Dengue fever is a disease caused by any of four closely related dengue viruses (DENV 1, DENV 2, DENV 3, or DENV 4) that are carried by mosquitoes of the genus Aedes. These mosquitoes then transmit the virus to humans.
Health experts have long known about dengue fever. It used to be called break-bone fever, as it sometimes results in severe joint and muscle pain. The first record of a case of dengue fever appeared in a ancient Chinese medical encyclopedia, dating from between 265 and 420 CE. The first recognized dengue epidemics occurred simultaneously in Asia, Africa, and North America in the 1780s. The disease was named dengue in 1779, with Benjamin Rush, a Philadelphia physician, describing the first case report in 1789.
Before 1970, only nine countries had witnessed severe dengue epidemics. As of 2018, dengue was endemic in more than 100 countries in Africa, the Americas, the Eastern Mediterranean, Southeast Asia, and the Western Pacific, with the latter two being the most seriously affected. By some estimates, 40%–50% of the world's population is at risk for contracting the disease. The growing prevalence of dengue is linked with climate change. Warmer temperatures decrease the extrinsic incubation period in mosquitoes and increase the mosquitoes range and urbanization, creating opportunity for dengue to spread more easily. Globalization and long-distance travel also provide an opening for this poorly controlled disease to spread.
Dengue fever is caused by arboviruses, which are arthropod-borne viruses. Mosquitoes are a type of arthropod. In many tropical and subtropical climates, mosquitoes carry this virus and are responsible for passing it to humans.
Many common illnesses, including the common cold, viral causes of diarrhea, and influenza, spread because the viruses that cause these illnesses can pass directly from person to person. However, dengue fever cannot be passed directly from one infected person to another person. Instead, the virus responsible for dengue fever requires an intermediate vector, a mosquito that transmits the virus from one host to another. In the Western Hemisphere, the Aedes aegypti mosquito is the most important vector of dengue viruses, although in other places other members of the genus Aedes serve as vectors.
Dengue occurs primarily in warm climates where Aedes aegypti or Aedes albopictus mosquitoes are found, including most tropical urban areas of the world. Dengue viruses may be introduced into new areas by travelers who become infected while visiting other areas where dengue outbreaks commonly occur.
As of 2018, the U.S. Centers for Disease Control and Prevention (CDC) estimates that as many as one-third to one-half the world's population live in areas at risk for dengue infection. In tropical regions, dengue viruses are endemic, meaning that the virus naturally and consistently lives in these areas. As many as 400 million people are infected with dengue viruses each year.
Dengue rarely occurs in the continental United States, where 100 to 250 cases occur each year, mostly in people who have recently traveled abroad. However, the mosquitoes that spread dengue can be found in the Southeastern United States, so outbreaks are possible. Dengue is endemic in Puerto Rico, the U.S. Virgin Islands, and in multiple tourist destinations in the Caribbean, Latin America, and Southeast Asia. Outbreaks periodically occur in Samoa and Guam. The most common victims are children younger than ten years of age.
Dengue can occur when a mosquito carrying the arbovirus bites a human, passing the virus on to the new host. Once in the body, the virus travels to various glands where it multiplies. The virus can then enter the bloodstream. The presence of the virus within the blood vessels, especially those feeding the skin, causes changes to these blood vessels. The vessels swell and leak fluid. The spleen and lymph nodes become enlarged, and patches of liver tissue die. A process called disseminated intravascular coagulation (DIC) occurs, in which chemicals responsible for blood clotting are used up. DIC leads to the risk of severe bleeding (hemorrhage), a life-threatening condition.
After the virus has been transmitted to the human host, an incubation period of about five to eight days occurs during which the virus multiplies. Symptoms of the disease appear suddenly and include high fever, chills, headache, eye pain, red eyes, enlarged lymph nodes, a red flush to the face, lower back pain, extreme weakness, and severe aches in the legs and joints.
This initial period of illness lasts two or three days. After this time, the fever drops rapidly, and the patient sweats heavily. After about a day of feeling relatively well, the patient's temperature increases again, although not as much as the first time. A rash of small red bumps begins on the arms and legs, spreading to the chest, abdomen, and back. It rarely affects the face. The palms of the hands and the soles of the feet become swollen and turn bright red. The characteristic combination of fever, rash, and headache is called the dengue triad.
Most people recover fully from dengue fever, although weakness and fatigue and joint pain may last for several weeks. Dengue can be caused by four closely related viruses. Infection with one variant of the virus does not guarantee immunity to other variants. That means individuals can and often do become sick with dengue more than once.
A diagnosis of dengue infection should be suspected in endemic areas whenever a high fever goes on for two to seven days, especially if accompanied by bleeding. Symptoms of shock should suggest the progression of the disease to DSS.
The arbovirus causing dengue fever is one of the few types of arbovirus that can be isolated from the serum of the blood. The serum is the clear fluid in which blood cells are suspended. Serum can be tested because the phase during which the virus travels throughout the bloodstream is longer in dengue fever than in other arboviral infections.
Several tests are used to look for reactions between the patient's serum and laboratory-produced antibodies. Antibodies are special immune system cells that recognize the protein markers (antigens) present on invading organisms. During these tests, antibodies are added to a sample of the patient's serum. Healthcare workers then look for reactions that would only occur if viral antigens were present in the serum.
As of 2018, there was no treatment available to shorten the course of dengue fever, DHF, or DSS. Medications can be given to lower the fever and to decrease the pain of muscle aches and headaches. If available, anti-viral medications may be used with limited success. Fluids are given through a needle in a vein to prevent dehydration. Blood transfusions may be necessary if severe hemorrhaging occurs. Oxygen should be administered to patients in shock.
Dengue fever represents one of the most important public health issues in tropical developing countries and also has a major economic and societal impact. In the Western Hemisphere, the estimated economic burden of dengue is at least $dol;2.1 billion per year. The incidence of dengue dramatically increased worldwide between 1985 and 2015. As of 2018, over 2.5 billion people were at risk from dengue, and the World Health Organization (WHO) estimated that there may be as many as 100 million dengue infections worldwide every year. The number of dengue cases was clearly increasing as the disease spread to new areas, and explosive outbreaks were observed. Dengue outbreaks are possible in Europe with local transmission reported for the first time in France and Croatia in 2010.
WHO has responded by doing the following:
The prognosis for uncomplicated dengue fever is very good, and almost 100% of patients fully recover. However, as many as 6–30% of all patients die when DHF occurs. The death rate is especially high among the young children. In places where excellent medical care is available, close monitoring and immediate treatment of complications lower the death rate among DHF and DSS patients to about 1%.
Mosquito control is critical in preventing dengue fever and other mosquito-borne diseases. All sources of standing water (buckets, vases, birdbaths, etc.) where the mosquitoes can breed must be eliminated. Widespread spraying with insecticides also helps control the mosquito population. At the individual level, mosquito repellant is recommended in those areas where dengue fever is endemic. To help break the cycle of transmission, sick patients should be placed in bed nets so that mosquitoes cannot bite them and become vectors.
A vaccine against dengue fever called Dengvaxia that is made by the French company Sanofi Pasteur was approved in 2015. It is for use in people who are 9–54 years of age but with serious limitations. The World Health Organization recommends that Dengvaxia be given only to people who have previously had a dengue infection. When people who have never had dengue are vaccinated and later become infected (the vaccine does not provide perfect protection against all strains of the virus), the infection is much more severe. This was discovered when 830,000 children, many of whom had never had dengue fever, were vaccinated in the Philippines. On later becoming infected, some of these vaccinated children became severely ill. As a result, the government of the Philippines stopped the vaccination program and forced the manufacturer to recall the vaccine from the Philippines and set stricter limits on its use. The government of the Philippines has also demanded the company to reimburse it close to $100 million for the aborted vaccination program. As of 2018, additional dengue vaccines by other manufacturers were under development.
See also Endemic ; Vaccination ; Vector (mosquito) control ; Viruses .
Hilgenfeld, Rolf. Dengue and Zika: Control and Antiviral Treatment Strategies. New York: Springer Berlin Heidelberg, 2018.
Miller, Petra. Dengue Fever. New York: Cavendish Square, 2016.
Grady, Denise, and Katie Thomas. “Drug Company Under Fire After Revealing Dengue Vaccine May Harm Some.rdquo; New York Times, December 17, 2017. https://www.nytimes.com/2017/12/17/health/sanofi-dengue-vaccine-philippines.html (accessed April 16, 2018).
Centers for Disease Control and Prevention. “Dengue.” https://www.cdc.gov/dengue/index.html (accessed April 16, 2018).
MedlinePlus. “Dengue Fever.” https://medlineplus.gov/dengue.html (accessed April 16, 2018).
Shepherd, Suzanne M. “Dengue.” Medscape. https://emedicine.medscape.com/article/215840-overview (accessed April 16, 2018).
World Health Organization. “Dengue Control.” http://www.who.int/denguecontrol/disease/en (accessed April 16, 2018).
World Health Organization. “Updated Questions and Answers Related to the Dengue Vaccine Dengvaxia and Its Use.” http://www.who.int/immunization/diseases/dengue/q_and_a_dengue_vaccine_dengvaxia_use/en (accessed April 16, 2018).
U.S. Centers for Disease Control and Prevention (CDC), 1600 Clifton Rd., Atlanta, GA, 30329-4027, (404) 639-3534, (800) 232-4636, http://www.cdc.gov .
World Health Organization (WHO), Avenue Appia 20, 1211 Geneva 27, Switzerland, +2241 791 21 11, Fax: +2241 791 31 11, firstname.lastname@example.org, http://www.who.int .
Rosalyn Carson-DeWitt, MD
Revised by Tish Davidson, AM