CAUSING CHRONIC INFECTIONS. 97 



patients. It is a short rod about the size of the tubercle 

 bacillus, which it resembles closely both in appearance 

 and in staining peculiarities. It takes stains with diffi- 

 culty, but once stained it resists decolorizing with 

 acids. For this reason it is spoken of as being acid- 

 fast. It is very difficult to cultivate on the culture 

 media at our disposal. Efforts to transmit the disease 

 to animals have not been successful. 



Leprosy is one of the oldest diseases known, and Distribu . 

 Dr. Osier says it existed in Egypt three or four thou- t he n dis f - 

 sand years before Christ. It is referred to many times 

 in the Bible, but there is reason to believe that other 

 diseases were included under the same name. The dis- 

 ease has continued to exist to the present time, but was 

 particularly prevalent in the Middle Ages. At pres- 

 ent it exists in Iceland, Norway, Sweden, Russia, 

 Spain, Portugal, England, West Indies, China, India, 

 and the Philippines. In the United States small num- 

 bers of cases are to be found in Louisiana, Minnesota, 

 Florida, and Texas, with isolated cases widely 

 scattered. 



The disease manifests itself either as tubercular 

 leprosy or as anesthetic leprosy. In the former, 

 nodules develop in the skin which soften and finally 

 form discharging sores. In the anesthetic form the 

 nerves are principally affected, and this leads to loss 

 of sensation in the skin. Both forms may exist at the 

 same time. 



The way that infection takes place is not posi- 

 tively known, but many believe that it enters the skin 



