260 PUBLIC HEALTH BACTERIOLOGY 



Cimex lectularius, or the common bed-bug, has lately 

 been investigated as a carrier of plague bacilli. Enormous 

 numbers can be found in the stomach of the bug after 

 infection, and for four to five days. Two bugs were still 

 alive eighty-three days after the feeding, and broth and 

 agar cultures were obtained from their bodies. Inoculation 

 of mice produced typical results, and the B. pestis was 

 recovered. 



Other types of plague are described, which do not come 

 under the above headings. These are : the ambulant form, 

 in which the patient has a few days of fever, with swelling 

 of the glands of the groin, and possibly suppuration. 

 These cases are often found at the beginning of an epidemic, 

 and are a source of great danger to the community, as the 

 urine and faeces contain bacilli ; and the septicemic type, in 

 which the patient succumbs to a virulent infection before 

 the buboes appear. There are also cutaneous and intestinal 

 types, the former showing petechias and subcutaneous 

 haemorrhages ; the latter, diarrhoea and haemorrhages from 

 the mucous membranes, and sometimes the features of 

 enteric. 



In India, an analysis of n,6oo cases gave 77-65 per cent 

 of bubonic type, 14-25 per cent of the septicaemic type, 

 and 4-4 per cent of the pneumonic type. The mortality 

 was highest in the pneumonic type (96-69 per cent), and 

 almost as high in the septicaemic. In the bubonic form, 

 out of 9,500 cases, 5,130 (54 per cent) showed the glands 

 of the groin first affected, and usually on the third to 

 the fifth day.* Resolution may occur, or suppuration, 

 or in rare cases, gangrene. Suppuration is noted as a 

 favourable feature. 



The appearance of petechiae, or " plague spots," or 

 " tokens of the disease," gave to it in the middle ages the 

 name of the " black death." 



Toxins. The filtrate of a plague culture has a very 

 slight toxic effect, but not capable of inducing immuniza- 

 tion. Hence it is believed that little or no soluble toxin 

 exists. Injection of dead bacilli produces distinctly toxic 



* The areas of skin surface which drain respectively into the glands of the groin, 

 axilla, and neck, are as 5 : 1*8 : 1, and the number of primary buboes observed in 

 hospital in these glands were as 5-8 : 1-3 : 1 respectively. 



