Last month the USDA announced plans to create seven climate change “hubs” to provide outreach and training on behalf of the farm, agriculture and forestry sectors in the seven regions they serve. The effort represents a realignment of existing government resources rather than new investment. It’s a welcome development, and a model for other government agencies to collectively address climate change-related impacts outside the realm of agriculture. A good place to start would be in the historically overlooked area of public health. Of particular note is infectious disease, still the #2 cause of death worldwide.
Disease has plagued humans and shaped our evolution. Development of the first human settlements, domestication of animals and discovery of the New World triggered three eras of infectious disease. The rise of dense urban centers and explosion of global commerce are creating a fourth. Connecticut has already experienced more than its share of new diseases, including Lyme disease and West Nile virus, and increasing new threats from old diseases such as influenza. How climate might influence these disease threats is poorly understood, Now, there is a new disease threat where a link with climate change seems fairly clear.
Chikungunya virus, whose name in the Makonde language of East Africa describes the contorted posture of those afflicted with its arthritis-like symptoms, could become one of the largest epidemics in modern times. Historically spread by the yellow fever mosquito , the same mosquito responsible for dengue, it’s rarely posed a threat beyond the tropics. In 2004, however, the virus was determined to have mutated, becoming more easily transmitted by the Asian tiger mosquito, a highly invasive and hardier species which can survive as far north as New York City. With Chikungunya virus suddenly epidemic in the Caribbean, it’s poised to spread to the American tropics everywhere dengue is present. Even worse, the presence of Asian tiger mosquito throughout the southeastern states forms a conduit for Chikungunya to reach the Northeast, although introductions from infected travelers may bring it here first.
Evidence exists that the Asian tiger mosquito has adapted to a warmer climate by delaying the time its eggs prepare to overwinter, allowing more generations per season and, consequently, producing more mosquitoes with more time to transmit chikungunya. How events like the Chikungunya epidemic and mosquito adaptation to climate change will play out over the coming years is not known, but it would be in our best interests to find out.
How should scientists and the public health community respond to the threat of Chikungunya, and more significantly the hundreds of other insect-borne viruses whose territories shift northward as temperatures warm? Starting in 1999 when flocks of dead crows announced the arrival of West Nile virus in New York’s Bronx Zoo, the National Institutes of Health expanded its Epidemiology Laboratory Capacity program. $280 MM later, there’s infrastructure in place to identify the incursion of new diseases but virtually no growth in the arsenal of responses to deal with them.
Even after hundreds of thousands of deaths from yellow fever and malaria in the 18th and 19th centuries the options for preventing the spread of mosquito-borne disease are limited to DDT, air conditioning and the hoe. Use chemicals to kill them, tools to drain their breeding grounds or take shelter in doors. Leading entomologists admit that the most fundamental aspects of mosquito and tick biology of the sort that might allow for more systemic and strategic intervention remain unknown.
Recent announcement that the state of Connecticut will create its own center for outreach to deal with the impacts of climate change suggests an opportunity to emulate the federal government’s model of cross-departmental collaboration. Just as the USDA redistributes resources to allow experts across departments to collaborate on research that will result in practical responses to regional challenges in agriculture, farming and forestry, experts in public health, ecology, epidemiology and biology should collaborate to better understand the basic eco-epidemiological parameters of infectious disease and how they’ll be impacted by a changing climate. Creating the nation’s first climate-related infectious disease center in Connecticut has a certain symmetry; it’s near ground zero for West Nile, and is home to the community that gave Lyme disease its name, and with Asian tiger mosquito identified for the first time in Fairfield County last summer, it’s the front line for the latest disease that calls the research community to action.