The US Food and Drug Administration (FDA) recently announced approval of the first commercial laboratory test to help diagnose dengue fever. In an April 8, 2011 press release, the FDA stated that the test has been cleared for marketing and will be available for use in clinical laboratories to help diagnose people with signs and symptoms of the disease.
Dengue fever is a viral infection spread from person to person by the bites of mosquitos. People who become infected produce antibodies in response to the virus. The new test detects the IgM class of these antibodies in the blood of infected people, and a positive result aids in the diagnosis of a person with characteristic signs and symptoms. The newly approved test will assist health care providers in identifying and caring for people with the potentially serious infection.
As noted by the FDA, laboratory diagnosis of dengue fever can be challenging. Antibodies are generally not detectable until 3 to 5 days after onset of fever, so there is a period of time in which a person can be infected and the test result will be falsely negative. The FDA also cautions that the new test can cross react with antibodies produced in response to other related viral illnesses like West Nile Virus, giving a false positive result. Therefore, results from the new test must be interpreted in conjunction with signs and symptoms to diagnose dengue fever. Currently, there is no FDA-approved test that can detect the virus directly.
Worldwide, there are about 100 million cases of dengue fever each year, according the Centers for Disease Control and Prevention (CDC). In the US, it is usually seen in travelers returning from areas with high infection rates such as South America, the Caribbean, and Southeast Asia. It also occurs in residents of Puerto Rico, US Virgin Islands, Guam, and Samoa. Recently, Texas, Florida, and Hawaii have seen some outbreaks.
Dengue infections can range from mild to severe. The first signs and symptoms generally appear 4 to 7 days after being bitten by an infected mosquito and may include high fever (up to 105°F), severe headache and pain behind the eyes, joint, muscle and bone pain, a rash over most of the body that can come and go, easy bruising, and nose or gum bleeding.
Most people recover within a week or two although they may have some lingering fatigue for several weeks. In some, however, the illness can progress to the more serious dengue hemorrhagic fever. This form is characterized by the presence of a fever for 2 to7 days, which then subsides and other symptoms appear. There may be severe abdominal pain, persistent vomiting, difficulty breathing and, a point at which blood vessels become increasingly "leaky," with fluid accumulating in the abdomen (ascites) and/or the area around the lungs (pleural effusion). Complications can lead to heavy bleeding, shock, and death.
A diagnosis of dengue fever in the early stages can allow for close monitoring. Though there is no specific treatment for the disease, those affected can be given supportive treatment, such as plenty of fluids and acetaminophen for pain. Aspirin and non-steroidal anti-inflammatory medications, such as ibuprofen, should not be used as they may increase the risk of bleeding. Patients with the more serious form of the illness usually require hospitalization.
There is no vaccine available to prevent infection, but travelers and those who live in endemic areas can take steps to avoid becoming infected. The CDC advises taking precautions, such as using mosquito repellent and wearing long sleeves and pants, avoiding the outdoors from dusk to dawn, the most active time for mosquitos, and sleeping under a mosquito net if accommodations don't have window screens or air conditioning.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
(April 8, 2011) FDA News Release: FDA permits marketing of first test to help diagnose dengue fever. Available online at http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm250584.htm through http://www.fda.gov. Accessed April 2011.
(October 5, 2010) Centers for Disease Control and Prevention. Dengue Information. Available online at http://www.cdc.gov/Dengue/ through http://www.cdc.gov. Accessed April 2011.
(September 30, 2010) Mayo Clinic. Dengue Fever. Available online at http://www.mayoclinic.com/health/dengue-fever/DS01028 through http://www.mayoclinic.com. Accessed April 2011.