NRDC: Climate and Disease

Q & A with NRDC's Kim Knowlton

OnEarth spoke to Kim Knowlton, a senior scientist with NRDC's health and environment program and co-author, with Gina Solomon and Miriam Rotkin-Ellman, of Fever Pitch, a July 2009 report on the spread of dengue fever in the Americas.

What are the main risk factors we should be aware of in our everyday lives?

International travel is one area of concern. More than 63 million Americans traveled abroad in 2008. So infectious diseases can move more rapidly into new, non-immune populations. Also, as our increasingly diverse American population visits friends and family back home with greater frequency, it increases the possibility of people returning to the United States acutely ill.

So what can people do to protect themselves against dengue when they travel?

The single best thing you can do is arm yourself with information before you leave. If dengue outbreaks are a threat in the country you're visiting, stay in screened or air-conditioned places, wear insect repellent with 20 percent to 30 percent DEET, and wear pants and loose, long sleeves if you're out in the morning or early evening, when dengue mosquitoes most like to bite. If you develop a fever within two weeks of returning home, see a doctor and tell him or her where you've been.

What would NRDC like to see in the way of public health planning to help deal with the threat of dengue?

We'd like to see a coordinated strategy involving stronger monitoring, surveillance, and mosquito control; creating disease- and climate-resilient communities; improved travel information; and legislation to reduce global warming pollution. Steps like these for dengue fever fit into an overall, multidisciplinary capacity to predict, plan for, and respond to emerging infectious disease risks right now, as well as in the future. And NRDC will continue to be a strong advocate for better climate-health preparedness.

Why don't you walk us through each element of that strategy in greater detail?

• Improve environmental monitoring.

  Mosquito trapping, geographic information systems (GIS) mapping, and remote-sensing tools can help detect and track the occurrence and spread of dengue's vector species, their habitat areas, and the presence of the dengue virus in mosquitoes. Ongoing research is needed because global warming's effects on temperature and rainfall patterns can affect the risks of dengue outbreaks differently in specific areas.

• Support for stronger health surveillance.

  Dengue should be made a nationally notifiable disease throughout the United States. A surveillance system should be established for collection and timely virologic testing and analysis of blood samples from suspected dengue cases. Consistent, centrally reported and confirmed dengue case surveillance data -- with enhanced international coordination, data sharing, lab capacity, and outbreak notification among nations like the United States and Mexico who share border communities -- are needed to better understand the changing incidence of the disease and evaluate control programs.

• Improve mosquito control.

  Pest management that targets larval mosquito reduction should be implemented at a community level. Emptying, cleaning, treating, or removing stagnant water containers -- including waste tires -- is an important step that will help prevent transmission of dengue, as well as other diseases such as West Nile virus. After storms, floods, and hurricanes, federal assistance for emergency vector surveillance and control should be made available immediately to affected localities.

• Improve infrastructure to help create climate- and disease-resilient homes and communities.

  Government programs to upgrade housing and municipal services will help reduce community vulnerability to dengue. Intact window and door screens, for example, can significantly reduce the transmission of mosquito-borne disease. Access to dependable piped water and trash collection will further reduce mosquito breeding habitat and improve the overall health status of community residents. When storms, hurricanes or floods damage homes, timely response efforts can help reduce infectious disease risks.

• Reduce global warming pollution to decrease the extent and severity of warming.

  Because climate change may expand the geographic range of dengue's vectors, addressing global warming at its source could help limit dengue and other climate-health risks. Governments should enact mandatory legislation to reduce global warming pollution and combat climate change, and protect communities from the impacts of climate change already underway.

• Get information to travelers visiting high-risk dengue areas.

  The CDC has estimated that as many as 1 in 1,000 travelers to dengue-endemic countries become ill. Better education of travelers -- as well as clinicians and health departments -- is essential to help recognize dengue infections and treat them immediately.