842 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



anci small rounded organisms in numbers varying with the severity 

 of the disease. The rods are frequently arranged in chains of two, 

 three or even four, and present deeply stained granules at one or both 

 extremities. Examined in fresh preparations they are found to move 

 slowly without marked change of shape through the interior of the 

 red cell. Cross-forms are rare and probably represent fortuitous 

 arrangement rather than segmentation of the organisms. The endo- 

 thelium of the blood-vessels of the lymph nodes, spleen and liver 

 contain organisms in various stages of development, small rod-shaped 

 forms similar to those of the red cells eventually being formed. The 

 distention of the endothelial cells is often sufficient to occlude many 

 of the blood-vessels and in the lymph foUicles of the large intestine 

 this has apparently led to the necrosis of the surrounding tissue and 

 ulceration. The organism of this disease is smaller than that of East 

 Coast fever, the rod forms being very slender and nuclear material is 

 not so readily differentiated. Its resemblance in other respects 

 together with the similarity of its distribution in the tissues indicates a 

 relationship to this group of organisms. 



The disease has not been transmitted to lower animals. Carrion, 

 a Peruvian student, who inoculated himself with the blood of a patient 

 suffering from Verruga peruviana died from a disease which may have 

 been Oroya fever, although the evidence on tliis point is inconclusive. 

 Oroya fever and Verruga peruviana not infrequently occur simul- 

 taneously in the same individual, just as the latter disease is frequently 

 complicated by malaria, and this together with the result of Carrion's 

 experiment led many Peruvian physicians to the erroneous belief that 

 Oroya fever and Verruga were different stages or manifestations of a 

 single infection. Verruga is, however, readily transmitted to lower 

 animals. The mode of transmission of Oroya fever has not been 

 conclusively determined. 



Anaplasmosis 



In a pernicious anaemia of cattle and at times in babesiasis the red 

 blood corpuscles contain minute deeply stained, rounded bodies. These 

 are frequently in pairs and are commonly situated near the margin 

 of the cell so that they have been given the name Anaplasma marginale 

 (Theiler), by those who are convinced of their parasitic nature. They 

 have also been found in other domestic animals and similar structures 



