Whatever the new plague mutates into, it can only sustain itself and spread if there are enough host victims to carry and spread the germs. That means, for the Muslims to be felled by it, the germs would have to be able to infect non-Muslims as well, just so that enough carriers exist to get the germs to the Muslims. Besides, there is no guarantee any new plague will be unable to overcome past defenses (least of all, defenses evolved over 600+ years ago, whose selection and sustenance has been silenced due to the end of the previous plague. That means Europeans will fall en-masse as well. Then again, a large proportion of Muslims are Europeans too, converts and Eastern European migrants. Add to that the propensity for white women to marry and mate with Muslims there (and here as well) while the males jump from affair to affair, unwilling to be monogamous.
Ever been through "family" aka divorce court as the modern day pariah known as a white, western male? If you did you would not come to such a conclusion. It's no wonder white, western males refuse to "settle down" and have offspring, knowing very well that the courts can legally take their wallet (no self support reserve; Title IV-D prop up) and wink at the mothers estranging the children from them.
Western Europeans, particularly the Irish, have a very high incidence of the mutant CF genes.
The Middle East, North Africa, East Asian, Africa, India, populations have a low incidence.
At the same time the mutant CF genes are found world wide in whatever population you want to study.
Assume for a second that this is the gene that allows 2/3 to survive the black death, the European recovery AFTER the great plagues of the 1300s, which affected all the more advanced nations, could definitely been the key to the European conquest of the entire world in the 1500 to 1900 period!
The muzzies, if they want to live through the coming great global pandemics had probably best start handing over their sisters to the blond blue-eyed kaf'r as soon as possible!
The oldest CF mutation seems to be about 56,000 years old ~ and that's the time when the White Folk went West from Central Asia and those who were to turn into Chinese went East from Central Asia.
The Cro Magnon's who went to Europe walked right into an interstadial where RATS and other rodents were cock of the walk ~ and the black death is rodent born, in part, by fleas that live on those rodents.
Humans exist in large numbers in Europe only by having an immunity to rat born diseases ~ CF may well be the gene that confers that immunity.
In between the great plagues humans prosper, more and more of those with no CF gene mutations survive, and next thing you know there's another great plague (usually the same old same old ~ the bacterium, Yersinia pestis)