TYPHOID FEVER 83 



the body often fail to agglutinate with typhoid serum, and only 

 acquire that property after cultivation for several generations 

 on artificial media : this, the best test, is not always conclusive. 

 But all cases clinically resembling early typhoid which give a 

 culture of motile, non-sporulating, Gram-negative bacilli of 

 the morphological characters described above, should be 

 regarded as early typhoid, and in all probability the appearance 

 of the Widal reaction will soon settle the matter. The other 

 possible diagnoses are extremely unlikely. The further identi- 

 fication of the bacillus is dealt with at the end of this section. 



The mesenteric glands and liver are, of course, not available 

 for the purpose of diagnosis. 



Another method in which typhoid fever can be diagnosed 

 with ease and certainty by a demonstration of the specific 

 bacillus is by an examination of material drawn directly from 

 the spleen by means of a hypodermic needle. The organism 

 occurs constantly in this situation, -and its demonstration is not 

 difficult. The necessary operation, however, is by no means 

 devoid of risk, and is now generally abandoned. 



This brings us to the method in which typhoid fever is now 

 usually diagnosed by the bacteriologist Widal's reaction. 

 This reaction is a special example of a general law which was 

 discovered by Durham and others, and which is to the effect 

 that the blood-serum of a person who has been through an 

 attack of a bacterial disease will cause the specific organism 

 of that disease to collect into clumps. For instance, if we 

 take a broth culture of the vibrio of Asiatic cholera (which is 

 turbid and opalescent) and add to it a small quanity of blood- 

 serum from a patient who has recovered from an attack of 

 cholera, we shall find that the culture becomes clear, a sedi- 

 ment collecting at the bottom of the tube ; and if we examine 

 this sediment we shall find that it consists of felted masses 

 of the vibrios. This reaction is a g'eneral one, and is given 

 in most, if not all, bacterial diseases. But Widal, Grunbaum, 

 and others, working independently about the same time, 

 showed that, whereas in many diseases it is a reaction of 

 immunity (i.e., does not occur until late in or after the 

 disease), in typhoid fever it is a reaction of infection, and 

 occurs so early in the course of the disease that it is of great 

 value in diagnosis. 



The test is applied by adding a small quantity of the serum 



