Mosquitoes and Dengue Fever

There are a lot of great things about vacationing in Puerto Rico, including beautiful beaches, fine dining, and rich historical sites. And even if you don’t buy any souvenirs, I guarantee you’ll leave with a few mementos from your trip. By which I mean about 20 mosquito bites. Probably in the most annoying places too, like your ankles.

It’s true, I am a little bitter right now because I cannot stop scratching and I am convinced that no anti-itch cream actually works for mosquito bites. So I thought I would distract myself by researching a little about these little buggers, especially as they relate to public health in Puerto Rico.

What is Dengue Fever?

Dengue is an acute febrile disease that is transmitted by Aedes aegypti mosquitoes, which also carry Yellow Fever and Chikungunya. These putrid creatures bite primarily in the daytime and favor densely populated tropical areas, though they also inhabit rural environments. Symptoms of Dengue are flu-like, including severe joint pain, fever, rashes, and nausea, often leaving victims bed-ridden for a week. Patients may die from dehydration if not given proper treatment. Five percent of cases will develop into Dengue Hemorrhagic Fever (DHF), which can be fatal. DHF patients display fever, minor or major bleeding, thrombocytopenia (decreased platelet count), increased vascular permeability (markedly increased hematocrit), and pleural or abdominal effusions. Dengue Shock Syndrome (DSS) may also occurs, and is essentially DHF with signs of circulatory failure (narrow pulse pressure, hypotension, and shock). Elderly populations are particularly at risk for the progression of Dengue fever into DHF or DSS.

Dengue is often diagnosed clinically, but can be definitively diagnosed by obtaining serum samples during acute phase of the disease (to screen for virus) or 1-2 weeks after contraction (to screen for anti-Dengue antibody). Treatment for Dengue is symptomatic, and should include plenty of fluids, bed rest and monitoring. Antipyretics may be used to counteract fever. Non-steroidal anti-inflammatory drugs (like aspirin) are contraindicated in these patients because of their anti-coagulant properties, which can exacerbate any bleeding problems caused by Dengue. Patients who have previously been exposed to one of the four strains will develop immunity to that strain, but will be more likely to develop DHF if exposed to another strain, so careful history taking is crucial in a patient with suspected Dengue fever. Doctors should make themselves familiar with the symptoms of Dengue, and should maintain an index of suspicion in patients who have recently traveled to places where Dengue is endemic.

Dengue in Puerto Rico

Dengue was thought to be essentially eliminated in Latin America until the early 1980s, when it returned with a vengeance. It has become a major public health issue in Puerto Rico, with many cases reported every year. 11,000 cases were reported (and many more unreported) here in 2007, with 8 reported deaths. This, along with 2004, was considered an “epidemic year” for the island. Possible reasons for high levels during these years include changing weather patterns (especially increased rain), increased migration or travel, and increased migration into urban areas. You shouldn’t be surprised to know that global warming, which leads to unstable weather patterns, also has a lot to do with the Dengue surges we’ve seen recently. In addition, the CDC points to the increased use of nonbiodegradable products, which hold fresh water where mosquitoes breed, as another reason for the recent surge in Dengue. As if you needed another reason to take care of your planet!

Because there is no vaccine, public health officials in Puerto Rico have had to resort to other methods, including fumigation and public education on eliminating standing water and recognizing the signs and symptoms of the illness. Larval control, especially the elimination of standing water, seems to be the most effective means of transmission control. Cut to public health spending cuts and a desperate need for tourism revenues have led some countries, like Mexico, to focus their Dengue programs primarily in tourist areas, leaving poorer areas defenseless (how sad is that?).

What can you do to protect yourself?

There is no vaccine currently available for Dengue. According to the CDC (and me), to protect yourself from Dengue, you can:

*Hide in your hotel room all day

*Wear long sleeves, pants, closed shoes (yeah right!)

*Apply insect repellent containing 25%-50% DEET or 20% picaridin (awesome name!). Do not use these products in children under two years of age.

*Sleep with a mosquito bed net.

*Peak Dengue transmission time is September to November, so take extra precautions if traveling during this time.

*Make sure there is no standing water nearby, or places where standing water might accumulate (like buckets). That’s where these flying devils lay their eggs.

*May seem obvious, but if you are traveling in Puerto Rico (or anywhere) and begin to develop the symptoms of Dengue, get yourself to a hospital immediately.

*Realize that you are in the Caribbean, and that despite all your best efforts, you probably WILL get a few mosquito bites and you will most likely NOT die from Dengue, so try not to worry about it enjoy Puerto Rico!

For more information on Dengue:

Download the entire WHO Dengue publication here.
Dengue Fact Sheet
Dengue Patient Education Sheet (English)
Dengue Patient Education Sheet (Spanish)