Ebola virus infection
One of the most frightening viruses to come out of the African subcontinent, the Ebola virus first appeared in 1976. More than 400 persons in Zaire (now known as the Democratic Republic of Congo) and the neighboring Sudan died because of the hemorrhagic fever that the virus causes. Ebola virus has been responsible for several outbreaks since then, including one that occurred in Zaire in the summer of 1995.
An unclassified ribonucleic acid (RNA) virus, Ebola virus is morphologically similar to the Marburg virus. Both viruses cause headache, malaise, myalgia, and high fever, progressing to severe diarrhea, vomiting, and internal and external hemorrhage.
Four strains of the Ebola virus are known to exist: Ebola Zaire, Ebola Sudan, Ebola Tai, and Ebola Reston. All four types are structurally similar but have different antigenic properties. One type, Ebola Reston, affects only monkeys; the other three types affect humans.
The prognosis for Ebola virus disease is extremely poor, with a mortality rate as high as 90%. The incubation period ranges from 2 to 21 days.
Ebola virus disease is caused by an unclassified RNA virus that’s transmitted by direct contact with infected blood, body secretions, or organs. Nosocomial and community-acquired transmission can occur. The virus remains contagious even after the patient has died.
Signs and symptoms
The patient’s health history usually reveals contact with an infected person. However, no clear line of infection may be apparent at the beginning of an Ebola virus outbreak. The patient usually complains of flulike signs and symptoms, such as headache, malaise, myalgia, fever, cough, and sore throat, which first appear within 3 days of infection.