Spirochcetosis of Fowls 235 



days. These new forms are virulent, for a monkey was infected 

 by inoculating a single crushed louse which had fed on infected blood 

 fifteen days before. 



Natural infection is indirect. Those attacked by the insect 

 scratch, and in this act they excoriate the skin, crush the lice and 

 contaminate their fingers. The least abrasion of the skin serves for 

 the entrance of the spirochaetes. Even the contact of the soiled 

 fingers on the various mucosa. such as the conjunctive of the eye, 

 is sufficient. 



As in the case of Spiroch&ta dnttoni, the organism is transmitted 

 hereditarily in the arthropod vector. The progeny of lice which 

 have fed on infected blood may themselves be infective. 



Spirochaetosis of Fowls One of the best known of the spirochaetes 

 transmitted by arthropods is Spiroch&ta gallinarum, the cause of a 

 very fatal disease of domestic fowls in widely separated regions of 

 the world. According to Nut tall, it occurs in Southeastern Europe, 

 Asia, Africa, South America and Australia. 



In 1903, Marchoux and Salimbeni, working in Brazil, made the 

 first detailed study of the disease, and showed that the causative 

 organism is transmitted from fowl to fowl by the tick Argas persicns. 

 They found that the ticks remained infective for at least five months. 

 Specimens which had fed upon diseased birds in Brazil were sent to 

 Nuttall and he promptly confirmed the experiments. Since that 

 date many investigators, notably Balfour and Kindle, have contri- 

 buted to the elucidating of the life-cycle of the parasite. Since it 

 has been worked out more fully than has that of any of the human 

 spirochastes, we present Hindle's diagram (fig. 143) and quote the 

 brief summary from his preliminary paper (19116). 



''Commencing with the ordinary parasite in the blood of the fowl, 

 the spirochaete grows until it reaches a certain length (16-19^) and 

 then divides by transverse division. This process is repeated, and 

 is probably the only method of multiplication of the parasite within 

 the blood. When the spirochastes disappear from the circulation, 

 some of them break up into the coccoid bodies which, however, 

 do not usually develop in the fowl. When the spirochaetes are 

 ingested by Argas persicns, some of them pass through the gut wall 

 into the ccelomic fluid. From this medium they bore their way into 

 the cells of the various organs of the tick and there break up into a 

 number of coccoid bodies. These intracellular forms multiply by 



