Read this to get a better understanding of how Ebola spreads

October 13, 2014

A member of the CG Environmental HazMat team disinfects the entrance to the residence of a health worker at the Texas Health Presbyterian Hospital who has contracted Ebola in Dallas

The Centers for Disease Control and Prevention confirmed Sunday that a nurse at a Dallas hospital who cared for Thomas Eric Duncan, who died from Ebola last week, was the first person to become infected with the virus on U. S. soil. The nurse reportedly wore a gown, gloves, a mask and a face shield while caring for the Liberian national at Texas Health Presbyterian Hospital. Many, including CDC Director Tom Frieden, are questioning how the nurse became infected despite wearing the appropriate personal protective equipment, which should have shielded her from direct contact with Duncan and his bodily fluids.

Once again, the specter of airborne Ebola is being raised.

No virus that causes disease in humans has ever been known to mutate to change its mode of transmission. This means it is highly unlikely that Ebola has mutated to become airborne. It is, however, droplet-borne — and the distinction between the two is crucial.

Doctors mean something different from the public when they talk about a disease being airborne. To them, it means that the disease-causing germs are so small they can live dry, floating in the air for extended periods, thus capable of traveling from person to person at a distance. When inhaled, airborne germs make their way deep into the lungs.

Chickenpox, measles and tuberculosis are airborne diseases. Droplets of mucus and other secretions from the nose, mouth and respiratory tract transmit other diseases, including influenza and smallpox.

When someone coughs, sneezes or, in the case of Ebola, vomits, he releases a spray of secretions into the air. This makes the infection droplet-borne.  Some hospital procedures, like placing a breathing tube down a patient’s air passage to help him breathe, may do the same thing.

Droplet-borne germs can travel in these secretions to infect someone a few feet away, often through the eyes, nose or mouth. This may not seem like an important difference, but it has a big impact on how easily a germ spreads. Airborne diseases are far more transmittable than droplet-borne ones.

Richard Preston‘s remarkable book, The Hot Zone, chronicled an Ebola Reston virus outbreak at a primate quarantine facility just outside Washington. The monkeys didn’t have direct contact with each other. CDC and military experts had to consider the possibility that Ebola Reston virus might be airborne. But feces thrown about the room, aerosols used in pressure washing the monkey cages or contaminated gloves used to handle the animals could also have transmitted the virus.

It is important to emphasize that Ebola Reston virus does not cause disease in humans. It also survives longer than Ebola Zaire—the species responsible for the West African epidemic—when aerosolized in the lab. But even Ebola Zaire can remain infectious when aerosolized for at least 90 minutes. What happens in the lab, however, doesn’t always represent the real world.

Since the Reston scare, scientists have learned more about Ebola transmission from other outbreaks.

In 1995, more than 300 people became sick with Ebola in Kikwit, Democratic Republic of the Congo. Disease detectives were unable to determine how 12 of the patients were exposed — again raising questions about the possibility of airborne transmission. But if Ebola could be transmitted through the air, at least some family members of Ebola patients should have gotten sick even without direct contact. That didn’t happen.

Ebola struck again in 2000, this time affecting more than 400 people in Gulu, Uganda. Not all had direct contact with another Ebola patient. Bedding and mattresses seemed to be one source of infection. So did sharing a meal with an Ebola patient — which often meant using fingers to eat from the same plate. Each had in common likely exposure to infected bodily fluids.

In the lab, scientists studied how Ebola virus infects different species and causes disease. In humans and primates, Ebola Zaire spreads from the cells of the immune system to the lymph nodes, blood, liver and spleen. It causes minimal disease in the lungs. But in pigs, Ebola Zaire causes severe lung disease.

Researchers infected pigs with Ebola Zaire and then placed them near but not in direct contact with primates. The primates became infected. Because Ebola Zaire causes severe lung disease in pigs, their respiratory secretions are laden with the virus. With all their snorting and snuffling, pigs are very good at generating aerosols. The infected monkeys, however, didn’t transmit the virus onward.

For Ebola Zaire to become airborne in humans, it would need to cause lung disease significant enough to release lots of virus into respiratory secretions. The virus would then need to survive outside the body, dried and in sunlight for a prolonged time. And it would need to be able to infect another person more than a couple feet away.

There’s no evidence from previous epidemics or laboratory experiments that Ebola Zaire behaves in this way. Although the virus is mutating as the Ebola epidemic continues to grow in West Africa, it has multiple hurdles to overcome in order to become airborne.

As we rule out Ebola being airborne, the droplet-borne risk of Ebola must be addressed. Most important, those on the frontlines—especially nurses and doctors—should be provided with the necessary training and personal protective equipment to ensure that there are no more transmissions within hospitals.

PHOTO: A member of the CG Environmental HazMat team disinfects the entrance to the residence of a health worker at the Texas Health Presbyterian Hospital who has contracted Ebola in Dallas, Texas, October 12, 2014.REUTERS/Jaime R. Carrero 


We welcome comments that advance the story through relevant opinion, anecdotes, links and data. If you see a comment that you believe is irrelevant or inappropriate, you can flag it to our editors by using the report abuse links. Views expressed in the comments do not represent those of Reuters. For more information on our comment policy, see

A big question is how it affects domestic animals and it can spread to and from animals to humans. Rural people in third world live close to their animals as does factory farm workers. In cities pet owners live with their pets. The pig spreading is real frightening because it is a popular animal in Asia and US factory farms. If the pigs and some other animals spread far from lungs expect a wide spread problem as soon it hits nations where those animals outnumber people.

Posted by SamuelReich | Report as abusive

Well in most societies there lots of children who go to school and there are lots of domestic animals. When went to school most of teachers where woman who did minimal peace between boys. So there where lots of fights including wrestling holds. There was also lots of hand holding during folk dancing. The children are also in close contact with their pets. They may feed the animals if they live on a farm. In the US domestic animals out number people. Animals used for food are kept in close quarters.

Diseases that hit children and animals have them as their main vectors. Adult workers in factories or those that work on computers may have little close contact during work. But young school age children have lots of close body contact with each other and their pets and parents.

Posted by SamuelReich | Report as abusive

In the American culture of, let’s say the 1950’s (Dwight Eisenhower was President back then), America as a nation stood up for the American people, and defended them as a good parents defend their biological children, against threats of any kind.

Back then for a serious threat like today’s Ebola danger, the American government of President Eisenhower (a Republican) and the American congress, would not have hesitated to immediately prohibit all flights from Western Africa.

But today, as America disintegrates and crumbles as a nation and as a culture, such an edict is considered unfriendly to Africa or some other social entity. And therefore the American government vacillates, and sends a cowardly flavor into articles like this one, disdaining the action that everyone knows would be best for American children: strict prohibition of flights of immigrants from the infected countries.

Posted by AdamSmith | Report as abusive

All during the rise of America to greatness, from George Washington to Teddy Roosevelt, to Dwight Eisenhower, the American government protected the children of the American people, period. Ebola? They would not have hesitated.

One may read the Anti-Immigration Act of 1924 to see but one example.

As it built itself into the mightiest industrial power on Earth, the American culture had an identity threaded deeply with its European roots.

Then President Bill Clinton, loosened the gates to America, kicked them down, and let the globalists pillage the American homeland. The same globalism now spreading Ebola and more to come.

Posted by AdamSmith | Report as abusive

If the hospital care givers were filmed dressing in gear, treating the patient, and removal of protective gear afterwards that probably should be discarded they might be able to find how the breach might have happened.

Posted by Weedwreckslives | Report as abusive

Ebola is unlikely to transform itself into an airborne virus, but it doesn’t mean that it is not mutating to become more communicable. Like the influenza, the ability to stay alive in aerosol form will increase the likelihood of transmission, especially through fomites that are not viewed as important under conventional Ebola protocol. If this version of the virus has become more durable, then any object which comes in contact with the aerosol of an Ebola patient becomes potentially a way to transmit the virus. And given that aerosol particles can stay in the air and move with air movement, the virus may be able to spread through out the vicinity of an infected person, like in a hospital with centralised air circulation. At the moment, Ebola patients are not kept in BSL level 4 containment. Perhaps the CDC should re-evaluate this.

Posted by WolfintheWilds | Report as abusive

The fact is, U.S. airlines don’t fly to the countries with ongoing Ebola outbreaks. But of course the loud extreme right of the US doesn’t even consider this.

Posted by Steve99999 | Report as abusive

What apparently has not been considered seriously is ‘indirect contact’. An infected and sick person can handle an item with sweaty hands only for the same item to be handled by a healthy person moments later. Think of a toilet facility and door handles, cups, glasses, floors etc.

Posted by okullo | Report as abusive

“CDC chief: After Dallas nurse’s Ebola infection, U.S. must ‘rethink’ protocols.”

Ahh; You Think. Mandatory screening should have been initiated at all US ports of entry.

Nice write-up Ms. Gounder

Posted by bikeamtn | Report as abusive

All we do know is that we don’t know. We don’t have a full understanding of Ebola

Posted by sarkozyrocks | Report as abusive

Obama missed ISIS by 2 years – ditto Ebola – keep them OUT of America

Capiche Bozo ?

Posted by jackdanielsesq | Report as abusive

The article’s author states:
“No virus that causes disease in humans has ever been known to mutate to change its mode of transmission. This means it is highly unlikely that Ebola has mutated to become airborne.”


Bubonic plague:
“At least 75 million people—including more than half of Britain’s population—are believed to have died during the 14th and 15th centuries from the plague known as the Black Death. For years, the fatal disease’s spread was widely blamed on infected rats’ fleas. But now, thanks to a trove of 25 skeletons unearthed by work on a new London railway line last year, scientists now believe the disease was instead likely airborne. How was this historic information gleaned? Teeth pulled from the centuries-old skeletons.”

Why is our government’s response to this current RISK so muted?

Posted by swips88 | Report as abusive

Posted by AdamSmith:
“Then President Bill Clinton, loosened the gates to America”

Actually someone more to blame would be President Johnson in signing 1965 Hart-Celler Immigration Bill. The bill was an outgrowth of Civil Rights era. We may forget that Johnson was a very effective skilled politician who typically got what he wanted in Washington. Many surmise that John Kennedy may not have been as successful with regards to many of the things Johnson got through. migration:
“This resultant new, enlarged immigration flow came from countries in Asia and Latin America which heretofore had sent few of their sons and daughters to the United States. And finally, although the average level of education of immigrants has increased somewhat over the past 30 years, the negative gap between their education and that of native-born Americans has increased significantly, creating a mismatch between newcomers and the needs of a modern, high-tech economy”

And thanks to Sen Ted Kennedy who was Chairman of the Senate Immigration Committee who was a big supporter of Hart-Celler, for decades allowed unfettered immigration from third world countries while reducing European immigrant numbers.

Posted by swips88 | Report as abusive

(1) It’s time for Television Public Service announcements that remind people to cover their mouths when coughing and sneezing, and to wash their hands, etc.

Hygiene has become a lost art.

(2) This NIH study found that Ebola survived on plastic and glass for over 3 weeks: 340

(3) And here are more interesting facts:

–> ONE cough expels 3,000 droplets which fly out of your mouth at up to 50 miles per hour

–> ONE sneeze can expel as many as 40,000 droplets which fly out of your mouth at more than 200 miles per hour

Posted by DontBeLate | Report as abusive

Here’s something to consider – follow the medical waste the Ebola patients created while hospitalized. Since the CDC says Ebola medical waste can only be rendered safe via autoclaving, or incinerating, any waste that was flushed down a toilet had the potential to become air-borne in water droplets and could contaminate anyone and any surface nearby. What is happening to this type of waste in hospitals? Come to think of it, what happens to the contents of an airplane toilet if an Ebola infected person on that plane deposits infected urine, feces or vomit in that toilet?

Posted by SandpaperSal | Report as abusive

The outbreak so far is nothing. Wait until it gets to Asia. And if not this outbreak, then the next one. Next year. Two years down the road, three. Containment is futile.

Should have been working on an ebola cure. We’ve known about it for 40 years. It is 100 times deadlier than AIDS. But because rich white actors had not contracted it….. no effort. This is a racist problem, not a medical problem.

Posted by AlkalineState | Report as abusive

[…] 14/10/13/read-this-to-get-a-better-under standing-of-how-ebol… […]

Posted by アメリカでエボラ出血熱に感染した看護師に驚愕の事実が・・・(※画像あり) | ウェーイ速報 | Report as abusive

Ebola is the cover for the vaccine parasites (viruses) that are set to activate on a mass scale now. Deaths & symptoms are on schedule to go exponential now, so they use the Ebola outbreak to hide the systematic extermination of the population.

Parasites (viruses) require a host with an iron supply to replicate. atesPathogenGrowth.htm
Thus, the iron poisoned population is on schedule to be exterminated now.

Encourage you to read:


Posted by cabouth | Report as abusive

This is certainly genuinely legitimate matter as greater included in the blog website. Truly appreciate speaking about in the vicinity of.

Posted by lenskart discount coupons | Report as abusive

Any anxieties concerning Ebola will be forgotten, once everybody (kids and adults) start doing my WVD – The Weapon of Virus destruction – Just an exercise for a minute a day – The most powerful and lethal response to Ebola virus on Earth – I will disclose it to everyone, if the world pays me 50 billion EURO – Then everybody will be protected 100% from any viruses, bio-weapons (like Ebola and AIDS), any cancers, diabetes and strokes all the time.

Posted by Worldsavior7 | Report as abusive

[…] this to get a better understanding of how Ebola spreadsSource: Reuters Richmond clinic evaluating whether patient is at risk of EbolaSource: Richmond […]

Posted by Africa News Headlines – Special Ebola Edition – 13 October 2014 | Sub-Saharan Monitor | Report as abusive

Thanks. Good article. Very nice information. Keep up the good work. Will come again. Keep posting and blogging.

Posted by Eugene Steckel | Report as abusive

Very informative article. Now I know what actually Ebola is.

Posted by rahul345 | Report as abusive