How contagious is Ebola really?

The Centers for Disease Control (CDC) has confirmed that a patient in the US has Ebola. It seemed timely to have a discussion of just how contagious Ebola really is.

As you probably already know, other American Ebola patients have already been flown back to the US for treatment, but they were brought in under conditions of quarantine. This patient traveled back from Africa (Liberia) on a commercial flight, arriving on September, 20th. He was asymptomatic while traveling.

Ebola can only be transmitted when the patient is displaying symptoms. The patient developed Ebola symptoms on September 24th, four days after returning to the US.

Upon developing symptoms, the patient sought treatment on September 26th. He was treated and sent home. When his symptoms continued, he went to a local hospital in Dallas on Sunday, September 28. He was admitted and placed in “strict quarantine” per the hospital.

Specimens were taken to test for Ebola, and sent to he CDC and a Texas State Health Department laboratory. Both sites showed that he has Ebola based on highly specific tests.

A sign warns visitors that area is a Ebola infected. Signage informing visitors that it is a ebola infected area. September 27, 2013, Congo, Africa. Sergey Uryadnikov /

A sign warns visitors that area is a Ebola infected. Signage informing visitors that it is a ebola infected area. September 27, 2013, Congo, Africa. Sergey Uryadnikov /

Since the patient had symptoms for four days before being admitted, the possibility exists that some family members could have become infected if they came into contact with body fluids from the patient.

The CDC estimates that there may be “a handful” of people who could be exposed and potentially develop Ebola. Additionally, health care workers at the first treating facility will be tracked and monitored. The epidemiologists have interviewed family members and are working on locating and interviewing others with whom the patient may have had contact. At this time, none of the contacts are symptomatic. All contacts will be monitored for 21 days.

Remember that Ebola is not transmitted via the airborne route as something like influenza virus is. Patrick Sawyer, for example, flew into Lagos, Nigeria, symptomatic with Ebola. He was feverish and vomiting on the flight. Yet, only one other person on the flight developed Ebola – that was Sawyer’s personal assistant who had been traveling with him for days. His assistant might have even gotten Ebola from the same source as Sawyer.

If Ebola could be spread via airborne transmission, I’d expect dozens of people on that flight, and members of the crew and cleaning crew, to have gotten Ebola. That didn’t happen. And in any case, the Dallas patient wasn’t symptomatic with Ebola when he flew.

Epidemiologists from the CDC are en route to Dallas. They will coordinate with the hospital and public health agencies in Texas. Dr. Thomas Frieden, Director of the CDC, and Texas public health officials did a press briefing on this case of Ebola. Dr. Freiden says that he is quite confident that Ebola can be contained in the area. He stressed that, as long as the outbreak continues in Africa, we need to be vigilant and have a high index of suspicion that Ebola could be present in people who have returned from West Africa within the last 21 days, or health care workers who could have had contacts with Ebola patients.

Dr. Freiden stated that the patient can be treated adequately in Texas. He emphasized that any hospital that can isolate a patient in a private room with its own bathroom, and use basic isolation precautions (hand washing, mask, goggles, gown, gloves, limiting visitors, keeping a log of visitors, etc.) can care for Ebola patients.
Patients would also need to be treated symptomatically for dehydration, shock and other problems that Ebola may cause.

Ebola is much more difficult to treat in developing countries than is it in more developed areas. For example, the clinics and hospitals in Africa where Ebola patients are treated are basically large rooms filled with many patients. There are few doctors and nurses, hundreds to treat million of people. Isolation equipment and supplies are limited. There is often no running water, electricity or adequate sanitation. IV fluids, necessary to treat severe dehydration, are at a premium. Many workers have only limited training and experience using isolation techniques. Transportation may be primitive or lacking. Advanced medical techniques (dialysis, ventilators, etc.) are not available. There are difficulties communicating with and educating the local people. Medical infrastructure is poor. Tracking contacts of Ebola patients is often hit-or-miss. These, and other factors, can easily contribute to high mortality and continued spread of the disease in Africa.

In the US and other developed nations, almost all of these problems don’t exist. Most hospitals would have no problems with handling isolation and intensive medical treatment. The local health departments could handle tracking, reporting, monitoring and education. There are many more physicians, nurses and allied health personnel available. Laboratories are ready to test patient samples.

The upshot is that containing and treating Ebola in a developed nation will be easier that it would be in areas like Africa. That doesn’t mean that Ebola isn’t dangerous – it is. But it can be controlled.

Mark Thoma, MD, is a physician who did his residency in internal medicine. Mark has a long history of social activism, and was an early technogeek, and science junkie, after evolving through his nerd phase. Favorite quote: “The most exciting phrase to hear in science... is not 'Eureka!' (I found it!) but 'That's funny.'” - Isaac Asimov

Share This Post

42 Responses to “How contagious is Ebola really?”

  1. docsterx says:

    No, Transmission is NOT airborne. That’s clear. McClatchy is hardly an expert in viral diseases. The CDC, NIH, WHO, MSF and other organizations agree that it is NOT airborne.

    From the CDC:

    “When an infection does occur in humans, the virus can be spread in several ways to others. Ebola is spread through direct contact (through broken skin or mucous membranes) with

    blood or body fluids (including but not limited to urine, saliva, feces, vomit, and semen) of a person who is sick with Ebola

    objects (like needles and syringes) that have been contaminated with the virus

    infected animals

    Ebola is not spread through the air or by water, or in general, food. However, in Africa, Ebola may be spread as a result of handling bushmeat (wild animals hunted for food) and contact with infected bats.”


    “The Ebola virus is highly contagious, but is not airborne. Transmission requires close contact with the bodily fluids of an infected person, as can occur during health-care procedures, home care, or traditional burial practices, which involve the close contact of family members and friends with bodies. In Guinea, around 60% of cases have been linked to these burial practices, with women, who are the principal care-givers, disproportionately affected.”


    “Ebola can be caught from both humans and animals. It is transmitted through close contact with blood, secretions, or other bodily fluids.

    Health care workers have frequently been infected while treating Ebola patients. This has occurred through close contact without the use of gloves, masks, or protective goggles.”

    I’ve written several other articles here, outlining how Ebola is transmitted, with citations from medical and professional groups, research centers, public health groups, virologists, physicians and others stating how Ebola can be transmitted and that it it NOT transmissible via the airborne route.

    McClatchy, and other commercial purveyors of information,may well try to increase revenue by publicizing information that is suspect or flat-out incorrect to generate revenue. Additionally, very often the reporters who write the stories may not, themselves have a very good grasp on the information.

    This site: has a tremendous amount of information on Ebola, including how it is transmitted. It’s a much better source than McClatchy.

  2. Bookbinder says:

    This is not correct. McClatchy reports that Ebola is present in mucous, ie the micro-drops you sneeze or cough out of your mouth or nose and that inhaling these droplets can produce Ebola disease in the recipient. The disease may not be “airborne” per se, but it certainly can be borne through the air on these mucous droplets. You are getting suckered by the semantics. That’s why Ebola victims are fucking quarantined. If this were not the case you wouldn’t need to stand 15 feet away when interviewing them.

  3. docsterx says:


  4. docsterx says:

    Thomas Duncan, the Dallas Ebola patient, has improved somewhat. His condition has been upgraded from critical to serious.

  5. BeccaM says:

    Okay. Just that particular outlet sets off my alarm bells. They’ve been way less than responsible in their reporting.

  6. docsterx says:

    2 local Dallas news stations reported the story plus statement from Thompson. USA Today has it, too.

  7. BeccaM says:

    But… Fox News?

  8. docsterx says:


  9. docsterx says:

    BREAKING: POSSIBLE 2nd Ebola case in Dallas. Dallas Health and Human Services Director, Zachary Thompson, says that they are paying particular attention to one potential patient who may also have Ebola. While Mr. Duncan’s (the initial Dallas case) family and friends are being monitored, there may be one who is more likely to have the disease. Confirmation as to whether this person does have Ebola is pending.

  10. GarySFBCN says:

    Given that we Americans are so ignorant about geography, the nurse may not have know that Liberia is a nation in Africa.

  11. Mark_in_MN says:

    Talking heads love to speculate. Whether that speculation has any connection to an actual fact or is just some imaginative yarn is another matter.

  12. Mark_in_MN says:

    Thanks for the post. It’s good to read something that is careful and factual without the hysterics and speculation that’s so easy to find.

  13. BeccaM says:

    Indeed: People, get your damned flu shots.

  14. docsterx says:

    Maybe, but the paramedics knew about it. In my experience, they’d probably have radioed ahead to alert the ER. I’m wondering if the “nurse” will be the sacrificial victim. You know how Ebola rolls downhill.

  15. Naja pallida says:

    Someone didn’t read the flyer from the CDC. :)

  16. docsterx says:

    The patient DID state that he was from Liberia when he first presented to the hospital ion the 26th. He also told the paramedics the same thing. Apparently, a nurse involved failed to tell the treating doctor about the patient’s travel.

  17. docsterx says:

    BREAKING: The patient with Ebola was in contact with 5 school children (presumably members of his family) in the Dallas area. All five children have been tested and are negative for Ebola. They will be monitored to make sure that they remain negative. The paramedics who were in contact with the patient have all tested negative for Ebola, as well.

  18. docsterx says:

    Gary, you probably have a point. But in most of the hospitals where I’ve worked, if we got something from the CDC or local health department, it got shared widely. Of course, that doesn’t mean that it got READ by everyone who should have read it.

    Naja, one problem is that in the early stages of Ebola, the PCR test may be negative because viral load is too low. So I believe the suggestion is, if the first Ebola test is negative, draw another at least 24 hours later and repeat. If the second one is also negative, the patient can be released. I believe that it takes at least 6 hours to do a PCR.

    I’d also think that, if this man is a Liberian, he’d have a West African accent. That should have been a tip off to ask about recent travel. I’d like to see what the CDC/local epidemiologists uncover about his first trip to the hospital.

  19. Naja pallida says:

    That’s just it. When someone shows up without insurance, if they’re not puking up their guts or bleeding all over the floor, hospital staff often don’t pay them enough attention to even determine if they have such a pathogen. The early stages of Ebola don’t present any differently than a countless number of other possible conditions. If you show up with only a fever and diarrhea, unless they have a clear reason to suspect Ebola, you’re going to be sent packing as soon as they can possibly get you out of there.

  20. GarySFBCN says:

    If it is known or discovered that the patient has a deadly, communicable pathogen, they can’t be turned away.

  21. GarySFBCN says:

    Having worked in public health, it was my experience that there was often no consistent correlation between what officials know and what front-line medical staff know. We implemented a protocol and systems to inform both hospital executives AND doctors AND ID staff AND ER/ED staff during outbreaks.

  22. Naja pallida says:

    It’s a question that nobody who supports our for-profit healthcare system has ever bothered to even try to address: What happens when someone with a potentially deadly pathogen is turned away from care for lack of ability to pay for treatment, and that leads to the spread of the disease?

  23. docsterx says:

    I’d think if the “came to the US for treatment” story were true, the first time he went to the ER, he’s have been telling everyone that he was just in from Liberia and was afraid that he had Ebola. Instead, he’s now back at the same hospital in critical condition.

    I was on several sites last night (medical and non-medical) re:Ebola. The sites that allow comments to be posted have a LOT of wild rumors posted by viewers. None seems to be evidence-based.

    I’d suggest keeping an eye on the CDC website for confirmation of things that you hear on the net, TV, radio or in the press. Though, the CDC website is a little slower to post than sites like CNN. So confirmation from the CDC may be somewhat later than news coverage.

  24. docsterx says:

    I don’t doubt that that’s a possibility. But Texas officials (at the start of the CDC press conference yesterday) were very happy to tell us just how well prepared they were to handle Ebola. I’d assume that they’d have a flyer with Ebola symptoms and questions to ask (especially recent travel history) poster at triage and lots of other places in the ER, clinics and other areas. I’m really interested in getting the full story. Didn’t the patient mention Liberia or Ebola? Wasn’t he asked? Did they think that he had some disease with similar symptoms, like gastroenteritis? It will be interesting, and educational, to get the story.

  25. docsterx says:

    Right now, the risk to US citizens is much higher from influenza than from Ebola. In 2012-2013 about 120 people died from influenza, millions became ill. It would be a good idea to get your flu vaccine now. To help prevent the spread of infectious diseases, it’s best to wash hands frequently (especially after contact with surfaces like doorknobs, handles, keyboards, etc.), avoid touching your face with unwashed hands, avoid people who are obviously ill, basically common sense precautions. Those preventive tips are just as valid for flu as for Ebola, and many other diseases.

  26. Naja pallida says:

    I guarantee, if all he presented with was flu-like symptoms, and no one thought to ask if he had recently been to west Africa, someone with no insurance would be told to rest, drink fluids, take a Tylenol, and be summarily dumped out of any Texas hospital ER moments after being seen by the triage nurse. Probably without even actually seeing a doctor. Having lived for some time without insurance in Texas, when you show up at the ER, the very first thing they ask you is for your insurance information, before even your name.

  27. docsterx says:

    This section of the CDC website has a great deal if information on Ebola that isn’t too medically complex. It’s a good source of information and might be useful to answer questions that you might have.

  28. timncguy says:

    some talking heads were speculating that he may have known that he had been exposed to someone who had the disease

  29. Except he didn’t exhibit symptoms until 4 days after arriving, so he might have been exposed, but there’s no reason to have thought he’d had it, I think.

  30. timncguy says:

    There were reports last night that the patient is an African citizen. And, there was further speculation that he may have known that he had possibly contracted ebola and traveled to the US to make sure he could get good care. Just trying to find out if we have any more concrete information.

  31. GarySFBCN says:

    “The Centers for Disease Control and Prevention (CDC) confirmed today, through laboratory tests, the first case of Ebola to be diagnosed in the United States in a person who had traveled to Dallas, Texas from Liberia. The patient did not have symptoms when leaving West Africa, but developed symptoms approximately four days after arriving in the U.S. on Sept. 20.”

  32. Bill_Perdue says:

    What could possibly go wrong.

  33. GarySFBCN says:

    What difference does it make?

  34. timncguy says:

    Can we get some clarity on whether the patient is a US citizen who traveled to Africa and then returned after his trip to Africa. Or, is the patient a NON US CITIZEN who traveled to the US to visit friends and family and was not “returning” to the US after a trip abroad.

  35. docsterx says:

    It really isn’t behaving that much differently than it has in the past, but the virus is in a new area. Outbreaks in the past usually occured in remote, sparsely populated areas. This time, Ebola is being found in cities with populations from a few hundred thousand to 21 million. It’s much easier to isolate patients and track contacts when you have an outbreak in a village that houses 100 people, everyone knows everyone else and there is no transportation other than foot travel. You can send in a team of a few doctors, nurses and assistants and handle the cases. When you have a million people, 80 doctors, a thousand nurses and some assistants, the picture changes.

    In the past, Ebola has started off being spread from animals to humans, then human-to-human transition occurs. The symptoms are the same. Incubation period is the same. Modes of transmission are the same. At least now, we have a few drugs and vaccines that we may be able to use.

    Nigeria, seemingly, has controlled its outbreak. Nigeria has a better medical infrastructure, better economy, more native doctors and nurses. They had CDC epidemiologists there involved in training local health care personnel in tracking contacts of people with HIV. They had more medical supplies on hand. Liberia, Guinea and Sierra Leone didn’t have those advantages. Hospitals in more developed countries have even more of an advantage against Ebola.

  36. docsterx says:

    Reports I read said that he initially felt unwell and went to Texas Health Presbyterian Hospital for treatment on the 26th. It’s not clear if the symptoms weren’t recognized as possible Ebola, if the patient didn’t report travel to Liberia, if he wasn’t asked about foreign travel, etc. The health insurance question may be a rumor, since he was seen at the hospital and not turned away. There are quite a few unsubstantiated rumors on the net right now.

  37. docsterx says:

    UPDATE: You can view the CDC press conference here:

    CDC’s statement on the Dallas case:

    The paramedics who transported/treated the patient are under observation. None is showing any symptoms at this time. They will be monitored for 21 days.

    The hospital has not ruled out using experimental drugs or using immune plasma on the patient. Though there is still no ZMapp (the drug given to Brantley, Writebol and others) TKM-Ebola and at least one other are available.

  38. Indigo says:

    That’s what I heard.

  39. HereinDC says:

    Is it true the hospital released him the first time because he didn’t have Health Insurance?

  40. Robert Gary (Tulane University Professor and Ebola expert living and working in Sierra Leone) said in a New York Times interview that up to 20% of Africans may be immune to Ebola, citing a large study in Gabon. We are presumably 0% immune. How can we be so sure we aren’t the Aztecs when it comes to this virus? I wish reporters would stop telling us how much we KNOW about this disease when it is behaving so drastically different than it has in the past.

  41. Indigo says:

    That’s reassuring but I’m guarded, waiting to see how this situation works out.

© 2020 AMERICAblog Media, LLC. All rights reserved. · Entries RSS