Is the Ebola Virus Contagious?

What Is the Ebola virus?

Ebola (also termed Ebola hemorrhagic fever) is a viral disease that, until the 2014 outbreak in West Africa, was considered a rare but deadly disease that causes a potentially fatal fever in humans as well as infection of nonhuman primates (for example monkeys, gorillas, and chimpanzees) and African fruit bats. Before 2014, small outbreaks were usually confined to small isolated villages in Africa. In 2014, an outbreak had villagers going to local cities for treatment and resulted in spreading the disease to a number of countries in Africa. A few individuals transferred the disease to other countries (for example, the U.S., Spain); caregivers got the disease from those individuals being treated for Ebola. The 2014 outbreak of Ebola was the largest in history; current estimates are that about 29,000 individuals were probably infected, with about 15,200 laboratory-confirmed infections that resulted in about 11,200 deaths, according to statistics from the U.S. Centers for Disease Control and Prevention (CDC). The CDC states that there are no current infectious Ebola patients in Senegal, Nigeria, Spain, United States, the United Kingdom, and Italy. Since the 2014 outbreak, there have been others. The Congo reported an outbreak in May 2018 that is still not stopped as of August 2018.

There is some evidence that four of the five viral types that cause Ebola likely circulate in nonhuman primates; in addition, there is some evidence that Ebola virus types may be carried by African fruit bats. If these primates and/or bats are handled or eaten (Bush meat) by people, humans may contract the disease and then pass it on to other humans.

Ebola is contagious. The virus spreads through direct contact (via broken skin or mucous membranes, in the nose, mouth, or eyes). Blood or body fluids from infected individuals are capable of causing infection in others. Examples of body fluids include urine, saliva, sweat, feces, vomit, breast milk, and semen. Unfortunately, objects such as needles and syringes that have been contaminated with blood or body fluids can also transmit the disease. Furthermore, contact with animals such as primates and/or African fruit bats may also transmit the Ebola virus from these animals to humans.

When a person dies from Ebola, the person's body has high concentrations of the virus both a few days before and after death. Also, the virus is in high concentration on contaminated sheets, clothing, or other items that have touched the recently deceased person. In these situations, Ebola is highly contagious.

Full protective gear is advised to protect health care workers from becoming infected; for more details, the reader is referred to CDC's guidelines (see http://www.cdc.gov/vhf/ebola/healthcare-us/evaluating-patients/think-ebola.html).

The incubation period for Ebola varies from about two to 21 days. People are not contagious for the disease until the first symptoms appear (sudden onset of fatigue, fever, muscle pain, headache, and/or sore throat).

It is sometimes difficult to know if a person is infected with the Ebola virus; however, if a person has been a medical caregiver to a patient with Ebola or if a person has recently spent time in an area where Ebola infection is present, then a person who develops early signs and symptoms, such as fever, headache, weakness, stomach pain, fatigue, lack of appetite, diarrhea, vomiting, joint and muscle aches, or unexplained bleeding, should be suspected to be infected with Ebola until proven otherwise.

The diagnosis of Ebola is usually done by special blood tests (PCR or polymerase chain reaction, virus isolation, and/or enzyme-linked immunosorbent assay or ELISA test). These tests are available in some state labs and the CDC in the United States and can help distinguish between Ebola, Marburg, and other viral diseases that produce similar symptoms.

Outbreaks often begin with a single individual or small group that contacts an infected primate and/or African fruit bat. Members of such a small group then can pass an Ebola infection from person to person by blood or body fluid contact as the virus travels through breaks in the skin or mucous membranes. Ebola usually does not begin to become contagious to other people until symptoms develop. Rapid spread can occur when an individual is dying or dies because of the massive viral load within the individual's body and body secretions.

The disease can spread quickly in hospitals, clinics, and among families because of the close proximity to the infected patient's body fluids. Appropriate protective equipment and sterilization of needles and other items are needed to avoid the spread of Ebola viruses to other individuals, especially medical caregivers.

Ebola is not spread through the air or by water or foods that have not come in contact with infected humans, primates, or African fruit bats.

In general, individuals who spontaneously self-cure or, after hospitalization and supportive care, survive the infection, become noncontagious after about 21 days from the onset of symptoms (a few investigators suggest 42 days should be considered the length of time to become noncontagious since the risk is 0.2%-12% that some individuals are contagious longer than 21 days). This time period is complicated by the fact that some men who survived the disease have Ebola virus in their semen for three months, and in a few men, the semen has had Ebola virus present for over nine months. In addition, some patients may have dormant Ebola virus in their eyes for extended time periods. Researchers are still trying to determine if these dormant viruses can reactivate and cause disease in the previously infected patient or in uninfected individuals who come in contact with them; they advise precautions be taken to avoid exposure to body fluids in patients with dormant Ebola infection.

Because Ebola can be a devastating disease, anyone who is likely to have been exposed to Ebola should immediately contact a medical caregiver, preferably someone at the CDC in the United States. This notification allows the CDC to do close monitoring of potentially infected or infectious individuals according to current CDC guidelines and will afford those individuals who develop the infection early treatment, to increase their chances for survival and decrease the possibility of transferring infection to others. In addition, an experimental vaccine (rVSV-ZEBOV) helps to prevent infections with Ebola, and a new antiviral drug, mAb114, helps the body render the Ebola virus ineffective.

Individuals and health care workers who have been exposed to Ebola-infected patients and develop early symptoms of Ebola need to isolate themselves from other uninfected individuals and go to a clinic or hospital in their country that is capable of taking care of Ebola-infected patients. Ideally, such individuals should be careful (use barrier techniques and/or inform EMS or other transporters) not to contaminate anyone while they are transported to the appropriate health care facilities.