Dengue fever is a viral infection that is carried predominately by mosquitoes and is most prevalent in tropical climates. There are actually four related strains of the dengue virus that can cause this fever, but they are so closely related that researchers and epidemiologists usually group them all together under the broad “dengue fever” heading. Infection isn’t usually fatal, though it tends to be very unpleasant. Victims often suffer prolonged headaches, nausea, and itchy skin rash; muscle and joint pain is also common. It is not possible for people to spread the fever amongst themselves as it is only transmitted by mosquitoes. Only mosquitoes in certain geographical regions, predominately in the tropics of Asia and Africa, are known to carry the virus, too. There is no known cure for the condition, but it most cases it will go away on its own after a week or so. The best way for people to avoid exposure is to shield themselves from mosquitoes, including wearing repellants and sleeping under nets.
Transmission Basics
Dengue viruses are transmitted exclusively by Aedes mosquitoes. This means that in order for someone to get infected, he or she must be bitten by a “carrying” insect. Mosquitoes contract the disease initially from contaminated water sources and, in some cases, other animals, then pass it along in their saliva and fluids that are transferred in the process of a bite. The bite actually transmits the small amount of blood necessary to spread the illness.
Sharing bodily fluids with an infected person is not enough to cause the disease to spread. It is exclusively blood-born. Theoretically, sharing blood with an infected person could lead to secondary infection, but the circumstances in which this could happen are very rare. As such, healthcare workers and caregivers aren’t usually considered to be at risk.
Prevalence and Problem Areas
Dengue doesn’t occur everywhere. The fever is all but non-existent in Europe, for instance, and most of the world’s northern climates have no reported cases most years. The disease is rampant in many tropical climates, however, including much of India and Southeast Asia, Sub-Saharan Africa, and the Caribbean. The viruses causing dengue seem to thrive in these moist, warm environments, and the mosquitoes that carry them tend to have very long life spans in these places.
Symptoms
Infection usually becomes symptomatic five or six days after the infecting bite. The first symptoms are a high fever, generally 104° to 105°F (40°C), vomiting, nausea, and a headache. Joint and muscular pain follow within the next days, and a flat, red rash may appear and spread from the torso to the limbs and face. The severe pains most victims experience have led to the fever being called break-bone fever in many communities.
Despite their intensity, most symptoms of the disease subside within about a week of their onset. Most patients are expected to make a full recovery, particularly if they get treatment promptly. It’s sometimes the case that exposure once can lead to immunity later on, particularly for children. People need to remember, though, that the disease is cause by any one of four related strains, and immunity to one won’t usually protect against the others.
Treatment and Prognosis
There isn’t usually a cure for dengue fever, though quick treatment has been credited with lessening the symptoms of many sufferers. Diagnosis is usually made through blood tests that scan for antibodies to dengue viruses. Once these are identified, patients can take antiviral drugs and pain medications.
Rare Complications
In a small number of cases, the fever advances beyond its initial state and becomes a much more serious condition known as dengue hemorrhagic fever. This secondary condition usually develops if the virus penetrates the soft tissues of the body, like the lymph nodes. It has a much higher fatality rate in children and individuals with suppressed immune systems, and can cause intense complications for others.
Every year, some 20 million people contract dengue fever leading to roughly 24,000 deaths worldwide. About 100 infections are reported annually in the U.S., mostly from travelers returning from the tropics.
Protection Strategies
The best way for people to protect themselves from dengue and its complications is to shield themselves from carrying mosquitoes. Wearing long clothing is usually a good place to start, as is sleeping under nets and keeping screens on external windows whenever possible. Wearing repellant and staying indoors at sunrise and dusk, two of mosquitoes’ most favored times to bite, can also help.