There is also the fact that the population is living longer. All of us have a host of bacteria and viruses
within our bodies, that one could say are living in tolerance with each other if not quite in harmony.
Almost all of us get infected with chickenpox at an early age and this virus lives in our nerve cells for ever.
This can, of course, manifest itself as shingles in later life, if the immune systems wanes somewhat or during some period of stress or other disease that weakens
the immune system. Herpes viruses, also live in a similar fashion, often causing chronic or recurrent orofacial
or even genital herpes infections. Other less obvious viruses are Epstein-Barr virus. This is the virus that
causes glandular fever syndrome. Of a somewhat higher profile, the cytomegalovirus (CMV) also lives
within our body systems and has become a deadly threat in the emerging AIDS epidemic. Again, many
of our bodies contain cytomegalovirus, but it's only when the immune system becomes severely suppressed
that it emerges, causing widespread disease, but particularly causing a cytomegalovirus retinitis, which can
and usually does lead to blindness. The phenomenon of AIDS has unmasked many of these latent infections and
they are not all viruses.