Breakbone Fever Attacks Enchanted Island: Battling the 2010 Dengue Epidemic in Puerto Rico

by Tyler M. Sharp, PhD

Paradise Has Its Risks
Given the choice I prefer my bones to remain unbroken. For that reason I began to worry when I found out that the disease I would be studying for the next two years in Puerto Rico was also referred to as “breakbone fever.”

In April of 2010, I accepted an assignment to study dengue fever as an Epidemic Intelligence Service Officer at the CDC Dengue Branch in San Juan, Puerto Rico.  While I was thrilled to be moving to “The Island of Enchantment,” reality began to sink in when I realized that I was running head first into an ongoing epidemic of a painful and deadly disease.

Earlier that year, CDC had issued an update on the status of dengue in the Caribbean, warning of impending epidemics.  From my time in graduate school I knew that the four viruses that cause dengue are transmitted by mosquitoes, but I didn’t know much about the illness itself. When I started reading up on dengue, I found out that the name “breakbone fever” comes from the intense bone and joint pain that accompanies the disease. Patients with severe forms of dengue can experience hemorrhage, shock, and even death.  I also discovered that the World Health Organization estimates that there are about 100 million cases of dengue each year, including 500,000 hospitalizations and more than 25,000 deaths.  This was serious business!  What had I gotten myself into?!

Getting to Know the Enemy
On my first day on the island the Dengue Branch had arranged for me to meet with a realtor.  We spent the day looking at apartments throughout San Juan and eventually I found a nice spot in Punta Las Marias.  Afterwards, my realtor invited me to her house to sign papers and celebrate over dinner with her husband.  I immediately accepted, drooling at the chance for a home-cooked Puerto Rican meal: chuletas de puerco (pork chops), chillo ala parilla (grilled red snapper), arroz con habichuelas (rice and beans), and amarillos (fried sweet plantains).  A full belly and a cubalibre (rum and coke with a lime) later, I was a happy guy!

After dinner, we retired to the back porch where the first thing I noticed was the mosquitoes.  They were everywhere! Clouds of them clustered in the corners and they seemed to follow my realtor’s dog around like a permanent shadow. Soon enough I was swatting at my own cloud of blood sucking pests.

As we were watching the sun slowly slip over the horizon, my supervisor from the Dengue Branch called to check in on me.

“Hi, Tyler! I’m so glad that you’re on the island!  Look, Puerto Rico is in the middle of a really bad dengue epidemic right now, so try not to go anywhere where there are mosquitoes, OK!?  AVOID MOSQUITO BITES!”�
Slap, splat, smoosh! Went the mosquitoes as I tried to stop them from gorging on my delicious gringo blood.  “‘Mosquitoes,’ you say..?”

Reality Sets In
The gravity of the epidemic soon came into sharp focus.  My very first day on the job one of my co-workers informed me that Puerto Rico’s Secretary of Health was going to have a meeting that night to discuss the dengue epidemic.  “It’ll be a great introduction to public health in action in Puerto Rico,” he said, encouraging me to attend.  I eagerly agreed.

Once the meeting got going, it was clear that the Secretary was concerned about the number of reported dengue cases which continued to rise, as did the number of deaths.  From the Secretary’s point of view, even one death from dengue was too many.

The meeting focused on efforts to heighten awareness and clinical management among physicians across the island.  In response to previous dengue epidemics in Puerto Rico, the Dengue Branch and the Puerto Rico Department of Health (PRDH) had designed a train-the-trainer course on the clinical management of dengue. In this course, Dengue Branch staff educated local physicians in Puerto Rico on how to clinically diagnose and treat patients with dengue; these “Master Trainers” then relayed their training to other local physicians.  The course included instruction on how to identify and respond to warning signs for severe disease (such as abdominal pain and persistent vomiting) and the “critical phase” of illness (24–48 hours after fever has broken) when patients should be closely monitored.  The Secretary announced at that meeting that all physicians in Puerto Rico who see patients with dengue would have to attend the course or risk losing their license to practice medicine. 

Various ideas for containing the spread of disease were discussed during the meeting. The most interesting by far came from an older gentleman who described a traditional Puerto Rican method of keeping mosquitoes out of the house: 

“When I was growing up, we had a way to keep the mosquitoes away that never failed.  What you have to do is take a bottle of tequila and pour it ALL over the walls!  After that, you’ll never see another mosquito land on that wall!” 

I will confess that I have not experimentally tested this approach to mosquito control; however, I can think of several more interesting and efficacious uses for a good bottle of tequila.

Arming the Resistance
Because there is still no vaccine for dengue (although several are in clinical trial), methods of preventing dengue focus on employing strategies to avoid mosquito bites.  The good news is that use of mosquito repellent, wearing long-sleeved shirts and pants, and staying in air conditioned or screened-in housing can all reduce the risk of getting dengue. 

The bad news is that the dengue mosquito, Aedes aegypti, has quite literally evolved alongside humans.  The mosquito has learned to cohabitate with humans, thriving in manmade creations that contain stagnant water such as discarded tires, septic tanks, and neglected flower pots.  Once hatched, the mosquitoes take up residence in and around human dwellings, especially in closets and under beds.  So not only should you avoid mosquitoes while you’re out and about, you should especially be vigilant while at home and while visiting other people’s homes. Once infected with dengue virus, the female mosquito remains infected for her lifetime (~ 1 month) and passes the virus to humans when she takes a blood meal.  

Instead of sitting idly by and counting cases as they came in, the Dengue Branch and PRDH focused on raising the public’s awareness of the on-going epidemic and bolstering PRDH staff responsible for mosquito control.  Public health teams from across the island worked together to organize public health messaging campaigns.  People were instructed to turn over or cover water storage containers and recycle old tires to eliminate mosquito breeding sites, kill adult mosquitoes in their homes, use mosquito repellent, and seek medical care if they developed acute febrile illness with dengue-like symptoms.  In addition, more than 8,000 clinicians attended the course on the clinical management of dengue.  

The Fallout
By the time the dengue epidemic was officially over in December, nearly 25,000 cases were reported and 38 people were confirmed to have died from dengue.  To put that in perspective, at least 1 in 100,000 people living in Puerto Rico in 2010 died from dengue, which is only slightly less than the number of annual deaths due to influenza in the United States.  All in all, it was the worst dengue epidemic Puerto Rico had seen since monitoring began in 1969.
One thing that still amazes me is the response that PRDH and the Dengue Branch had to the epidemic, for which they ultimately received awards for excellence in both Partnering and Emergency Response.  This was a testament to the herculean task that faced public health in Puerto Rico in 2010 following the dengue epidemic. 

As a novice to public health and CDC, the dengue epidemic allowed me to experience firsthand CDC’s mission of supporting local health departments to keep people healthy and safe.  As a result of that mission, I and countless others never got dengue.  We therefore owe both PRDH and CDC a debt of thanks for keeping our bones unbroken, as I prefer them to be.