Introduction to Ebola hemorrhagic fever
• Ebola [ee-BO-luh] hemorrhagic fever is a deadly disease that has occurred in outbreaks in Central Africa.
• Ebola hemorrhagic fever is caused by several Ebola viruses. The source of these viruses in nature is not known.
• People can get Ebola hemorrhagic fever by direct contact with virus-infected blood, body fluids, organs, or semen.
• There is no known cure or treatment.
• Recent outbreaks in humans have occurred in areas where medical supplies and care were inadequate. The outbreaks were controlled by using barrier nursing techniques.
• Under normal circumstances, travelers are at low risk of getting the disease. To eliminate the risk, travelers should avoid areas where Ebola outbreaks are occurring.
What is Ebola hemorrhagic fever?
Ebola hemorrhagic fever is one of the deadliest of a group of diseases called viral hemorrhagic fevers. They range in seriousness from relatively mild illnesses to severe and potentially fatal diseases. All forms of viral hemorrhagic fever begin with fever and muscle aches. Depending on the virus, the disease can get worse until the patient becomes very ill with breathing problems, severe bleeding (hemorrhage), kidney problems, and shock. You die, bleeding from every pore as your internal organs are liquefied and turned to mush. Ebola is the 2nd most lethal disease of the 20th Century. Untreated rabies is 100% fatal, treated Ebola is 80-90% fatal. The virus has a very brief survival period outside its host. When anywhere around Ebola, masks and gloves are minimal requirements.
Viral hemorrhagic fevers are caused by viruses from four families: 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, the natural host for the virus is not known.
What is the infectious agent that causes Ebola hemorrhagic fever?
Ebola hemorrhagic fever is caused by several Ebola viruses. Ebola viruses are members of the filovirus family; when magnified several thousand times by an electron microscope, these viruses look like threads (filaments). Ebola virus was discovered in 1976 and named for a river in Zaire, Africa, where it was first detected.
Where is Ebola hemorrhagic fever found?
Ebola viruses are found in Central Africa. The source of the viruses in nature remains unknown. Monkeys, like humans, appear to be susceptible to infection and might serve as a source of virus if infected.
How do people get Ebola hemorrhagic fever?
People get the disease by direct contact with virus-infected blood, body fluids, organs, or semen.
The disease is spread mainly by close person-to-person contact with severely ill patients. This happens most often to hospital-care workers and family members who care for an ill person infected with Ebola virus. Close personal contact with persons who are infected but show no signs of active disease is very unlikely to result in infection.
Transmission of the virus has also been linked to the re-use of hypodermic needles in the treatment of patients. Re-using 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 re-use needles.
Ebola virus can be spread from person to person through sexual contact. Persons who have recuperated from an illness caused by Ebola virus can still have the virus in their genital secretions for a short time after recovery and can spread the virus through sexual activity.
What are the signs and symptoms of Ebola hemorrhagic fever?
People infected with Ebola virus have sudden fever, weakness, muscle pain, headache, and sore throat, followed by vomiting, diarrhea, rash, limited kidney and liver functions, and both internal and external bleeding. Death rates range from 50% to 90%.
How soon after exposure do symptoms appear?
Symptoms begin 2 to 21 days after infection.
How is Ebola hemorrhagic fever diagnosed?
Diagnosis requires specialized laboratory tests on blood specimens. Handling blood from a persons infected with Ebola virus is an extreme biohazard and can be done only in specially equipped laboratories. Diagnosis in patients who have died can be made by testing tissue samples.
Who is at risk for Ebola hemorrhagic fever?
• Persons traveling to areas where Ebola hemorrhagic fever is occurring
• Hospital staff and family members who care for patients with Ebola hemorrhagic fever
• Central African residents of rural areas and small towns
What is the treatment for Ebola hemorrhagic fever?
There is no known cure or treatment. Severe cases need intensive supportive care.
How common is Ebola hemorrhagic fever?
Until recently, only three outbreaks of Ebola hemorrhagic fever in humans had been reported. The first two, in 1976 in Zaire and in western Sudan, were large outbreaks that resulted in more than 550 cases and 340 deaths. The third outbreak, in 1979 in Sudan, was smaller, with 34 cases and 22 deaths. In each of these outbreaks, most cases occurred in hospitals where medical supplies were inadequate and where needles and syringes were re-used. The outbreaks were quickly controlled by isolating sick patients in a place requiring the wearing of mask, gown, and gloves; sterilizing needles and syringes; and disposing of wastes and corpses in a sanitary way.
In 1995, an outbreak in Kikwit and surrounding areas in Bandundu Province, Zaire, caused 316 deaths. The outbreak was amplified in a hospital by staff who became infected through poor nursing techniques. At the request of health officials in Zaire, medical teams from CDC and the World Health Organization, and from Belgium, France, and South Africa, collaborated to investigate and control the outbreak.
Two isolated cases of Ebola hemorrhagic fever were identified in Cote d’Ivoire in 1994-1995. The most recent outbreaks were in rural Gabon in 1994 and in 1996. A patient from the 1996 Gabon outbreak traveled to Johannesburg, South Africa, and fatally infected a health-worker there as well.
How can Ebola hemorrhagic fever be prevented?
Under normal circumstances, travelers are at low risk of getting the disease. To eliminate the risk, travelers should avoid areas where Ebola outbreaks are occurring.
A notoriously deadly virus that causes fearsome symptoms, the most prominent being high fever and massive internal bleeding. Ebola virus kills as many as 90% of the people it infects. It is one of the viruses that is capable of causing hemorrhagic (bloody) fever.
Epidemics of Ebola virus have occurred mainly in African countries including Zaire (now the Democratic Republic of Congo), Gabon, Uganda, the Ivory Coast, and Sudan. Ebola virus is a hazard to laboratory workers and, for that matter, anyone who is exposed to it.
Infection with Ebola virus in humans is incidental — humans do not “carry” the virus. The way in which the virus first appears in a human at the start of an outbreak has not been determined. However, it has been hypothesized that the first patient (the index case) becomes infected through contact with an infected animal.
Ebola virus is transmitted by contact with blood, feces or body fluids from an infected person or by direct contact with the virus, as in a laboratory. People can be exposed to Ebola virus from direct contact with the blood or secretions of an infected person. This is why the virus has often been spread through the families and friends of infected persons: in the course of feeding, holding, or otherwise caring for them, family members and friends would come into close contact with such secretions. People can also be exposed to Ebola virus through contact with objects, such as needles, that have been contaminated with infected secretions.
The incubation period –the period between contact with the virus and the appearance of symptoms — ranges from 2 to 21 days.
The initial symptoms are usually high fever, headache, muscle aches, stomach pain, and diarrhea. There may also be sore throat, hiccups, and red and itchy eyes. The symptoms that tend to follow include vomiting and rash and bleeding problems with bloody nose (epistaxis), spitting up blood from the lungs (hemoptysis) and vomiting it up from the stomach (hematemesis), and bloody eyes (conjunctival hemorrhages). Then finally come chest pain, shock, and death.
A protein on the surface of the virus has been discovered that is responsible for the severe internal bleeding (the death-dealing feature of the disease). The protein attacks and destroys the endothelial cells lining blood vessels, causing the vessels to leak and bleed.
There is no specific treatment for the disease. Currently, patients receive supportive therapy. This consists of balancing the patient’s fluids and electrolytes, maintaining their oxygen level and blood pressure, and treating them for any complicating infections. Death can occur within 10 days of the onset of symptoms.
The prevention of the spread of Ebola fever involves practical viral hemorrhagic fever isolation precautions, or barrier nursing techniques. These techniques include the wearing of protective clothing, such as masks, gloves, gowns, and goggles; the use of infection-control measures, including complete equipment sterilization; and the isolation of Ebola fever patients from contact with unprotected persons. The aim of all of these techniques is to avoid any person’s contact with the blood or secretions of any patient. If a patient with Ebola fever dies, it is equally important that direct contact with the body of the deceased patient be prevented.
Bioterrorism — There has been concern about Ebola virus as a possible weapon for bioterrorism. However, the General Accounting Office, the investigative arm of the US Congress, in a 1999 report considered Ebola virus to be an “unlikely” biologic threat for terrorism, because the virus is very difficult to obtain and process, unsafe to handle, and relatively unstable.
Table: Cases of Ebola Hemorrhagic Fever in Africa, 1976 – 2008
|Dem. Rep. of Congo||Yambuku||318||280||Ezaire||1976|
|Dem. Rep. of Congo||Tandala||1||1||Ezaire||1977|
|Ivory Coast||Tai Forest||1||0||EIvoryCoast||1994|
|Dem. Rep. of Congo||Kikwit||315||250||Ezaire||1995|
|Republic of Congo||Not specified||57||43||Ezaire||2001|
|Republic of Congo||Mbomo||143||128||Ezaire||2002|
|Republic of Congo||Mbomo||35||29||Ezaire||2003|
|Dem. Rep. of Congo||Luebo||264||187||Ezaire||2007|
|Dem. Rep. of Congo||Luebo||32||15||Ezaire||2008|