Filovirsus

 


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[Sep 17, 2014]
Center for Infectious Disease Research and Policy
Health workers need HEPA filtered positive-air-flow respiratory protection for Ebola
http://www.cidrap.umn.edu/news-perspective/2014/09/commentary-health-workers-need-optimal-respiratory-protection-ebola

We believe there is scientific and epidemiologic evidence that Ebola virus has the potential to be transmitted via infectious aerosol particles both near and at a distance from infected patients, which means that healthcare workers should be wearing [HEPA-filtered positive-air-flow] respirators, not facemasks.

The Center for Infectious Disease Research and Policy (CIDRAP; "SID-wrap") is a global leader in addressing public health preparedness and emerging infectious disease response. Founded in 2001, CIDRAP is part of the Academic Health Center at the University of Minnesota.

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How the Gods Kill
http://morecrows.wordpress.com/2014/10/13/ebola-updates/

Emory hospital works closely with the CDC, and hence has some of the best isolation facilities in the world. The clinical care section of the document is the single best description of the course of the disease I have ever seen (http://www.magnetmail.net/actions/email_web_version.cfm?recipient_id=252410565&message_id=7159249&user_id=IDSociety&group_id=1191715&jobid=22381830)

There is 5-10 liters of fluid loss per day, largely through leaking into tissue outside the bloodstream due to loss of albumin (the protein that keeps fluid in the blood.) The disease also depletes electrolytes, which we all know and love from gatorade commercials. As well as facilitating muscle contraction, electrolytes are the electrical "juice" for nerve and heart cells, and screwed up electrolytes (from, say, prolonged vomiting) can lead to heart arrhythmias and death.

Albumin, for the record, is produced by the liver, and is one of the first proteins "economised" in a starvation situation. This is why the typical image of kwashiorkor starvation is a skeleton with a pot-belly: that belly is actually fluid that has leaked out of the bloodstream because there isn't enough protein to hold it in. Not blood, not bleeding, just fluid. I'm not clear why Ebola patients would lose albumin during the illness, the document mentions "nutritional depletion" but there may be more liver-specific reasons as well. I'm speculating.

Clinical care seems to be electrolyte replacement, nutritional support, in liters of fluid. The Emory team "engaged the FDA, CDC and pharmaceutical manufacturers in active discussions" about experimental therapies, but its not clear what was used and without more data points we can't know if anything helped.

On the question of airborne transmission, I mentioned in the last post that testing was by reverse-transcriptase PCR which means looking for viral RNA. The Emory team tested every fluid and (it seems like) every surface the patients were exposed to, and found Ebola virions only in the fluid samples. That makes a dry airborne transmission less likely. However, its also worth noting that, again as I mentioned before, wearing Personal Protective Equipment (PPE) consistently and constantly is grueling and in some climates impossible for the human body. Staff at Emory switched to using battery Powered Air Purifying Respirators or PAPRs for their own comfort, as these are cooled by airflow. Whether they become the standard of care for comfort reasons, compliance reasons, or as a hedge against fear of "airborne" viruses, they seem to be acceptable for use in a hospital setting at least.

... if I were a hospital administrator, I'd be on the phone to purchasing right now.

[Well, I am not a hospital administrator and I think it may be a good idea to have several of these around the house before they become unavailable.]

October 8, 2014
Ebola Ebola
http://morecrows.wordpress.com/2014/10/08/ebola-ebola/

Ebola presents like most any other viral fever, with severe headaches, runny snot, puking, diarrhea, muscle aches, fatigue, and mental vagueness ("depersonalization"). It also causes intravascular hemolysis and disseminated intravascular coagulation (DIC) and means, pretty much, blood clots randomly until it runs out of fibrin, then it never clots. It is this profusion of blood clots and uncontrolled bleeding that leads to the rash (small specks of bleeding from capillaries under the skin), the black vomit (bleeding into the stomach) and the bloody stool. Ebola also causes nosebleeds, bloody spit, and bloody urine (from bleeding in the kidneys.) Ebola also causes profound hiccuping.

... facts aren't really there to support the idea that Ebola has mutated to spread through the air. Just to be clear, air transmission means Ebola virions traveling on air currents into your lungs, without the protective shell of a droplet of fluid, has yet to be demonstrated.

That doesn't mean that everyone who shares space with an Ebola patient and who doesn't touch them directly is safe. In fact, given how rapidly this disease is spreading without airborne transmission, its hard to see why so much emotional energy is caught up in this fairly technical distinction.

... [Worst case] If everybody gets sick. 19% of the population will survive and everyone else dies. Incidentally, there's a bunch of BS about case fatality in the press - at any time in the course of this outbreak, the number of deaths is likely to be half the number of sick people. However, most of those sick people were infected too recently to have died or not, and the epidemic is growing. These factors combine to make it look less lethal than it is. The ratio of currently dead, to infected-sixteen-days-ago, has been 0.81 from the start of the epidemic, with very tight confidence intervals. This is likely the "true" case fatality rate (CFR) and closer to what we'll see on the way down. Almost certainly everybody getting sick is not going to happen; there's too much else going on.

If the average person interacts with a hundred people over the course of their illness, and potentially infects two of them, what difference does it make if 50% of those people are immune? [R0 of x is the ratio of contagion where R0 of 1 is stable and R0 of 2 is doubling, etc.] The R0-Effective has to take this into account. This is why measles doesn't kill every unvaccinated American - the high R0-20 for measles crashes into the high vaccination rate to produce an effective R0 below 1.0.

For Ebola, a "raw" R0 of 1.4 will still die out if ~71% of people are immune. To get there without a vaccine, of course, 93% of your population has to get infected and 75% of your population dies - the remaining 18% who got sick and survived make up 72% of the remaining quarter. This isn't much better than everyone getting sick, but it at least shows how everybody does not have to die.

The CDC's Excel-based model terminates some time in 2015 (its a 300-day model) based on moving more and more of the population to hospitals. As noted above, transmission does occur in hospitals, but the R0 is less than 1.0, and far, far below the R0 in the wild. These hospitals don't exist, but the US and the rest of the international community is building them like crazy. Without a vaccine, this is probably the most sensible response available. Remember that not everyone has to be hospitalized, only enough people that the overall transmission rate drops below replacement. Other guesses generally range from two to four years (Summer 2016-Fall 2018).

This is the scariest outcome of all, and the one that popped up in my own clumsy model. Essentially, Ebola reaches a stable island bio-geography - an outbreak here, an outbreak there, none lasting more than a year, but never really burning up the planet, but never quite catching the last case or immunizing enough people to contain the spread altogether.

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[2-Oct-14]
Estimating and Predicting Epidemic Behavior for the 2014 West African Ebola Outbreak
http://grantbrown.github.io/Ebola-2014-Analysis-Archive/Oct_02_2014/Ebola2014/Ebola2014.html

... models appear to have resumed predicting a fairly catastrophic continued spread, especially in Liberia. In particular, the models predict that the epidemic will take off in Nigeria, as the countries are assumed in this case to share several intensity parameters. We may hope that this particular simplifying assumption is invalid, however it is not a hopeful sign that WHO predictions are also becoming catastrophic.

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[Late 13-Oct-14]
The survival of filoviruses in liquids, on solid substrates and in a dynamic aerosol
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2672.2010.04778.x/full
Article first published online: 22 MAY 2010

This study has demonstrated that filoviruses are able to survive and remain infectious for cell culture, for extended periods when suspended within liquid media and dried onto surfaces. In addition, decay rates of a range of filoviruses, within small-particle aerosols, have been calculated, and these rates suggest that filoviruses are able to survive and remain infectious for cell culture for *at least 90 min*.

Our study has shown that Lake Victoria marburgvirus (MARV) and Zaire ebolavirus (ZEBOV) can survive for long periods in different liquid media and can also be recovered from plastic and glass surfaces at low temperatures for *over 3 weeks*. The decay rates of ZEBOV and Reston ebolavirus (REBOV) plus MARV within a dynamic aerosol were calculated. ZEBOV and MARV had similar decay rates, whilst REBOV showed significantly better survival within an aerosol.

Survival of EBOV and MARV dried onto solid substrates over 14 days.
Survival of EBOV and MARV dried on to solid substrates over 50 days
Inactivation rates of MARV, ZEBOV and REBOV within an aerosol

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[Early 13-Oct-14]
Yes, Ebola appears to be less transmissible than influenza, but its transmission vectors are not well understood. The problem, of course, is that Ebola mortality seems to be as high as 76% in Africa. The key questions are: does the virus transmit as an 'aerosol' and how long can the virus remain viable on an open air surface.

Here is the Wikipedia entry on influenza vectors. These seem to be reasonable vectors for Ebola as well. Also, like any virus, the longer Ebola remains in human hosts, the higher the probability it will evolve into a more transmissible, but less virulent, form.

http://en.wikipedia.org/wiki/Influenza
Wikipedia: Influenza can be spread in three main ways: by direct transmission (when an infected person sneezes mucus directly into the eyes, nose or mouth of another person); the airborne route (when someone inhales the aerosols produced by an infected person coughing, sneezing or spitting) and through hand-to-eye, hand-to-nose, or hand-to-mouth transmission, either from contaminated surfaces or from direct personal contact such as a hand-shake. ... In the airborne route, the droplets that are small enough for people to inhale are 0.5 to 5 µm in diameter and inhaling just one droplet might be enough to cause an infection. Although a single sneeze releases up to 40,000 droplets, most droplets are large and quickly settle out of the air.

As the influenza virus can persist outside of the body, it can also be transmitted by contaminated surfaces such as banknotes, doorknobs, light switches and other household items. The length of time the virus will persist on a surface varies, with the virus surviving for one to two days on hard, non-porous surfaces such as plastic or metal, for about fifteen minutes from dry paper tissues, and only five minutes on skin. However, if the virus is present in mucus, this can protect it for longer periods (up to 17 days on banknotes). Avian influenza viruses can survive indefinitely when frozen. They are inactivated by heating to 56 °C (133 °F) for a minimum of 60 minutes, as well as by acids (at pH <2).

Oh, and according to John M. Barry
(http://www.amazon.com/Great-Influenza-Deadliest-Pandemic-History/dp/0143036491) the pandemic did not reach New Zealand.

T-
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On 10/13/2014 06:27 AM, wrote:
> Obviously the government is not being completely truthful about
> Ebola's spread but with about 8,000 total cases in the course of
> this 28 week outbreak it is obviously far less transmissible than
> the flu (see below)
>
> The global mortality rate from the 1918/1919 pandemic is not known,
> but
> an estimated 10% to 20% of those who were infected died. With about a
> third of the world population infected, this case-fatality ratio means
> 3% to 6% of the entire global population died. Influenza may have
> killed as many as 25 million people in its first 25 weeks. Older
> estimates say it killed 40–50 million people, while current
> estimates say 50–100 million people worldwide were killed.
>
> This pandemic has been described as "the greatest medical holocaust in
> history" and may have killed more people than the Black Death. It is
> said that this flu killed more people in 24 weeks than AIDS has killed
> in 24 years, more in a year than the Black Death killed in a century.
>
> The disease killed in every corner of the globe. As many as 17 million
> died in India, about 5% of the population. The death toll in India's
> British-ruled districts alone was 13.88 million. In Japan, 23
> million people were affected, and 390,000 died. In the Dutch East
> Indies (now Indonesia), 1.5 million were assumed to have died from 30
> million inhabitants. In Tahiti, 14% of the population died during
> only two months. Similarly, in Samoa in November 1918, 20% of the
> population of 38,000 died within two months. In the U.S., about 28%
> of the population suffered, and 500,000 to 675,000 died. Native
> American tribes were particularly hard hit. In the Four Corners area
> alone, 3,293 deaths were registered among Native Americans. Entire
> villages perished in Alaska. In Canada 50,000 died. In Brazil
> 300,000 died, including president Rodrigues Alves. In Britain, as
> many as 250,000 died; in France, more than 400,000. In West Africa,
> an influenza epidemic killed at least 100,000 people in Ghana.
> Tafari Makonnen (the future Haile Selassie, Emperor of Ethiopia) was
> one of the first Ethiopians who contracted influenza but survived,
> although many of his subjects did not; estimates for the fatalities in
> the capital city, Addis Ababa, range from 5,000 to 10,000, or
> higher. In British Somaliland one official estimated that 7% of the
> native population died.
>
> This huge death toll was caused by an extremely high infection rate of
> up to 50% and the extreme severity of the symptoms, suspected to be
> caused by cytokine storms. Symptoms in 1918 were so unusual that
> initially influenza was misdiagnosed as dengue, cholera, or typhoid.
> One observer wrote, "One of the most striking of the complications was
> hemorrhage from mucous membranes, especially from the nose, stomach,
> and intestine. Bleeding from the ears and petechial hemorrhages in
> the skin also occurred." The majority of deaths were from bacterial
> pneumonia, a secondary infection caused by influenza, but the virus
> also killed people directly, causing massive hemorrhages and edema in
> the lung.
>
> The unusually severe disease killed up to 20% of those infected, as
> opposed to the usual flu epidemic mortality rate of 0.1%

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On 10/12/2014 05:11 PM, wrote:
> Yes, I saw that on the news this AM.  The report I saw on CNN early
> today made no mention of anyone being very concerned.  To the
> contrary –  local officials claim the situation is under control yet
> admit they haven't a clue how the nurse got infected.
>
> When is the press going to figure out these assholes are making
> political decisions and not factual decision?  The current situation,
> which will likely only worsen, is a direct consequence of the
> decision not to quarantine the Ebola hot spots.  I predict they will
> blame the nurse for not following procedures.  Pretty soon they won't
> have any doctors and nurses willing to treat Ebola patients and
> demonize them.
>
> All the temperature taking and questionnaires at airports is a joke.
> Experience has shown that air travel helps spread infection.  The
> tight quarters in an airliner make it very easy to pass on an
> infection.  A flight to the US takes about 14+ hours – plenty of time
> for a sick patient to pass their silly ass tests at departure and be
> infectious upon arrival.  Any process that does not take this into
> consideration places us at risk.  Of course those at most risk from
> repeated exposure are the flight crew.  Imagine a flight attendant
> serving food while becoming sick during flight.

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[12-Oct-14]
A health care worker at Texas Health Presbyterian Hospital who provided care for the Ebola patient hospitalized there has tested positive for Ebola ... *even though he followed Centers for Disease Control and Prevention (CDC) precautions* ...

The healthcare worker was not considered at high risk of contracting Ebola, Varga said. The individual was following full CDC precautions, Varga added. "We're very concerned."

http://thehill.com/policy/healthcare/220503-second-us-ebola-case-confirmed

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[6-Oct-14]
Questions and Answers on Ebola
http://raconteurreport.blogspot.com/2014/10/do-math.html

Read the comments. Docs, hospital staff, and airline pilots discuss Hemorrhagic fever virus vectors, procedures, and policy.

Consensus - stay home or die. Distance is life.