While the two diseases are different in several ways, the massively coincidental part is the fact of the timing, the possibilities, the similarity in death rates where black death took aprox 7 days to kill and Ebola takes a couple weeks with also a high percentage kill rate, and how it wiped out two thirds of the European population.
Black Plague rises with the Ottoman Empire
In 1394, relations between the Byzantines and the Ottomans changed for the worse and the war between the two resumed when the Ottoman Sultan Bayezid (ruled 1389–1402) ordered the execution of Manuel II after the Emperor attempted to reconcile his nephew John VII. The Ottoman Sultan then later changed his decision and demanded that a mosque and a Turkish colony be established in Constantinople. Manuel II not only refused this, he also refused to pay the Sultan tribute and went so far as to ignore the Sultan’s messages, leading to a siege of the city in 1394. Manuel II called for a Crusade, which came in 1396. Under the future Holy Roman Emperor Sigismund, the Crusade was crushed at Nicopolis in 1396.
Right in the middle of this rise since China was one of the busiest of the world’s trading nations, it was only a matter of time before the outbreak of plague in China spread to western Asia and Europe. In October of 1347, several Italian merchant ships returned from a trip to the Black Sea, one of the key links in trade with China. When the ships docked in Sicily, many of those on board were already dying of plague. Within days the disease spread to the city and the surrounding countryside. People were dying everywhere, lawyers refused to draw will and people were frantically fleeing Italy at this time.
In just 5 short years from 1347 to 1352 over 25 million people equally around two thirds of the European population had died. The black plague had it’s peak times during flea and bug season and slowed in the winter months as the bugs could not transfer the plague.
While Europe was strong, the plague weakened it to the point of takeover.
Ebola and the rise of ISIS simultaneously
Here we are in 2014 and when they say history repeats itself, they mean it because if there is any coincidence, this is certainly one of them. The black plague is spread by flea bites and contact with coughing, bodily fluids and alike. Ebola is spread by coughing, bodily fluids and whatever else we have not been told, but I would certainly presume bugs and fleas would easily transfer Ebola as well.
Ebola comes out almost exactly simultaneously with the rise of ISIS of the Levant with promises to hang their flag on several western iconic regions.
While Ebola certainly has not spread to any kind of masses outside of Africa as of yet, but it seems the actions we are taking to stop the rise of Ebola are certainly lacking leadership roles and spread to many seems more likely, hopefully never to the extent of the black plague.
Will ISIS try to conquer the west
At this time even if they did try to conquer, it is highly unlikely that there would be any success. The west is far to strong, although has been chaotic and weakened somewhat over the last decade or so with the massive immigration and job loss. If Ebola was to make it into the west in any numbers, ISIS could have much greater success just like that of the Ottoman Empire.