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INITIAL SYMPTOMS:
Flu-like illness with high fever, severe headache, myalgia, arthralgia, and lymphadenopathy, followed by rash; Mild cases remit within 72 hours, usually without lymphadenopathy. Some patients have cough, sore throat , and rhinitis. [Merck Manual, p. 1431]
FINDINGS:
About 75% of infections are asymptomatic. The three phases of disease are febrile, critical, and convalescent. Fever lasts 2-7 days and may be biphasic. In the first phase, patients may have severe pain in the head, eyes, joints, and extremities. Other early symptoms are rash, minor hemorrhagic manifestations (petechiae, ecchymosis, purpura, epistaxis, bleeding gums, hematuria) and erythema of the face and oropharynx. It is important to recognize the early warnings of shock and begin intensive care treatment. Warning signs of severe dengue in the late febrile phase include persistent vomiting, severe abdominal pain, mucosal bleeding difficulty breathing, shock, and rapidly dropping platelet count and hematocrit (thrombocytopenia and hemoconcentration). Findings in the critical phase include pleural effusions, ascites, hypoproteinemia, hematemesis, bloody stool, melena, and menorrhagia. Atypical findings include hepatitis, myocarditis, pancreatitis, and encephalitis. Bradycardia and diuresis occur during convalescence. [CDC Travel, p. 162-8] This illness begins with 3-7 days of fever and severe myalgias followed by a maculopapular rash. The rash spares the palms and soles, but desquamation may involve the palms and soles. Hematuria is infrequent, and jaundice is rare. [Guerrant, p. 954] DHF/DSS typically occurs at the time of defervescence with the onset of lethargy, thrombocytopenia, and hemoconcentration, and in severe cases, shock, cyanosis, hepatomegaly, ascites, pleural effusions, and GI bleeding. [Harrison, p. 722, 726-7] During convalescence, some patients develop an erythematous rash that may later desquamate. [CCDM, p. 144-5] CNS adverse effects in <5% of cases: encephalopathy or seizures. [ABX Guide]
EPIDEMIOLOGY:
The incidence of Dengue fever is highest in urban areas in tropical and subtropical regions around the world. It is endemic in Puerto Rico, the US Virgin Islands, and US-affiliated Pacific Islands. Sporadic outbreaks have occurred in Florida, Hawaii, and near the Texas-Mexico border. [CDC Travel, p. 162] Dengue hemorrhagic fever affects mainly children < 10 years of age living in endemic areas. The mortality rate ranges from <1% (experienced medical centers) to 30%. [Merck Manual, p. 1432] Monkeys may be reservoirs for dengue fever in Southeast Asia and West Africa. [CCDM, p. 166] There are 4 serotypes of the virus carried by the mosquito Aedes aegypti, which also carries yellow fever virus. The illness lasts about 1 week, and a rash is often present at the time of defervescence. A small proportion of dengue fever patients (usually children under the age of 12) develop dengue hemorrhagic fever/shock syndrome (DHF/DSS). This occurs when the patient has a subsequent infection with a different serotype. "The severe syndrome is unlikely to be seen in U.S. citizens since few children have the dengue antibodies that can trigger the pathogenic cascade when a second infection is acquired." [Harrison ID, p. 1036, 1049]
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