47 



Treponema pertenue is the spirochsete of yaws or fram-' 

 fccesia. 



Spirochceta recurrentis causes European relapsing fever. 



Spirochceta duttoni is the cause of human tick-fever or 

 relapsing fever of Tropical Africa, prevalent in the Congo 

 State and other parts. 



How are the Spirochcete parasites conveyed from one person 

 to another ? 



By lice or by ticks. Spirochceta recurrentis is transmitted 

 by bed-bugs and by lice. Infection from lice is commonly 

 brought about by scratching the skin, and thus crushing 

 the lice containing the spirochsetes which then enter by 

 the abrasions. 



Spirochceta duttoni is transmitted by a tick, Ornithodorus 

 moubata, which frequents the ground of camping sites 

 a,nd places where the natives have built their huts. The 

 parasites are taken up by the tick when it sucks the blood 

 of an infected individual. The tick remains infective for 

 some time. The parasites also penetrate the ovaries of 

 the tick and enter the immature eggs ; so that the nymphs 

 which arise from these eggs also transmit the germs to 

 healthy individuals. 



While the tick is feeding, it voids excrement containing 

 the parasites and they find their way into the wound. 

 That is the mode of infection. 



CLASS CILIATA (INFUSORIANS). 



JState briefly the General Characters of the Ciliata. 



The body has a definite shape and has short, vibratile, 

 hair-like cilia which act like oars for locomotion. The 

 cilia may be all over the body (e.g., Paramecium), or may 

 be restricted to- one area (e.g., Vorticella). Stinging hairs 

 or trichocysts are (in one order) present among the cilia. 



There are two nuclei (a large macro- or meganucleus 

 ,nd a small micronucleus which differ also in structure 



