In red are counties that have one of the 2 Dengue mosquito vector species. Blue are are vulnerable areas. Image: NRDC
That's Pretty Concrete and Scary
Matthew recently wrote a post about the climate change induced expansion of the tropics and the consequences of it. One of the main ones is the Northward movement of certain tropical diseases. The NRDC has just released a report on the subject (subtitle: "Mosquitoes Known to Spread Dengue Fever Now Found in More than Half of US States"), and it shows that 28 US states are at risk of being affected by Dengue Fever. Trust us, it's not a fun disease to have; in fact, TreeHugger founder Graham Hill got it while in South-America and he shares his experience below.
Aedes aegypti mosquito. Photo: Public domain
The NRDC report (pdf) states:
Global warming is likely to increase the number of people at risk of dengue epidemics by expanding both the area suitable for the mosquito vectors and the length of dengue transmission season in temperate areas. By 2085, an estimated 5.2 billion people--more than 3 billion additional people worldwide--are projected to be at risk for dengue because of climate change-induced increases in humidity that contribute to the disease's spread, based on models that use observed relationships between weather patterns and dengue outbreaks.6 Researchers in Australia and New Zealand calculated that climate change is projected to increase the range and risk of dengue in these countries. According to their study, another 1.4 million Australians could be living in areas suitable for the dengue mosquito vector by 2050. Moreover, the number of months suitable for transmission may rise, increasing the costs of dengue management three- to fivefold.
In the United States, dengue fever outbreaks have so far been limited to the U.S.-Mexico border region and Hawaii. However, our analysis reveals that global warming could result in increased vulnerability to dengue fever throughout the United States and the Americas. The findings are cause for concern: The analysis shows an increase in dengue fever in recent years in the United States and its neighbors to the south. And the mosquitoes that can transmit this disease have become established in a swath of at least 28 states, making disease transmission more likely.
Graham Hill's Dengue Fever Experience
When I saw this report, the first thing that I thought about was Graham. A few years ago we were all quite scared when we learned that he got Dengue Fever. I asked him to quickly describe his experience, here's what he had to say:
"While living in Buenos Aires, we took a trip to Rio. Upon entering the Copacabana beach hotel room I unplugged the AC and opened the windows in order to lessen emissions while there. I don't recall being bit by a mosquito but I must have as upon returning to Buenos Aires I felt deathly sick and went to the hospital immediately. Ended up there for 5 days on I.V., felt brutally sick for a couple of weeks thereafter and took months to feel normal again (still felt tired, weak, maybe some nausea). What's worse is that if I get it again (simple mosquito bite), I am at risk for dying of internal or external hemmoraghing. All this from an extremely urban situation."
Map showing the distribution of dengue fever in the world, as of 2006. Map produced by the Agricultural Research Service of the US Department of Agriculture. Cyan: Areas infested with Aedes aegypti. Red: Areas with Aedes aegypti and recent epidemic dengue fever. Public domain.
But don't panic! None of this will happen overnight, and it might be avoided. But right now the trend seems to point in the direction of more tropical diseases migrating North, including Dengue Fever.
Full disclosure: NRDC is a Planet Green non-profit partner.
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