Till-: BLOOD-SERUM DIAGNOSIS OF TYPHOID FEVER. 181 



has given satisfactory results. The plan, which is a, modifica- 

 tion of the New York Board of Health method, is as follows : 



At the diphtheria depots blood slides are left with blank 

 forms giving directions (Fig. 65). 



FIG. 65. 



Outfit used by the Municipal Laboratory of New Orleans for the collection 

 of blood for the typhoid fever test. 



Directions for Preparing Specimen of Blood. Clean thor- 

 oughly the tip of the finger or lobe of the ear, and prick with 

 a clean needle deep enough to cause several drops of blood to 

 exude ; two or three drops are then placed on the slide of the 

 outfit. Let the blood dry, then place the slide in holder, fill 

 out the blank form, and return to depot where obtained. On 

 the following day a report of the result of examination will 

 be mailed or telephoned to the attending physician. 



The blood only of fever patients is to be used. Should the 

 report be negative and the case be suspicious, the physician 

 in attendance is requested to send another specimen, and in 

 every case to notify the bacteriologist as to whether the labo- 

 ratory diagnosis is finally in harmony with the clinical diag- 

 nosis or at variance with it. 



Sources of Error. One, which must be remembered, is due 

 in some cases to the persistence of the reaction for a number 

 of years after a typhoid attack : so that a reaction may appear 

 in health or in affections other than typhoid fever, if the 

 patient has previously suffered from the disease. In cases in 

 which the reaction is marked, it may apparently be positively 

 stated that the patient has, or has had, typhoid fever within 

 a few years. 



