CHLAMYDOZOA 



191 



blood of infected individuals, and in the primary sore. These 

 he believed to be piroplasma-like organisms, and named them 

 Theileria tsutsugamushi. From the description and figures of 

 these organisms, however, it seems more probable that they are 

 related to Rickettsia or Dermacentroxenus. The blood of infected 

 individuals injected subcutaneously causes the disease. The 

 organisms do not pass through bacterial filters. 



Prevention in the endemic regions obviously consists in avoid- 

 ing mites by skin applications or other means. The extinction 

 of the field-mice and with them most of the mites would un- 

 doubtedly lessen the danger of the disease. 



Chlamydozoa 



The protozoan affinities claimed for the parasites or parasite- 

 like bodies included in the so-called Chlamydozoa is, as said 

 before, doubtful, and new investigations do not, in most cases, 

 tend to substantiate the claim of these structures to considera- 

 tion as animal parasites. A brief account of the parasites or cell 

 inclusions in some of the principal diseases attributed to this group 

 is all that can be given here. 



Smallpox and Vaccine. The youngest forms of the parasite 

 are minute granules or " elementary bodies " measuring about 

 0-5 M (soTJoo of an inch) in diameter. As growth takes place 

 the granules increase in number and become surrounded by 

 material which is usually interpreted as a reaction product of 

 the cell, forming the " Guarnieri bodies " (Fig. 59A). These 

 eventually rupture, liberating the granules to infect new cells. 

 The smallpox parasites differ from those of cowpox in that they 

 attack the nuclei as well as the cytoplasm of the cells. 



Scarlet Fever. In the skin cells of scarlet-fever patients are 

 found characteristic inclusions which have been referred to the 

 Chlamydozoa and named Cyclasterion scarlatince (Fig. 59B). 

 These bodies in one stage of their development are of irregular 

 shape with numerous enclosed granules, while in another stage 

 the granules become radiately arranged around a larger central 

 body. 



Hydrophobia or Rabies. There usually occur in certain brain 

 cells of animals suffering from hydrophobia specific bodies which 

 are popularly known as " Negri bodies " in honor of their discov- 

 erer, and which have been given the scientific name Neuroryctes 



