Polio

Polio

Poliomyelitis was a common acute viral infection; it occurs naturally only in human beings. Infection with the polio virus produces a wide variety of clinical manifestations. Its most severe form attacks part of the central nervous system. After an incubation period of 3 to 35 days, the poliovirus infection may assume one of four forms: 1) Inapparent infection. 2) Minorillness, such as a transient respiratory or gastrointestinal disturbance. 3)Nonparalytic Poliomyelitis, which usually produces temporary stiffness of the neck and other symptoms of spinal meningitis. 4) Paralytic poliomyelitis.
In the latter, most serious form, the virus attacks specialized cells in the spinal cord and brain stem, producing paralysis in the face or extremities. This varies from mild affliction to respiratory paralysis. Some of the most heroic medical treatments have been developed to save the lives of these respiratory polio cases, often maintaining the patient for years in an “iron lung.” Some of the most dramatic uses of hydrotherapy have also been effective in the treatment of advanced polio cases, especially the Kenny packs, used for severe muscle spasm. Rehabilitation in a specialized setting offers maximal potential for complete recovery. Prevention, however, is the best approach.With several vaccines available for each type of polio, childhood immunization offers an inexpensive and relatively safe medical practice to avoid this dreaded disease.

The first effective polio vaccine was developed in 1952 by Jonas Salk at the University of Pittsburgh, but it would require years of testing. To encourage patience, Salk went on CBS radio to report a successful test on a small group of adults and children on March 26, 1953; two days later the results were published in JAMA.


The Salk vaccine, or inactivated poliovirus vaccine (IPV), is based on three wild, virulent reference strains, Mahoney (type 1 poliovirus), MEF-1 (type 2 poliovirus), and Saukett (type 3 poliovirus), grown in a type of monkey kidney tissue culture (Vero cell line), which are then inactivated with formalin. The injected Salk vaccine confers IgG-mediated immunity in the bloodstream, which prevents polio infection from progressing to viremia and protects the motor neurons, thus eliminating the risk of bulbar polio and post-polio syndrome.