CAUSING CHRONIC INFECTIONS. 
101 
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 
Dr. Osier says it existed in Egypt three or four thou¬ 
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 
Distribu¬ 
tion of 
the dis¬ 
ease 
