Biohazard Levels

[Tom J. Smith]

A question about biohazard level 4 (and maybe even 3) diseases. Prior to 
Ebola and Marburg, were there any known level 4 diseases? Is level 4 the
maximum level?

Your help in stemming my curiousity is appreciated.

Tom
--


========================================
= Tom J. Smith                         =
= email: tjsmith at freenet.calgary.ab.ca =
= Amataeur Radio: VE6SJT               =
========================================