BARTONELLA BACILLI FORM IS 



503 



protozoa, and probably the cause of the disease. In the same year 

 Gastiaburu and Rebagliati confirmed these findings and regarded 

 the organism as the cause of Oroya or Carrion's fever. In 1915 

 Strong, Tyzzer, Brues, Sellards, and Gastiaburu, confinned and 

 enlarged these discoveries and named the parasite. 



Morphology. — -In fresh blood- films the parasite appears as a 

 rounded or rod-shaped body, 0-5-1 -o microns in diameter in the 

 former case, and 1-5-2 -5 microns in length in the latter. They are 

 very abundant in severe cases, and are endowed with a definite 

 motility which is totally distinct from pedesis. They glide slowly 

 about the cell. Sometimes a dot or bead-like body can be seen at 

 the two poles. 



Fig. 165. — Life-Cycle of Bartonella haccilliformis Strong, Tyzzer, Brues, 

 Sellards, and Gastiaburu, 191 5. 



(Constructed from the illustrations in the Report of the First Expedition of the 

 Harvard School of Tropical Medicine to South America in 1913.) 



When stained they are seen to be slightly curved, and to be 

 present as single individuals, pairs, or in chains of three to five. 

 V and Y forms are not uncommon, and are considered to represent 

 dividing forms. Cross forms are rare, and due to organisms being 

 superimposed. 



The ends of the rods are more intensely coloured than the rest 

 of the organism. 



Some fonns are rounded, oval, or almost pyriform. As many as 

 ten parasites may be found in a single cell, which they apparently 

 destroy. 



Life-Cycle.- — They are also to be found in large swollen endothelial 

 cells, free or attached to the vessel Wall, in the spleen and the lymph 

 glands. An endothelial cell may be so distended with rounded and 

 rod-shaped parasites as to occlude a vessel. In these cells the para- 

 site, when coloured by Giemsa's stain, appears as rounded bodies, 

 composed of bluish cytoplasm and containing small granules of 

 chromatin, which vary in number from one to many, and it is sug- 



