INFECTIOUS DISEASES. 297 



demic in Ireland and in Scotland. Subsequent epidemics have 

 occurred in these countries on numerous occasions. The last epi- 

 demic period in the British Isles was from 1868 to 1873, when it 

 prevailed in several of the larger cities of England as well as in Scot- 

 land: Upon the continent of Europe it has prevailed chiefly in 

 Russia and in Germany, and the earliest reliable accounts only date 

 back to the year 1833, when it first appeared at Odessa. In 1863 

 a widespread epidemic occurred in Russia, and in 1868 it prevailed 

 extensively in Germany. It again prevailed in Germany in 1871 to 

 1872, and in 1878 to 1879. In North America its prevalence has 

 been limited to a few outbreaks in seaport cities having commercial 

 relations with infected localities in Europe. In 1844 it was brought 

 to Philadelphia by emigrants sailing from Liverpool; in 1847 it was 

 brought in the same way to New York and spread to some extent to 

 neighboring towns; in 1869 it was again imported into Philadelphia, 

 and during the two following years spread to a slight extent in this 

 city and in the State of Pennsylvania. 



If we may judge from past experience, the predisposing causes of 

 relapsing fever are not sufficiently active in this country to give rise 

 to a serious epidemic, even if cases of the disease should again be 

 brought to our shores. In Egypt, in India, in China, and in the 

 Oriental countries generally, the conditions favorable for the epi- 

 demic prevalence of this disease are more commonly met with, and 

 there is evidence that it exists in some of these countries at the 

 present day and has probably been endemic for a considerable period, 

 especially in India. But it is only recently that the English physi- 

 cians in India have recognized its presence, it having been con- 

 founded for many years with the widely prevalent malarial fevers of 

 the country. 



Smallpox, like typhus and relapsing fever, is transmitted by 

 personal contagion, but the susceptibility to this disease is so general, 

 independent of predisposing causes, that in the prevaccination period 

 it had a wide diffusion, not only in the overcrowded tenements of the 

 poor, but also in the dwellings of the rich and even in the palaces 

 of kings. The writings of the distinguished Greek physician Galen, 

 who was born about 130 a. d., indicate that he was acquainted with 

 smallpox, but the origin of the disease is lost in the obscurity of the 

 remote past. According to Hirsch, " the native foci of smallpox 

 may be looked for in India and the countries of central Africa." 

 It still prevails extensively in these countries, where vaccination is 

 only practiced to a limited extent. In the years 1873 and 1874 the 

 mortality from this disease in India is said to have been five hundred 

 thousand. " On European soil the smallpox, up to the beginning 

 of this century, or to the introduction of vaccination, had been one 



