The Looming Threat of Dengue Fever in the U.S.
Posted July 9, 2009 in Health and the Environment, Solving Global Warming
It's summertime, and one of the rites of the season is the onset of mosquito activity in many parts of the country. For most Americans, these pests are simply an annoyance, but in many parts of the world they can be deadly, and they could become more dangerous here too.
A new report from the Natural Resources Defense Council, Fever Pitch, describes some of the factors that have contributed to the 30-fold increase in a mosquito-carried viral disease, dengue fever, over the last fifty years.
Two mosquito species that the new NRDC report maps in the US, Aedes aegypti and Aedes albopictus (also known as the Asian Tiger), have been known to carry the dengue fever infection. That doesn't mean they are all teeming with the virus naturally, but rather that they are able to contract the virus by biting someone sick with dengue and then transmit the virus to others. Just because the mosquitoes are in your state or county doesn't always mean that dengue fever disease outbreaks will occur, or that you'll get the disease - it simply means that your state or county may be vulnerable to an outbreak in the future. NRDC's report finds that more than 173 million Americans in at least 28 states live in counties where one or both of these mosquitoes have been found.
We would like to see more testing of mosquitoes in the US so we can know if, when, and where mosquitoes are carrying the dengue virus. When travelers infected with dengue fever "import" the virus back into the US, especially during the summer months when mosquitoes are active, it could increase the possibility of local transmission to other people.
Unless there's a large outbreak of the disease, you may not be able to find out how many cases of dengue fever are being reported in your state for months or years. Because the reporting system is so slow, and filled with holes, we'd like to see the system changed and updated. NRDC is advocating for dengue to become a nationally notifiable disease, with more rapid central reporting of suspected dengue fever cases, so individuals and scientists can get up-to-date information about the number of dengue cases in their state in a matter of weeks.
To help prevent an outbreak in your community, be sure to remove mosquito habitats around your home: empty any standing water from flower pots, buckets, or empty cans, and get rid of old tires or empty containers. Clean your pet water bowls daily, and watch out for clogged rain gutters: the mosquito vectors breed in standing water. Cover outdoor cisterns if you have them, and ask your neighbors to do the same.
And since global warming may be affecting dengue, an effective way to reduce the likelihood of spread is to address climate change at its source by reducing global warming emissions. Call your Senator or Representative to ask them what they're doing to protect their constituents from dengue fever and other climate-change related health risks (which include increases in deadly heat waves, air pollution-related illnesses, and the frequency of extreme storms with flooding.)
Is NRDC saying that global warming is the main cause of the increase in dengue fever infections in recent years? Nobody knows precisely why dengue fever infections have been increasing, and there are likely multiple reasons. But global warming and its associated increasing temperatures, lengthening summers, and changing patterns of rainfall and droughts, are among the factors that can make it easier for dengue to spread. Other factors include uncontrolled, unplanned urbanization and population growth; rapid international travel and trade; and widespread poverty. All these factors can help dengue-carrying mosquitoes exist in closer proximity to people. Global warming may work in conjunction with these factors by helping the mosquito "vectors" live longer, in more, and in different, places. NRDC is advocating for more funding for local environmental monitoring and disease surveillance that will, in the future, make it easier to understand the relative importance of all the different factors that may be giving dengue fever such a strong foothold in the Americas.
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Comments
Paul Reiter — Jul 10 2009 11:52 AM
This article is an absolute disgrace. It is so full of error that it borders on the mendacious.
May I suggest you read a little on the history of dengue and yellow fever in the United States, with major epidemics as far north as Boston.
May I suggest you acquaint yourself a little with the dynamics of transmission of dengue, and the factors that influence it.
May I suggest you look at the distribution of Aedes aegypti until the 1980s. States included New York, Indiana, Illinois, Ohio...
May I suggest that you and your sort are intent on deluding the public by peddling fear and despair.
Why do you do it? What drives you to such drivel? Is it just power? Or for kudos? Or anarchistic obsessions?
Yes, I am furious!
Please have a look at the following:
http://www.malariajournal.com/content/7/S1/S3
http://www.cdc.gov/ncidod/EID/vol6no1/reiter.htm
and decide for yourselves whether all these claims about global warming are based onthe science of vector-borne diseases.
Perhaps of interest: I was the first to find Ae. albopictus in the Western Hemisphere, it was I who chanced upon the used tire trade, I was Chief of Entomology for 14 years at the CDC Dengue Branch in Puerto Rico, I am involved in studies of Ae. aegypti here annd in Singapore and other places, and Ae. albopictus as well.
Not to mention that I was an expert reviewer for the IPCC 2007 report, but that is a long story.
I hesitate to give my name, but, hell, why not!
Paul Reiter PhD
Professor of Medical Entomology
Insects and Infectious Disease Unit
Institut Pasteur
Paris
France
Hey guys! Clean up your act. One day people will realise that you have been changing the world by peddling such nonesence.
The sad thing is that the blame will be put on science, not on this sort of activism.
But of course, by that time you will have launched on another crusade of manipulation
Kim Knowlton — Jul 10 2009 04:07 PM
Dr. Reiter, thank you for your opinions and important historical perspective on dengue fever in the United States. Your many years of work on these issues have provided much useful scientific information.
To address some of your concerns:
1.) The report has undergone extensive internal and external scientific peer review.
2.) In terms of dengue fever’s history - it is correct that in the 18th and 19th century, diseases such as dengue and malaria did exist in the United States. However, they have not been a problem here for many decades. Our concern is that the pendulum may be swinging back to make the expansion of dengue more likely in the future. There are other scientists and publications that have raised the same concerns, so our opinion is certainly not unique. [Costello et al. 2009, The Lancet; Morens and Fauci 2008, Journal of the American Medical Association; Benedict et al. 2007, Vector Borne Zoonotic Diseases; Hales et al. 2002, The Lancet]
3.) It's clear that dengue fever is a multi-factorial disease, and that a changing climate is only one of many factors that can affect disease trends and spatial patterns; we say that many times in the report. As your own work has shown, temperature is highly relevant to mosquito spread. Thus, rising temperatures related to global warming could be one element that may increase risks.
This is an issue with serious implications for public health, and I hope you can support our call for increased public health resources for disease and vector surveillance and control.