“God has cared for these trees, saved them from drought, disease, avalanches, and a thousand tempests and floods. But he cannot save them from fools.”
—John Muir
In my book “Comprehending the Climate Crisis,” chapter five addresses the consequences of global warming. The title of the chapter is “Global Warming and its Devastating Effects.” In one subheading, I address the spread of disease. In fact, I previously posted an excerpt from this chapter and you can read it here if you’re interested. Briefly, I pointed out that as global warming continues, disease vectors such as mosquitoes are going to extend their territories, and diseases such as malaria and West Nile virus are going to affect greater numbers of people in regions previously safe from such diseases.
Sadly, we are seeing the evidence: that is precisely what is happening. The Centers for Disease Control and Prevention (CDC) is reporting that as of August 21, 2012, West Nile has been detected in 47 states within the US in either birds, humans, or mosquitoes. A total of 1,118 cases have been documented with 41 deaths among them.
From the CDC website:
“The 1118 cases reported thus far in 2012 is the highest number of West Nile virus disease cases reported to CDC through the third week in August since West Nile virus was first detected in the United States in 1999. Approximately 75 percent of the cases have been reported from 5 states (Texas, Mississippi, Louisiana, South Dakota, and Oklahoma) and almost half of all cases have been reported from Texas.”
The CDC simply reports the facts and doesn’t draw conclusions about the cause, but most people concerned about global warming including myself point out that this is exactly what the science predicted would happen. Milder winters mean more mosquitoes survive for breeding. Unusually hot summers means longer and faster breeding seasons, with greater concentrations of the virus building up in the salivary glands of the mosquitoes. (West Nile didn’t show up in the US until 1999 when it was detected in New York City, and that also happened to be a particularly hot summer.)
West Nile isn’t the only disease on the rise. Other diseases where mosquitoes are the vector are also seeing an extension of their territories compared with previous years. For example there’s Dengue fever, something you’ve probably not heard of before. I studied it in microbiology class in medical school but to this day I’ve never seen a case. That’s because it used to be restricted to the tropics. But now it’s being reported in southern Texas as well as the Florida Keys.
And then there’s Chagas disease. This is most commonly found in Central and South America, caused by a parasite that is transmitted not by mosquitoes but by “kissing bugs” that also feed on blood through insect bites. This disease I have seen because one of the problems it can cause is a large weak heart, something referred to as dilated cardiomyopathy. (In North America, dilated cardiomyopathy is most often due to viral infections of the heart, or sometimes from alcohol abuse, but in Latin America Chagas is the most common cause.) I remember twenty years ago meeting an Argentinian immigrant during my training who ended up going on to need a heart transplant.
Chagas had its first US case reported just last month, proving the vector is on the move.
In my book, I talked about the potential devastation that an increase in mosquito vector territories could cause, particularly for malaria. But West Nile, Dengue fever and Chagas disease are all a little closer to home, especially for our friends living in the southern US.
Just one of the many negative consequences of global warming and climate change. And one of the many reasons why we should do our best to minimize it.
