Experts worry Ebola could mutate to spread by air

[theforeigner]

Experts worry Ebola could mutate to spread by air

Read more: http://www.ctvnews.ca/health/expert...tate-to-spread-by-air-1.2003633#ixzz3D7aaizTL

Helen Branswell, The Canadian Press
Published Friday, September 12, 2014 6:28AM EDT
Last Updated Friday, September 12, 2014 11:56AM EDT

TORONTO -- The unprecedented spread of the Ebola virus in West Africa may be pushing the world toward a viral disaster, a commentary published in Friday's New York Times suggests.
The article reveals that experts are worried ongoing transmission of the virus through people runs the risk of giving rise to mutations that might allow Ebola to spread through the air, like some of the world's most contagious viruses. The virus currently spreads when a person has contact with contaminated bodily fluids.
The article bears the headline: What We're Afraid to Say About Ebola. It was written by Michael Osterholm of the University of Minnesota's Center for Infectious Diseases Research and Policy.

snip

Osterholm suggested each infection gives the mutating virus "trillions of throws of the genetic dice."
"The current Ebola virus's hyper-evolution is unprecedented; there has been more human-to-human transmission in the past four months than most likely occurred in the last 500 to 1,000 years," he said in his Times commentary.
Ebola currently spreads through exposure to bodily fluids like vomit, blood or feces. Exposure is high risk for those who encounter these fluids, but only those caring for sick patients or preparing the dead for burial do.
"If certain mutations occurred, it would mean that just breathing would put one at risk of contracting Ebola. Infections could spread quickly to every part of the globe, as the H1N1 influenza virus did in 2009, after its birth in Mexico," Osterholm wrote.

 

[franzpick]

Re: Experts worry Ebola could mutate to spread by air

Liberian SitReps #116 and #118 show a 2 day, 9/9-9/10, increase of 231 new cases (or 223 new cases in a different table), which if continued would double the 9/10 new case Liberian total from 2415 to 4830 in just 20 days, by Sep. 30, and then double again to 10,000 total cases by Oct. 20, if the trends persist.

If these statistics are not new case overstatements due to difficulties and errors in data capture, classification and reporting, the 100% increases in the 2 day new Liberian case numbers could be signaling the beginning of an infection rate runaway.

 

[Emily]

Re: Experts worry Ebola could mutate to spread by air

The Zaire strain became less virulent as it adapted to humans during the 1976 outbreak.


1976 Zaire strain outbreak study: Fewer haemorrhagic manifestations & fatalities during later stages of the epidemic after the virus had undergone several generations in man

 

[Donners]

Re: Experts worry Ebola could mutate to spread by air

Osterholm suggested each infection gives the mutating virus "trillions of throws of the genetic dice."
"The current Ebola virus's hyper-evolution is unprecedented; there has been more human-to-human transmission in the past four months than most likely occurred in the last 500 to 1,000 years," he said in his Times commentary.

It wiped out thousands upon thousands of non-human primates - 5,000 in a single study area - a decade ago.

That provoked very little interest, despite the potential for mutation being just as high as in humans.

 

[Vibrant62]

Re: Experts worry Ebola could mutate to spread by air

Accepted, but it gives rise to an interesting question.

Primates do not (generally) live in large groups, and dont have 'funeral rites'; so how did it spread so widely?

 

[Emily]

Re: Experts worry Ebola could mutate to spread by air

Accepted, but it gives rise to an interesting question.

Primates do not (generally) live in large groups, and dont have 'funeral rites'; so how did it spread so widely?

What do you mean by 'large groups'? Chimps are 'highly affiliative.'

http://janegoodall.ca/get-involved/ebola-outbreaks-cause-crisis-great-apes-humans/

 

[curiosity]

Re: Experts worry Ebola could mutate to spread by air

Accepted, but it gives rise to an interesting question.

Primates do not (generally) live in large groups, and dont have 'funeral rites'; so how did it spread so widely?

Grooming

 

[Emily]

Re: Experts worry Ebola could mutate to spread by air

It wiped out thousands upon thousands of non-human primates - 5,000 in a single study area - a decade ago.

That provoked very little interest, despite the potential for mutation being just as high as in humans.

Do you have a link to a study that shows that a mutation was involved? Goodall just describes a prolonged outbreak, (discovered through retrospective analysis), spanning years as racking up those numbers.

 

[Vibrant62]

Re: Experts worry Ebola could mutate to spread by air

Grooming

As each group of say 25 primates became infected, there would have been survivors, but these would be unlikely to join a new group rapidly, and in theory, survivors should have been immune. The amount of cross group interactions are highly limited, according to behavioural studies I have read.

I think that possibly rather than passing the infection repeatedly amongst differing groups (i.e successive transmissions), this may have come about through repeated introductions over time, probably via consumption of fruit infected by ebola carrying fruit bats. Need to read the full papers...

 

[Emily]

Re: Experts worry Ebola could mutate to spread by air

As each group of say 25 primates became infected, there would have been survivors, but these would be unlikely to join a new group rapidly, and in theory, survivors should have been immune. The amount of cross group interactions are highly limited, according to behavioural studies I have read.

I think that possibly rather than passing the infection repeatedly amongst differing groups (i.e successive transmissions), this may have come about through repeated introductions over time, probably via consumption of fruit infected by ebola carrying fruit bats. Need to read the full papers...

You must not have been reading about chimps.

http://www.janegoodall.ca/about-chimp-behaviour-social-organization.php

Chimpanzees live in social groups called communities or unit groups. At Gombe, the number of individuals in the main study community, Kasakela, has ranged between 40 and 60 since 1960. Communities may be smaller or larger in other areas.

Chimpanzees' social structure can be categorized as "fusion-fission." This means they travel around in small subgroups of up to 10 chimps, the membership of which is always changing as individuals wander off on their own or join other groups. At times many of a community's members come together in large excited gatherings, usually when fruit is available in one part of the range, or when a sexually popular female comes into oestrus (period of female sexual receptivity).

As for contaminated fruit - it might protect, rather than harm.

http://www.nytimes.com/2014/09/06/health/ebola-immunity.html?_r=0

One of France?s leading Ebola experts says he believes that many rural villagers are ?vaccinated? by eating fruit gnawed on by bats and contaminated with their saliva.

?We imagine that this is the main route,? said Dr. Eric M. Leroy, a veterinarian and virologist at the International Center for Medical Research in Franceville, Gabon. ?But it is a hypothesis. We do not have the evidence.?

Also ebola seems to thrive when fruit and other food sources are affected by drought:

http://ucsdnews.ucsd.edu/archive/newsrel/science/sebola.asp

However, according to the findings, the spread of Ebola also depends on climate factors. Illness and deaths among animals were most prevalent during periods of prolonged drought-like conditions in the rainforest, which indicates that severe environmental stress may facilitate disease transmission.

 

[Vibrant62]

Re: Experts worry Ebola could mutate to spread by air

OK - I stand corrected, if the group studied and subject to ebola was chimps rather than Gorillas or other primates. Always happy to learn. As I said, I need to read the papers

Donners - do you have a link to the study that was referred to?

 

[Donners]

Re: Experts worry Ebola could mutate to spread by air

Do you have a link to a study that shows that a mutation was involved? Goodall just describes a prolonged outbreak, (discovered through retrospective analysis), spanning years as racking up those numbers.

Ah, that's exactly my point.

This is the part I was reacting to:

Osterholm suggested each infection gives the mutating virus "trillions of throws of the genetic dice."

"The current Ebola virus's hyper-evolution is unprecedented; there has been more human-to-human transmission in the past four months than most likely occurred in the last 500 to 1,000 years," he said in his Times commentary.

That is strictly true, but it completely ignores the vast number of non-human primate infections in recent years.

The Ebola virus is marching steadily across western and central Africa, wiping out more than 90 percent of the gorillas in its path and threatening the species with extinction, a new study says.

About 5,000 gorillas were killed by the virus in one study area alone, according to results to be published in tomorrow's issue of the journal Science.

http://news.nationalgeographic.com.au/news/2006/12/061207-ebola-gorillas.html

Each of those infections had the same "trillions of throws of the genetic dice" the article refers to as the human infections.

That adds quite a bit of context to the scenario the article is describing. If the human cases have the potential of making it transmissible in a different manner, so did all of those.

 

[Vibrant62]

Re: Experts worry Ebola could mutate to spread by air

So my query remains valid. If the infection in gorillas arose from multiple unique point introductions with limited transmission amongst troops before burning out, as opposed to sequential infections throughout the gorilla population, that observation may not hold true. What we are currently seeing is extensive h2h2h2h etc infections, not multiple unique introductions. In the current human transmission scenario, any mutations and adaptations would be cumulative.

I am not sure we can draw parralels?

 

[Emily]

Re: Experts worry Ebola could mutate to spread by air

Thanks for posting the article, Donners. I think I see your point - the massive epidemic among gorillas launched no airborne ebola version.

Vibrant, I don't think there is evidence that the gorilla epidemic was not spread from animal to animal. They do have inter-group social movements.

http://pin.primate.wisc.edu/factsheets/entry/gorilla/behav

The timing spelled out in this paper indicates that the nastiness started before the epidemic due to a recombination event, not as a result of the epidemic.

http://www.pnas.org/content/104/43/17123.short

Isolates of Zaire ebolavirus from wild apes reveal genetic lineage and recombinants

...
...Based on data from two ZEBOV genes, we also demonstrate, within the family Filoviridae, recombination between the two lineages. According to our estimates, this event took place between 1996 and 2001 and gave rise to a group of recombinant viruses that were responsible for a series of outbreaks in 2001?2003. The potential for recombination adds an additional level of complexity to unraveling and potentially controlling the emergence of ZEBOV in humans and wildlife species.

 

[Gemineye]

Re: Experts worry Ebola could mutate to spread by air

Another expert, Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases (NIAID). says airborne Ebola would be very unusual:

http://time.com/3342305/airbone-ebola-not-happening/

 

[AnnaLisa]

Re: Experts worry Ebola could mutate to spread by air

Norovirus in an RNA virus, (albeit not the same family as Ebola.) It's not airborne, but it spreads very rapidly. It appears to have a lot longer life on fomites than Ebola and perhaps it aerosolizes more effectively. It spreads like wildfire and isn't airborne.

 

[Nika]

Re: Experts worry Ebola could mutate to spread by air

The infectiousness of norovirus is hard to overestimate. It's disease course is vicious (1st hand experience) but mostly over quickly then gone - tho we don't seem to mount a very effective nor enduring immune response to it. Because it causes very impressive explosive projectile vomiting often coupled with uncontrollable and forceful diarrhea the virus is easily aerosolized. I don't know that it's quite the same physio-dynamic with ebola.

 

[AnnaLisa]

Re: Experts worry Ebola could mutate to spread by air

Interestingly 20% of the population is immune to Norovirus, due to status as FUT2 non-secretors. (No blood antigens present in saliva and mucous membrane secretions). I am one of the lucky ones. That said, it has a downside, making me more susceptible to other infections and influenza. I assume this genetic immunity has been studied in terms of Ebola.

 

[Graupel]

Re: Experts worry Ebola could mutate to spread by air

Noro is so nasty as it is absurdly infective- a single vireon is probably sufficient.

My worry for EBV is not mutation to be airborne (that seems like a big evolutionary leap) but simply a shift in when viral shedding begins. Currently, viral shedding doesn't appear to happen before acute febrile illness, but if that were to change....

Can any virologists comment?

 

[foxp3]

Re: Experts worry Ebola could mutate to spread by air

To become a true airborne pathogen would the virus not have to change tissue tropism and be able to infect the upper airways, i.e. the respiratory epithelium. I thought it was confined to entering immune cells such was monocytes and macrophages, and endothelium cells. It is well known monocytes and dendritic cells in the airways are very unique from other locations. They are at different differential stages and express many different surface molecules than those present in other mucosal and systemic surfaces.

Being an RNA virus makes it inherently unstable and let's hope it becomes less virulent with the passages through humans. Confections with parasites, HIV, and other chronic infections that can result in immunosuppression, may also effect the ongoing evolution of this virus.

As for changes in Ebola shedding times, it is naive to think everyone will shed at a defined time. As I previously highlighted in in another post, in immunocompromised hosts the cytokines response required to raise the temperature etc is often delayed, by which point the viral load is probably very high and already being shed.

Immune responses are often over generalised and although much is controlled by your genetic make up, various outside factors, environmental exposures, past and present infections influence your future responses. The immune system can be split into two components innate and adaptive, the adaptive response is the more variable piece, where past and present exposures leave lasting footprints that may shape the pathway your body takes in response to infections in the future. I think what I am saying is that an individuals immune system is a self educating entity, it never stands still. Of course therefore different individuals will have different shedding times, it is just about what proportion will shed before symptoms and if this number is significant.

Really good points on this topic which have made good reading.

fp

Ps the dreaded Noro. In UK hospitals it seems at times impossible to get it through to staff that alcohol based gels do nothing to penetrate the virus. So great against influenza, but these gels don't penetrate noro viral membranes. Also the rise in use of pH neutral soaps which don't disrupt a whole range of bacterial and viral outer membranes. You need a good alkaline soap to break many infectious agents open. Also require hot water to make many enzymes in soap work. Simple steps often missed