Dengue Fever (DF) and dengue hemorrhagic fever (DHF) are caused by related virus serotypes (DEN-1, DEN-2, DEN-3, and DEN-4), of the genus Flavivirus. Once contracted the individual is immune to that particular serotype for life. A person can contract more than one dengue infection during his/her lifetime.
Both diseases are considered tropical diseases and all four involve human and the Aedes mosquito. The illnesses can be a mild nonspecific viral syndrome or it can be a severe and fatal hemorrhagic disease.
Risk Factors for Dengue Infection
The history of prior dengue infection of the patient
Age of the patient
The particular strain of the dengue virus
A pandemic of dengue began in Southeast Asia after WWII and spread around the world since that time. Dengue viruses are not emerging in the Pacific and the Americas.
In the 1980s Sri Lanka, India and the Maldive Islands had their first major DHF epidemics. Dengue infection has also been reported in Pakistan, the People’s Republic of china, Singapore and other countries of Asia with epidemics becoming larger in scope in the last 15 years. Dengue viruses first arrived in the Pacific in the early 1970s and dengue in Africa has dramatically increased since the 1980s.
In 1970, only the DEN-2 dengue virus appeared in the Americas, and possibly DEN-3 in a focal distribution in Colombia and Puerto Rico.
The first major DHF epidemic in the Americas (Cuba) happened in 1981 with a new strain of DEN-2. Following the epidemic the new strain spread rapidly causing outbreaks of DHF in Brazil, Columbia, French Guiana, Puerto Rico, Suriname and also Venezuela.
There is a small chance that dengue could break out in the United States as two of the mosquito vectors (Ae. aegypti and Aedes albopictus) are present in the states and under certain circumstances, each of these could transmit dengue viruses. Six times in the past 25 years South Texas has been associated with dengue epidemics in northern Mexico by the Aedes aegypti and in Hawaii the Ae. albopictus has occurred.
Travelers carry the viruses back to the U.S. when they visit countries where these viruses are active. Detection depends on doctors being able to recognize the symptoms of dengue viral infection and to report it. Many cases go unreported because the U.S. is passive about detection and reporting.
The proper diagnostic samples must be obtained in order to make the correct diagnosis. Doctor’s also need to ask the right questions to determine the fact that the individual had traveled to a foreign country.
Even though there has been a very limited amount of outbreaks in the U.S., most of the cases of dengue infection have been among residents in some of the U.S. territories.
Symptoms of dengue fever begins with a sudden and high fever (104-105 degree Fahrenheit). Then a flat, red rash appears over most of the body during the fever. A second rash that looks like measles appears later.
People with dengue fever may have increased skin sensitivity and feel very uncomfortable. People who have dengue infection also have headache, joint aches, muscle aches, nausea,, swollen lymph nodes and also vomiting.
Testing that doctors do to make the diagnosis is a complete blood count, serology studies to look for dengue virus antibodies, and a antibody titer for dengue virus types.
There is no actual treatment for dengue fever other than to keep the patient hydrated by giving fluids. Acetaminophen is also given to treat the high fever. Aspirin should be avoided.
Prognosis is usually for a full recovery. The complications that are possible are febrile convulsions and severe dehydration.
You should contact a doctor if you have been in a region where there is known to be dengue fever and you develop any of the symptoms for the disease.
Where long sleeved tops and long pants, use a mosquito repellent and a top quality bed netting to help reduce the chance for exposure to mosquitoes. Travel during periods of minimal mosquito exposure.
Illustration: By Percherie. Distribution de la dengue sur Commons GFDL CC-BY-SA-3.0