What are viral hemorrhagic fevers?
Viral hemorrhagic fevers are a group of diseases caused by viruses from four distinct families of viruses: filoviruses, arenaviruses, flaviviruses, and bunyaviruses. The usual hosts for most of these viruses are rodents or arthropods (such as ticks and mosquitoes). In some cases, such as Ebola virus, the natural host for the virus is unknown. All forms of viral hemorrhagic fever begin with fever and muscle aches. Depending on the particular virus, the disease can progress until the patient becomes very ill with respiratory problems, severe bleeding, kidney problems, and shock. The severity of viral hemorrhagic fever can range from a relatively mild illness to death.
What is Ebola virus?
The Ebola virus is a member of a family of RNA viruses known as filoviruses. When magnified several thousand times by an electron microscope, these viruses have the appearance of long filaments or threads. Ebola virus was discovered in 1976 and was named for a river in Zaire, Africa, where it was first detected.
Ebola virus hemorrhagic fever: How common is it?
Until recently, only three outbreaks of Ebola hemorrhagic fever among people had been reported. The first two outbreaks were in 1976: one in Zaire and one in western Sudan. These were large outbreaks, resulting in more than 550 cases and 340 deaths. The third outbreak, in 1979 in Sudan, was smaller, with 34 cases and 22 fatalities. During each of these outbreaks, a majority of cases occurred in hospital settings under the challenging conditions of the developing world. These conditions, including a lack of adequate medical supplies and the frequent reusing of needles and syringes, played a major role in the spread of disease. The outbreaks were quickly controlled when appropriate medical supplies and equipment were made available and quarantine procedures were used.
The source of the Ebola virus in nature remains unknown. In an attempt to identify the source, investigators tested thousands of specimens from animals captured near the outbreak areas, but their efforts were unsuccessful. Monkeys, like humans, appear to be susceptible to infection and may serve as a source of virus if infected.
What do we know about the recent outbreak of Ebola virus infection?
The recent Ebola virus outbreak is centered in Kikwit, Zaire. (Kikwit is a city of 400,000 located 400 kilometers east of Kinshasa, the capital of Zaire.) The outbreak appears to have started with a patient who had surgery in Kikwit on April 10, 1995. Members of the surgical team then developed symptoms similar to those of a viral hemorrhagic fever disease. Ebola hemorrhagic fever was suspected by a Belgium physician who reported the disease to the Zairian government. At the request of Zairian health officials, medical teams from CDC, the World Health Organization, and from Belgium, France, and South Africa are collaborating to investigate and control the outbreak in Zaire.
What are the symptoms of Ebola hemorrhagic fever?
Symptoms of Ebola hemorrhagic fever begin 4 to 16 days after infection. Persons develop fever, chills, headaches, muscle aches, and loss of appetite. As the disease progresses, vomiting, diarrhea, abdominal pain, sore throat, and chest pain can occur. The blood fails to clot and patients may bleed from injection sites as well as into the gastrointestinal tract, skin, and internal organs.
How is the Ebola virus spread from person to person?
Ebola virus is spread through close personal contact with a person who is very ill with the disease. In previous outbreaks, person-to-person spread frequently occurred among hospital care workers or family members who were caring for an ill person infected with Ebola virus. Transmission of the virus has also occurred as a result of hypodermic needles being reused in the treatment of patients. Reusing needles is a common practice in developing countries, such as Zaire and Sudan, where the health care system is underfinanced. Medical facilities in the United States do not reuse needles.
Ebola virus can also be spread from person to person through sexual contact. Close personal contact with persons who are infected but show no signs of active disease is very unlikely to result in infection. Patients who have recovered from an illness caused by Ebola virus do not pose a serious risk for spreading the infection. However, the virus may be present in the genital secretions of such persons for a brief period after their recovery, and therefore it is possible they can spread the virus through sexual contact.
How is Ebola hemorrhagic fever diagnosed?
A diagnosis is made by detection of Ebola antigens, antibody, or genetic material, or by culture of the virus from these sources. Diagnostic tests are usually performed on clinical specimens that have been treated to inactivate (kill) the virus. Research on Ebola virus must be done in a special high-containment laboratory to protect scientists working with infected tissues.
How will health officials control the outbreak?
Previous outbreaks of Ebola hemorrhagic fever have been limited. These outbreaks were successfully controlled through the isolation of sick persons in a place requiring the wearing of mask, gown, and gloves; careful sterilization of needles and syringes; and proper disposal of waste and corpses.
How do hospital personnel isolate an ill person?
Hospital personnel isolate ill persons through a method called "barrier technique." Barrier technique includes the following actions: 1) doctors and nurses wear gowns, mask, gloves, and goggles when caring for patients; 2) the patient's visitors are restricted; 3) disposable materials are removed from the room and burned after use; 4) all reusable materials are sterilized before reuse; and 5) since the virus is easily destroyed by disinfectants, all hard surfaces are cleaned with a sanitizing solution.
Are persons in the United States at risk?
Persons in the United States are at risk only if they have had close personal contact with patients in Zaire who are infected with Ebola virus. There are no reports that infected persons have left the country of Zaire. The Zairian government has quarantined all persons in the affected areas and restricted movement of persons in and out of these areas. Any persons who wish to travel to Zaire are encouraged to contact the U.S. State Department (202-647-5225) for travel advisories.