Work Step by Step
Poliomyelitis: Poliomyelitis has afflicted humans for thousands of years. Its transmission is by the fecal-oral route and pharyngeal secretions. Most poliovirus infections are unapparent or mild and nonparalytic. Polio can be caused by three strains of picornaviruses. Sabin vaccine contains live, attenuated polioviruses whereas Salk vaccine viruses that were inactivated by formalin at neutral pH.