The complex interplay between the environment, agriculture, and infectious diseases is explored in a new technical report, Research Priorities for the Environment, Agriculture and Infectious Diseases of Poverty, released in June 2013 by the United Nations World Health Organization (WHO Technical Report Series 976; ISBN 9789241209762; 135 pages; US$48). Because the interaction between environment, agriculture, and infectious diseases is poorly understood, the report advocates a new approach to fighting infectious diseases based on interdisciplinary cooperation and completion of research that considers the entire disease system in improving public health.
Although there is some comprehension of the underlying and growing systemic influence of today’s large-scale social and environmental changes on some infectious diseases, the significance and potential future impacts of these changes are poorly understood. Nevertheless, such changes now constitute a significant influence on the working of the Earth’s systems that will have increasing consequences for patterns of occurrence of infectious diseases. (Section 1.1)
The report was prepared by the Thematic Reference Group on Environment, Agriculture and Infectious Diseases of Poverty (TRG 4), part of an international consortium of experts established by the WHO to identify key research priorities in the area of infectious disease control.
The report is written in an easy-to-read narrative style. It contains a thorough overview of human infectious diseases, their origins and causes, environmental factors (e.g., climate change, deforestation, habitat fragmentation), and agricultural practices (e.g., plantation farming, concentrated animal husbandry) that interact to cause emergence of new diseases (e.g., HIV/AIDS, SARS), transmission of existing diseases to new populations or geographic locations (e.g., small pox, measles, tuberculosis), or amplification of diseases within existing populations via new or existing feedback loops influenced by social factors, environmental change, insecticide resistance, and modern agricultural practices.
A Complex Web
Most of the report is devoted to explaining the complex interactions of environment, agriculture, and infectious diseases, and it is in this depiction that the report really shines. One example that illustrates the multi-faceted impacts of human activity on infectious diseases can be seen in the extended chain of consequences that could occur when a forest is cleared for agricultural purposes. Although this activity could lead to swamp draining (with the potential to reduce malaria-bearing mosquitos), it could also create irrigation ditches that are new breeding grounds not only for the same mosquitos but also for parasite-bearing snails. The irrigation ditches would likely be located closer to human populations than the swamps that they replaced, increasing the potential for malaria in local populations. Also, loss of forest habitat could displace rodents, bats, and other vertebrates that in turn carry infectious diseases; it could also contribute to a regional rise in air temperature that might cause mosquitos to breed more quickly and bite more often.
On the other hand, the nutritional value of food crops grown on the cleared land could completely or partially offset the increased disease burden caused by forest clearing. (This last scenario seems unlikely, however, given the propensity of large land clearing to result in plantations that do not produce foods with the proper nutrient profile to positively affect local health.) Regardless of the overall impacts, impoverished people are likely to bear a disproportionate share of the new or altered disease burden.
Key Research Priorities
A multi-criteria variable analysis was used to screen 100 possible initiatives that had been identified by a global team of experts and stakeholders. The evaluation criteria included an evaluation of the feasibility of the proposed alternatives, the degree to which the alternatives encouraged an interdisciplinary approach to research, overall policy relevance, and the potential to reduce disease burden.
After screening, the following research priorities were proposed:
- Develop integrated preventive public health strategies for infectious diseases of poverty.
- Develop and test novel intersectoral control of neglected tropical diseases.
- Influence funding agencies to support inter-disciplinary approaches to infectious diseases of poverty.
- Determine how to link health, veterinary, and wildlife surveillance systems.
- Determine which population groups are most vulnerable to climate change.
- Determine the interactions between agriculture, water use, and infectious diseases of poverty.
- Apply systems-based research to environmentally induced transmission pathways of vector-borne diseases.
- Assess the impacts of novel approaches such as community-led total sanitation on helminth infections.
- Assess the impacts of water management projects on disease.
- Develop and assess community-based vector-borne disease control models.
Limitations
Unfortunately, the technical report comes to an abrupt halt after identifying the top research priorities, leaving the reader to wonder how the top-scoring alternatives will be implemented and what effect they will have in controlling diseases of poverty. What activities should be conducted to meet each key research priority? What benefits are likely to accrue from these activities? How will this research actually make a difference? The report is silent on these matters. In failing to analyze the benefits and challenges associated with the key priorities, the Thematic Reference Group seems to have missed a golden opportunity to recruit researchers to its cause, build the international team that it advocates, and inspire the next round of collaborative, multi-disciplinary research that could unlock the secret to controlling and preventing infectious diseases.
Another limitation of the report appears to be the authors’ reliance on policy, politics, and research to control and prevent infectious diseases without involving the impoverished or other stakeholders associated with implementing and maintaining the developed solutions. Although the word “community” does appear in two of the top-scoring research priorities, the report spends very little time exploring the role of local communities in disease prevention and control and criticizes local initiatives that have been previously implemented. One illustration from the report:
Other work in Ethiopia has shown that simple interventions can harm health and development. For example, provision of (potable water) wells closer to dwellings lowered the caloric expenditure of women, by reducing the time and effort they spent in fetching and carrying water. Child survival also improved; however, birth intervals were reduced and infants suffered from worse nutrition and greater stunting. (Section 5.1, Box G)
The influence of local culture and values on solution effectiveness was recently observed by a colleague of mine, who was working in a remote jungle village in Honduras. Although malaria and dengue are frequently encountered in this area, children were observed playing near a large pool of stagnant water that could have potentially contained disease-bearing mosquitos. When my colleague asked the children’s mother if she worried about them contracting malaria from mosquitos in the puddle, the mother shrugged her shoulders and responded that malaria was a way of life in the village — some people get it and some people don’t. The woman also pointed out that another aid group had constructed a canal the previous year to drain away the stagnant water, but the system didn’t work. A quick inspection of the drainage system revealed that a sidewall of the canal had collapsed, blocking the drainage pathway with soil and vegetation. Using a shovel, the aid workers cleared the obstruction in less than an hour, and the stagnant water drained away.
In this example, the woman most likely to be affected by disease-bearing mosquitos did not feel empowered to maintain the drainage system or to take simple actions that would have lowered the chances of her children contracting malaria. The same thing could happen with the research priorities identified in this technical report — too much focus on policy, politics, and academics; too little focus on target audiences and the effectiveness of implemented solutions.
Conclusion
The technical report provides a fascinating, easy-to-read overview of infectious diseases, their origin and spread, and the complex, often unintended effects on public health that result from human interaction with the environment. The report is on-target in its call for a broad, systemic multi-disciplinary approach to research into the infectious diseases of poverty, but it should go further in analyzing the benefits of the identified research priorities and calling for active participation of stakeholder communities in developing public policy and conducting research. The report is highly recommended for public health officials, environmental and agricultural scientists, medical researchers, and sociologists — in fact, anyone who is seeking a better understanding of the complex interactions of environment, agriculture, and infectious diseases.
About the Author
Michael Bittner, CPEA, is a senior partner in the Boston, U.S.A. office of Environmental Resources Management, an international environmental, health, and safety (EHS) consultancy. Mr. Bittner specializes in global EHS solutions, including strategic planning, sustainability, management systems, compliance assurance, performance improvement, and audits. He edits the EHS Journal, an on-line magazine for EHS professionals, and is a member of the Board of Directors for the Auditing Roundtable, an international organization devoted to the practice of EHS auditing.
About the World Health Organization
The World Health Organization was established in 1948 as a specialized agency of the United Nations. It serves as the directing and coordinating authority for international health matters and public health. Through its publications, WHO seeks to support national health strategies and address the most pressing public health concerns of populations around the world. The WHO Technical Report Series makes available the findings of various international expert groups that provide WHO with the latest scientific and technical advice on a broad range of medical and public health subjects. Members of expert groups serve without remuneration in their personal capacities rather than as representatives of governments or other bodies, and their views do not necessarily reflect the decisions or the stated policy of WHO.
Photograph: Anopheles stephensi, a known malarial vector with a distribution that ranges from Egypt to China. Courtesy of the U.S. Department of Health and Human Services, Centers for Disease Control and Prevention.
