What is Dengue Fever?
Dengue fever has become the second most common reason for hospitalization, after malaria, among travelers to countries in the tropics. Dengue is a viral disease cause by a Flavivirus and transmitted by the mosquito Aedes aegypti. Dengue hemorrhagic fever, DHF, is a life-threatening form of dengue fever related to other hemorrhagic fevers such as Ebola. No drugs or vaccines can prevent or treat the disease, so prevention lies primarily on avoiding mosquito bites.Where is Dengue Found?
Dengue fever is now endemic in cities in more than 100 countries and is present in every continent except for Antarctica. You do not have to travel to a tropical country to get dengue. The mosquito that carries dengue fever, Aedes aegypti, is present in much of the United States during the summer time and especially Texas, Arizona, New Mexico, Louisiana, Mississippi, Alabama, Georgia, and mid to south Florida. From 1977 to 2004, there were about 3,800 suspected cases of dengue fever in the United States imported from other countries. In the past 25 years, direct transmission of dengue in the continental United States has only been recorded six times, in Texas and Hawaii. United States citizens with dengue usually get the disease in endemic dengue U.S. territories such as as Puerto Rico or by traveling to a dengue endemic country. The World Health Organization provides a complete list of countries where dengue fever is present.What Causes Dengue Fever?
Dengue is produced by a Flavivirus with 4 different serotypes (DEN-1, DEN-2, DEN-3, and DEN-4). The person infected with the virus becomes immune to that specific serotype, so a person can have up to 4 different episodes of dengue. I recently met a European woman who had been hospitalized with dengue fever three times, once in the Philippines, once in Malaysia and once in Indonesia. If she survives a fourth episode of dengue fever, it is likely she will finally be immune to dengue.The Mosquito
The worst aspects of the Aedes mosquito are that it bites during the day, it likes cities, and it is very aggressive but silent. This little mosquito can host yellow fever, Chikungunya and dengue fever. Aedes mosquitoes like to live in and around houses and lays its eggs in stagnant water. The expansion of cities in tropical countries has spurred the increase of Aedes aegyptii mosquitoes and the number of people infected. Aedes aegyptii has been invading new countries, like Spain in 2004. These mosquitoes are survivors, so when they come, they come to stay. In countries with a monsoon weather pattern, the number of Aedes aegypti mosquitoes and dengue fever both increase during the rainy season. Another mosquito, Aedes albopictus, is not as common as Aedes aegypti, but can also carry dengue fever and is present in the United States.Symptoms of Dengue Fever
Three to 14 days after bitten by an infected mosquito, the classical symptoms of dengue fever are:- High fever, sometimes with two peaks (more than 104 F).
- Frontal headache
- Retro-orbital pain (Pain behind the eye)
- Muscle and joint pain
- Nausea
- Vomiting
- Rash
Dengue Hemorrhagic Fever (DHF)
Some patients develop a serious form of dengue with high fever, internal hemorrhage, often with enlargement of the liver, and in severe cases, shock. People with dengue hemorrhagic fever (DHF) have an increased blood concentration, low platelets, a fever that lasts from 2 to 7 days, petechiae and a positive tourniquet test. They may bruise easily and bleed at the site of an injection. The critical period of the disease is reached at the end of the fever.Patients exposed to more than one dengue fever serotype have a higher risk to develop DHF. Note that DHF is not caused by inappropriate treatment of classical dengue fever but is related to the immune response of the patient.
Diagnosis of Dengue Fever
Direct isolation of the dengue virus in a serum culture is the best way to diagnose dengue, but this is only possible the first 2 to 3 days of the disease and requires good laboratories facilities. The serological test that tests for specific antibodies and uses the enzyme-linked immunosorbent assay (ELISA) is the most feasible test.Dengue rapid diagnosis tests are available on the market, but they often have false positive results, so you need to ask for the ELISA test to be sure of the diagnosis.
The cell count shows a reduction in the platelets and an increase in hematocrit values.
How Is Dengue Treated?
- Note that no special medication is used to treat dengue fever or dengue hemorrhagic fever.
- Good hydration is a key point in managing dengue fever and includes keeping hydrated by drinking adequate fluids and occasionally, through intravenous fluids.
- Acetaminophen (known to many people from the United States as Tylenol and to Europeans and Latin Americans as paracetamol) is used for fever and pain reduction. Aspirin and non-steroidal anti-inflammatory medications (NSAIDs) like ibuprofen are off limits since they may make bleeding worse.
- In the hospital: monitoring for signs of hemorrhagic fever, clinical monitoring and lab tests.
- In case of dengue hemorrhagic fever (DHF) or shock, the patient will need to be in the intensive care unit and possibly need a blood transfusion.
When to Go to the Doctor
If you live or are traveling in an area endemic for dengue fever, go to the doctor if:- You experience a combination of the signs and symptoms of dengue fever.
- Anytime you or your children have a high fever, over 104 F.