Ebola outbreak 'out of all proportion' and severity cannot be predicated

Ebola
A scanning electron micrograph of Ebola virus budding from a cell (African green monkey kidney epithelial cell line). Credit: NIAID

A mathematical model that replicates Ebola outbreaks can no longer be used to ascertain the eventual scale of the current epidemic, finds research conducted by the University of Warwick.

Dr Thomas House, of the University's Warwick Mathematics Institute, developed a model that incorporated data from past that successfully replicated their eventual scale.

The research, titled Epidemiological Dynamics of Ebola Outbreaks and published by eLife, shows that when applying the available data from the ongoing 2014 outbreak to the model that it is, according to Dr House, "out of all proportion and on an unprecedented scale when compared to previous outbreaks".

Dr House commented: "If we analyse the data from past outbreaks we are able to design a model that works for the recorded cases of the virus spreading and can successfully replicate their eventual size. The current outbreak does not fit this previous pattern and, as a result, we are not in a position to provide an accurate prediction of the current outbreak".

Chance events, Dr House argues, are an essential factor in the spread of Ebola and many other contagious diseases. "If we look at past Ebola outbreaks there is an identifiable way of predicting their overall size based on modelling chance events that are known to be important when the numbers of cases of infection are small and the spread is close to being controlled".

Chance events can include a person's location when they are most infectious, whether they are alone when ill, the travel patterns of those with whom they come into contact or whether they are close to adequate medical assistance.

The Warwick model successfully replicated the eventual scale of past outbreaks by analysing two key chance events: the initial number of people and the level of infectiousness once an epidemic is underway.

"With the current situation we are seeing something that defies this previous pattern of outbreak severity. As the current outbreak becomes more severe, it is less and less likely that it is a chance event and more likely that something more fundamental has changed", says Dr House.

Discussing possible causes for the unprecedented nature of the current outbreak, Dr House argues that there could be a range of factors that lead it to be on a different scale to previous cases;

"This could be as a result of a number of different factors: mutation of virus, changes in social contact patterns or some combination of these with other factors. It is implausible to explain the current situation solely through a particularly severe outbreak within the previously observed pattern".

In light of the research findings and the United Nations calling for a further $1bn USD to tackle the current outbreak, Dr House says that "Since we are not in a position to quantify the eventful scale of this unprecedented outbreak, the conclusion from this study is not to be complacent but to mobilise resources to combat the disease."


Explore further

Global impact of the Ebola outbreak

More information: The paper can be viewed here: elifesciences.org/content/elif … eLife.03908.full.pdf
Journal information: eLife

Citation: Ebola outbreak 'out of all proportion' and severity cannot be predicated (2014, September 16) retrieved 23 October 2019 from https://medicalxpress.com/news/2014-09-ebola-outbreak-proportion-severity-predicated.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
 shares

Feedback to editors

User comments

Sep 16, 2014
There can be an explanation for an outbreak that defies the models. The "outbreak" is engineered, by deliberately spreading of the germ into the environment, or even by the "outbreak" being a lie. How many in the West have as much understanding of, or even general interest in, the world around them that they would be able to find the truth when the "news" lied to them? The flaws in the claims during the "Nayirah" fraud that led to the First Gulf War were obvious, but most seem never to have caught on. Most did not perceive the lie in the claim that there were banned weapons systems in Iraq. How many asked why Spain would blow up the U.S.S. Maine? But they are using this "crisis" to "justify" universal house arrest in Sierra Leone, just as they used the fabrication of the "Boston Marathon" incident to "legitimize" wholesale lockdown there. That's important to the New World Order, to get the gullible to accept house arrest, even without there being an actual cause!

Sep 16, 2014
Serious commentary: I feel so sad for the genocide that continues to be perpetrated. The money has been there all along to stop this. So why did they wait so damn long? Since the below has been known for many years and the amount of money is in the trillions, and that money in question was there, the question becomes why did the powers-that-be let the Ebola get out of hand in the first place? Genocide anyone? Search Greg Szymanski's 2006 Interviews with Lee Wanta the 27.5 Trillion Dollar Man (Full transcript)

Sep 16, 2014
Here's an idea. How about the UN issue a request for $1b NON-US dollars?

Sep 17, 2014
Simply rubbish. It is a model. A trend. A set of parameters using known and givens. Nothing more. Yes, all secondary causes changes the model. In this case. Social customs, population density, number of infected, medical treatment received and fitness of population. It all relies on the facts. I suggest the (model) seems not to work because of that. When a case has to be "confirmed" via test. Medical treatment only and no ratio of confirmed vs non-confirmed cases NOT established then certainly any model would fail to predict future growth rates. This article is rubbish at best. At worst a deliberate attempt to hide the truth.

Sep 20, 2014
I think the First World countries are safe from an Ebola outbreak,if for no other reason than we don't personally bathe our dead.Third World countries suffering outbreaks are doing everything wrong,mistrusting clinics treating the disease,and staying away from them when they are sick,and actually attacking aid workers at clinics.Eating bush meat is not helping matters either,and probably explains how Ebola originally infected the first human victim.

Sep 21, 2014
the worst thing you could do in an uneducated country is to tell a bunch of sick people to come meet your doctors and troops at a clinic. They're better off staying home and hoping to ride it out, or dying there, so it doesn't spread.

There isn't enough of the experimental vaccine for all those people, so what good does it do to expose more troops and doctors to the sick?

Most of the people getting infected at one point were the nurses and doctors treating the sick, so now they have brought in doctors and troops from the UN (insert U.S., because we're the ones putting troops and normal ER nurses on the ground). A young nurse from a local hospital was called to go to one of the countries for the ebola outbreak...

wtf...

You have a level 5 virus outbreak and the first thing you do is yell, "EVERYBODY, GO TO THE INFECTED SITE AND SEE IF YOU MANAGE TO LIVE, OR WHETHER YOU DIE TOO."

Maybe he should try modeling it by breaking it down into sub-outbreaks...probably thought of that...

Sep 21, 2014
Just wait, it gets spread back to the monkeys somehow, it does. Maybe they scavenge on humans? Who knows. Humans eat monkeys, monkeys might eat humans...

...humans eat monkeys again...

As for mutation, I noticed a few weeks ago it was claimed death rates in previous outbreaks were in the 90% range, but this one was only in the 60% range (at that time).

Perhaps something significant in the life cycle changed. A pathogen that is too lethal doesn't make very good pathogen, because it kills it's host before it manages to spread. So perhaps the lethality of the individual viruses (less toxic by-products or something) allows it to increase the chance of spreading, by delaying death a bit longer...

That's conjecture, of course, but plausible.

There was this episode of "Fringe" where a virus evolved to brainwash it's host to spread the disease.

There is also a youtube video from (Discovery) I think, with a complex system of caterpillar, wasp, and virus which has similar properties.

Sep 21, 2014
The sick thing is if the individual mortality rate is decreasing, that increases the possibility of it turning into a strain which can perpetually grow in humans. The longer the outbreak goes on, the more likely such strains are mutated, and it's a matter of time before one gets out...

Then it'll be like the Spanish Flu.

God forbid, but with polio, leprosy, plague, yellow and scarlet fever, and small pox being irradicated in the west, we just aren't used to seeing pandemics of this type of disease.

Of course, the common cold and the regular seasonal flu already kill more than this strain has so far every year. Even the "hybrid" flu from a couple years ago didn't actually kill as many as the regular flu in the same year...

...that could change if this ebola strain keeps spreading and mutating.

What will we do if some unfortunate incident causes a squad or a whoe platoon worth of U.S. troops to become infected?

It's unethical / immoral to send people over there like that.

Sep 21, 2014
Here is the link to the youtube video. It's actually national geographic. There used to be one with the voice, I don't know what happened to this one.

vMG-LWyNcAs

Put that in youtube and watch it.

Virus in wasp.
Wasp lays eggs in caterpillar.
Larva eat their way out of caterpillar
Virus is in caterpillar and brainwashes it to make a cocoon for the wasp larva
Wasp larva have virus.

Symbiosis.

It's a real life "Zerg" pathogen, and demonstrates emergent psuedo-intelligence. Virus demonstrating Mind control and coding for a specific set of actions in a complex organism.

I swear, almost anything science fiction can dream up already exists in some form right here on Earth. Who needs aliens?

Viruses...who knew?

You wonder about irrational human behavior? Viruses might cause that too.

Toxoplasmosis causes Rats seek out cats, which then eat the rats and contract the disease. Another instance of complete mind control of a "higher" life form, and coding specific behavior.

Sep 22, 2014
"You can not start an Ebola epidemic without a reservoir of people that eat apes and monkeys, which is illegal in all the affected countries"

-Ebola can be spread by bites and fluids left on surfaces. And you're right, crowding results in closer contact with infected animals.

"And a pox on the houses of all who don't address the human birthrate that creates conditions where starving people start eating everything in sight"

-Bush meat is a preferred food. Indigenes can be persuaded to give up eating other endangered species but are most reluctant to give up ape and monkey. This may hint at how prevalent cannibalism was in our prehistory.

"Vermin carrying pestilence. Controlling the vermin is a big part of the solution. All humans are vermin"

-I think misanthropes are the vermin which need particular controlling. Don't you?

Sep 22, 2014
Any consequence of being short-sighted with your decision making, can be seen rampantly in Africa. I feel for them and their situation, hopefully they will try to improve their situation and embrace the foreigners who are there to help. And hopefully, useful help can be provided.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more