Ebola has been studied since the mid-1970s, when the first cases near the Ebola River in Africa were identified. This summary is based on a review of some of the major studies and briefings by some of the world’s top experts as part of my role at work.
People in the United States can protect themselves by spreading facts, not fear. There’s plenty still unknown, but we know way more than a lot of people think. For example, there’s been a lot of lab research to determine whether Ebola can be transmitted in the air or other casual contact. None of the studies indicate that it can be.
Here are some things we know about the Ebola virus, which scientists have been studying since the 1970s:
- A person infected with Ebola is not contagious until after symptoms appear. In fact, the virus frequently is undetectable in the blood of an infected person – even with the most precise tests available – until after symptoms appear. This is why the risk to other people is extremely low until the infection begins to trigger symptoms.
- There is no evidence at all to suggest that casual contact transmits Ebola. Many health care workers and others have safely been in rooms or other close quarters with Ebola patients. In Dallas, four people were in the apartment with Thomas Eric Duncan when he was very sick with Ebola and all have been free of infection, more than 21 days later. All 43 people who were near Mr. Duncan but not involved in his hospital care are confirmed to be free of infection.
- The virus replicates extremely rapidly once symptoms begin, which is why the protocol for health care workers who have left an outbreak area calls for twice daily temperature checks. This is a known way to identify possible Ebola infection at the earliest point.
- While the Ebola virus replicates quickly in a person who has symptoms of Ebola Virus Disease, the virus does not have much strength once outside an infected person. If a droplet lands on a surface like a doorknob or countertop, the virus survives only a few hours and is easily killed by ordinary household cleaners (bleach is recommended.)
- There has been no evidence that Ebola is transmitted through the air, nor have lab studies indicated this happens.
- In order for the disease to spread, a droplet of body fluid must be transferred directly from a symptomatic person to an entry point in another person within about three feet — through a cut or other break in the skin, eyes, nose, mouth, or other opening.
- Body fluids include – quoting the CDC here – “pee, poop, spit, sweat, vomit, semen, or breast milk” or blood. The virus does survive in blood longer than in other fluids.
- Transmission via sweat is a theoretical possibility but remote — and relatively far-fetched outside of the rural parts of Africa where the facilities are so poor. It would require sweat from a symptomatic patient to be transferred directly onto another person and enter their system through eyes, mouth, a cut or other opening. The viral load in sweat is low until patients are violently sick. There was one documented case in 2001 in Uganda involving a person who contracted the disease after sleeping on a blanket that had been used by another person who died of Ebola. No other cases like this have been reported, and most cases where contact with sweat was suspected involved people who also had other exposure, such as to an Ebola patient’s blood.
- One of the reasons the CDC recommends isolation and confirmatory tests as soon as fever first occurs in a person who was in the outbreak area is that the viral load grows logarithmically after the first couple of days from symptom onset – 3 days seems to be typical. In New York, an Ebola blood test takes a few hours. That’s different from most other places where test results can take overnight, days or even longer. A test before symptoms wouldn’t find the virus, but a test at the earliest onset of symptoms probably would — and increases the chances of successful treatment. This is what happened in the case of Dr. Craig Spencer, who was isolated as soon as his temperature went above normal (to 100.3 degrees.)
If you are concerned about Ebola in the United States, get a flu shot. This will help both because the flu sickens and kills many more people than Ebola and because flu symptoms may be mistaken for Ebola symptoms in people who misunderstand their risks. If you have a flu shot and exhibit fever, nausea, or other possible signs of Ebola, doctors will have an easier time figuring out what your illness actually is. Mayor DiBlasio said that preventing the flu in New York is important so that the city’s emergency departments are not flooded with people who think they have Ebola but have no actual risk of getting it.
For more information, visit the NYC Department of Health website at http://www.nyc.gov/html/doh/html/diseases/ebola.shtml or the U.S. Centers for Disease Control and Prevention website at http://www.cdc.gov/vhf/ebola/index.html.
The source for most of this article is http://www.cdc.gov/vhf/ebola/transmission/human-transmission.html and the studies that are cited on that page. This article is not intended as medical advice. For that, please consult your own health care professional.