Dengue Fever: Has Global Climate Change Fueled the Spread of This Disease?

Few Americans are aware of dengue fever and what it is. However, with the news that New York has now reported its first case of the virulent disease, that may be about to change. It’s understandable that Americans are largely unaware of this disease since the last major outbreaks occurred in the distant past-in places like Charleston, S.C. in 1828 and Savannah, Georgia, in 1850, according to Slate.com. Yes, dengue has kept a low profile in the U.S., even though it’s been on the rampage in much of the rest of the world.

Dengue, however, like so many other natural processes, appears to be fueled by global climate change, and not in a good way.

National Geographic reports that there’s plenty of evidence to suggest that global climate change is spurring the spread of this devastating disease, and in the United States, it’s making a comeback, Slate.com reports. In Hawaii, 122 people were sickened by the disease in 2001, and in Brownsville, Texas, 25 cases were reported, and 90 cases were reported in Key West between 2009-2010. In many cases, outbreaks in Key West weren’t transmitted in the usual fashion-imported by a tourist or a wandering mosquito. No, instead the virus has been on the island long enough and is now considered a genetically distinct local strain.

From World War II to 1970 severe dengue epidemics were only recorded in nine tropical countries. Since then, the disease has skyrocketed and now regularly occurs in 100 countries. Worldwide, the crush of humanity is also contributing to the spread of the disease as more and more slums form when people migrate from rural areas in search of employment. Settling on the edges of civilization they are beyond the reach of infrastructure so they dig latrines, keep jugs and barrels of water and toss trash into open dumps. Stagnant pools form. Easy pickings for a mosquito. And these mosquitoes can breed in as little as one ounce of water.

Enter climate change, which is causing an uptick in rainfall in some areas and warming temperatures worldwide. This is proving to be a boon for breeding mosquitoes, allowing them to spread into new areas, according to National Geographic.

The Americas have been hit particularly hard, and the number of cases reported has risen drastically from 66,000 in 1980 to 552,000 in 2006. In Mexico, dengue cases showed an increase of 600 percent since 2001 and the disease shows no signs of slowing down.

The World Health Organization reports that 2.5 billion people-40 percent of the world’s population is at risk for dengue. The WHO estimates that 50-100 million people are infected each year. It’s expected that as the climate continues to warm some 3.5 billion people will be at risk of dengue fever by 2085, according to the United Nations Intergovernmental Panel on Climate Change (IPCC) as reported in National Geographic.

Aedes aegypti, is the mosquito that is generally associated with dengue, but the Asian tiger mosquito (Aedes albopictus) has also been known to carry the disease. In California, populations of A. aegypti were discovered this summer in Fresno and Madera counties as well as in San Mateo County, Science Daily reports.

Having suffered through dengue fever twice I’m well aware of the exhausting and painful symptoms of this disease. My last bout was about three weeks ago and I’m still recuperating. Both times a stubborn, throbbing headache grabbed hold behind my eyes and didn’t let go for days. This was accompanied by a 102 degree fever and a heavy sense of exhaustion that lingered for at least a week after the virus passed. My appetite also vanished and I had to deal with perhaps the weirdest manifestation of dengue: An extremely itchy rash that made me want to scratch my skin right off. I wished I could take a wire brush and just scratch, scratch, scratch. It just about drove me wild; it was that itchy and it spread from my hands, wrists, and arms to my face, mid-section and legs.

Fortunately, my fever never rose to 106 degrees, which is something that can happen with dengue, according to the Mayo Clinic. Even though I was reasonably miserable, I was lucky I didn’t get some of the other nasty symptoms, which include:

• Nausea and vomiting.
• Minor bleeding from the gums and nose.

In most cases, dengue passes in a week or two, but on rare occasions it can become life-threatening when blood vessels become damaged and start to leak. This causes the number of cells that form clots in the bloodstream to drop.

These are the life-threatening symptoms that can occur if this happens:

• Bleeding from the nose and mouth.
• Severe abdominal pain.
• Persistent vomiting.
• Bleeding under the skin.
• Problems with the lungs, heart, and liver.

Occasionally dengue fever erupts into a more serious form and becomes severe, the WHO reports, noting that some 500,000 people-mostly children-are hospitalized because of this. Out of this number, approximately 2.5 percent of those afflicted die.

While A. aegypti doesn’t generally survive in places with cool winter weather, A. albopictus can survive, and unlike its cousin, it can bite all day long, not just at dawn and dusk, according to Slate.com. This critter can even survive a drought.

Fortunately, most Americans have things at their disposal that can keep mosquitoes at bay-things that people in many other countries can only wish for.

Things like:

• Air conditioning.
• Window screens (my house has none).
• Reliable access to piped water.
• Regular garbage service. (Mine is regular. Most of the time.)

There are also some sure-fire ways to discourage mosquitoes-simple, everyday things like dumping excess water anywhere it may be found in the garden-old pots that aren’t being used, watering cans, tires, and anything else that might contain water, the WHO reports. We can also wear insect repellents, long-sleeved shirts and pants instead of shorts. I used to wear shorts all the time, but not anymore. I do whatever I can to keep from being bitten.

In global climate change, we have awakened a sleeping giant and the rapid escalation in cases of dengue fever worldwide is one of the many consequences humans will have to deal with.

Will we have enough know-how to send this giant back to sleep?