MODES OF TRANSMISSION 7 



Sarcosporidiosis was proved in a Barbadian negro; the sporozoa 

 were found in a portion of the biceps muscle (Darling), but the disease 

 aborted in three weeks, leaving the patient free. 



Rhinosporidium seeberi is similar to tlie above, but has a well- 

 defined sporoblast. The parasite has been obtained from nasal polypi 

 and penile papilloma (Ingram). The growth has a raspberry appear- 

 ance, with white spots on a general red background. The dots are 

 the cysts. The irritation of the parasite causes proliferation of the 

 mucosa and sub-mucosa of the affected part. The source of the infection 

 is unknown. 



The condition is known as Rhinosporidiosis. 



It has been seen in South America, India and Ceylon. 



The treatment is to remove the growth and cauterize the base. 



Balantidium coli and minutum cause diarrhoea and abdominal pain 

 in man (enterocolitis). See the Dysenteries. 

 (4) Ciliata. 



Numerous forms of ciliated protozoa existing in man but not pro- 

 ducing any symptoms are not dealt with here. 



MODES OF TRANSMISSION. 



Insects become infected witii animal parasites in various ways : — 

 (i) Insects suck up parasites with the blood when they are feeding 

 upon that medium. Such parasites develop and multiply in the insects 

 and are later injected into man during the act of drawing more blood. 



(2) The development of the parasite taken up with the blood may 

 continue in the eggs of the host, which process of development is not 

 completed until the eggs are hatched. Young ticks, having developed 

 from an infected egg, may bite a warm-blooded host and infect him, 

 although it has not previously fed on infected matter. This process 

 takes place in the case of the piroplasma and spirochete. 



(3) Parasites drawn up with the blood may develop in the alimentary 

 tract of the insect and infective sporozoites may be passed with the 

 feces . 



(4) Larve of the invertebrate host living in water may become 

 infected directly by means of their food. These larve and their 

 ingested parasites develop simultaneously, so that by the time maturity 

 of the insect is reached the parasites are very numerous. Such parasites 

 may then be passed with the feces and live independently, to enter 

 into other larve later. Flagella may thus be transmitted. This 

 method applies not only to protozoa, but also to metazoa and bacteria. 



The following facts show briefly how the most important protozoal 

 diseases are transmitted : — 



