Ebola virus and Marburg virus are related viruses that may cause hemorrhagic fevers. These are marked by severe bleeding (hemorrhage), organ failure and, in many cases, death. Both viruses are native to Africa, where sporadic outbreaks have occurred for decades.

Ebola virus and Marburg virus live in animal hosts. Humans can get the viruses from infected animals. After the initial transmission, the viruses can spread from person to person through contact with body fluids or unclean items such as infected needles.

No drug has been approved to treat Ebola virus or Marburg virus. People diagnosed with Ebola virus or Marburg virus receive supportive care and treatment for complications. One vaccine has been approved for Ebola virus. Scientists are studying other vaccines for these deadly diseases.

Signs and symptoms typically begin abruptly within five to 10 days of infection with Ebola virus or Marburg virus. Early signs and symptoms include:

• Fever
• Severe headache
• Joint and muscle aches
• Chills
• Weakness

Over time, symptoms become increasingly severe and may include:

• Nausea and vomiting
• Diarrhea (may be bloody)
• Red eyes
• Raised rash
• Chest pain and cough
• Sore throat
• Stomach pain
• Severe weight loss
• Bruising
• Bleeding, usually from the eyes, and when close to death, possible bleeding from the ears, nose and rectum
• Internal bleeding

Ebola virus has been found in African monkeys, chimps and other nonhuman primates. A milder strain of Ebola has been discovered in monkeys and pigs in the Philippines.

Marburg virus has been found in monkeys, chimps and fruit bats in Africa.

Transmission from animals to humans

Experts suspect that both viruses spread to humans through an infected animal's bodily fluids. Examples include:

• Blood. Killing or eating infected animals can spread the viruses. Scientists who have operated on infected animals as part of their research have also caught the virus.
• Waste products. Tourists in certain African caves and some underground mine workers have been infected with the Marburg virus, possibly through contact with the feces or urine of infected bats.

Transmission from person to person

People who have Ebola virus or Marburg virus typically don't become contagious until they develop symptoms. The viruses can spread through blood, body fluids, or contaminated items such as bedding, clothing or needles. Family members can be infected as they care for sick relatives or prepare the dead for burial.

Medical personnel can be infected if they don't use specialized personal protective equipment that covers them from head to toe.

There's no evidence that Ebola virus or Marburg virus can be spread via insect bites.

For most people, the risk of getting Ebola virus or Marburg virus is low. The risk increases if you:

• Travel to Africa. You're at increased risk if you visit or work in areas where Ebola virus or Marburg virus outbreaks have occurred.
• Conduct animal research. People are more likely to contract the Ebola virus or Marburg virus if they conduct animal research with monkeys imported from Africa or the Philippines.
• Provide medical or personal care. Family members are often infected as they care for sick relatives. Medical personnel also can be infected if they don't use specialized personal protective equipment that covers them from head to toe.
• Prepare people for burial. The bodies of people who have died of Ebola virus or Marburg virus are still contagious. Helping prepare these bodies for burial can increase your risk of getting the viruses.

Both Ebola virus and Marburg virus lead to death for a high number of people who are affected. As the illnesses progress, the viruses can cause:

• Multiple organ failure
• Severe bleeding
• Jaundice
• Delirium
• Seizures
• Coma
• Shock

One reason the viruses are so deadly is that they interfere with the immune system's ability to mount a defense. But scientists don't understand why some people recover from Ebola virus and Marburg virus and others don't.

For people who survive, recovery is slow. It may take months to regain weight and strength, and the viruses remain in the body for weeks. People may experience:

• Hair loss
• Sensory changes
• Liver inflammation (hepatitis)
• Weakness
• Fatigue
• Headaches
• Eye inflammation
• Testicular inflammation

Prevention focuses on avoiding contact with the viruses. The following precautions can help prevent infection and spread of Ebola virus and Marburg virus.

• Avoid areas of known outbreaks. Before traveling to Africa, find out about current epidemics by checking the Centers for Disease Control and Prevention website.
• Wash your hands frequently. As with other infectious diseases, one of the most important preventive measures is frequent hand-washing. Use soap and water, or use alcohol-based hand rubs containing at least 60% alcohol when soap and water aren't available.
• Avoid bush meat. In developing countries, avoid buying or eating the wild animals, including nonhuman primates, sold in local markets.
• Avoid contact with infected people. In particular, caregivers should avoid contact with an infected person's body fluids and tissues, including blood, semen, vaginal secretions and saliva. Also avoid the person's clothing, bedding or other items that may have touched him or her. People with Ebola virus or Marburg virus are most contagious in the later stages of the disease.
• Follow infection-control procedures. If you're a health care worker, wear specialized personal protective equipment that covers you from head to toe. Keep people who have the viruses isolated from others. Safely throw away needles and sterilize other instruments.
• Don't handle remains. The bodies of people who have died of Ebola virus or Marburg virus are still contagious. Specially organized and trained teams should bury the remains, using appropriate safety equipment.

Vaccine approval and research development

The U.S. Food and Drug Administration (FDA) recently approved an Ebola vaccine. It's given as a single dose and has been found to be effective and safe to use.

Another Ebola vaccine has been developed and used in the Democratic Republic of Congo in a research study. It requires two doses, taken 56 days apart.

Scientists continue to work on a variety of vaccines that would protect people from Ebola virus and Marburg virus. Research is ongoing.

Ebola virus and Marburg virus are difficult to diagnose because early signs and symptoms resemble those of other diseases, such as typhoid and malaria. If doctors suspect that you have Ebola virus or Marburg virus, they use blood tests to quickly identify the virus, including:

• Enzyme-linked immunosorbent assay (ELISA)
• Reverse transcriptase polymerase chain reaction (PCR)

No antiviral medications have proved effective in treating infection with either Ebola virus or Marburg virus. Supportive hospital care includes:

• Providing fluids
• Maintaining blood pressure
• Providing oxygen as needed
• Replacing lost blood
• Treating other infections that develop

The possibility of getting Ebola virus or Marburg virus is extremely low unless you've had direct contact with the body fluids of a person or an animal infected with one of the viruses.

If you think that you or a family member may have been exposed to one of the viruses, call your doctor or go to the nearest emergency room immediately. If you're not referred to an infectious disease specialist, ask to see one.

If you're from the United States and traveling or working abroad, the nearest U.S. Embassy can help you find a doctor. If you're from another country, contact your country's embassy. Be sure to tell your doctor or hospital about your symptoms before your visit so that precautions can be taken to prevent transmission of the virus to others.

What you can do

Before your appointment, to help your doctor find the cause of your symptoms, write a list that answers the following questions:

• What symptoms do you have? When did they start?
• Have you recently traveled in Africa? If so, what part?
• If you were recently in Africa, did you hunt or eat monkeys?
• Did you recently visit caves or underground mines in Africa?
• Are you employed in a lab that uses monkeys from Africa or the Philippines in research?

If possible, take a family member or friend with you. Sometimes it can be difficult to remember all the information provided to you in the hospital or during an appointment. Someone who accompanies you may remember something you missed or forgot.