No, Seriously, How Contagious Is Ebola?

Oct 7, 2014

Adam Cole/NPR

By Michaeleen Doucleff

Holy moly! There’s a case of Ebola in the U.S.!

That first reaction was understandable. There’s no question the disease is scary. The World Health Organization now estimates that the virus has killed about 70 percent of people infected in West Africa.

The Ebola case in Dallas is the first one diagnosed outside Africa, the Centers for Disease Control and Prevention said Tuesday. And the health care system in Texas didn’t quarantine the man right away. He was sick with Ebola — and contagious — for four days before he was admitted to the hospital.

But when you look at health officials responding to the case in Dallas, they seem cool as cucumbers, despite the initial misstep.

“I have no doubt that we will control this importation, or case, of Ebola so that it does not spread widely in this country,” said the director of the CDC, Dr. Tom Frieden.

Why is Frieden so sure this virus won’t spread beyond a handful of cases?

It boils down to something called “R0.”

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20 comments on “No, Seriously, How Contagious Is Ebola?

  • Meanwhile in Spain!

    Spanish nurse’s Ebola infection blamed on substandard equipment

    Staff at Madrid’s Carlos III hospital say protective suits do not meet WHO standards as second nurse undergoes tests for virus

    Health professionals in Madrid have blamed substandard equipment and a failure to follow protocol for the first case of Ebola to be contracted outside west Africa.

    Health authorities announced on Monday that a Spanish nurse at Madrid’s Carlos III hospital who treated a patient repatriated from Sierra Leone had twice tested positive for Ebola.

    Her husband had also been admitted to hospital and was in isolation, and a second nurse from the same team that treated both repatriated Ebola victims was also being tested. In this case, the nurse contacted the authorities on Monday complaining of a fever. She was in isolation in the Carlos III Hospital while authorities waited for the test results, a spokesperson for the Madrid regional government said.

    The nurse had alerted the ministry of a slight fever on 30 September and been checked into a hospital in Alcorcón, on the outskirts of Madrid, with a high fever on Monday. She was transferred to Carlos III hospital early on Tuesday morning.

    El Mundo reported that it was the nurse who asked to be tested for Ebola, having to insist repeatedly on being tested before it was done on Monday.

    While staff at the Alcorcón hospital were waiting for the test results, the nurse remained in a bed in the emergency room, separated only by curtains from other patients, hospital staff told El Mundo. Their version of events clashes with that of health authorities, who have said the patient was isolated from the first moment.

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  • He’s not worried because anybody in the US with Ebola exposure will be locked in their house with armed police ouside the door.

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  • This outbreak is unlike none other. The genus Ebolavirus is thought to be ten million years old. It must be kept from becoming endemic. If that was to happen we can speculate on it becoming airborne in a relatively short timespan. It mutates with every jump, although not at the same rate as Influenza A. About half as fast. If it is “out” of the jungle and not extinguished, it will have an opportunity to do so. It must be put out at all costs including temporary liberty. If we had spent the energy on This outbreak instead of dumping ice on our heads, thousands would be alive and this would not be a subject. As long as we as a first nation allow west africa to stay in the state of utter “oilless” devastation none of us need worry about climate change or anything else.

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  • 4
    Robert Firth says:

    Gee, each infected person infects only two others.

    Did anyone else remember the king’s chessboard? The one where he is asked to place one grain of corn on the first square, two grains on the next, four grains on the next, …?

    I listened to Dr Tom Frieden’s interview, and was no longer afraid – I was terrified. “The US is not Africa”, he said smugly. I’ve lived in both the US and Africa, and sorry, much of the US is like Africa, only worse. If Ebola reaches the inner cities of Detroit, or Pittsburgh, or Atlanta, or (add your favouriyte ghetto here) it’s over. I doubt one emergency room in 10 in those areas even has the necessary protective equipment, and I doubt one health-care worker in 10 would have any idea what to do with it. As happened in Detroit.

    Once established, Ebola will spread to other mammals (bats preferred), and they will become a permanent reservoir. And every new case is a new opportunity for Ebola to mutate and become airborne. Not impossible – not even unlikely, because airborne infection between monkeys has already been observed.

    We are closer to the brink than the WHO or the CDC realises.

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  • The “nice” things about Ebola:

    You die quickly before you can infect others.
    You are not infections if you do not have symptoms.
    It is very obvious you are infected.

    Compare that with HIV.

    you can can live for a decade without knowing you are infected, all the while you are infectious.
    You look perfectly normal to others and to yourself.

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  • I’m confident ebola will be controlled by vaccination before long.

    then it’ll make a huge comeback as soon as people forget what it actually does and start preaching the virtues of “natural resistance” and linking the vaccine to an increase in ginger babies or something

    just lucky it’s much less contageous than measles eh?

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  • It looks like things are getting worse in Spain!

    WHO warns of Ebola health care risks

    A prominent World Health Organization adviser has warned that more Ebola cases can be expected among medical staff – even in developed countries with modern health care systems.

    Professor Peter Piot said he was not surprised that a Spanish nurse had contracted the disease.

    The nurse, Teresa Romero, is the first person known to have contracted the deadly virus outside West Africa.

    She treated two Spanish missionaries who died of Ebola in Madrid.

    In all, more than 50 people in Spain are under observation.

    Ms Romero, a 40-year-old auxiliary nurse, had been part of a team of about 30 staff at the Carlos III hospital in Madrid looking after Manuel Garcia Viejo and Miguel Pajares when they were repatriated from Sierra Leone and Liberia respectively.

    She remains in quarantine in the Spanish capital along with her husband and three other people.

    A fifth person was admitted on Wednesday morning with a slight fever. She is said to be a friend of Ms Romero and, like her, an auxiliary nurse in the Carlos III Ebola care unit.

    In all, more than 50 people in Spain are under observation.

    Ms Romero told Spain’s El Mundo’s newspaper on Wednesday that she had followed the correct protocol and had “no idea” how she had become infected. She said she was feeling “a little better” but was very tired.

    Officials say earlier she had twice gone into Mr Garcia Viejo’s hospital room, first to treat him and later to disinfect the room after his death.

    . . . . . . .
    The BBC’s Lucy Williamson in Madrid says hospital staff reported scenes of panic at work on Tuesday, with some people crying and others leaving the premises.

    The hospital was reported to have had extreme protective measures in place

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  • things are getting worse in Spain

    Purportedly, the patient’s dog was put down, and citizens are outraged. True heartbreak for the owner – necessary evil or overkill? Nice to see compassion for other animals, usually overlooked in times of crises.

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  • 9
    Aber ration says:

    But isn’t this number “2” for Ebola based only on what we know as fact so far? What about what we don’t know?The guy in Texas lied about his contact with Ebola before arriving. Many of the cases in Africa have gone unregistered they must have done. Just think of the conditions where it is prevalent. People are being buried in gardens and nursed by relatives at home. No one is counting those people. It is quite easy to believe that at least double the number of victims would be nearer the truth. How would that affect the R0 number? And as the article says 2 in a week is not 4 over ten tears.

    2 in a week is thousands in a few months and how do you quarantine thousands, tens of thousands? While the thousands are being quarantined who is running the services we take for granted? How many staff run a power station. How many need to be missing before it is closed down. Water plants, hospitals, power, transport? Our Western lifestyles are way more fragile than living in a hut in the jungle because everything is specialised.

    You lose 70% of the population of a small village in a jungle and you have a smaller village in a jungle.

    You lose 70% of the population of Dallas and you have no city left. The remaining population will need to find a hut in the jungle to survive and they don’t know how to survive in a hut in the jungle.

    Look how America reacted to the Katrina event and that was just one city. It was just a few days before civilisation broke down.

    We are really not taking this seriously enough. I don’t think this is scaremongering. Viruses are the only real threat to humanity excluding boulders from out of space which we really have no control over. We know exactly what we are dealing with here and how to stop it and we aren’t doing what we need to to stop it.

    Just my opinion.

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  • 10
    Morgan says:

    The fearmongering over Ebola is ridiculous. There’s a reason, despite being an ancient virus, that its outbreaks are rare. The survivability (read: spread potential) of a virus, parasite, or other infectious agent is determined by 4 things:

    How long it can survive outside a host (Ebola loses its infectivity within a couple days above or below 70 degrees Fahrenheit)
    The stage of it’s infectivity in-vivo (Ebola is only transmissible from a host once their symptoms have begun showing)
    The intensity of the nonlethal symptoms (Ebola has incredibly obvious and powerful symptoms, making it a huge warning sign that a person should obviously be avoided)
    How fast it kills the host (if lethal) after the infectivity stage has begun (Ebola generally kills its host 4-10, sometimes up to 20 days after symptoms have begun, meaning the host will not have much time to spread the virus – especially considering point 3 above)

    Given these factors, Ebola has evolved to be quite lethal, but quite inefficient at spreading itself. There’s not much to be worried about for the average person.

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  • Just a comment on the presented Ro values for the different viruses (although perhaps the Ro values may already take the following into account. I stand to be corrected). . . .

    Measles: we’re vaccinated in Western countries: so the Ro value should be zero where vaccinated people are concerned;

    Mumps: we’re also vaccinated against this virus in Western countries: so the Ro value should also be zero where vaccinated people are concerned;

    SARS: I can’t cast doubt on this Ro value.

    HIV: you need to have a transfusion or intercourse to transmit this virus: so it’s not as easy as Ebola to transmit. Is the above Ro value compromised?

    Hepatitis C: same modeof transmission as HIV, plus consumption of contaminated water (eg ice in your drink). Nevertheless, HepC is less easy than Ebola to transmit. Is the above Ro value compromised?

    My paranoia will probably steer me clear of hotel swimming pools, saunas and jacuzzis in my overseas travels in the near future.

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  • This Ro chart is not exactly the right one, in my opinion, in order to compare Ebola with another infection in this way. Ebola is different. First of all, it’s an extremely deadly virus and its shot is like a sniper, almost every time for sure. Second, there is no cure for this. You can’t put together something that you can control with something that has “mind of it’s own”. Finally, we still don’t know much about Ebola. I didn’t believe in the panic, but we need to think everything through on it’s alien invasion and stop giving people false information.

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  • On average one person with Ebola will infect two people, and one of those two people, on average, will die. Let’s get all the facts in now.

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  • This is the worst sort of pseudo scientific scare mongering. You’ve even used ‘endemic’ because it sounds vaguely like pandemic and you couldn’t remember the right word.

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  • The problems seem to have now spread to Texas!

    Ebola: Health care worker tests positive at Texas hospital

    A Texan health worker who treated Ebola victim Thomas Eric Duncan before he died is also infected with the virus, according to a preliminary test.

    The worker, whose name was not given, wore full protective gear when treating Duncan on his second visit to a Dallas hospital, an official told reporters.

    The new patient has been placed in an isolation ward and is said to be in a stable condition.

    If confirmed, this is the first known transmission of Ebola on US soil.

    Duncan, who caught the virus in his native Liberia, died on Wednesday.

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  • 16
    Aber ration says:

    “But when you look at health officials responding to the case in Dallas, they seem cool as cucumbers, despite the initial misstep.”

    And now they don’t know how the nurse contracted it. Maybe they were too cool. And maybe we are not doing enough and maybe there are too many articles saying don’t worry folks we are quite safe in the well protected West, it really isn’t that infectious.

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  • Meanwhile the geographical spread continues using modern transport systems!

    A United Nations medical worker infected with Ebola has died at a hospital in Germany.

    Doctors at the hospital in Leipzig said the man, 56, originally from Sudan, died despite receiving experimental drugs to treat the virus.

    The outbreak has killed more than 4,000 people since March – mostly in Liberia, Sierra Leone, Guinea and Nigeria.

    The World Health Organization says the outbreak is the “the most severe, acute health emergency in modern times”.

    The US and UK are among countries to have introduced scanning at airports
    A unit of Sierra Leone’s international peacekeeping force on standby for deployment in Somalia has been placed in quarantine after one member was confirmed with Ebola

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  • HIV: you need to have a transfusion or intercourse to transmit this virus: so it’s not as easy as Ebola to transmit. Is the above Ro value compromised?


    HIV is much more difficult to transmit. But it is transmissible during a much longer time. In the end, Ebola is transmitted to two people in a few weeks; HIV is transmitted to two people in several years. R0 is the total transmission, not the rate of transmission.

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  • All the previous outbreaks of Ebola have caused a maximum of 400 deaths each.

    The present one has already caused more than 2,000.

    It seems that either the virus has changed, or the populations it affects have.

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