Q2 CLINICAL BACTERIOLOGY AND H^MATOLOGY 



still further, and if the patient dies may not occur at all. These 

 cases are usually severe ones, and do not present any difficulty 

 in diagnosis. Sometimes the reaction is delayed well into the 

 convalescence in mild attacks, but this is exceedingly rare. 



4. Paratyphoid fever is clinically much like typhoid fever, 

 but due to organisms presenting minute differences in their 

 chemical properties. Patients infected with these organisms 

 do not clump the ordinary typhoid bacilli, but give the 

 reaction when tested with the appropriate culture. This 

 should be borne in mind, and cases which appear to be typhoid 

 clinically should be tested with cultures of paratyphoid bacilli.* 



Vaccine Treatment. Antityphoid vaccines are used in the 

 treatment of the developed disease, and also as preventive 

 agents. Their curative use has not fully established itself as 

 a practical method, though very good results have been 

 claimed. Small doses only are used. For prophylaxis a dose 

 of 1,000 millions, followed by 2,000 millions after ten days or 

 a fortnight, are given, or, I think preferably, three doses of 

 500, 1,000, and 2,000 millions at the same interval. The injec- 

 tions should be made deep into the flank. There may be 

 some local and constitutional disturbance, but this is not 

 usually very severe, and appears to be diminished if a large 

 dose of calcium lactate is given at the same time as the injec- 

 tions, or shortly before. On account of the prevalence of 

 paratyphoid fever, a mixed vaccine (T.A.B.), containing 1,000 

 millions of typhoid bacilli and 750 millions each of para- 

 typhoids A and B is now used exclusively in the Army. 



DREYER'S METHOD OF AGGLUTINATION. 



The ordinary method of performing the Widal reaction is frequently 

 insufficient in view of the fact that many persons are now inoculated, 

 and their blood agglutinates the typhoid bacillus in a variable degree. 

 To avoid the difficulties arising in this way, Dreyer has introduced 

 an accurate and simple method by which variations in the agglutinat- 

 ing power of the serum can be followed from day to day, and any 

 alteration in the titre ascertained with precision. It has the advan- 

 tage of requiring only dead cultures, which keep well, and which 

 can be obtained without difficulty ready for use from the Department 



* In London at the present time, paratyphoid B appears to be the com- 

 monest of the enteric group. It should always be tested for in unexplained 

 febrile attacks, using about the same dilutions as for typhoid. In testing for 

 paratyphoid A use lower dilutions, up to i in 10. 



