What is Ebola Virus? What Does it Do and Where Does It Come From?

By Zachary Stieber
Zachary Stieber
Zachary Stieber
Reporter
Zachary Stieber covers U.S. and world news. He is based in Maryland.
September 30, 2014 Updated: September 30, 2014

The first confirmed Ebola patient in the U.S. was confirmed on Wednesday and people are wondering about the virus, such as what it’s caused by and what it does.

The virus, previously known as Ebola hemorrhagic fever, is a rare and deadly disease caused by infection with one of the Ebola virus strains, or a virus of the family Filoviridae, genus Ebolavirus.

“There are five identified Ebola virus strains, four of which are known to cause disease in humans: Ebola virus (Zaire ebolavirus); Sudan virus (Sudan ebolavirus); Taï Forest virus (Taï Forest ebolavirus, formerly Côte d’Ivoire ebolavirus); and Bundibugyo virus (Bundibugyo ebolavirus). The fifth, Reston virus (Reston ebolavirus), has caused disease in nonhuman primates, but not in humans,” notes the Centers for Disease Control.

The deadly disease was first discovered in 1976 near what is now the Democratic Republic of Congo, and all subsequent diseases have been found in Africa. The likely host is bats.

How Do You Get It? And Symptoms

People contract the virus after contact with an infected animal or an infected human.

The virus is spread through direct contact, with blood or body fluids such as urine, saliva, and semen of a person who is sick with Ebola.

Objects such as needles or syringes that have been contaminated are another source of transmission.

Symptoms include a high fever (higher than 101.5 Fahrenheit), severe headache, muscle pain, general weakness, and diarrhea.

Stomach pain, vomiting, and unexplained bleeding or bruising are among the other symptoms.

The symptoms sometimes don’t appear until up to 21 days after exposure, though the average is 8 to 10 days.

Some people can recover.

What Does It Do?

Dr. Edward Goodman, epidemiologist at Texas Health Presbyterian Hospital Dallas, and Dr. Mark Lester, Southeast Zone clinical leader for Texas Health Resources, answer questions during a media conference at Texas Health Presbyterian Hospital Dallas where a patient has been diagnosed with the Ebola virus on September 30, 2014 in Dallas, Texas. (Photo by Mike Stone/Getty Images)
Dr. Edward Goodman, epidemiologist at Texas Health Presbyterian Hospital Dallas, and Dr. Mark Lester, Southeast Zone clinical leader for Texas Health Resources, answer questions during a media conference at Texas Health Presbyterian Hospital Dallas where a patient has been diagnosed with the Ebola virus on September 30, 2014 in Dallas, Texas. (Photo by Mike Stone/Getty Images)

The virus attacks the body vigorously.

“Once the virus enters the body, it targets several types of immune cells that represent the first line of defense against invasion. It infects dendritic cells, which normally display signals of an infection on their surfaces to activate T lymphocytes—the white blood cells that could destroy other infected cells before the virus replicates further,” Science Mag notes.

“With defective dendritic cells failing to give the right signal, the T cells don’t respond to infection, and neither do the antibodies that depend on them for activation. The virus can start replicating immediately and very quickly. Ebola, like many viruses, works in part by inhibiting interferon—a type of molecule that cells use to hinder further viral reproduction. In a new study published today in Cell Host & Microbe, researchers found that one of Ebola’s proteins, called VP24, binds to and blocks a transport protein on the surface of immune cells that plays an important role in the interferon pathway.”

Put simply, “Ebola triggers a system-wide inflammation and fever and can also damage many types of tissues in the body.”

And patients die from the virus because the damage to blood vessels leads to a drop in blood pressure, which in turn leads to shock and multiple organ failure.

Current Outbreak

Nowa Paye, 9, is taken to an ambulance after showing signs of Ebola infection in the village of Freeman Reserve, about 30 miles north of Monrovia, Liberia, Tuesday Sept. 30, 2014. Three members of District 13 ambulance service travelled to the village to pickup six suspected Ebola  sufferers that had been quarantined Six months into the worlds worst-ever Ebola outbreak, and the first to happen in an unprepared West Africa, the gap between what has been sent by other countries and private groups and what is desperately needed is huge. Even as countries try to marshal more resources to close the gap, those needs threaten to become much greater, and possibly even insurmountable. (AP Photo/Jerome Delay)
Nowa Paye, 9, is taken to an ambulance after showing signs of Ebola infection in the village of Freeman Reserve, about 30 miles north of Monrovia, Liberia, Tuesday Sept. 30, 2014.  (AP Photo/Jerome Delay)

The current outbreak is suspected to have started in Guinea, a country on the West Coast of Africa. The initial announcement on March 25, 2014 said that there was 86 suspected cases with 59 deaths.

By April, the virus spread to Liberia. It was suspected in Sierra Leone and Mali soon after. Initial tests were negative in both countries but the disease was confirmed in the former by the end of May.

A big transfer came in July, when Liberian government official Patrick Sawyer traveled to Nigeria for a conference and brought to virus with him.

More recently, the virus has continued spreading rapidly in West Africa, but U.S. health officials said this week that the outbreak may be over in Nigeria and Senegal, although a new case popped up on August 29 in the latter.

As of the end of September, over 6,500 cases have been confirmed with over 3,000 deaths.

The overwhelming bulk of the cases have been in Guinea, Liberia, and Sierra Leone, with a handful in Nigeria and Senegal.

Ebola in the U.S.

The CDC said on Tuesday that the first case of Ebola in the United States was confirmed.

The unidentified person had traveled to Dallas, Texas from West Africa.

“The patient did not have symptoms when leaving West Africa, but developed symptoms approximately five days after arriving in the United States,” the agency said.

The person sought medical care at Texas Health Presbyterian Hospital of Dallas after developing symptoms consistent with Ebola.

“CDC recognizes that even a single case of Ebola diagnosed in the United States raises concerns. Knowing the possibility exists, medical and public health professionals across the country have been preparing to respond. CDC and public health officials in Texas are taking precautions to identify people who have had close personal contact with the ill person and health care professionals have been reminded to use meticulous infection control at all times,” the agency added in a statement.

“We know how to stop Ebola’s further spread: thorough case finding, isolation of ill people, contacting people exposed to the ill person, and further isolation of contacts if they develop symptoms. The U.S. public health and medical systems have had prior experience with sporadic cases of diseases such as Ebola. In the past decade, the United States had 5 imported cases of Viral Hemorrhagic Fever (VHF) diseases similar to Ebola (1 Marburg, 4 Lassa). None resulted in any transmission in the United States.”

Zachary Stieber
Zachary Stieber covers U.S. and world news. He is based in Maryland.