Monday, September 29, 2014

70% tippping point

Since so many of the apocalyptic novels that I review are pandemic in nature.  I thought this was a very good tool for a fictional writer trying to be a little more realistic in their pandemic scenario.

The Magic Number That Could End the Ebola Epidemic
Tom Randall, Bloomburg, 26 September 2014 (hat tip: NC)
But perhaps the most important Ebola number right now is 70 percent. That’s the proportion of patients who need to be isolated -- in treatment centers or at least in their homes -- in order to put a quick end to the Ebola outbreak, according to the U.S. Centers for Disease Control and Prevention.
“Once 70 percent of patients are effectively isolated, the outbreak decreases at a rate nearly equal to the initial rate of increase,” researchers wrote today in the CDC’s Morbidity and Mortality Weekly Report. If 70 percent of the current outbreak was achieved by late December, the epidemic “would be almost ended by January 20.”

Ebola's problem is that it kills its host too quickly (6 days assumed which includes burial time), and is not an airborne transmitted disease.  The studies transmission rate is set at 30%/day for those in the same home with no isolation .  The number is 2% for hospitalized, 3% for home care with appropriate precautions.
Note that killing your host does not actually help the virus/bacteria.  That is why a lot of lethal disease mutate to tone down their deadliness over time.  The lethal bugs are out competed by the less lethal ones that allow the host to walk around spreading them longer. 
On a second note, as best I can tell,  the reason why animal vectored diseases are often so deadly is because the "bug" often doesn't need to keep the host alive for as lengthy of a period.


PioneerPreppy said...

I thought they were saying you could walk around infectious for 21 days or longer without knowing you had it?

Matt said...

+1 to preppy's question

Harry Flashman said...

I saw one of the news shows where they brought in Dr. Ramadamjam Pajarhamindad or whatever, and he said the big deal with Ebola is that this epidemic is going to be going long enough for the virus to have potential for mutating to an airborne version. Of course, these guys on the news shows are about ratings, not veracity.

russell1200 said...

Pioneer: That is a potential incubation period, but not necessarily a contagious period. With a lot of diseases, the bad stuff (sneezing, throwing up, biting people, coughing) are how the disease spreads.

Harry: It might be possible, but that would greatly change its method of spreading, and would obviate the need for all the hemorrhaging. It's like if rabies became airborne: why would the virus need to get animals to bite each other? All the frothing and biting would become unproductive, as would all the bleeding and hemorrhaging of Ebola.

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