190 PROTOZOAN PARASITISM 



stitutions where these conditions are controlled it 

 still thrives and is readily transferred by direct con- 

 tact, unclean personal habits, direct finger to mouth 

 transmission, and the contamination of food by its 

 handlers. 



The ways and means of prevention of its spread 

 are obvious, although no doubt difficult of enforce- 

 ment under crowded conditions, particularly in a 

 certain type of institution for boarding homeless chil- 

 dren. 



Although generally believed, it is not definitely 

 show^n that some of our domesticated animals and 

 pets may not carry giardias transmissible to man. 

 If it should be the case that some infections may be 

 of this source, the ^^dirty" age of childhood, particu- 

 larly, would need to be protected against this possi- 

 bility. 



Specific eliminative treatment has proven largely 

 unsatisfactory to the present. 



It should be borne in mind that its absence from 

 the intestine is not provable by single or even a re- 

 peated examination, and that a supposed elimination 

 may not be real. Prolonged observation is necessary. 



Various drugs have been reported as efficacious by 

 some and as of no effect by others. Among these 

 are quinine, emetine, bismuth subnitrate, beta-naph- 

 thol, methylene blue, and the salvarsans. 



Zahorsky and McLoon (1927) recommend bismuth 

 salicylate, given in 5 grain (0.3 gram) doses three 

 times a day to a child of six years. 



