One Health is the concept for bringing together health promotion and delivery for humans, animals, and the environment (Figure 1). (1) The One Health concept recognizes that success in one profession such as human health often requires coordination with the other two. Failure to account for these relationships can have disastrous consequences.
Vector-borne disease control is an example of how the 3 disciplines are related. Over one million people die each year from diseases such as malaria, dengue, and yellow fever, which are transmitted by mosquito vectors. (2) When dichlorodiphenyltrichloroethane (DDT) was first identified as an insecticide in 1939, it was lauded as the solution to vector-borne diseases. It was inexpensive and persistent, and over the next few decades, DDT was widely used throughout the world with great success at reducing mosquitoes. For example, the Aedes aegyptii mosquito was eradicated from dozens of countries within the western hemisphere, which in turn led to significant reductions in the number of dengue cases. The vector control programs were so successful that some people soon began asserting that these diseases would be wiped out and no longer threaten the human race. Unfortunately, these assertions failed to recognize the negative impacts of DDT on the environment and animals. Bioaccumulation within the environment (a result of DDT's persistence) was linked to eggshell thinning and decreased reproduction rates in birds of prey. (3) Concern was also voiced that the birds were biosentinels and an early warning to potential human risks, which is supported by recent studies suggestive of possible adverse effects in humans. (4)
The negative animal and environmental effects of DDT eventually led to use restrictions and bans in the United States and many other countries. The bans in turn have been criticized as harmful to humans by increasing exposure to vector-borne diseases leading to increased mortality. (5) These criticisms may be partially responsible for the recent resurgence of DDT use. However, whereas DDT was indiscriminately used during the 1940s and 1950s, its use is more focused today. Perhaps the greatest change in DDT usage (as well as other pesticides) was the shift from widespread agricultural application to targeted indoor residual spraying. Indoor residual spraying takes advantage of the persistent tendencies of DDT to provide inexpensive protection against Anopheles species and other indoor feeding mosquitoes which transmit diseases, (6) while at the same time avoiding bioaccumulation in lakes, streams, and soils that harm the environment, animals, and humans. Used appropriately, such as treating bed nets and rotating insecticides to reduce resistance, indoor residual spraying saves human lives while protecting animal and environmental health.
The One Health Initiative recognizes the importance of an interdisciplinary medical team and "is dedicated to improving the lives of all species--human and animal--through the integration of human medicine, veterinary medicine and environmental science." (7) The One Health Initiative is supported by numerous organizations including the American Medical Association, the American Veterinary Medical Association, and the National Environmental Health Association. Multiple US government agencies, including the Centers for Disease Control and Prevention...
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