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FINDINGS: About 80% of infections are asymptomatic or mild. Findings of severe infections may include shock, pleural effusions, hemorrhages, seizures, encephalopathy, albuminuria, elevated liver enzymes, and nerve deafness. [CCDM, p. 289-92] The typical case starts as a flu-like illness with pharyngitis, cough, chest pain, conjunctivitis, and abdominal pain. Some patients then develop the severe form of the disease with neck swelling and mild bleeding from the conjunctiva, nose, mouth, gastrointestinal, and genitourinary tracts. Maculopapular or petechial rashes may be visible in patients with lighter skin complexions. Some patients deteriorate with delirium, respiratory distress, shock, coma, and death. [Guerrant, p. 744] By the end of the first week, patients are very ill with high fever. Common symptoms are conjunctivitis, stomatitis, pharyngitis, cervical lymphadenopathy, abdominal pain, myalgias, arthralgias, hypotension, and relative bradycardia. There is no typical rash. Most patients do not have evidence of neurological disease. Leukopenia is common early in the illness, and leukocytosis is seen later. Platelet counts are not depressed, but platelet function is impaired. [ID, p. 2136; JAMA] Common symptoms are fever, pharyngitis, chest pain, and proteinuria. Other findings are mucosal bleeding, encephalitis, stiff neck, pulmonary edema, and pericarditis. [PPID, p. 2095] EPIDEMIOLOGY: Lassa fever is a common disease in West Africa with thousands to tens of thousands of cases a year. [ID, p. 2133] For hospitalized patients, Lassa fever has a 15% case-fatality rate. Transmission occurs through contact with infected rodents or infected patients (blood, urine, throat secretions, and sexual contact). Patients excrete the virus in urine for several weeks. Ribavirin, given intravenously, is most effective when started early in the illness. [CCDM] |
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