THE INFECTIOUS DISEASES. 271 



DIAGNOSIS. 



In view of the importance of diagnosis, in animals which have died 

 or have been killed under suspicion of rabies, the spinal cord, medulla, 

 and ganglia should be saved. Portions of the fresh medulla in watery 

 emulsion should, if possible, be inoculated beneath the dura mater of three 

 healthy rabbits, and the development of rabic paralysis and other symp- 

 toms awaited. This operation for diagnostic purposes should be done 

 only by one experienced in this subject. Other portions of the medulla 

 and cord and the ganglia should be hardened in Orth's fluid and alcohol, 

 and carefully examined for ganglion-cell lesions, for small perivascular 

 accumulations of leucocytes, and for changes in the spinal ganglia. The 

 existence of these in the medulla and cord of an animal suspected of rabies 

 will go far toward confirming the suspicion. 



It is always wise not to kill suspected animals, but to keep them un- 

 der observation in confinement. Babies being always fatal, recovery 

 from a suspicious disease excludes it, so that further protective meas- 

 ures may be clearly unnecessary. On the other hand, the carefully ob- 

 served symptoms of a suspected animal may even in the event of a fatal 

 termination afford valuable evidence. If the laboratory for diagnosis be 

 accessible, it is well, if the suspected animal should die or be killed, to 

 send the whole animal or the head cut off low down, packed in ice. Cold 

 does not rapidly diminish the virulence of the rabic virus. If the mate- 

 rial is to be transmitted for a long distance, the brain of the animal with 

 the medulla, carefully removed to avoid contamination, may be sent in a 

 sterilized bottle containing a mixture of equal parts of glycerin and water, 

 which has been sterilized by boiling and cooled. * 



TYPHUS FEVER. (Hospital Fever ; Spotted Fever ; Jail Fever ; Ship 



Fever; etc.) 



This highly contagious, infectious disease has not, so far as we know, 

 any characteristic lesion save the petechial skin eruption ; but after death 

 the body may present lesions common to many of the infectious diseases. 



The body has a tendency to rapid putrefaction, and the blood is often 

 darker and more fluid than is usual in other diseases. 



The voluntary muscles may be the seat of waxy and albuminous de- 

 generation. The brain and its membranes may be congested ; the mucous 

 membrane of the pharynx and larynx may be the seat of catarrhal or croup- 

 ous inflammation. There may be bronchitis, broncho-pneumonia, or 

 hypostatic congestion of the lungs. The walls of the Jieart may be soft 

 and flabby. 



The agminated nodules of the ileum, and the mesenteric nodes may be 

 swollen. The spleen is often large and soft from hyperplasia. The kid- 

 neys and liver are frequently large and pale, and the seat of albuminous 



1 For an estimate of the frequency of rabies in the United States see Salmon, 16th 

 Annual Report of the Bureau of Animal Industry, 1900, p. 122. 



