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NPHW 2008: Migrating Disease

April 25, 2008

In honor of the APHA’s National Public Health Week, In Case of Emergency is running a series of posts on the effects of climate change on public health preparedness. The first post can be found here.

So much of public health preparedness deals with response to bioterror attacks that many in the field forget that not everything that falls under this rubric is done with ill intentions, and in many cases, not done by humans at all. Public health preparedness is, and should be known for, preparing for the possibility that the public’s health will be negatively impacted by something–anything. Yes, the terrorism stuff is very flashy, and where we make our cheese, but, as I’ve argued before, our planning benefits day to day disease response much more.

To that end, today I’m not going to talk about terrorism, but diseases. Diseases that are endemic to certain parts of the world, but are increasingly being found in our parts of the world. Diseases that can catch us unaware and unprepared and can kill. Diseases that can change the very nature of our public health system.

The most famous of these diseases is West Nile Virus. First identified in the US in New York City in 1999, it spread across the country and by 2006, cases had been reported in 47 of the 50 states (Maine is the only continental state that hasn’t reported a case). West Nile was originally, and is primarily, a disease found in tropical and sub-tropical regions. Spread by mosquitoes (three types in the US), the disease has slowly spread from its sub-Sahara African reservoir around the globe.

I’m not including this disease in today’s post because it isn’t native to North America (it is thought to have been brought here by an infected air traveler who was subsequently bitten by a mosquito), but because of its spread to traditionally cooler and cooler temperate zones. The astute amongst you will wonder how a mosquito vector can last in a place like New York State, Vermont or Idaho over the winter. The mosquitoes that harbor West Nile over-winter in sheltered places like barns and caves. As our winters have warmed, these places become more hospitable over the winter and more likely to shelter infected mosquitoes.

As our worldwide climate has warmed over the last decade or two, mosquito-borne diseases have spread more north and more south on the globe. West Nile is a good example of that spread in the Northern Hemisphere, but another example has been taking place in Rio de Janeiro.

The very scary disease, dengue, has been gripping the city’s populace for weeks now. An article in the NY Times has the number infected at more than 30,000. Severe cases of dengue resemble diseases like Ebola and Lhassa fever (those of Outbreak fame). Transmitted by mosquitoes, dengue has been increasingly found in developed countries in the last few years and is expected to continue to spread to new areas. The WHO addressed this in a report on the future spread of dengue here.

Now, it’s true that I can’t say for definitely sure that dengue and WNV are spreading because of climate change–global warming to be exact–but the fact remains that mosquitoes thrive in warm, humid environments. The type of environments that climate scientists are saying are moving out from the equator.

Photo by kainet

4 Comments leave one →
  1. April 26, 2008 11:49 am

    …and unfortunately, emerging and reemerging diseases are not “flashy” enough, as you put it, to attract adequate funding.

    The ‘problem’ is that prevention and control goes by the premise that expenditures will stave off outbreaks – very hard for financial tzars to measure and swallow.

    Even if scientists cannot agree on the causes of climate change, the fact that temperatures are indeed rising at all and that exotic disease vectors are expanding their reach globally will be proof sufficient that the dangers are real.

    Woodshed Environment Coalition

  2. April 28, 2008 5:09 pm


    I couldn’t agree more. To a bean counter, an ounce of prevention is just an ounce you no longer have-never mind the pound of cure you’ll get out of it. It something that public health folks have learned all too well over the last fifty years.

    Thanks for stopping by,


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