820 MICROBIOLOGY OF DISEASES OE MAN AND DOMESTIC ANIMALS 



unknown, but there are reasons for believing that infection does not 

 easily occur by way of the digestive organs nor through the respiratory 

 organs. The disease is apparently not communicated by simply 

 stabling diseased animals with healthy animals. 



Distribution in the body is very general, as shown by the wide dis- 

 tribution of characteristic lesions, and as shown by the fact that the 

 blood is infectious. 



The A^irus which causes swamp fever reduces greatly the number of 

 red blood corpuscles and also produces local haemorrhages which are 

 most frequently small and sharply defined. The reduction of red blood 

 cells produces inarked pallor, and there gradually develops noticeable 

 emaciation. 



Post-mortem lesions in many cases are sUght. The haemorrhages 

 may involve subcutaneous and intermuscular tissues, spleen, and 

 lymph glands and are rather common on the lungs and heart. Any 

 of the abdominal organs may show the characteristic haemorrhages. 

 The bone marrow has been reported in some cases as distinctly changed 

 in color, the yellow marrow of long bones becoming dark red. In 

 some cases the liver shows degeneration and necrosis or tissue death. 



Typhus Fever* 



Typhus fever (ship fjever, jail fever) has been known to exist foi 

 centuries but until very recently we have been without precise knowl- 

 edge concerning its cause. Typhus is found in all parts of the world; 

 it affects man only and is characterized by a high fever and an erup- 

 tion on the skin. The course of the disease is limited and lasts for 

 only about twelve days. In the years 1909 and 1910 Nicolle, working 

 in Tunis, and Anderson and Goldberger, and Ricketts and Wilder 

 working in Mexico, showed that typhus is communicated from man 

 to man by means of the body louse {Pediculus vesHmenti), and that 

 the disease is not contagious in the ordinary sense of the word. Nicolle 

 states that after biting a typhus fever patient the louse cannot convey 

 the infection until the fourth day thereafter and that it loses this power 

 after the seventh day. This indicates a similarity between the micro- 

 organisms causing yellow fever, malaria and typhus. The disease may 

 be communicated to monkeys by subcutaneous inoculations of blood 



* Prepared by M. Dorset. 



