254 PUBLIC HEALTH BACTERIOLOGY 



BACILLUS PESTIS. 



This plague bacillus belongs to a group of bacilli which 

 are all highly pathogenic to the animal world, and produce 

 in them a haemorrhagic septicaemia. The bacilli now 

 usually classed in this group are : the bacillus of human 

 plague, of swine plague, of chicken cholera, of septic pleuro- 

 pneumonia in cattle, and of rabbit septicaemia. The group 

 characteristics are : short, plump, non-motile bacilli ; non- 

 flagellar ; non-sporing ; Gram-negative ; non-gelatin-liquefy- 

 ing ; strongly aerobic, growing readily on simple media, 

 easily stained but showing a marked tendency to stain 

 more deeply at the ends than at the centre (bipolar 

 staining). They are believed by some to be varieties of 

 one organism. 



Plague is a specific, infective disease, caused by 

 the B. pestis, and characterized by inflammation of the 

 lymphatic glands (buboes), carbuncles, pneumonia, and 

 often haemorrhages (Osier). In the past the plague has 

 occurred in tremendous epidemics, and even to-day in 

 India it proves a terrible scourge. The large and extremely 

 fatal epidemic of pneumonic plague in China in 1910-11 

 shows that it still has very pathogenic powers for mankind. 



In the sixth century, in the reign of Justinian, Emperor 

 of Rome, half the population of the Roman Empire 

 perished of the disease. In the fourteenth century 

 the " black death " overran Europe and destroyed 

 25,000,000, or about one-fourth of the population. In the 

 seventeenth century it raged virulently, and in London 

 alone, in 1665, about 70,000 people died. During the 

 eighteenth and nineteenth centuries its ravages lessened. 



In 1893 an outbreak appeared at Hong-Kong, and since 

 then the disease has occurred in many parts of the world, 

 notably in India since 1896, in Egypt, in South Africa, 

 and in several Mediterranean ports, and, after an absence 

 from Great Britain of over two hundred years, it 

 obtained a foothold in Glasgow in 1900. It reached New 

 York quarantine station in 1899, and in San Francisco 

 broke out in 1900, continuing until 1904. In Australia, 

 cases appeared at Sydney and other ports. In the county 

 of Suffolk, in England, an epidemic ot rat plague, associated 



