Asian tiger mosquitoes were identified for the first time in Fairfield County last summer. This should raise your eyebrows because the Asian tiger mosquito, one of the world's most invasive species, can spread a terribly debilitating disease, chikungunya virus, currently barreling through the Caribbean.
Whether the Fairfield County colony survived our unusually cold winter is not yet known, but northward expansion of the mosquito's territory and evolution of its wintering behavior are further evidence of regional climate change and things to come.
To respond, Connecticut leaders might take a cue from the federal government, which has created seven Department of Agriculture climate-change "hubs" to provide outreach and training on behalf of the farm, agriculture and forestry sectors around the nation. In recognition of political realities, climate change hubs are a creative realignment of existing resources rather than a new investment. But they are welcome and a model to collectively address climate threats beyond agriculture. A good starting place would be the overlooked area of public health, especially infectious disease, the No. 2 cause of death worldwide.
Disease has plagued humans and shaped evolution. Human settlements, domestication of animals and discovery of the New World triggered three successive eras of infectious disease. Now, the unprecedented growth of dense urban centers, reliance on concentrated animal feeding operations and exploding global commerce are creating a fourth era of disease transmission.
The East Coast of the U.S. has already experienced more than its share of new maladies, including Lyme disease, West Nile virus and, increasingly, new threats from old ones such as influenza. Climate's influence on disease has long been the subject of conjecture. Now there is a novel threat where a link with climate change seems fairly clear — the chikungunya virus.
In the Makonde language of East Africa where it first occurred, chikungunya means "all bent up," a reference to the contorted posture of those afflicted with its arthritis-like symptoms. Typically, a bout of debilitating joint pain will last several days but can go on for weeks and in some cases lead to complications that contribute to death, according to the World Health Organization. There is no cure.
Historically spread by the yellow fever mosquito, chikungunya has generally been restricted to lower latitudes and was rarely lethal.
By 2005, however, circumstances had changed. An epidemic in the Reunion Islands sickened a third of its 770,000 residents and killed 260, but this time the yellow fever mosquito was not involved. Gene sequencing shows that the virus mutated, creating a strain that is 100 times more easily transmitted by the Asian tiger mosquito, now endemic in much of the U.S. This mutation is responsible for massive outbreaks driven by the Asian tiger mosquito elsewhere around the world.
In December, the original strain of chikungunya — spread by yellow fever mosquito — broke out in the Caribbean, where it seems poised to spread to the American tropics. Newspaper reports have acknowledged that potential, but overlook the threat of new viral mutations spread by Asian tiger mosquito beyond the tropics, as well as the link to climate: The Asian tiger mosquito has evolved to continue breeding despite the shorter day length of autumn. This translates into more generations per season, more mosquitoes and more time to transmit the virus along the East Coast.
The situation is reminiscent of 1999, when West Nile virus first appeared in New York City.
The National Institutes of Health responded by expanding its Epidemiology Laboratory Capacity program. Two hundred and eighty million dollars later, infrastructure is in place to identify the incursion of new diseases, but with little growth in our capacity to respond to them. Meanwhile, West Nile virus spread to every state in the continental U.S.
How events like the chikungunya epidemic and the mosquito's adaptation to climate change will play out is not clear, but it is in our best interest to learn quickly. Chikungunya could become one of the largest insect-borne epidemics in modern times.
Leading entomologists admit that the most fundamental aspects of mosquito and tick biology that might allow for more systemic and strategic interventions for insect-borne disease remain unknown. 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 — use chemicals to kill them and tools to drain their breeding grounds, or take shelter indoors.
Plans for Connecticut to create its own Institute for Community Resiliency and Climate Adaptation suggest an opportunity to emulate the federal government's model of cross-departmental collaboration. Experts in public health, ecology, epidemiology and biology need to collaborate to better understand the basic eco-epidemiological parameters of infectious disease and how they are impacted by climate.
Creating the nation's first climate-related infectious disease center in our state would have a certain symmetry: Connecticut was near ground zero for West Nile and home to the discovery of Lyme disease. The appearance of the sian tiger mosquito in Fairfield County marks Connecticut as the front line for the latest disease that calls the research community to action.
Durland Fish is a professor of epidemiology (microbial diseases) at the Yale School of Public Health and member of Yale Climate and Energy Institute. Eric Ellman is communications director at the Yale Climate and Energy Institute. Mark Pagani is the director of the Yale Climate and Energy Institute.