Keeping tabs on Dengue Fever: Stay tuned

Today, I attended the New York Academy of Sciences’ fascinating symposium on Emerging Infectious Diseases in Response to Climate Change. Experts from around the country are discussing a 21st-century health concern: how climate change can lead to “higher rates of emerging infectious diseases worldwide, reemergence of diseases previously under control, and redistribution of diseases across the planet.”

But one infectious disease in particular is on my mind today: Dengue Fever. I just learned about 22 confirmed cases of Dengue (“breakbone”) Fever that people acquired in Key West, Florida in the summer and fall of 2009. This may not sound like a lot, but these were the first locally-transmitted infections in Florida in more than 40 years. Recurring rains reportedly allowed dengue-carrying mosquitoes to thrive in Key West. Since then, even more dengue cases have been “imported” back into the state by infected travelers returning to Florida.

In another part of the Caribbean just last week, Health Secretary Lorenzo Gonzalez of Puerto Rico declared an epidemic of dengue fever. With more than 200 cases already confirmed and over 600 suspected, this is reportedly triple the usual rate. It’s troubling for cases to run so high at this time of the year, and health authorities are obviously taking notice.

Dengue Fever is one of the most painful viral illnesses known – that’s why it’s called “breakbone fever.” Symptoms include high fever and chills; severe headaches, joint and muscle pain; and rash on arms, legs and torso. It spreads not from person to person, but from the bite of an infected mosquito. However, many people who get the infection can be misdiagnosed with influenza. In a September 2009 door-to-door survey of 240 Old Town Key West residents, 41% tested positive for dengue antibodies, meaning they had a prior infection (and didn’t realize it), or had received a vaccination against a related disease, like yellow fever. Unfortunately, no vaccine against dengue exists as yet.

The 2009 Florida outbreak is also newsworthy because over 229,000 passengers arrived at the Key West Airport in 2009. Vacationers need to know about dengue fever - not to become obsessed by it nor to ruin their travels, but to be prepared and take simple steps to avoid getting bitten by potentially infected mosquitoes. These include using window and door screens, emptying water-filled containers in homes and yards to remove mosquito breeding areas, using insect repellent containing 20-30% DEET, and wearing long pants and sleeves when possible.

Since January 15, 2010, dengue fever is “officially” a nationally notifiable disease in the US. This is great news, but it seems to be … very quiet news. It’s taken months for the information to become official, so I expected at least a little fanfare and a Press Release. Being nationally notifiable will eventually help spread the word about how to diagnose, track, and protect against dengue. We talked about the need for improved case reporting and coordinated monitoring in NRDC’s July 2009 report Fever Pitch, about dengue fever in the Western Hemisphere. But more people know about dengue fever today: few among the experts at the conference knew about its new officially “notifiable” status in the US, nor about the recent outbreaks.

It took me a while to confirm the reported Key West outbreak. I called and e-mailed helpful Florida State Department of Health and Mosquito Control officials, as well as academic researchers. The Centers for Disease Control and Prevention (CDC) last put together an annual report on surveillance of dengue fever in the US in 2006. CDC has a lot on their plate – especially now, with the dengue fever epidemic in Puerto Rico, which is home to CDC’s Dengue Branch. Sharing information on where and when cases are happening can help people step up their precautions and prevent more illness.

This highlights that we still have a ways to go in coordinating national infectious disease surveillance. Information on confirmed dengue cases, whether imported by travelers or locally-transmitted, should be readily accessible to the public, along with prevention tips. That’s a fantastic goal for the CDC, state and local health agencies to aim toward.

Stay informed and stay tuned – because communication is the key.