the environment in a given area or setting. We applied this framework as a case study in Hanam Province to assess the health and environmental impact of human and animal excreta and of waste water reuse in agriculture. Three components of the framework were implemented, namely environmental, health, and socioeconomic assessments, leading to the identification of critical control points.

Figure 1: Integrated health and environmental assessment conceptual framework (Nguyen-Viet al al. 2009)

The results revealed that the agricultural system was a significant source of nutrients (N and P) due to the overuse of chemical fertilizers, which affect the surrounding environment. 48% of the farmers were infected with at least one of the three helminth species in the rainy season and 46% in the dry season. Other protozoal intestinal infections were also diagnosed. The estimated annual risks of diarrhoea values were at least 3-fold greater than the upper threshold risk of 10^-3 per person per year; and the annual burden of diarrhoeal disease was significantly higher than the health target of 10^-6disability-adjusted life years (DALYs) (≤ 1 DALY/million persons) recommended by the World Health Organization (WHO). The social assessment showed that people recognized the black colour and smell of wastewater, the smell of excreta, inappropriate practices of excreta management, and the suspected diseases associated with contact with excreta and wastewater as threats and that 63% of the households studied were willing to pay for the construction of flush toilets (US$ 800). No statistically significant difference in the willingness-to-pay by socioeconomic status was observed. Further studies were conducted on the factors influencing the die-off of human fecal pathogens, the nutrient values of excreta, and on assessing the pathways, frequency, and intensity of human exposure to excreta due to handling it throughout the process of storage or composting, and use in agriculture.

In light of this assessment, we conducted a field intervention that examined how the combination of human and animal excreta composting influences helminth egg die-off in excreta, while maintaining its nutrient value. The intervention aimed to improve the current storage practices of human excreta and to identify the best option for the safe use of excreta in agriculture. Results showed that the variation of the helminth concentrations of the different sampling dates was influenced by the composting options and the composting time.The average number of helminth eggs was less than 1 egg per gram in all of the composting options after 84 days . This parasite egg reduction meets the WHO standard (≤1egg/L or 1g total solid) for the safe use of wastewater, excreta, and greywater in agriculture and aquaculture. This implies a significant reduction in the estimated annual risk of infections. Therefore, the combined human and animal waste management strategy shows the benefit of financial savings and helps to reduce environmental and health risks. The model is currently being promoted in Hanam. This research was conducted with NCCR North-South and funded by SDC.

Agriculture intensification and health

Tackling the issue of health and agricultural intensification via the ecosystem approach to health (Ecohealth), the research “Using the Ecohealth Approach for Better Human and Animal Waste Management in Ha Nam Province, Vietnam” aims to i) study the impacts of human and animal waste management on health, the environment, and on socio-economics; ii)develop and implement practical and innovative solutions for better livestock and human waste management to improve the health and well-being of people and the environment; and iii) disseminate research outputs to related ministries, local and national institutions, NGOs, communities, and wider audiences through publications and presentations. The research is conducted within the framework of the regional Ecohealth Field Building Leadership Initiative (FBLI) funded by the IDRC to advance Ecohealth in Southeast Asia (SEA) (2012-2017). The field work of FBLI was conducted in Hoang Tay and Duy Tien Districts, Hanam Province.

Figure 2: Integrated Crop (V) – Fishery (A) – Livestock (C) (V-A-C) in Vietnam

We have involved many stakeholders (preventive medicine staff at all levels, veterinary experts, livestock and agriculture experts, and farmers) in identifying the health and environmental issues of Hanam. The issues identified are: i) household waste management (organic and inorganic waste), ii) hormone and antibiotic residues from human and livestock, iii) misuse of plant protection chemicals and pesticides, iv) management of animal waste and solid waste, v) water quality (arsenic contamination), iv) livestock diseases and weak veterinary services, v) knowledge and behavior of the population in regard to various environmental and health issues. The survey showed that the process of agricultural intensification of farming households has changed for the period analyzed from 2008-2013. Pig production is still a major activity at the sites studied, accounting for 47% of the households. Most of the pig production remains small or medium scale with the pig populations varying from 36 to 56 pigs per farm. Animal feed is normally bought from industrial feed markets. The most important problems faced by the farmers are risks from the market and from production (diseases, water contamination), and financial and personal risks (the health of producers). Pig production was ranked as having the second largest impact on farmer’s health after rice cultivation.

Disease transmission at the environment – human and animal interface

Leptospirosis is a zoonosis found worldwide; it causes major problems for human and animal health due to the complexity of its transmission pathway and the difficulties to diagnose it. This research aimed to estimate the seroprevalence of human leptospirosis and the risk factors associated with agricultural occupation in Thanh Hoa Province, Viet Nam in 2013. The research used the Leptospira immunoglobulin G enzyme-linked immunosorbent assay (IgG ELISA) method to diagnose Leptospirosis. An epidemiological survey was conducted in eight clusters, representing 300 randomly selected people 18-60 years of age. The findings demonstrate the high level of circulation of leptospires (49% positive with Leptospira) and the potential importance of leptospiral infections among the rural population in the area. They also identify groups of people and professions at high risk that should be prioritized for risk mitigation measures based on an integrated approach, such as One Health.