Ebola Transmissibility

[mac68DC]

Re: Ebola Transmissibility

foxp3, I think there is a chance there could be sexual transmission. Both with individuals who never displayed symptoms, and also individuals who survived Ebola and no longer display symptoms.

Human asymptomatic Ebola infection and strong inflammatory response
http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(00)02405-3/fulltext

"Ebola virus is one of the most virulent pathogens, killing a very high proportion of patients within 5?7 days. Two outbreaks of fulminating haemorrhagic fever occurred in northern Gabon in 1996, with a 70% case-fatality rate. During both outbreaks we identified some individuals in direct contact with sick patients who never developed symptoms. We aimed to determine whether these individuals were indeed infected with Ebola virus, and how they maintained asymptomatic status.
...
These findings show that some individuals were infected with the virus without developing symptoms. Results from previous outbreaks had only indicated that such an asymptomatic infection was possible.
...
Although it is possible that some individuals mount a local cellular mechanism that inhibits replication, or that the infectious dose in these individuals was so small that even a modest inflammatory response could clear virus, this response may be involved in some way in the rapid control of virus and absence of symptoms. The public-health impact of Ebola infection needs also to be reassessed in light of these new findings. The risk of transmission via blood products donated by such individuals or via semen should be taken into consideration in public-health policy since infectious filovirus have already been found in semen from symptomatic patients 2?3 months after symptoms"

 

[foxp3]

Re: Ebola Transmissibility

The American doctors treating Brantley said genetic material from the virus is in urine and semen, but it had never been shown to be viable.

So you may be right or perhaps the opposite happen, I.e. one of my outlandish ideas, perhaps exposure through the sexual route is protective.

Perhaps the viral material in semen may not be complete enough to be infectious, but may act as a vaccine. I am not saying the vaginal mucosal can prime immune responses, but if virus fragments entered the blood via this route ,then it may not be whole enough virus to cause Ebola, but instead the particles may be immunogenic enough to prime the immune system but not cause infection and symptoms. Dominant epitopes ( the parts of a pathogen that elicit the strongest responses) tend to be more resistant to enzyme attack, so probably survive to be excreted in urine and semen.



http://saharareporters.com/2014/08/...infected-americans-were-cured-dina-fine-maron

The World Health Organization maintains that patients can continue to be infectious via their sexual fluids for several months after recovery. What did you recommend to Brantly and Writebol?
There are data that go back several decades—over several outbreaks—that suggest when you have individuals that have recovered from Ebola virus infection they may still be shedding nuclear material [genetic material from the virus which could potentially help spread it] in semen in males and vaginal secretions in females and also, potentially in urine. People have done this by doing assays looking specifically at the nuclear material of the virus. There has been very little attempt to demonstrate if this is viable virus that these individuals are shedding. It’s important when looking at epidemiological investigations that no one has been able to show people shedding these nuclear materials as a source of infection after they are discharged.

 

[AnnaLisa]

Re: Ebola Transmissibility

Hmm, that is a reasonable thought.

 

[JimO]

Re: Ebola Transmissibility

Here are exerpts from an interview with the fiance (Dennis) of a nurse (Justina) who died after treating Mr. Sawyer. He is one of the survivors. One notable point is that Justina stated that she didn't have direct contact with Mr. Sawyer, so I wonder how she was infected. Dennis states later that he believes that an apparently healthy person cannot transmit the disease. Justina was pregnant, so I wonder if pregnant women and those with suppressed immune systems are more vulnerable. If so, perhaps they should not be working directly with ebola patients. It also sounds like the care received by Justina was pretty bad.

How I survived Ebola – Late Nurse fiance, Dennis Akagha speaks

Dennis Akagha, the fiance of Justina Ejelonu, the First Consultant Hospital nurse who died after being infected with the deadly Ebola virus by Liberian Patrick Sawyer, in this exclusive interview with Vanguard spoke about how his late fiancee contracted the deadly disease, how she lost their unborn child while battling with Ebola, and also revealed that Justina had just landed the job at the hospital and met Sawyer on her first day there. He also spoke on how he got infected with the virus and how he finally got discharged. Find the in-depth interview below.

On his relationship with the late Justina, Dennis said;

"... She was a qualified graduate nurse and got the job at the First Consultant Hospital in Lagos. She resumed duty at the hospital on the 21st of July, while Patrick Sawyer was admitted at the hospital on the 20th. He was her first patient. She was one of the nurses that nursed him. She was pregnant and so her immune system was weak, which made it easy for her to contract the disease... Sawyer was her first patient. The next day, Tuesday, she didn’t work on Sawyer. Wednesday and Thursday, she was off. Then on Friday, Patrick Sawyer died. They didn’t know he had Ebola, it was three days later that they realized it was Ebola” he said

-snip-

On how he found out she had contracted the deadly virus, he said

“It was after Sawyer died that she told me she nursed him but that she was on gloves. She even thanked God that she didn’t have direct contact with him. The fever continued and we thought it was just pregnancy symptoms and even when she went to her hospital, they confirmed the same thing. She took drugs and ran tests, yet it persisted. At night, she was usually cold and feverish and her body temperature was usually very high. At a point, I began to suspect that she had contacted the virus. I did some research on the disease and realised that she was having similar symptoms. On the 14th of August, it became serious, she started stooling and vomiting. I had to clean up everything...

-snip-

On what happened after he was exposed to the virus, Dennis said;

“14 days after I was exposed to Ebola, my temperature rose from the usual 35.2 degrees centigrade to 37.2... We should be reminded and educated that a healthy person with Ebola virus cannot get anybody infected, except if the person is sick and totally down with the virus like what happened to Sawyer and to my late wife-to-be, Justina. I contacted the virus because Justina was very sick and I was taking care of her without any appropriate protection...

-snip-

On the last day he saw his late fiancee, Dennis said

“The last day I saw her, I had to go inside the ward because she was so unkempt as nobody attended to her. At that time, the quarantined patients were in the former facility where there was no water and she had messed up herself again. I had to look for water to clean her up, change her pampers and arrange her bedding... I prayed for her. At a point, she needed oxygen and the hospital couldn’t provide it. Her friends had to provide it...

more...

http://yabaleftonline.com/2014/08/survived-ebola-late-nurse-fiance-dennis-akagha-speaks/

 

[Pathfinder]

Re: Ebola Transmissibility

Public Health Agency of Canada

PATHOGEN SAFETY DATA SHEET - INFECTIOUS SUBSTANCES
...
SURVIVAL OUTSIDE HOST: Filoviruses have been reported capable to survive for weeks in blood and can also survive on contaminated surfaces, particularly at low temperatures (4°C) <SUP>Footnote 52</SUP> <SUP>Footnote 61</SUP>. One study could not recover any Ebolavirus from experimentally contaminated surfaces (plastic, metal or glass) at room temperature <SUP>Footnote 61</SUP>. In another study, Ebolavirus dried onto glass, polymeric silicone rubber, or painted aluminum alloy is able to survive in the dark for several hours under ambient conditions (between 20 and 250C and 30–40% relative humidity) (amount of virus reduced to 37% after 15.4 hours), but is less stable than some other viral hemorrhagic fevers (Lassa) <SUP>Footnote 53</SUP>. When dried in tissue culture media onto glass and stored at 4 °C, Zaire ebolavirus survived for over 50 days <SUP>Footnote 61</SUP>. This information is based on experimental findings only and not based on observations in nature. This information is intended to be used to support local risk assessments in a laboratory setting.

A study on transmission of ebolavirus from fomites in an isolation ward concludes that the risk of transmission is low when recommended infection control guidelines for viral hemorrhagic fevers are followed <SUP>Footnote 64</SUP>. Infection control protocols included decontamination of floors with 0.5% bleach daily and decontamination of visibly contaminated surfaces with 0.05% bleach as necessary.
...
http://www.phac-aspc.gc.ca/lab-bio/res/psds-ftss/ebola-eng.php

 

[Sharky]

Re: NBC News freelancer in Africa diagnosed with Ebola

Re: NBC News freelancer in Africa diagnosed with Ebola

Again, I just think that this virus is a bit easier to get than the CDC says.

I agree. I think the experiences of people on the ground in West Africa over the last few months clearly proves this.

I don't know why they persist in saying one must have direct contact with a symptomatic individual.

I think the CDC is focused more on crowd control than they are on disease control.

 

[Emily]

Re: NBC News freelancer in Africa diagnosed with Ebola

Re: NBC News freelancer in Africa diagnosed with Ebola

This would be a known risk, nothing new.

?At one point he was trying to help decontaminate a car. He had most of the protective gear on, but he thinks something might have splashed on his body at that point. That?s one possibility, but really, one doesn?t know fully,? Diana said.

I hope CDC is conveying the risk. I wasn't under the impression they were only limiting risk to direct contact with an infectious person or body. Is that true?

 

[Sharky]

Re: NBC News freelancer in Africa diagnosed with Ebola

Re: NBC News freelancer in Africa diagnosed with Ebola

I hope CDC is conveying the risk. I wasn't under the impression they were only limiting risk to direct contact with an infectious person or body. Is that true?

In the recent CDC press conferences, they have said that transmission is only possible by direct contact with infected bodily fluids, and that "airborne" transmission is not possible (while saying nothing about droplets); that it's safe to sit next to someone who is infected; that transmission requires contact with an open sore on the skin or with mucus membranes.

Just today, I've started to see some CDC warnings about contact with surfaces that have been contaminated with infectious bodily fluids. Before today, their public announcements said that wasn't possible.

 

[Dani]

Re: NBC News freelancer in Africa diagnosed with Ebola

Re: NBC News freelancer in Africa diagnosed with Ebola

"Do not handle items that may have come in contact with an infected person’s blood or body fluids."

That is what the CDC has to say about transmission via fomites. If they mention this at all, the news outlets have explained that these items are bedpans, dirty needles, etc. Obviously risky items.

It just seems to me that perhaps it is a bit easier to acquire than that advice would suggest.

As Sharky mentioned, it's only lately that this has been mentioned in news conferences, and the news outlets don't even convey that much once their experts get going on the topic. Most of the experts seem mostly to want to reassure the citizenry. There was an interview with Peter Piot (one of the discoverers of the virus) which got a great deal of press, and he said "I'd happily sit next to an Ebola sufferer on the Tube." As far as I'm aware, no authority contradicted that statement, and it has gotten a great deal of play in the media.

This is straight from WebMD, and is fairly representative of what's out there:

Adalja: We know how people catch Ebola. It’s only passed through close contact with the bodily fluids of infected individuals.

http://www.webmd.com/news/20141003/ebola-expert-questions?src=RSS_PUBLIC&ecd=soc_tw_newsbot

From NPR:

Ebola isn't spread through the air, like the measles or flu. It requires close contact with some bodily fluid, such as blood or vomit, containing the virus.
http://www.npr.org/blogs/health/2014/10/02/352983774/no-seriously-how-contagious-is-ebola?utm_campaign=storyshare&utm_source=twitter.com&utm_medium=social

 

[Emily]

Re: NBC News freelancer in Africa diagnosed with Ebola

Re: NBC News freelancer in Africa diagnosed with Ebola

Thanks, Dani and Sharky. I agree CDC really needs to emphasize that contact with fluids can happen even if the patient is not near you at the time. Then that message needs to get to people at risk in a timely fashion, though some communications are handled at the local level.

As for that Peter Piot comment - it was awkward. In the British press he is quoted as adding that vomiting would changed the whole scenario. Well, that is unpredictable so that is why you need PPE to attend to Ebola patients and they should not be out riding subways.

In an unprecedented epidemic like this, I think even the experts are rattled at times.

 

[Zac]

Re: NBC News freelancer in Africa diagnosed with Ebola

Re: NBC News freelancer in Africa diagnosed with Ebola

Thanks, Dani and Sharky. I agree CDC really needs to emphasize that contact with fluids can happen even if the patient is not near you at the time.

CDC has since updated their ebola transmission mechanism page with this:

Although coughing and sneezing are not common symptoms of Ebola, if a symptomatic patient with Ebola coughs or sneezes on someone, and saliva or mucus come into contact with that person’s eyes, nose or mouth, these fluids may transmit the disease.

http://www.cdc.gov/vhf/ebola/transmission/qas.html

A recent study found cough and sneezing can eject droplets much farther than previously thought:

"Droplets that are 100 micrometers in diameter were found to travel five times farther than past estimates, while droplets 10 micrometers in diameter were found to travel 200 times farther. In addition, the team found that droplets less that 50 micrometers in size are often able to stay airborne long enough to enter ceiling ventilation units."

http://www.medicalnewstoday.com/articles/275309.php

So, the next questions are:

(1) what is the viral concentration in the ejected droplets of those infected with ebola?

(2) how many viruses are necessary to cause infection?

These won't be fixed numbers, but rather probability curves. I think it would be helpful if someone would calculate some ballpark numbers to give people some idea of the risk. For example, something like:

(1) the risk of contracting ebola is 1% if within 1 meter (or sitting/standing next to) of a sneezing symptomatic infected person

(2) the risk is 0.1% if within 5 meters (or in the same room)

(3) the risk is negligible (<0.001%) if 20 meters away

(I picked those numbers from my gut feelings and they are not based on any data )

 

[Sharky]

Re: NBC News freelancer in Africa diagnosed with Ebola

Re: NBC News freelancer in Africa diagnosed with Ebola

I was reading just a few weeks ago about how your personal biome -- mainly bacteria on your skin and in your mouth and sinus -- can completely re-colonize a hotel room within just a few hours after you arrive; that there's basically a "bio-cloud" that follows you wherever you go.

It's hard for me to believe that it would be much different with a virus that's present in sweat, saliva and mucus, even if it's not truly "airborne."

Especially given that contact with only 1 to 10 Ebola virons is required to spread the disease (and that there are at least a million of them in a small drop), what might at first seem like excessive caution is actually highly warranted.

I've heard many front-line workers in Africa say that they are careful to cover every inch of skin, leaving nothing exposed. No one there is saying you need to have a cut or abrasion for transmission.

 

[Zac]

Re: NBC News freelancer in Africa diagnosed with Ebola

Re: NBC News freelancer in Africa diagnosed with Ebola

Especially given that contact with only 1 to 10 Ebola virons is required to spread the disease (and that there are at least a million of them in a small drop), what might at first seem like excessive caution is actually highly warranted.

Is a viron a single intact encapsulated Ebola virus? If so, that doesn't sound right. If it only took contact with 1 to 10 viruses to become infected then far more people should have already been infected and Ebola would be much more readily transmitted than we have seen.

 

[theforeigner]

Re: NBC News freelancer in Africa diagnosed with Ebola

Re: NBC News freelancer in Africa diagnosed with Ebola

"Do not handle items that may have come in contact with an infected person?s blood or body fluids."

That is what the CDC has to say about transmission via fomites. If they mention this at all, the news outlets have explained that these items are bedpans, dirty needles, etc. Obviously risky items.

It just seems to me that perhaps it is a bit easier to acquire than that advice would suggest.

As Sharky mentioned, it's only lately that this has been mentioned in news conferences, and the news outlets don't even convey that much once their experts get going on the topic. Most of the experts seem mostly to want to reassure the citizenry. There was an interview with Peter Piot (one of the discoverers of the virus) which got a great deal of press, and he said "I'd happily sit next to an Ebola sufferer on the Tube." As far as I'm aware, no authority contradicted that statement, and it has gotten a great deal of play in the media.

This is straight from WebMD, and is fairly representative of what's out there:

Adalja: We know how people catch Ebola. It?s only passed through close contact with the bodily fluids of infected individuals.

http://www.webmd.com/news/20141003/ebola-expert-questions?src=RSS_PUBLIC&ecd=soc_tw_newsbot

From NPR:

Ebola isn't spread through the air, like the measles or flu. It requires close contact with some bodily fluid, such as blood or vomit, containing the virus.
http://www.npr.org/blogs/health/2014/10/02/352983774/no-seriously-how-contagious-is-ebola?utm_campaign=storyshare&utm_source=twitter.com&utm_medium=social

And sweat I presume, right?
And that would be the worst source of infection due to that it is invisible

 

[Dani]

Re: NBC News freelancer in Africa diagnosed with Ebola

Re: NBC News freelancer in Africa diagnosed with Ebola

And sweat I presume, right?
And that would be the worst source of infection due to that it is invisible

I hope the virologists on this board will correct me if I'm wrong, but I think this virus is readily transmitted through sweat, perhaps even more than other viruses.

So this is the disconnect between the news outlets and real life- those infected bodily fluids can be on surfaces- you don't have to be in direct contact with visibly contaminated items. This is what folks are not really hearing from the CDC or the news. The risk is all relative to the viral load on that surface and unfortunately you can't always tell by looking. But the CDC doesn't want people to panic, so they downplay the risk. I understand that, but it's also a little bit patronizing.

 

[AnnaLisa]

Re: NBC News freelancer in Africa diagnosed with Ebola

Re: NBC News freelancer in Africa diagnosed with Ebola

I agree with Dani, the surface need not be visibly contaminated. This concept confuses people who think that if they can't see it, that it isn't there. Skin to skin contact, even when no bodily fluid is evident can cause infection. Skin to contaminated fomite, ditto.

 

[Geonerd]

Re: NBC News freelancer in Africa diagnosed with Ebola

Re: NBC News freelancer in Africa diagnosed with Ebola

Maybe we don't know as much as we think we know about Ebola. That's what's been bugging me all summer. Either people are infectious before they get symptoms or fomite (surface) transfer is more likely than the CDC is letting on. But the " direct contact with bodily fluids" meme is getting a bit threadbare.

Got to agree about direct contact. WHO workers have been educating the Africans for many years, and even the most simple rural farmer must by now have some clue not to touch the oozing body of a dying Ebola victim. C'mon, the area may be poor, but the people aren't idiots.

The notion that sick people are not infectious until overtly symptomatic also sounds fishy. Unlike flu and other common airborne diseases, Ebola doesn't require inflamed, irritated mucous membranes to trigger the transmission mechanism (coughing, etc.) I'll bet the blood of an 'incubating' patient is infectious as hell. Other fluids too, depending on how the disease progresses, something I'd like to learn more about.

 

[AlaskaDenise]

Re: NBC News freelancer in Africa diagnosed with Ebola

Re: NBC News freelancer in Africa diagnosed with Ebola

Got to agree about direct contact. WHO workers have been educating the Africans for many years, and even the most simple rural farmer must by now have some clue not to touch the oozing body of a dying Ebola victim. C'mon, the area may be poor, but the people aren't idiots. ....

Welcome Geo.

I just posted a thread about an ebola mystery book describing the influence of magic & sorcery on the beliefs of some rural African areas. They believe that these terrible diseases are like a "hex" on a person for not living right, like not being generous enough. I can image that many will take action based on their traditional teachings rather than some new-fangled "education". It is what it is. He does say that one thing that will bring the disease rate down is better health care for these people - so they don't end up caring for their sick family members at home.

.

 

[BestlaStormcrow]

Re: NBC News freelancer in Africa diagnosed with Ebola

Re: NBC News freelancer in Africa diagnosed with Ebola

Got to agree about direct contact. WHO workers have been educating the Africans for many years, and even the most simple rural farmer must by now have some clue not to touch the oozing body of a dying Ebola victim. C'mon, the area may be poor, but the people aren't idiots.

The notion that sick people are not infectious until overtly symptomatic also sounds fishy. Unlike flu and other common airborne diseases, Ebola doesn't require inflamed, irritated mucous membranes to trigger the transmission mechanism (coughing, etc.) I'll bet the blood of an 'incubating' patient is infectious as hell. Other fluids too, depending on how the disease progresses, something I'd like to learn more about.

I agree. How can there be some abrupt cutoff between incubating and infectious? It's got to be on a continuum, depending on a number of variables.

But too many people can't deal with ambiguity, so the messaging has to simplify and sound certain.

 

[Gert van der Hoek]

Ebola Transmissibility

WHO

What we know about transmission of the Ebola virus among humans

Ebola situation assessment - 6 October 2014

The Ebola virus is transmitted among humans through close and direct physical contact with infected bodily fluids, the most infectious being blood, faeces and vomit.

The Ebola virus has also been detected in breast milk, urine and semen. In a convalescent male, the virus can persist in semen for at least 70 days; one study suggests persistence for more than 90 days.

Saliva and tears may also carry some risk. However, the studies implicating these additional bodily fluids were extremely limited in sample size and the science is inconclusive. In studies of saliva, the virus was found most frequently in patients at a severe stage of illness. The whole live virus has never been isolated from sweat.

The Ebola virus can also be transmitted indirectly, by contact with previously contaminated surfaces and objects. The risk of transmission from these surfaces is low and can be reduced even further by appropriate cleaning and disinfection procedures.

Not an airborne virus

Ebola virus disease is not an airborne infection. Airborne spread among humans implies inhalation of an infectious dose of virus from a suspended cloud of small dried droplets.

This mode of transmission has not been observed during extensive studies of the Ebola virus over several decades.

Common sense and observation tell us that spread of the virus via coughing or sneezing is rare, if it happens at all. Epidemiological data emerging from the outbreak are not consistent with the pattern of spread seen with airborne viruses, like those that cause measles and chickenpox, or the airborne bacterium that causes tuberculosis.

Theoretically, wet and bigger droplets from a heavily infected individual, who has respiratory symptoms caused by other conditions or who vomits violently, could transmit the virus – over a short distance – to another nearby person.

This could happen when virus-laden heavy droplets are directly propelled, by coughing or sneezing (which does not mean airborne transmission) onto the mucus membranes or skin with cuts or abrasions of another person.

WHO is not aware of any studies that actually document this mode of transmission. On the contrary, good quality studies from previous Ebola outbreaks show that all cases were infected by direct close contact with symptomatic patients.

No evidence for mutation of this virus

Moreover, scientists are unaware of any virus that has dramatically changed its mode of transmission. For example, the H5N1 avian influenza virus, which has caused sporadic human cases since 1997, is now endemic in chickens and ducks in large parts of Asia.

That virus has probably circulated through many billions of birds for at least two decades. Its mode of transmission remains basically unchanged.

Speculation that Ebola virus disease might mutate into a form that could easily spread among humans through the air is just that: speculation, unsubstantiated by any evidence.

This kind of speculation is unfounded but understandable as health officials race to catch up with this fast-moving and rapidly evolving outbreak.

To stop this outbreak, more needs to be done to implement – on a much larger scale – well-known protective and preventive measures. Abundant evidence has documented their effectiveness.

WHO