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There is no ribbon for diarrheal disease - but that's all the more reason to pay attention to it. This silent scourge that, according to some, is responsible for about 20% of child mortality is the topic of a recent paper by Michael Kremer and Alix Zwane, "Cost-Effective Prevention of Diarrheal Diseases: A Critical Review." The paper examines existing research on the cost-effective prevention and treatment of diarrheal diseases. The authors were interested in making a contribution to the question: what more should we do to reduce the diarrheal disease burden?

Preventive efforts fall into two categories: public health interventions and environmental health interventions. The paper points out that we know a lot more about the impact and cost-effectiveness of public health interventions that address diarrheal disease than we do about environmental approaches. In spite of the lack of knowledge around the effectiveness of environmental health interventions, the authors say it is critical to give them further consideration because "the marginal cost of expanding the child health interventions to uncovered populations may be high, even though the average cost of the interventions are often relatively low."

As the authors recommend, there are important avenues of research to pursue in environmental health, including:

  • Evaluating alternative transmission interruption mechanisms
  • Improving the understanding of determinants of individual-level technology adoption in the water and sanitation sector
  • Assessing the quality of infrastructure maintenance under different management schemes.

However, we must also be humble about how much we know about the impact and effectiveness of some of the public health interventions discussed - ORT, breastfeeding, vaccines, etc. We know a lot about how well these interventions work at an individual level, and how much they cost to disseminate. But we know very little about the kinds of health systems that are most efficient and cost-effective at getting these and other single interventions to the people who need them most. It is true that the marginal cost of expanding access to child health interventions may be high in most poor countries. But if a country had a system in place to provide primary care effectively, these interventions would be more easily integrated into an existing package of services. So, while it is crucial to learn more about which environmental health approaches work best and when, new learning and innovation around building effective health systems could go a long way.