Dengue

Dengue symptoms

• An acute infection caused by dengue virus.
• Signs and symptoms include sudden onset of fever, headache, rash, arthralgia, and myalgia.
• It is transmitted through mosquitoes.
• Dengue viruses are spread to people through the bite of an infected Aedes species (Ae. aegypti or Ae. albopictus) mosquito. These mosquitoes also spread Zika, chikungunya, and other viruses.
• Dengue is common in more than 100 countries around the world.
• Forty percent of the world’s population, about 3 billion people, live in areas with a risk of dengue. Dengue is often a leading cause of illness in areas with risk.
• Each year, up to 400 million people get infected with dengue.
• Approximately 100 million people get sick from infection, and 22,000 die from severe dengue.
• Dengue is caused by one of any of four related viruses: Dengue virus 1, 2, 3, and 4. 
• For this reason, a person can be infected with a dengue virus as many as four times in his or her lifetime.

Through Mosquito Bites

Dengue viruses are spread to people through the bites of infected Aedes species mosquitoes (Ae. aegypti or Ae. albopictus).  These are the same types of mosquitoes that spread Zika and chikungunya viruses.

• These mosquitoes typically lay eggs near standing water in containers that hold water, like buckets, bowls, animal dishes, flower pots, and vases.
• These mosquitoes prefer to bite people, and live both indoors and outdoors near people.
• Mosquitoes that spread dengue, chikungunya, and Zika bite during the day and night.
• Mosquitoes become infected when they bite a person infected with the virus. Infected mosquitoes can then spread the virus to other people through bites.

Dengue

From mother to child

• A pregnant woman already infected with dengue can pass the virus to her fetus during pregnancy or around the time of birth.
• To date, there has been one documented report of dengue spread through breast milk. Because of the benefits of breastfeeding, mothers are encouraged to breastfeed even in areas with risk of dengue.

Through infected blood, laboratory, or healthcare setting exposures

Rarely, dengue can be spread through blood transfusion, organ transplant, or through a needle stick injury.

Key Facts

• 1 in 4: About one in four people infected with dengue will get sick.
• For people who get sick with dengue, symptoms can be mild or severe.
• Severe dengue can be life-threatening within a few hours and often requires hospitalization.

Symptoms

Early Dengue Fever Rash

• Mild symptoms of dengue can be confused with other illnesses that cause fever, aches and pains, or a rash.

The most common symptom of dengue is fever with any of the following:

• Nausea, vomiting
• Rash
• Aches and pains (eye pain, typically behind the eyes, muscle, joint, or bone pain)
• Any warning sign

Symptoms of dengue typically last 2–7 days. Most people will recover after about a week.

Treatment

• There is no specific medication to treat dengue.
• Treat the symptoms of dengue and see your healthcare provider.

If you think you have dengue

• See a healthcare provider if you develop a fever or have symptoms of dengue. Tell him or her about your travel.
• Rest as much as possible.
• Take acetaminophen (also known as paracetamol outside of the United States) to control fever and relieve pain.
  • Do not take aspirin or ibuprofen!
• Drink plenty of fluids such as water or drinks with added electrolytes to stay hydrated.

Symptoms of dengue can become severe within a few hours. Severe dengue is a medical emergency.

Aedes aegypti

Severe dengue

• About 1 in 20 people who get sick with dengue will develop severe dengue.
• Severe dengue is a more serious form of disease that can result in shock, internal bleeding, and even death.
• You are more likely to develop severe dengue if you have had a dengue infection before.
• Infants and pregnant women are at increased risk for developing severe dengue.

Symptoms of severe dengue

Warning signs of severe dengue

Watch for signs and symptoms of severe dengue. Warning signs generally begin in the 24–48 hours after your fever has gone away.

If you or a family member develops any of the following symptoms, immediately go to a local clinic or emergency room:

• Stomach or belly pain, tenderness
• Vomiting (at least 3 times in 24 hours)
• Bleeding from the nose or gums
• Vomiting blood, or blood in the stool
• Feeling tired, restless, or irritable

Flavivirus

Diagnosis

Clinicians should consider dengue in a patient with a clinically compatible illness, and who lives in or recently traveled to a disease-endemic area in the 2 weeks before symptom onset. Patients typically present with acute onset of fever, headache, body aches, and sometimes rash spreading from the trunk. All patients with clinically suspected dengue should receive appropriate management to monitor for shock and reduce the risk of complications resulting from increased vascular permeability and plasma leakage and organ damage without waiting for diagnostic test results to be received. In the United States, because dengue is a nationally notifiable disease, all suspected cases should be reported to the local health department.

Diagnostic Testing

• Most state health departments and many commercial laboratories perform dengue diagnostic testing.
• Nucleic acid amplification tests (NAATs)
• For patients with suspected dengue virus disease, NAATs are the preferred method of laboratory diagnosis.
• NAATs should be performed on serum specimens collected 7 days or less after symptom onset.
• Laboratory confirmation can be made from a single acute-phase serum specimen obtained early (≤7 days after fever onset) in the illness by detecting viral genomic sequences with rRT-PCR or dengue nonstructural protein 1 (NS1) antigen by immunoassay.
• Presence of virus by rRT-PCR or NS1 antigen in a single diagnostic specimen is considered laboratory confirmation of dengue in patients with a compatible clinical and travel history.

Dengue fever symptoms

Serologic tests

IgM antibody testing can identify additional infections and is an important diagnostic tool.

• Interpreting the results is complicated by cross-reactivity with other flaviviruses, like Zika, and determining the specific timing of infection can be difficult.
• Later in the illness (≥4 days after fever onset), IgM against dengue virus can be detected with MAC-ELISA.
• For patients presenting during the first week after fever onset, diagnostic testing should include a test for dengue virus (rRT-PCR or NS1) and IgM.
• For patients presenting >1 week after fever onset, IgM detection is most useful, although NS1 has been reported positive up to 12 days after fever onset.
• In the United States, both MAC-ELISA and rRT-PCR are approved as in vitro diagnostic tests.
• IgM in a single serum sample strongly suggests a recent dengue virus infection and should be presumed confirmatory for dengue if the infection occurred in a place where other potentially cross-reactive flaviviruses (such as Zika, West Nile, yellow fever, and Japanese encephalitis viruses) are not a risk.
• PRNTs can resolve false-positive IgM antibody results caused by non-specific reactivity, and, in some cases, can help identify the infecting virus.

Course of Dengue illness vectorized

Cross-reactive flaviviruses

• If infection is likely to have occurred in a place where other potentially cross-reactive flaviviruses circulate, both molecular and serologic diagnostic testing for dengue and other flaviviruses should be performed.
• People infected with or vaccinated against other flaviviruses (such as yellow fever or Japanese encephalitis) may produce cross-reactive flavivirus antibodies, yielding false-positive serologic dengue diagnostic test results.

IgG antibody testing

IgG detection by ELISA in a single serum sample is not useful for diagnostic testing because it remains detectable for life after a dengue virus infection.

Treatment of severe dengue

• If you develop any warning signs, see a healthcare provider or go to the emergency room immediately.
• Severe dengue is a medical emergency and requires immediate medical attention or hospitalization.
• If you are traveling, find health care provider abroad.

Prevention

• Prevent dengue by avoiding mosquito bites.
• All four dengue viruses are spread primarily through the bite of an infected Aedes species (Ae. aegypti and Ae. albopictus) mosquito. These mosquitoes also spread chikungunya and Zika viruses.
• The mosquitoes that spread dengue are found in most tropical and subtropical regions of the world, including many parts of the United States.
• Ae. aegypti and Ae. albopictus bite during the day and night.
• A dengue vaccine is available for use in some parts of the world, including United States territories.

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