Dengue fever

[Anonymous]

Classical Dengue or “break-bone fever” has been known in India for a very long time. It is an acute viral infection, by at least 4 serotypes (DEN1, 2, 3 and 4) of dengue virus. Of all the arthropod-borne viral diseases, dengue fever is the most common. Dengue fever is one of the most important emerging diseases of the tropical and subtropical regions, affecting urban and periurban areas. Dengue fever can occur epidemically or endemically. Epidemics may be explosive and often start during the rainy season when the breeding of the vector mosquitoes (e.g., Aedes aegypti) is generally abundant. The geographical distribution of the disease has greatly expanded and the number of cases has increased dramatically in the past 30years. A pandemic in 1998, in which 1.2 million cases of dengue fever and dengue haemorrhagic fever were reported from 56countries, was unprecedented. Preliminary data for 2001 indicates a situation of comparable magnitude. However, only a small proportion of cases were reported to WHO; it is estimated that each year 50 million infections occur, with 5,00,000 cases of dengue haemorrhagic fever and at least 1200 deaths, manly among children, although fatalities could be twice as high. The increase of dengue and dengue hemorrhagic fever is due to uncontrolled population growth and urbanization without appropriate water management. The global spread of dengue via travel and trade has made every country to be aware about this threat.

Dengue virus infection can be asymptomatic or cause illnesses ranging from mild undifferentiated fever to severe disease, including hemorrhagic manifestations and shock. Dengue hemorrhagic fever (DHF) is characterized fever, minor or major bleeding phenomena, thrombocytopenia (<100,000 platelets/mm3), and evidence of increased vascular permeability (e.g., hemoconcentration [hematocrit increased by >20% from baseline], pleural or abdominal effusions, or hypoproteinemia). Dengue shock syndrome (DSS) is DHF with signs of circulatory failure, including narrow pulse pressure (<20 mmHg), hypotension, or shock, and might result in a case fatality rate of approximately 10% .
Health problems are self-reported by 22 to 64 percent of travelers to the developing world8; most of these problems are mild, self-limited illnesses such as diarrhea, respiratory infections, and skin disorders. More importantly, each year, up to 8 percent of the more than 50 million travelers to these regions, or 4 million persons, are ill enough to seek health care either while abroad or on returning home.

        

[Anonymous]

TREATMENT
Dengue fever is usually a self-limited illness, and only supportive care is required. Acetaminophen may be used to treat patients with symptomatic fever. Aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), and corticosteroids should be avoided.
Patients with known or suspected dengue fever should have their platelet count and hematocrit measured daily from the third day of illness until 1-2 days after defervescence. Patients with a rising hematocrit level or falling platelet count should have intravascular volume deficits replaced. Patients who improve can continue to be monitored in an outpatient setting. Patients who do not improve should be admitted to the hospital for continued hydration.
Patients who develop signs of dengue hemorrhagic fever warrant closer observation. Patients who develop signs of dehydration, such as tachycardia, prolonged capillary refill time, cool or mottled skin, diminished pulse amplitude, altered mental status, decreased urine output, rise in hematocrit levels, narrowed pulse pressure, or hypotension, require admission for intravenous fluid administration.
Successful management of severe dengue requires careful attention to fluid management and proactive treatment of hemorrhage. Intravascular volume deficits should be corrected with isotonic fluids such as Ringers lactate solution. Boluses of 10-20 mL/kg should be given over 20 minutes and may be repeated. If this fails to correct the deficit, the hematocrit value should be determined, and, if it is rising, limited clinical information suggests that a plasma expander may be administered. Starch, dextran 40, or albumin 5% at a dose of 10-20 mL/kg may be used. One recent study has suggested that starch may be preferable because of hypersensitivity reactions to dextran.[35] If the patient does not improve after this, blood loss should be considered. Patients with internal or gastrointestinal bleeding may require transfusion. Patients with coagulopathy may require fresh frozen plasma.
After patients with dehydration are stabilized, they usually require intravenous fluids for no more than 24-48 hours. Intravenous fluids should be stopped when the hematocrit level falls below 40% and adequate intravascular volume is present. At this time, patients reabsorb extravasated fluid and are at risk for volume overload if intravenous fluids are continued. Do not interpret a falling hematocrit value in a clinically improving patient as a sign of internal bleeding.
Platelet and fresh frozen plasma transfusions may be required to control severe bleeding. A recent case report demonstrated good improvement following intravenous anti-D globulin administration in two patients. The authors proposed that, similarly to nondengue forms of immune thrombocytopenic purpura, intravenous anti-D produces Fcγ receptor blockade to raise platelet counts.[36]
Patients who are resuscitated from shock rapidly recover. Patients with dengue hemorrhagic fever or dengue shock syndrome may be discharged from the hospital when they meet the following criteria:
Afebrile for 24 hours without antipyretics
Good appetite, clinically improved condition
Adequate urine output
Stable hematocrit level
At least 48 hours since recovery from shock
Absence of respiratory distress
Platelet count greater than 50,000 cells/μL.

        

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