<)6 AIDS TO BACTERIOLOGY 



In identification of the disease and of any suspicions 

 organisms isolated, agglutination tests are important. 

 Paratyphoid serum either fails to clump B. typhosus or 

 only does so in low dilution, but agglutinates the 

 appropriate paratyphoid bacillus in dilutions of over 

 1 in 100. Examination of the fseces is performed as for 

 typhoid. 



At the time of writing paratyphoid appears to be more 

 frequent in the services than typhoid, often occurring 

 as a chronic dysenteric condition. The diseases are fre- 

 quently as severe as typhoid. Anti-enteric vaccine is 

 frequently a mixed preparation of typhoid, paratyphoid 

 a and paratyphoid /3 bacilli. This gives protection 

 against any or all of the three diseases. A triple infection 

 with the three diseases has been described (Castellani). 



Bacillus Psittacosis. Imported parrots are liable to an 

 infectious enteritis with septicaemia (psittacosis) which is 

 communicable to man, producing a fatal broncho- 

 pneumonia. The psittacosis bacillus belongs to the 

 Gartner group, and is partly clumped by typhoid serum, 

 some bacilli between the clumps retaining motility. 



Bacillus Suipestifer (B. Suicholerae). This organism was 

 formerly regarded as the cause of swine fever. The disease 

 is now known to be due to an ultra-microscopic organism, 

 but B. suipestifer always seems to invade the tissues of 

 animals with swine fever (hog cholera), and is credited 

 with pathogenic properties for that animal. Its presence 

 in meat has caused food poisoning. B. suicJiolerce is 

 supposed to be identical with Sanarelli's B. icteroides and 

 with B. Aertryclc. While German authorities consider 

 B. suipestifer to be identical with B. paratyphosus /3, 

 Englishmen maintain them to be distinct organisms. 



Rat and Mouse Viruses. The Danysz bacillus, cultures 

 of which (' Danysz virus ') are sold for the extermination 

 of rats, belongs to this group, as do the B. typhi murium, 

 used as a mouse virus, and organisms found in other makes. 



Bainbridge showed that the viruses owe their potency 

 to bacilli indistinguishable from B. Aertryck and B. 

 enteritidis. Their destructive power on rats was incon- 

 stant, the death rate varying from 20 to 50 per cent. 

 Some of the rats recover and become immune, while 

 others do not even suffer at all. The use of rat viruses 

 appears to be sometimes attended with dangerous results. 



