922 



THE SPIROCHETES 



slightly susceptible, and usually remain perfectly well after inoculation (Martin and Pettit 

 1919). Cats, dogs, pigs, sheep, hens, pigeons, and monkeys are said to be refractory 

 (Uhlenhuth and Fromme 1916, Martin and Pettit 1919), but later evidence suggests that 

 Lepto. icterohcemorrhagice is responsible for some cases of infectious jaundice in the dog 

 (Dhont et al. 1934). 



Intraperitoneal injection of guinea-pigs with 1-2 ml. of infected human blood or ground- 

 up rat's kidney is followed by an illness lasting for 5 to 12 days, and terminating in death. 

 The chief symptoms of the disease are fever and jaundice. The fever commences the day 

 after inoculation, reaches its acme in a few days, falls to normal, and finally to subnormal 

 just before death. Jaundice first becomes visible when the temperature begins to fall — • 

 usually on the 4th or 5th day ; it increases till death, and is often accompanied by choluria. 

 Ansemia and conjunctival congestion are frequent, and external haemorrhages from the 

 rectum, nose, and genitals may occur. Blood counts reveal a lymphocytosis during the 

 first few days of the disease, and an anaemia (Buchanan 1927). Spirochsetes appear in the 



blood about the 4th day, but are not easy 

 to find microscopically. Post mortem, 

 the animal shows generalized jaundice ; 

 there are haemorrhages into various parts 

 ( )f the body, particularly the lungs, intes- 

 tinal walls, retroperitoneal tissues, and 

 fatty tissues of the inguinal region. The 

 haemorrhages in the lungs form irregular 

 spots of varying size, sharply demarcated 

 from the surrounding tissue — giving the 

 lungs a resemblance to the mottled wings 

 of a butterfly (Inada et al. 1916). The 

 spleen is enlarged and congested ; the kid- 

 neys show an acute parenchymatous 

 nephritis and capsular haemorrhages ; the 

 suprarenals are often enlarged and hsemor- 

 rhagic. Histologically the chief lesions 

 are cloudy swelling of the liver, sometimes 

 accompanied by focal necroses, acute 

 parenchymatous nephritis, endothelial cell 

 jjroliferation in the spleen and lymph 

 glands, and haemorrhages m practically 

 every structure of the body (Buchanan 

 1927). Spirochaetes are most numerous in 

 the hver, and are best demonstrated by 

 dark-ground illumination. They occur in 

 the spaces between the cells, and when 

 numerous are arranged about the cells like a garland. Their appearance is different 

 from that seen under dark-ground illumination ; they are short and thick ; the primary 

 spirals and tapering extremities are not evident, and numerous irregular undulations 

 are seen. They are found in smaller numbers in the kidneys and adrenals. 



By passage from guinea-pig to guinea-pig the virulence of the organism can apparently 

 be increased. Stokes (Stokes et al. 1917), for example, found that the average time to 

 death of animals inoculated intraperitoneally with human blood was 10 days, but that 

 when passage strains were used it was only 5 days. Noguchi (1917) likewise noticed a 

 reduction in survival time after passage of a strain through guinea-pigs. 



Fig. 218. — Lej)tospira icterohcemorrkagicB. 



Electron micrograph (X 12,000). 



Kindly supplied by Dr. H. E. Morton and 



Dr. T. F. Anderson. 



