When i saw this topic i thought of ebola, aids/hiv, sars, and other level 4 diseases. I remember a movie called something and it had Dustin Hoffman in it. And they were battling a dieseases that transferred into a cold... airborne. Anything is possible, Aids was started form monekys, and genetically mutated to transfer to other living creatures like humans. It started in Africa. Than theres the West Nile with miqusticos and crows etc. And that once the body has the virus deeated once it shouldnt come back in.... well it does... a mutated one. remeber aids scientits said they stopped it... but it mutated to another form. and colds mutate daily. Colds/Flu is a leading killer, if they dont get a cure for it. Vaccine is a permanent cure of the illness in that conditioned state. Also remember Cancer... so many different types of it. Breast, back, lung, heart, head, etc. Also tumours of the brian. Most of these diseases are humand made. or animal related.