What are the most serious viral infections?

There are numerous amounts of serious viral infections, but with the advent of vaccines, many of them, for example smallpox, have been eradicated. However, a few deadly viruses still exist. HIV is a serious viral infection that can be controlled but, as yet, has no cure. Hepatitis C can damage your liver. Viral infections that attack the nervous system, such as rabies and West Nile virus can be fatal if not treated immediately. SARS, and the H1N1 virus are the newer problematic viruses. What's more, polio and malaria have begun to resurface of late.