Dengue fever is a disease caused by a family of viruses transmitted by mosquitoes. It is an acute illness of sudden onset that usually follows a benign course with symptoms such as headache, fever, exhaustion, severe muscle and joint pain, swollen lymph nodes (lymphadenopathy), and rash. The presence of fever, itchy rash, and headache (the “dengue triad”) is characteristic of dengue. Other signs of dengue fever include bleeding gums, severe pain behind the eyes, and red palms and soles.
Dengue (pronounced DENG-gay) can affect anyone but tends to be more severe in people with compromised immune systems. Because it is caused by one of five serotypes of the dengue virus, it is possible to get dengue fever multiple times. However, an attack of dengue produces immunity for a lifetime to that particular viral serotype to which the patient was exposed.
Dengue goes by other names, including “breakbone fever” or “dandy fever.” Victims of dengue often have contortions due to the intense pain in the joints, muscles, and bones, hence the name breakbone fever. Slaves in the West Indies who contracted dengue were said to have dandy fever because of their postures and gait.
Dengue hemorrhagic fever is a more severe form of the viral illness. Symptoms include headache, fever, rash, and evidence of bleeding (hemorrhage) in the body. Petechiae (small red spots or purple splotches or blisters under the skin), bleeding in the nose or gums, black stools, or easy bruising are all possible signs of hemorrhage. This form of dengue fever can be life-threatening and can progress to the most severe form of the illness, dengue shock syndrome.
How is dengue fever contracted? Is dengue fever contagious?
The virus is contracted from the bite of a striped Aedes aegypti mosquito that has previously bitten an infected person. The mosquito flourishes during rainy seasons but can breed in water-filled flower pots, plastic bags, and cans year-round. One mosquito bite can cause the disease.
The virus is not contagious and cannot be spread directly from person to person. It is mosquito-borne, so there must be a person-to-mosquito-to-another-person pathway. The full life cycle of the virus involves the mosquito as the vector (transmitter) and the human as the source of infection.
What is the incubation period for dengue fever?
After being bitten by a mosquito carrying the virus, the incubation period for dengue fever ranges from three to 15 (usually five to eight) days before the signs and symptoms of dengue appear in stages.
What are dengue fever symptoms and signs?
Dengue fever starts with symptoms of chills, headache, pain in the back of the eyes that may worsen upon moving the eyes, appetite loss, feeling unwell (malaise), and low backache. Painful aching in the legs and joints occurs during the first hours of illness. The temperature rises quickly as high as 104 F (40 C), with relatively low heart rate (bradycardia) and low blood pressure (hypotension). The eyes become reddened. A flushing or pale pink rash comes over the face and then disappears. The lymph nodes in the neck and groin are often swollen.
High fever and other signs of dengue last for two to four days, followed by a rapid drop in body temperature (defervescence) with profuse sweating. This precedes a period with normal temperature and a sense of well-being that lasts about a day. A second rapid rise in temperature follows. A characteristic itchy rash (small red spots, called petechiae) appears along with the fever and spreads from the extremities to cover the entire body except the face. The palms and soles may be bright red and swollen.
What tests do health care providers use to diagnose dengue fever?
The diagnosis of dengue fever is usually made when a patient exhibits the typical clinical symptoms of headache, high fever, eye pain, severe muscle aches, and petechial rash and has a history of being in an area where dengue fever is endemic. Dengue fever can be difficult to diagnose because its symptoms overlap with those of many other viral illnesses, such as West Nile virus and chikungunya fever.
Health care professionals may use a blood test called the DENV Detect IgM Capture ELISA to diagnose people with dengue fever. The FDA notes that the test may also give a positive result when a person has a closely related virus, such West Nile disease.
What is the treatment for dengue fever?
Because dengue fever is caused by a virus, there are no specific antibiotics to treat it. Antiviral medications are also not indicated for dengue fever. For typical dengue, the treatment is concerned with relief of the symptoms and signs. Home remedies such as rest and fluid intake (oral rehydration) are important. Pain relievers such as aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) should only be taken under a doctor’s supervision because of the possibility of worsening bleeding complications. Acetaminophen (Tylenol) and codeine may be given for severe headache and for joint and muscle pain (myalgia).
Patients hospitalized for dengue may receive IV fluids.
Carica papaya leaf extract (papaya leaf) has been shown in several clinical studies to be an effective treatment for dengue fever.
How long does dengue fever last?
The acute phase of dengue with fever and muscle pain (myalgia) lasts about one to two weeks. Convalescence is accompanied by a feeling of weakness (asthenia) and fatigue, and full recovery often takes several weeks.
What is the prognosis for typical dengue fever?
The prognosis for dengue is usually good. The worst symptoms of the illness typically last one to two weeks, and most patients will fully recover within several additional weeks.
Typical dengue is fatal in less than 1% of cases; however, dengue hemorrhagic fever is fatal in 2.5% of cases. If dengue hemorrhagic fever is not treated, mortality (death) rates can be as high as 20%-50%.
What is dengue hemorrhagic fever?
Dengue hemorrhagic fever (DHF) is a specific syndrome that tends to affect children under 10 years of age. This complication of dengue fever causes abdominal pain, hemorrhage (bleeding), and circulatory collapse (shock). DHF is also called Philippine, Thai, or Southeast Asian hemorrhagic fever or dengue shock syndrome.
DHF starts abruptly with continuous high fever and headache. There are respiratory and intestinal symptoms with sore throat, cough, nausea, vomiting, and abdominal pain. Shock occurs two to six days after the start of symptoms with sudden collapse, cool, clammy extremities (the trunk is often warm), weak pulse, and blueness around the mouth (circumoral cyanosis).
In DHF, there is bleeding with easy bruising, red or purple blood spots in the skin (petechiae), spitting up blood (hematemesis), blood in the stool (melena), bleeding gums, and nosebleeds (epistaxis). Pneumonia is common, and inflammation of the heart (myocarditis) may be present.
Patients with DHF must be monitored closely for the first few days since shock may occur or recur precipitously (dengue shock syndrome). Cyanotic (having a bluish coloration to the skin and mucus membranes) patients are given oxygen. Vascular collapse (shock) requires immediate fluid replacement. Blood transfusions may be needed to control bleeding.
The mortality (death) rate with DHF is significant. With proper treatment, the World Health Organization estimates a 2.5% mortality rate. However, without proper treatment, the mortality rate rises to 20%. Most deaths occur in children. Infants under 1 year of age are especially at risk of dying from DHF.
What are potential complications of dengue fever?
If dengue fever is severe, complications include leakage of fluid from the bloodstream causing fluid accumulation in the extremities, respiratory distress, severe bleeding, or organ impairment. Without proper treatment, these symptoms can be fatal.
Dengue hemorrhagic fever (DHF; see above) is a complication of dengue that usually affects children under 10 years of age when it occurs. This complication of dengue fever starts abruptly with continuous high fever and headache. DHF causes abdominal pain, sore throat, cough, nausea, vomiting, hemorrhage (bleeding), and circulatory collapse (shock). It can be fatal.
Another complication is postinfectious fatigue syndrome, which can occur in about one-quarter of hospitalized dengue patients.
Is it possible to prevent dengue fever?
The transmission of the virus to mosquitoes must be interrupted to prevent the illness. To this end, patients are kept under mosquito netting until the second bout of fever is over and they are no longer able to transmit the virus to a biting mosquito.
The prevention of dengue fever requires control or eradication of the mosquitoes carrying the virus that causes dengue. In nations plagued by dengue fever, people are urged to empty stagnant water from old tires, trash cans, and flower pots. Governmental initiatives to decrease mosquitoes also help to keep the disease in check but have been poorly effective.
To prevent mosquito bites, wear long pants and long sleeves. For personal protection, use mosquito-repellant sprays that contain DEET when visiting places where dengue is endemic. There are no specific risk factors for contracting dengue fever except living in or traveling to an area where the mosquitoes and virus are endemic. Limiting exposure to mosquitoes by avoiding standing water and staying indoors for two hours after sunrise and before sunset will help, as the Aedes aegypti mosquito is a daytime biter with peak periods of biting around sunrise and sunset. It may bite at any time of the day and is often hidden inside homes or other dwellings, especially in urban areas.
Is there a dengue fever vaccine?
In April 2016, the WHO approved Sanofi Pasteur’s Dengvaxia (CYD-TDV), a live recombinant tetravalent vaccine for dengue fever. Dengvaxia can be administered as a three-dose series in people 9-45 years of age who live in areas where dengue is endemic.
Dengvaxia was initially approved in 2015 for use only in Mexico, the Philippines, Brazil, and El Salvador.
Several other vaccines for dengue are undergoing clinical trials, but none have yet been approved for use.
Original Article: Medicinenet
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