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Ebola Virus and Marburg Virus Infections

By Craig R. Pringle, BSc, PhD, University of Warwick

Marburg and Ebola virus infections cause bleeding and organ malfunction. These infections often result in death.

  • These infections are spread through contact with skin or body fluids of an infected person who has symptoms or who has died.

  • Symptoms begin with a fever, muscle and body aches, headache, cough, and a sore throat, followed by vomiting and diarrhea as well as bleeding from the mouth, nose, or internal organs.

  • To confirm the diagnosis, doctors do blood and urine tests.

  • Strict isolation and sanitary precautions (and, for health care practitioners, use of protective clothing) are needed to prevent spread of the infection.

  • Treatment includes giving fluids and other treatments to maintain body functions.

Marburg and Ebola virus infections are hemorrhagic fevers (see Hemorrhagic Fevers Overview), characterized by bleeding. They are caused by viruses called filoviruses. (Other viruses can cause other hemorrhagic fevers.)

Outbreaks of Ebola and Marburg virus infections started in Central and West Africa, probably because the infections are common in wild animals there. Such outbreaks are rare and, in the past, have not spread very far because they typically occurred in isolated, rural areas. However, travelers from those areas sometimes carry the infection to nearby areas or, rarely, outside of Africa.

In December 2013, a large Ebola virus outbreak began in rural Guinea (West Africa), then spread to densely populated urban regions in Guinea and to neighboring Liberia and Sierra Leone. It was first recognized in March 2014. So far, it has involved thousands of people, and about 59% of infected people have died. A very small number of infected travelers (including health care workers returning home) have spread Ebola virus to Europe and North America. A few health care workers who helped treat the infected people in Europe and North America also acquired the infection.

Transmission of Ebola and Marburg viruses

The Ebola and Marburg viruses are highly contagious.

These viruses usually infect animals and only occasionally spread to people. Because the original animal source of these viruses has not yet been identified precisely, doctors are not sure how the virus infects the first person in an outbreak. However, experts think that the first person is infected by handling or eating an infected animal, such as a fruit bat or primate (apes and monkeys). Marburg virus infections have occurred in people exposed to bats (for example, in mines or caves).

Once a person has been infected, the infection can then spread from person to person when people come in direct contact with the skin or body fluids (saliva, blood, vomit, urine, stool, sweat, breast milk, or semen) of an infected person. Evidence shows that people cannot transmit the infection before they have developed symptoms. However, body fluids from dead people often transmit the infection, particularly in people who transport and prepare corpses for burial, but even touching a body can spread the infection.

Ebola is not thought to spread through the air (for example, in droplets dispersed when people cough or sneeze). If such spread does occur, it is probably very rare.

In people who recover, the virus is eventually completely eliminated from their system, and they are no longer contagious. However, some virus is detectable in recovering people for a week to several months. The length of time the virus can be detected varies depending on the body fluid. Although no infections are known to have been transmitted by sexual intercourse or breastfeeding, the number of people studied has been low, so doctors are not sure how contagious such people are. Thus, there are no firm guidelines on how long recovering people should abstain from sexual intercourse, breastfeeding, or close personal contact. However, to be safe, doctors from the World Health Organization (WHO) recommend that men refrain from sexual intercourse for at least 7 weeks after recovery. If the men do have intercourse before 7 weeks, they should wear a condom.

Symptoms

People develop the first symptoms about 2 to 20 days after exposure to the virus. At first, the symptoms usually resemble those of other, less dangerous viral infections. People have muscle aches, headache, sore throat, and cough. People also become sensitive to light, and the whites of the eyes may turn red.

Within a few days, people become more seriously symptoms such as

  • Abdominal pain

  • Yellow skin (jaundice)

  • Severe vomiting and diarrhea

  • A tendency to bleed

  • Confusion, delirium, and coma

The vomiting and diarrhea cause dehydration (see Dehydration), which, if untreated leads to low blood pressure (shock—see Shock), abnormal heart rhythms, and death.

Bleeding begins within the first few days. Bleeding under the skin can be seen as purplish spots or patches (bruises), and the gums, nose, rectum, or internal organs may bleed, as may puncture wounds (as result from drawing blood or starting an intravenous line).

After about 5 days, a rash, mainly on the trunk, appears.

During the second week of symptoms, the fever breaks and people begin to recover, or their organs malfunction (called organ failure). From 25 to 90% of infected people die. Compared with Marburg virus infection, Ebola is more likely to be fatal, averaging a 59% death rate. Recovery takes a long time.

Diagnosis

  • Blood and urine tests

Identifying Ebola in people who have been infected for only a few days is difficult because early symptoms, such as fever, can be caused by more common infections. However, if people with these symptoms have traveled from areas where Ebola is occurring, doctors suspect Ebola. The Centers for Disease Control and Prevention (CDC) has provided guidelines for health care practitioners to enable them to evaluate travelers returning from such areas.

Public health officials are notified.

If doctors suspect Ebola, they take samples of blood and urine from the person and test them to confirm the infection.

A similar approach can be used if Marburg virus infection is suspected.

Prevention

Several vaccines and antiviral drugs are being developed but are unlikely to be available in the near future.

Strict isolation is needed to prevent spread. Isolating people with symptoms of possible Ebola or Marburg virus infection in facilities used only for that purpose can help. These facilities can safely handle the infected body fluids. Standard intensive care units (ICUs) in public hospitals are less suitable.

Staff members caring for people with Ebola must be completely covered in protective clothing, including head gear equipped with a respirator. Even though the infections are not thought to be spread through the air, precautions against such spread are taken. Other staff members must be available to help those wearing protective clothing remove the protective clothing.

Diligently cleaning and disinfecting surfaces and equipment that may be contaminated is crucial, as is making sure body fluids (such as blood, sweat, vomit, feces, and urine) are handled safely.

For people who have traveled to or are in an area affected by an Ebola outbreak, the following is recommended:

  • Using good hygiene, such as washing their hands with soap and water or an alcohol-based hand sanitizer and avoiding contact with other people's blood and body fluids

  • Not handling items that may have come in contact with an infected person’s blood or body fluids (such as clothes, bedding, needles, and medical equipment)

  • Not participating in funeral or burial rituals that require handling the body of someone who has died of Ebola

  • Avoiding contact with bats and primates (such as apes and monkeys) and not eating raw meat prepared from these animals

  • Avoiding facilities in West Africa where Ebola patients are being treated

  • After returning, monitoring their health for 21 days and seeking medical care immediately if symptoms suggesting Ebola develop

Treatment

  • Supportive care

There are no effective antiviral drugs for Ebola, although a number have been tried. Thus, treatment is mainly supportive. It involves

  • Giving fluids intravenously (IV) to maintain blood pressure and the balance of electrolytes (such as sodium, potassium, and calcium—see Electrolytes)

  • Transfusing clotting factors (see Blood clotting factors) to help slow or stop the bleeding

  • Treating symptoms, including giving pain relievers

During the 2014 outbreak, doctors used several experimental drugs and gave blood transfusions from people who had recovered from Ebola. However, these treatments have not been evaluated in a scientific study, and thus whether they are safe and effective has not been determined. Also, these treatments are not readily available. Researchers continue to look for effective treatments.

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