Lassa fever
Lassa fever: Excerpt from Professional Guide to Diseases (Eighth Edition)
Lassa fever is an epidemic hemorrhagic fever caused by the Lassa virus, an extremely virulent arenavirus. This highly fatal disorder kills 10% to 50% of its victims, but those who survive its early stages usually recover and acquire immunity to secondary attacks.
Causes and incidence
A chronic infection in rodents, Lassa virus is transmitted to humans by contact with infected rodent urine, feces, and saliva. The virus enters the bloodstream, lymph vessels, and respiratory and digestive tracts. It then multiplies in the cells of the reticuloendothelial system. In the early stages of this illness, when the virus is in the throat, human transmission may occur through inhalation of infected droplets.
As many as 100 cases of Lassa fever occur annually in western Africa; the disease is rare in the United States.
Signs and symptoms
After a 7- to 18-day incubation period, this disease produces a fever that persists for 2 to 3 weeks, exudative pharyngitis, oral ulcers, lymphadenopathy with swelling of the face and neck, purpura, conjunctivitis, and bradycardia. Severe infection may also cause hepatitis, myocarditis, pleural infection, encephalitis, and permanent unilateral or bilateral deafness.
Virus multiplication in reticuloendothelial cells causes capillary lesions that lead to erythrocyte and platelet loss; mild to moderate thrombocytopenia (with a tendency toward bleeding); and secondary bacterial infection. These capillary lesions may also cause focal hemorrhage in the stomach, small intestine, kidneys, lungs, and brain and, possibly, hemorrhagic shock and peripheral vascular collapse.
Diagnosis
CONFIRMING DIAGNOSIS Isolation of the Lassa virus from throat washings, pleural fluid, or blood confirms the diagnosis.
Recent travel to an endemic area and specific antibody titer support the diagnosis.
Treatment
Treatment of Lassa fever includes I.V. ribavirin, I.V. colloids for shock, analgesics for pain, and antipyretics for fever. Infusion of immune plasma from patients who have recovered from Lassa fever may be useful, but test results on the benefit of this type of therapy are inconclusive.
Special considerations
❑Carefully monitor fluid and electrolyte status, vital signs, and intake and output. Watch for and immediately report signs of infection or shock.
❑Contact precautions are necessary for at least 3 weeks, until the patient's throat washings and urine are free of the virus. To prevent the spread of this contagious disease, carefully dispose of, or disinfect, all materials contaminated with the infected patient's urine, feces, respiratory secretions, or exudates. Watch known contacts closely for at least 3 weeks for signs of the disease.
❑Provide good oral care. Remember to clean the patient's mouth with a soft-bristled toothbrush to avoid irritating any oral ulcers. Ask your facility's dietary department to supply a soft, bland, nonirritating diet.
❑Immediately contact the Viral Diseases Division of the Centers for Disease Control and Prevention in Atlanta to get specific guidelines for managing suspected or confirmed cases of Lassa fever.
❑Report all cases of Lassa fever to the local health department.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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