The theoretical rates people like to put out, strike me as similar to when i was in school and would play with my calculator by entering 2*2*2=======.... Theoretically, as long as Ebola has been around, the earth should be humanless
Actually,
Ebola first appeared in 1976:
The Ebola virus causes an acute, serious illness which is often fatal if untreated. Ebola virus disease (EVD) first appeared in 1976 in 2 simultaneous outbreaks, one in Nzara, Sudan, and the other in Yambuku, Democratic Republic of Congo. The latter occurred in a village near the Ebola River, from which the disease takes its name.
The current outbreak in west Africa, (first cases notified in March 2014), is the largest and most complex Ebola outbreak since the Ebola virus was first discovered in 1976. There have been more cases and deaths in this outbreak than all others combined.
It's exponential growth is a power of "e" (2.718...) not 2. Nf = Ni * e^(kT), where T is the time and "k" equals natural log of (e) divided by the time it takes the quantity to double or reduce by half. All naturally occurring growths and declines are functions of e. e^x rises more rapidly than 2^x.
Ebola has had rates of lethality varying between 10% and 90%, which shows that its various forms may have mutated or that the peoples it initially infected may have had some immunities due to infections of similar viruses which are no longer around. However, with an annual percentage growth rate of 840% (double every month) and a 50% lethality, humanity could be wiped out within 3 1/2 years, assuming that logistic feedback didn't slow the rate, which it will.
The places that are of greatest risk are those where population densities are high, medical facilities are marginal and educational levels are low. Countries like China and India. Metropolitans with populations over 10 million, like NYC, LA, Huston, Beijing, Bombay, Mexico City, Miami, etc... With an incubation period of almost 3 weeks before symptoms appear, a lot of infected people could be walking, driving and flying around, spreading Ebola unknowningly. Consider that 1/3rd of all Americans have STDs and continue to have frequently sex with multiple partners. Add to that an unknown Ebola transmission and you have the recipe for disaster.