Observations on the Virus Recovered from 1934–35 Poliomyelitis Epidemic in Los Angeles

Attempts were made to recover virus from 19 autopsy cases during the recent epidemic of poliomyelitis in Los Angeles, Seven of these were successful in 1934, four in 1935, as judged by the following results upon inoculation of the emulsified human cord into Macacus rhesus monkeys:

(1) Occurrence of pyrexia, roughness of coat, hyperirritability and tremor with subsequent development of paralysis.

(2) Transmission of the virus in successive animal passage of selected strains.

(3) The histopathology was characteristic in that oedema and hemorrhage, perivascular and diffuse infiltration, and necrosis of nerve cells were apparent.

Since the 1934–35 epidemic of poliomyelitis in Southern California has been described as being especially mild in its clinical manifestations with a corresponding low mortality rate and a low residual paralysis rate, it seemed desirable to compare the viruses recovered from this epidemic with other strains of poliomyelitis virus. To date these Los Angeles strains and the “M.V.” strain from the Rockefeller Institute have been compared with reference to symptomatology and pathology produced and comparative immunologic studies have been made in detail with one Californian strain, the “McK” recovered from an autopsy in 1935. Observations include (a) symptomatology as shown by incubation period, temperature changes, type and degree of paralysis, residual paralysis rate and death rate; (b) histopathology produced in the brain and cord, (c) immunity produced and (d) neutralizing substance developed. Symptomatology. Both pyrexia and paralysis appeared in monkeys on an average of 2 days later with the “McK” strain than with the “M.V.” strain. In comparing the paralysis and recovery rate in monkeys infected with these 2 strains, it was found that monkeys inoculated with the “M.V.” strain showed a partial paralysis rate of 3.7%, a complete paralysis rate of 96.3%, with 4.7% of the total number recovering, while the monkeys inoculated with the “McK” strain showed a partial paralysis rate of 78%, a complete paralysis rate of 22%, with 84% recovering.