MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 865 



taken from infected animals. The microorganism passes through the 

 Chamberland and Berkefeld niters with little or no loss in disease- 

 producing power. "Flexner and Noguchi, employing the technic 

 previously used for cultivating pathogenic spirochaetes, have succeeded 

 in obtaining from infected tissues cultures of a minute round organism 

 which they believe to be the cause of infantile paralysis." The virus 

 withstands freezing or drying for long periods of time but is quickly 

 destroyed by heating at a temperature of 50. It is likewise quickly 

 killed by the ordinary disinfectants. Monkeys may be infected by the 

 subcutaneous, intraperitoneal, intravenous, or intracranial injection 

 of material from an infected spinal cord, but attempts at infection 

 through feeding have been unsuccessful. The virus appears to be 

 eliminated from the body through the nasal mucous membranes. 



It appears probable that one attack of the disease protects from a 

 second attack. No cases of a second attack have been reported. 

 Furthermore, monkeys which have recovered from the infection appear 

 to be entirely immune as shown by Flexner. Active immunity in 

 monkeys has been established by repeated infections of gradually 

 increased amounts of the virus. The blood of human beings and of 

 monkeys that have recovered from an attack of the disease is capable 

 of neutralizing a certain amount of the virus. This protective quality 

 of the blood serum may be increased by repeated inoculations of virus, 

 and infection in monkeys can be prevented by injecting simultaneously 

 the virus into the brain and the serum into the sub-arachnoid space. 

 The serum treatment of this disease is, however, not developed to such 

 a state that it can be regarded as of practical use. 



PELLAGRA* 



Pellagra is a disease of man characterized by the annually recurring 

 manifestation, each spring or summer, of erythema on the backs of 

 the hands and forearms and sometimes on the face and neck, feet and 

 ankles, coupled with digestive disorder and more or less well-marked 

 mental disturbances. During the winter the signs of the disease usually 

 disappear. 



At present there are two main groups of theories concerning the 

 causation of pellagra, each of which includes a multitude of hypotheses. 

 According to one group of theories, pellagra is a food poisoning due to 



* Prepared by W. J. MacNeal. 

 55 



