392 TYPHOID FEVER 



Space does not permit us to discuss at length the evidence in 

 favour of this method of inoculation. It has been strongly, and 

 perhaps unfairly, opposed in certain quarters, but a careful and 

 unprejudiced study of the statistics of the British Army in South 

 Africa and elsewhere seems to render it quite clear that the process 

 develops a real though not absolute protection against an attack 

 of the disease, and is still more valuable in diminishing the 

 mortality rate amongst those attacked. The analysis of these 

 figures is by no means easy, but certain isolated cases are in 

 themselves very convincing. As an example (one out of many) 

 we may quote the Manchester Regiment, in which, out of 

 200 men inoculated there were 3 cases, without a death, whilst of 

 the 517 uninoculated 23 were attacked and 3 died. In general 

 terms we may say that the mortality from an attack fell from 

 over 12 per cent, in the uninoculated to below 6 per cent, in the 

 inoculated, taking the results from the whole of the Transvaal 

 and Natal. One caution is necessary : the first result of the in- 

 jection is the production of a negative phase of increased suscep- 

 tibility, and injections should not be practised, if avoidable, when 

 the patient is already exposed to the infection. 



The vaccine is prepared by the Lister Institute, and can be 

 bought ready for use. 



Numerous modifications of the process have been adopted. 

 Pfeiffer and Kolle prepare their vaccine from agar cultures. 

 Bassenge and Rimpau do the same, but use very small doses 

 T5 t I milligramme. Friedberger and Moreschi give intra- 

 venous injections of infinitesimally small doses of bacilli killed at 

 120 C. Wassermann's vaccine is prepared by killing a culture at 

 60 C., allowing it to undergo autolysis at 37 C. for five days, 

 filtering, and desiccating in vacuo at 35 C. It forms a yellowish - 

 white powder, of which the dose is 0-0017 gramme, equal to 

 12 milligrammes of the culture. Numerous other methods might 

 be enumerated, but they have mostly been investigated on a small 

 scale only, and Wright's vaccine is of proved efficacy and easy to 

 prepare. 



Antityphoid serum has often been employed, and in all proba- 

 bility is of value in that it affords a rapid (or practically instan- 

 taneous) means by which immunity can be produced, and eliminates 

 the negative phase altogether. The serum is prepared from the 

 horse, which is injected with gradually increasing doses of dead 

 bacilli, and subsequently of living ones. It can be obtained of 



