CHAPTER XLIX 

 INFECTIOUS DISEASES OF UNKNOWN CAUSATION 



Of the diseases afflicting man that have been differentiated about one-half 

 are caused by known organisms. 



The method of transmission from person to person, the mode of onset and 

 the course of many other diseases indicate that they too are due to infection, 

 although attempts to isolate and identify the causative organisms have failed. 

 The success of research from time to time is happily reducing this group. It 

 is yet too early for the medical profession to have adequately tested and con- 

 firmed the remarkable discoveries of the last 4 years relative to typhus fever, but 

 the evidence strongly suggests that the specific cause of this disease has been 

 disclosed. 



Bacillus typhi-exanthematici, first described by Plotz, Olitsky and Baehr, 

 has been obtained in blood cultures from typhus patients, using a 2 per cent, 

 glucose-ascitic-fluid-agar medium. It has also been isolated from lice caught 

 where the disease prevailed and from mice, guinea-pigs and monkeys injected 

 with the blood of typhus patients. 



It is a Gram-positive, obligate anaerobic bacillus. The spleen of mice 

 inoculated with this organism is said to show characteristic lesions. 



Infection of man has been known for a long time to depend upon transmis- 

 sion by the body louse and hence the prevention of typhus epidemics and the 

 curtailment of existing epidemics is effected by extermination of body lice. 



Occasionally before crisis, frequently at the time of the crisis, and in nearly 

 all cases after crisis, the blood serum of typhus patients will cause agglutination 

 of the bacillus typhi-exanthematici, and will cause complement fixation with 

 this antigen. 



Opinion differs widely as to the prophylactic and therapeutic value of vac- 

 cine. It is worthy of note that Strong has not yet indorsed the conclusions of 

 those who believe in the efficacy of this vaccine. 



ACUTE ANTERIOR POLIOMYELITIS 



(Epidemic Poliomyelitis) 



Acute anterior poliomyelitis is a disease caused by a filterable virus. Emul- 

 sions of the brain and cord of persons dead of the disease injected into monkeys 

 and rabbits frequently produce malaise, fever, paralysis and death. 



One attack confers immunity and when inoculation is not fatal immunity 

 results. 



Flexner and Noguchi isolated a minute coccus and cultivated it anaerobic- 

 ally in fluid serum. They believe this organism the specific cause of the disease 

 but their view has not been generally accepted. 



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