Ebola has been in the headlines a lot lately, mostly because the current outbreak is the largest one we’ve ever seen. There have also been people transported into the United States who were infected, raising concerns about an Ebola outbreak happening in the country. However, while Ebola is a terrifying disease, it is unlikely to spread in the U.S. Here we’ll explore what Ebola is, what makes it so scary, and why there won’t be an outbreak in the U.S.
Ebola (also called hemorrhagic fever) is a disease caused by a virus. (It specifically belongs to the RNA virus family Filoviridae, which are filamentous viruses, in the genus Ebolavirus.) It was first discovered in 1976 in the Democratic Republic of the Congo, near the Ebola River, which it is named after. Researchers have since then identified five subspecies of the Ebola virus, four of which cause the Ebola disease in humans (the fifth causes it in nonhuman primates). An outbreak usually happens when people come in contact with infected wild animals (typically fruit bats [a highly suspected reservoir], rodents, pigs, or primates), and then the virus is transmitted from person-to-person.
When a person becomes infected by the Ebola virus, it can take 2 to 21 days before they show symptoms (although it’s typically 8 to 10 days). Symptoms include fever (above 101.5°F), chills, muscle aches, and a headache initially. By the fifth day, a rash may appear on the skin. Symptoms can progress to nausea, vomiting, diarrhea, and chest and abdominal pain, and then to jaundice (yellow skin), confusion, bleeding (hemorrhaging), severe weight loss, and organ failure. Ebola usually kills 50% to 90% of infected people (although the current epidemic has about a 55% to 60% fatality rate).
What makes the Ebola virus so effective at killing a person once they’re infected? It has to do with which types of cells the virus goes after. Its main targets are the cells in the immune system. The virus is able to evade the immune system by blocking how those cells normally signal each other. At the same time, the virus also hitches a ride on the immune system’s cells so that they carry it through the body to different organs. The damage the virus inflicts on the body triggers a fever and inflammation, as the immune system attacks the body itself. Additionally, the virus infects cells that are lining the interior of blood vessels, causing those cells to be unable to adhere to each other well and leading to bleeding disorders (i.e., hemorrhaging).
The current Ebola outbreak, which was first reported in late March of this year, is unusual and concerning because it is larger than any other recorded Ebola outbreak. As of July 27, 2014, there have been 729 fatalities and 1,323 cases total. Previously, there has always been fewer than 1000 people infected by Ebola each year. What’s also different about the current outbreak is its location – prior outbreaks have been in Central Africa (near tropical rainforests), whereas this year’s is in West Africa. Specifically, the current outbreak is in Guinea, Sierra Leone, and Liberia, with a few suspected cases in Nigeria.
But, there still should not be concern for an outbreak occurring in the U.S. The Ebola virus is spread through bodily fluids (i.e., blood, sweat, saliva, urine, semen, and breast milk), but it cannot be caught through air, water, or food. This means that for a person to get infected, they’d need to directly touch bodily fluids from a person who is sick with Ebola and is showing symptoms (or died from Ebola), or they’d need to handle objects (like syringes) that were directly touched by infected bodily fluids. So, basically, a person needs close contact with somebody who’s clearly sick to get Ebola. (An exception is transmission via semen – a man’s semen is still infectious up to 7 weeks after he’s recovered from the disease.) To prevent the disease from spreading, medical workers wear masks, gloves, and goggles. Other precautions need to be taken as well, such as properly cooking meat that could be infected, properly disposing of bodies and tissues/fluids from a sick person, and washing hands when around a person who is sick.
Another reason that an outbreak in the U.S. is not of concern is that Ebola is relatively rare. Even if a person has a fever and is from an area where Ebola is present, it’s more likely they’re sick with a different infectious disease. Other similar-looking diseases include malaria, cholera, hepatitis, meningitis, typhoid fever, and other hemorrhagic fevers caused by viruses. (To confirm that a person has Ebola, a blood sample is tested for the presence of antibodies the body has made against the virus, or the RNA of the virus itself.) But even still, the Centers for Disease Control and Prevention (CDC) in West Africa is actively working to prevent sick passengers from getting on planes, and is prepared to immediately isolate any sick passengers (and disinfect other passengers and crew) who might land in the U.S. And if a person with Ebola needs treatment in the U.S., there are clear transportation guidelines and hospital guidelines for safely treating them.
Due to the relative rarity of the Ebola virus and its inability to spread via air, water, and food, it shouldn’t be too surprising that Ebola has only ever had outbreaks in Africa — there have been no cases of people contracting Ebola outside of the continent.
While there is no specific treatment available for Ebola, just last week two American medical workers received an experimental drug and appear to be doing well after the treatment. The drug, called ZMapp (made by Mapp Biopharmaceutical Inc.), is an antibody made against the virus (it prevents the virus from infecting new cells) and had never been tested in humans before. Dr. Kent Brantly started feeling better just one hour after receiving the drug in Liberia, while Nancy Writebol felt improved after two doses. Both have been evacuated back to the U.S. since then. Legal and cultural barriers need to be overcome before Africans can be treated with the drug. (Other drugs, such as TKM-Ebola, are also being developed, and while there is no vaccine yet, one may be in clinical trials in September.)
So while it is easy to be concerned about Ebola due to its horrific nature and high mortality rate, it’s important to keep in mind that there are many other ways you’re much more likely to die, such as getting in a car accident, having the measles, or catching syphilis.
For further reading:
- CDC’s webpage About Ebola Hemorrhagic Fever
- CDC’s webpage Guidelines for Evaluation of US Patients Suspected of Having Ebola Virus Disease
- CDC’s webpage Questions and Answers on Ebola
- IFLScience!’s article “What Happens To Your Body When You Get Ebola?”
- Tracy Vence’s article “International Action on Ebola”
- Teisha J. Rowland’s book Biology Bytes: Digestible Essays on Stem Cells and Modern Medicine