CHAPTER XIX 



SCARLET FEVER HYDROPHOBIA INFANTILE PARALYSIS 

 ENCEPHALITIS LETHARGICA TYPHUS FEVER TRENCH 

 FEVER ROCKY MOUNTAIN SPOTTED FEVER DENGUE 

 PHLEBOTOMUS FEVER VACCINIA AND VARIOLA- 

 MALIGNANT DISEASE 



Scarlet Fever 



THE setiology of scarlet fever is still unsettled. Many 

 claim a streptococcus to be the causal agent, others a 

 protozoon and others a filter-passer. The disease is 

 inoculable only on apes. 



The streptococcus first came into prominence in the 

 historic Hendon outbreak which was investigated by 

 Klein and Power in 1885. Scarlet fever occurred in Mary- 

 lebone. and was traced to infection conveyed by milk 

 supplied from a farm at Hendon. The infection could 

 not be traced to any human source, and it was therefore 

 concluded that the cows themselves were affected with 

 scarlet fever, and infected the milk. A vesicular eruption 

 was found on the udders and teats of the cows, and this 

 was regarded as the local manifestation of bovine scar- 

 latina. From the vesicles and crusts Klein isolated a 

 streptococcus which, although closely resembling the 

 Streptococcus pyogenes (as then known), differed slightly 

 from it ; on inoculation into calves it produced death, 

 with lesions of the kidney resembling those of the human 

 disease. Klein also isolated the same streptococcus in 



