Why viral (SARS, Ebola and AIDS) epidemics now?

In the last three decades we have seen several viral (and bacterial;i.e TB) epidemics which took place at an era where we would have expected the eradication of many infectious diseases. There are many hypotheses to explain this paradox; 1) Is it the hygiene theory, namely extensive use of wide spread and too potent antibiotics which eliminate protective infecting agent? And hence the beneficial effect of probiotics? Is it the widespread use of vaccine? is it a mistake or a terror acts of leakage of viral mutant from research or other laboratories? Be it as it may, the globalization and the employment of long distance flights make the spread easy to extreme points in the globe (Shanghai-Toronto). The new epidemiology? Immunology fields will have to deal with these novel aspects to combat and to prevent more events.