As to the West Nile Virus theory, Iunderstand it is connected with a phenomenon of mass bird deaths that was noticed in the area of Babylon in the Spring of 323, which seems to me a slender thread of evidence.
That is why Iunderstand, at least in theory, the bitterness that seems to come to people who have been unlucky in love for the first 3-4 decades of their lives.
Much theoretical work has been done to understand and model such changes, but the lesson I draw from chaos theory is that recognizing such changes in hindsight may be simple, but predicting them in advance is and will continue to be extremely difficult.