Dengue is a mosquito-borne disease caused by any one of four closely related dengue viruses (DENV-1, -2, -3, and -4). Infection with one serotype of DENV provides immunity to that serotype for life, but provides no long-term immunity to other serotypes. Thus, a person can be infected as many as four times, once with each serotype. Dengue viruses are transmitted from person to person by Aedes mosquitoes (most often Aedes aegypti) in the domestic environment.
Classic dengue fever, or “break bone fever,” is characterized by acute onset of high fever 3–14 days after the bite of an infected mosquito. Symptoms include frontal headache, retro-orbital pain, myalgias, arthralgias, hemorrhagic manifestations, rash, and low white blood cell count. The patient also may complain of anorexia and nausea. Acute symptoms, when present, usually last about 1 week, but weakness, malaise, and anorexia may persist for several weeks
The main medical complications of classic dengue fever are febrile seizures and dehydration. Treatment of dengue fever emphasizes
• Relieving symptoms of pain.
• Controlling fever.
• Reminding patients to drink more fluids, especially when they have a high fever.
Dengue Hemorrhagic Fever and Dengue Shock Syndrome
Some patients with dengue fever go on to develop dengue hemorrhagic fever (DHF), a severe and sometimes fatal form of the disease. Around the time the fever begins to subside (usually 3–7 days after symptom onset), the patient may develop warning signs of severe disease. Warning signs include severe abdominal pain, persistent vomiting, marked change in temperature (from fever to hypothermia), hemorrhagic manifestations, or change in mental status (irritability, confusion, or obtundation)
The patient also may have early signs of shock, including restlessness, cold clammy skin, rapid weak pulse, and narrowing of the pulse pressure (systolic blood pressure − diastolic blood pressure). Patients with dengue fever should be told to return to the hospital if they develop any of these signs.
DHF is currently defined by the following four World Health Organization (WHO) criteria:
• Fever or recent history of fever lasting 2–7 days.
• Any hemorrhagic manifestation.
• Thrombocytopenia (platelet count of below100, 000/mm3).
• Evidence of increased vascular permeability.
Dengue shock syndrome (DSS) is defined as any case that meets the four criteria for DHF and has evidence of circulatory failure manifested by (1) rapid, weak pulse and narrow pulse pressure (20 mmHg [2.7 kPa]) or (2) hypotension for age, restlessness, and cold, clammy skin. Patients with dengue can rapidly progress into DSS, which, if not treated correctly, can lead to severe complications and death.
Unequivocal diagnosis of dengue infection requires laboratory confirmation, either by isolating the virus or detecting dengue-specific antibodies. For virus isolation or detection of DENV RNA in serum specimens by serotype-specific, real-time reverse transcriptase polymerase chain reaction (RT-PCR), an acute-phase serum specimen should be collected within 5 days of symptom onset.
If the virus cannot be isolated or detected from this sample, a convalescent-phase serum specimen is needed at least 6 days after the onset of symptoms to make a serologic diagnosis by testing for IgM antibodies to dengue with an IgM antibody-capture enzyme-linked immunosorbent assay (MAC-ELISA).
How to Treat Dengue Fever
• Tell patients to drink plenty of fluids and get plenty of rest.
• Tell patients to take antipyretics to control their temperature. Children with dengue are at risk for febrile seizures during the febrile phase of illness.
• Monitor your patients’ hydration status during the febrile phase of illness. Educate patients and parents about the signs of dehydration and have them monitor their urine output.
• If patients cannot tolerate fluids orally, they may need IV fluids. Assess hemodynamic status frequently by checking the patient’s heart rate, capillary refill, pulse pressure, blood pressure, and urine output.
• Perform hemodynamic assessments, baseline hematocrit testing, and platelet counts.