Dengue fever

Related Terms

Arbovirus infections, breakbone fever, circulatory collapse, dengue hemorrhagic fever, dengue infection, dengue shock syndrome, dengue virus, DENV, DENV 1, DENV 2, DENV 3, DENV 4, DF, DHF, DSS, epidemic, Flaviviridae, Flaviviridae infections, Flavivirus, RNA virus infections.

Background

Dengue (pronounced den'-ghee) fever is a leading cause of illness and death in the tropics and subtropics, with more than one-third of the world's population living in areas at risk for transmission.
Dengue fever is caused by any one of four related viruses (DENV 1, DENV 2, DENV 3, and DENV 4) transmitted by mosquitoes. In the Western Hemisphere, the Aedes aegypti mosquito is the most important vector (transmitter) of dengue viruses. However, in 2001, an outbreak in Hawaii was found to be transmitted by the Aedes albopictus mosquito. Currently, there are no preventive dengue virus vaccines and no specific medications to treat a dengue infection. Since dengue fever is a mosquito-transmitted infection, prevention and protection against bites is essential. Early detection and rapid response can reduce the severity of the infection.
As many as 100 million people are infected yearly. In 2007, a total of 900,782 cases of dengue fever were reported in the Americas, with 26,413 cases of dengue hemorrhagic fever. According to the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO), outbreaks were reported in 11 countries.
Dengue fever has been a worldwide problem since the 1950s. Occurring rarely in the continental United States, dengue fever is endemic in Puerto Rico and in many popular tourist destinations in Latin America and Southeast Asia. There have been periodic outbreaks in Samoa and Guam. Other locations of outbreaks include northern Argentina, northern Australia, the entirety of Bangladesh, Barbados, Bolivia, Belize, Brazil, Cambodia, Costa Rica, the Dominican Republic, El Salvador, Guatemala, Guyana, Honduras, India, Indonesia, Jamaica, Laos, Malaysia, Mexico, Micronesia, Panama, Paraguay, Philippines, Puerto Rico, Singapore, Sri Lanka, Suriname, Taiwan, Thailand, Trinidad, Venezuela, and Vietnam, and increasingly in southern China.

Signs and symptoms

Dengue virus: Dengue virus can be asymptomatic or manifest along a continuum, from a nonspecific viral infection to the life-threatening dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). The principal symptoms of dengue fever (DF) are high fever, severe headache, severe pain behind the eyes, joint pain, muscle and bone pain (hence the name "breakbone fever"), rash, and mild bleeding (e.g., nose or gums bleed, easy bruising). Leukopenia (a decrease in white blood cells) is usually observed. Clinical features of the dengue rash include bright red petechiae (small skin hemorrhages) that typically appear first on the lower limbs and the chest. Eventually, the rash spreads to the rest of the body. Gastritis (inflammation of the stomach lining) accompanied by abdominal pain, nausea, vomiting, or diarrhea may also occur. Infants, younger children, and those with their first dengue infection typically have less severe symptoms than older children and adults.
Dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS): The primary difference between DF and DHF is vascular leakage, which results in hemoconcentration (increased concentration of blood cells from the loss of fluid) and pleural effusions (excess fluid between the layers of tissues that line the lungs), which can lead to circulatory collapse or dengue shock syndrome. DHF is characterized by four major clinical manifestations: high fever, hemorrhagic phenomena, hepatomegaly (enlarged liver) occasionally, and circulatory failure (inability of the cardiovascular system to supply sufficient amount of blood to tissues). High fever typically lasts from two to seven days, with general signs and symptoms consistent with dengue fever. Patients with DHF present with moderate-to-marked thrombocytopenia (lowered platelet counts in the blood) with or without concurrent hemoconcentration. These patients are considered to have dengue fever with unusual bleeding. Along with hemorrhagic phenomena, patients with DHF may have hepatomegaly and circulatory failure.
Laboratory findings in DHF and DSS include increased hematocrit, thrombocytopenia, and transformed lymphocytes (white blood cells) on peripheral smear. There may be evidence of liver inflammation, lowered serum sodium, and altered kidney function, indicated by tests that reveal increased chemical wastes, such as the amount of nitrogen in blood from urea (blood urea nitrogen [BUN]) and creatinine. These tests may reveal if the patient is dehydrated. In severe disease, there may be laboratory evidence of disseminated intravascular coagulation (blood clotting in the veins and arteries). X-ray film of the chest may show fluid in the lungs. An ultrasonogram of the abdomen may detect a thickened gallbladder wall with an enlarged liver and ascites (fluid in the abdomen). In some patients there are abnormalities in the electrocardiogram and echocardiogram.

Diagnosis

Detection of the dengue virus can be confirmed by viral culture, which should be obtained from the individual during the early stage of illness. Identification of IgM antibodies against dengue virus is a confirmatory test and may be obtained between five and 90 days after the onset of the illness. Polymerase chain reaction (PCR) tests can also confirm the diagnosis.
The diagnosis is usually made clinically, with a typical picture of high fever without a localized source of infection, petechial rash with low platelet count (called thrombocytopenia) and relatively low white blood cell count (called leukopenia).

Complications

Mild complications: Some individuals, particularly adults, may feel lethargic and/or depressed for several weeks to months after being infected.
Severe complications: The more severe forms of dengue infection, dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), are associated with hemorrhage and shock, respectively, and can be fatal.
According to the Centers for Disease Control and Prevention (CDC), the case fatality rate can be as high as 10% but can be lowered to less than 1% with early recognition and proper treatment.

Treatment

There is no specific medication or treatment for dengue fever. Supportive care is the only known effective therapy. Adequate hydration and blood pressure control are essential in patients with dengue fever.
Analgesics (pain relievers) with acetaminophen should be used for fever control. Nonsteroidal anti-inflammatory medications (NSAIDs) such as aspirin and ibuprofen should not be used, as these agents may further hinder platelet function (elements needed for blood clotting) and increase the risk of bleeding.
According to the Centers for Disease Control and Prevention (CDC), management of dengue hemorrhagic fever (DHF) usually requires hospitalization. Supportive care by intravenous fluids and oxygen are typically administered.

Integrative therapies

Note: Currently, there is insufficient evidence available on the safety and effectiveness of integrative therapies for the prevention or treatment of dengue fever. The therapies listed below have been used as mosquito repellent and should be used only under the supervision of a qualified healthcare provider. They should not be used in replacement of other proven therapies or preventive measures. There has been some early research on the use of a homeopathic combination medication and a traditional Chinese combination product for dengue fever, as well as a combination of essential oils as a larvicide for mosquito control. However, high-quality scientific evidence is limited.
Unclear or conflicting scientific evidence:
Celery: Wild celery can be found throughout Europe, the Mediterranean, and parts of Asia. The leaves, stalks, root, and seeds can be eaten. According to an early study, celery extract may be an effective mosquito repellent. Although study results have been promising, additional research is needed in this area.
Avoid if allergic or hypersensitive to celery (Apium graveolens), its constituents, or members of the Apiaceae (or Umbelliferae) family, or with birch pollen-related allergens. Use cautiously if exposed to ultraviolet radiation. Use cautiously with bile secretion disorders. Avoid if eating large amounts of psoralen-containing foods or herbs. Avoid high celery intake in pregnant patients. Use cautiously if breastfeeding.
Clove: In laboratory and field tests, undiluted clove oil repelled multiple species of mosquitoes for up to two hours. However, undiluted clove oil may also cause dermatitis. Further research is needed to better determine the effectiveness of clove as a mosquito repellant.
Avoid if allergic to balsam of Peru, clove, eugenol, or some licorice and tobacco (clove cigarette) products. Avoid with a history of seizures or stroke, or with liver damage. Use cautiously if taking medications for diabetes, bleeding problems, or male impotence. Stop use two weeks before surgery or dental or diagnostic procedures with a bleeding risk, and do not use immediately after these procedures. Use cautiously if driving or operating machinery. Avoid if pregnant or breastfeeding, due to insufficient evidence of safety.
Garlic: There is currently not enough evidence to suggest that garlic helps repel mosquitoes. In one study, subjects consumed garlic (one time) and were exposed to mosquitoes in a laboratory. There was a lack of evidence to show repellence. However, prolonged ingestion of garlic may be required. More research is needed in this area.
Avoid if allergic or hypersensitive to garlic or other members of the Liliaceae(lily) family such as hyacinth, tulip, onion, leek, or chive. Avoid with history of bleeding problems, asthma, diabetes, low blood pressure, or thyroid disorders. Stop using supplemental garlic two weeks before dental or surgical or diagnostic procedures, and avoid using immediately after such procedures to avoid bleeding problems. Avoid supplemental doses if pregnant or breastfeeding, due to insufficient evidence of safety.
Jojoba: Jojoba (Simmondsia chinensis) is a shrub native to deserts in Arizona, California, and Mexico, and is also found in some arid African countries. It is traditionally used as a carrier or massage oil. There is currently not enough available evidence to recommend for or against the use of jojoba oil as a mosquito repellent.
Avoid if allergic or hypersensitive to jojoba, its constituents, or members of the Simmondsiaceae family. Avoid oral consumption of jojoba products. Avoid if pregnant or breastfeeding.
Neem: Neem oil and neem cream exhibited protective effects against mosquito bites from various species in nonrandomized controlled studies. However, the studies are limited by small sample size and lack of randomization and blinding. Further research is necessary before a conclusion can be reached on the use of neem as a mosquito repellant.
Avoid if allergic or hypersensitive to neem (Azadirachta indica) or members of the Meliaceae family. Use cautiously with liver disease. Avoid in children and infants, because several cases of death in children from neem oil poisoning have been reported. Avoid if pregnant, because neem may cause miscarriage. Avoid if breastfeeding, due to insufficient evidence of safety.

Prevention

The primary prevention measure against dengue fever is mosquito control, primarily by eliminating locations where mosquitoes lay eggs, such as standing water in artificial containers. Drums to collect rainwater or to store drinking water and objects likely to collect and hold rainwater (such as discarded automobile tires) should be covered or properly processed. Pet dishes and flower vases should have the water changed weekly to remove eggs.
Use of air conditioning or window and door screens will reduce indoor mosquito risk.
Use of mosquito repellents (containing 20-30% DEET (N,N-diethyl-meta-toluamide)) on skin and clothing can provide 6-8 hours of protection against mosquito bites.
Wear long sleeves and long pants for additional protection.
If a household member has dengue fever, take extra precautions to prevent mosquitoes from biting the infected person and other household members. These measures would include sleeping under mosquito netting, eliminating indoor mosquitoes as much as possible, and wearing mosquito repellent.

Author information

This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography

Centers for Disease Control.
Jacobs J, Fernandez EA, Merizalde B, Avila-Montes GA, Crothers D. The use of homeopathic combination remedy for dengue fever symptoms: a pilot RCT in Honduras. . 2007;96(1):22-26.
Kabra SK, Jain Y, Singhal T, Ratageri VH. Dengue hemorrhagic fever: clinical manifestations and management. . 1999;66(1):93-101.
Pitasawat B, Champakaew D, Choochote W, et al. Aromatic plant-derived essential oil: an alternative larvicide for mosquito control. . 2007;78(3):205-210.
Ryan KJ RC(, Ryan KJ, Ray CG (editors). . 4th ed. McGraw Hill; 2004.
Wilder-Smith A, Chen LH, Massad E, Wilson ME. Threat of Dengue to Blood Safety in Dengue-Endemic Countries. . 2009;15(1):8-11.
World Health Organization.

Causes

Dengue fever is caused by four closely related virus serotypes of the genus Flavivirus (of the Flaviviridae family). The virus is transmitted to a human host by a bite from a mosquito that is infected with the virus, usually from having bitten another human who has dengue virus in the blood, whether he or she is symptomatic or asymptomatic. Dengue is not contagious, meaning that it cannot be spread directly from one person to another.
It has been reported that in countries where dengue is endemic, it is rarely transmitted via transfusion of infected blood.

Risk factors

The World Health Organization (WHO) estimates that 2.5 billion people, two-fifths of the world's population, are at risk to contract dengue fever.
Location: Dengue fever is endemic in tropical and subtropical climates, mostly in urban and suburban areas, throughout the world, and residing in such an area is a risk factor for contracting an infection. Spending significant time outdoors or living in quarters without screened windows and doors or air conditioning will increase the risk of mosquito bites and therefore the risk of contracting dengue fever.
Contaminated water: Mosquito populations may enhance in areas where there is a significant presence of standing water. For instance, artificial containers such as rain barrels, plastic containers for storing drinking water, pet dishes, flower vases, and discarded automobile tires that hold rain water are optimal locations for mosquitoes to lay eggs.
High-risk groups: According to the Centers for Disease Control and Prevention (CDC), high-risk groups include both residents and visitors to tropical and subtropical environments. Children under 15 years of age, living in either rural or urban communities, have an increased risk of severe and fatal disease.

Types of the disease

Dengue hemorrhagic fever (DHF) is a severe form of dengue infection caused by the same viruses that cause dengue fever. It is characterized by thrombocytopenia (abnormally low platelets) and hemoconcentration (decreased fluid content in the blood; grades I and II) and is distinguished by a positive tourniquet test (the appearance of small hemorrhages (bleeding from ruptured blood vessels) or petechiae (small red dots caused by broken blood vessels) on the skin after the application of a tourniquet or blood pressure cuff). If unrecognized or left untreated, DHF can be fatal. With proper treatment, the Centers for Disease Control and Prevention (CDC) estimates a mortality rate of less than 1%.
When accompanied by circulatory failure and shock (grades III and IV), DHF is called dengue shock syndrome (DSS).
As there is no cross-immunity or form of competitive interference between strains, it is possible to have DF four times, once from each DF virus.