HOST-PARASITE RELATIONS: INTESTINAL PROTOZOA 



autopsies. Educational campaigns and the automobile 

 have already lessened the danger from dissemination by 

 flies. The use of cresol to kill cysts in fecal material be- 

 fore they could be ingested by flies and other animals 

 might be effective. Any efforts to bring about a decrease 

 in soil pollution v^ould also be helpful. The control and 

 treatment of carriers are difficult problems that have 

 been discussed freely of late. Stiles (1922), for example, 

 has attempted to determine the feasibility of diagnos- 

 ing United States veterans of the World War and of 

 treating those who are found to be infected. He esti- 

 mated that the microscopic v^^ork alone would cost $5,- 

 000,000 and that the hospitalization, treatment, etc., 

 would add $25,000,000 more. The sterilization of food- 

 handlers in markets, hotels and restaurants has also been 

 advocated but the difficulties and expense involved make 

 this proposal likewise impracticable. 



IV. Host-Parasite Relations between Man and Other 

 Species of Amoehce 



The species of amoebae, other than E. histolytica, that 

 live in man are considered by practically every proto- 

 zoologist to be harmless commensals. For this reason 

 they have not been the subject of such intensive study 

 as their near relative, E. histolytica. There is conse- 

 quently nothing or very little to be said regarding them 

 with respect to such subjects as pathogenesis, sympto- 

 matology, immunology, resistance to infection, suscepti- 

 bility of the host, aggressivity of the parasite, relapse, 

 etc. Furthermore, many of the subjects presented under 



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