152 APPLIED BACTERIOLOGY 



LEPROSY. 



Discovery and morphology of the organism — Staining in sections — Dis- 

 tribution of the bacilli in the body — Growth on artificial media- 

 Conveyance of disease — Leprosy in India Commission Eeport— 

 Occurrence and distribution— Pathogenesis— Preventive measures. 



The Bacillus leprce was first described by Hansen in 

 1871. The organism is a small rod, the length of which 

 is half to three-quarters the diameter of a blood-corpuscle. 

 The bacillus is straight or slightly bent, with more or less 

 pointed extremities, and it is not quite so large as the 

 tubercle bacillus. Within the protoplasmic contents may 

 be seen clear spaces (which some authorities believe to be 

 endogenous spores), surrounded by a delicate membrane. 



It is devoid of motility. The leprosy bacillus is stained 

 in the same manner as the tubercle bacillus by the Ziehl- 

 Neelsen method, as follows : 



1. Treatment of the section of tissue or film, Jioced upon 

 a cover-glass, with warm, Ziehl-Neelsen carbol-fuchsine 

 solution for tvjelve minutes. 



2. Decolourisation of the specvmen in 25 per cent. H^SO^. 



3. Washing in 60 per cent, alcohol. 



4. Washing in distilled water. 



' Cover-glass specimens are at once examined in water or 

 after drying in xylol balsam. Sections are treated with 

 absolute alcohol, and removed to clove-oil before mounting 

 in balsam. A saturated solution of acetate of potash is the 

 best medium in which to mount specimens, as the colour 

 disappears less rapidly.' 



By this method the bacilli of leprosy are isolated and 

 distinguished as bright red rods (Baumgarten). They may 

 also be differentiated from those of tubercle by treatment 

 with potash solution (1 in 12). The bacilli then appear as 



