Experiencing Dengue fever and lessons to prevent it during travel

by Rachel Henrickson

Everyone wants to feel like they are making a difference.

This is why, in my opinion, international medical mission trips are what every med student dreams of upon completing his or her first year of medical school. With one year of basic sciences and numerous standardized patient encounters under our belt, we are already eager to utilize our skills with “real patients” and make a difference in the world, no matter how small it may be.

After settling into a routine in medical school this past fall, I felt I was ready to take on a bit more. With so many options, I started to narrow down a location for the mission trip I had been looking forward to since beginning my career as a pre-med student years ago. Unfortunately, my biggest requirement wasn’t looking for the city in the greatest need, the most beautiful place or the even the cheapest trip – it was to find a location where Dengue fever was the least prevalent. This led me to Cambodia.

Why did I avoid Dengue fever above all other potential illnesses? Prior to medical school, I worked in the great city of Washington, DC where newspaper ads for highly paid experimental clinical trials were as prevalent as apartment listings. I stumbled upon a clinical trial conducted through Johns Hopkins (the most respected medical institution in the country) for an experimental Dengue fever vaccine and I enrolled, partially for the money and partially to help in their efforts to create a vaccine (to be honest, it was mostly the money). To make a long story short, I was not one of the lucky 8 volunteers to get the placebo. I received a live, attenuated strain of one of the four types of Dengue fever, a disease I had never even heard of until I entered the trial.

For those who aren’t familiar with Dengue fever, it is caused by four similar, single positive-stranded RNA viruses known as dengue viruses (DENV-1 through DENV-4). It is transmitted by the Aedes mosquito. If an individual is infected with one strain, he or she is protected for life against that strain but not against others. However, if an individual is infected once and subsequently again by a different strain, the ensuing disease is usually much worse. The symptoms of Dengue fever are fairly mild, including pain behind the eyes, joint pain, rashes, low WBC and fever. I am quite familiar with the appearance of the rash because it showed up shortly after I received the vaccine (a benefit to the researchers of my extreme paleness) – again, not one of the lucky ones in the trial.

The more serious consequences are Dengue hemorrhagic fever, which occurs due to vascular leakage, and is characterized by bleeding, high fevers and vomiting and can lead to death, and Dengue Shock Syndrome, which occurs with severe hypotension. Because I have been exposed to one of the 4 serotypes of dengue, I am more likely to have a more serious reaction, including Dengue hemorrhagic fever, if I am infected by a mosquito carrying one of the other 3 strains.

The disease itself is most common in South America, Africa and Asia (the darker orange in the maps below). In Cambodia, serious outbreaks occur every 3 to 5 years. Unfortunately, this year happens to be one of them. I did find something promising, however. I learned that Cambodia had just launched a large-scale campaign to mark the national day against Dengue fever with the onset of the rainy season. The statistics of this year’s outbreak thus far are strong evidence of the need for greater protection and awareness:

“At least 11 Cambodian children have died from the disease so far this year with other 1,924 infected,” said Ngan Chantha, Director of Dengue Control at the Ministry of Health. “It is a sharp increase from last year’s 7 deaths with 1,395 infected cases.”

The last major outbreak occurred in 2007, which resulted in 40,000 hospitalizations with over 10,000 in one week. This only highlights the severity of Dengue in Cambodia. Worldwide, the WHO estimates that up to 50 million infections occur every year and approximately 500,000 individuals with Dengue hemorrhagic fever are hospitalized annually, with a death rate of 2.5%.

With no real cure and currently no vaccine for Dengue fever, what is the best way to prevent its spread? Most important, the breeding grounds of mosquitoes must be controlled. In the past, Cambodia has received a grant to implement programs aimed at reducing the number of mosquitoes carrying Dengue fever. With this money they have used larvicide as well as introduced guppy fish to eat the mosquito larvae. With limited funds, though, designing these seemingly simple efforts are in actuality, much more difficult. That leaves each traveler with the responsibility of protecting him or herself with DEET, long clothes and a general awareness of the symptoms of Dengue fever followed by supportive therapy, should it occur.

Personally, I have enough DEET for a small village and I plan to suffer through the heat in long pants and sleeves. I will also be upgrading my room at the Victory Guest House from the standard room with a fan for $7/night to an air-conditioned room for $12/night in hopes that the bugs will remain outside.

I’m sure most people think I am crazy but I am happy to have entered the trial – it shed light on a disease that I had never heard of, one that deserves much more attention. I recently contacted a nurse from my trial and found out that they are currently testing a tetravalent vaccine that would protect against all four strains of Dengue fever. That means that because of me, they were able to move forward with the hope of one day having a vaccine available. I personally consider that a success and a step in the right direction.

Rachel Henrickson is a medical student who blogs at Little White Coats.

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