Protozoa of the Digestive and Urogenital Tracts 561 



iodide, although generally considered therapeutically effective, has ac- 

 quired such a reputation for toxicity that it is undesirable for treatment 

 of mild amoebiasis (8, 40, 41). However, oral dosage with emetine-hydro- 

 chloride in enteric-sealed tablets has given good results in a small group 

 of patients, some of whom were children (149). This method apparently 

 permits dosage with emetine at levels high enough for amoebacidal effec- 

 tiveness without any serious danger to the patient. 



Aureomycin, in contrast to penicillin, seems to be decidedly amoebaci- 

 dal and has produced apparent cures in cases of intestinal amoebiasis 

 (114). Likewise, terramycin is proving to be effective in treatment of 

 primary amoebiasis (123a). In addition to the usual amoebacidal drugs, 

 supplementary treatment with penicillin or a sulfonamide, such as sulfa- 

 guanidine, may be beneficial when intestinal amoebiasis is aggravated by 

 secondary bacterial invasion (1). 



Secondary amoebiasis. Treatment of secondary invasions is a more diffi- 

 cult problem than the treatment of intestinal amoebiasis and should be 

 started as early as possible. For hepatic amoebiasis, emetine-hydrochloride 

 apparently is the most effective drug available at present (86), although 

 preliminary results with chloroquine are quite encouraging (34, 116). 

 Many hepatic cases, in which treatment w^as begun early, have been cured 

 by emetine alone. In more advanced hepatic invasion, aspiration of 

 abscesses may be necessary in conjvuiction with chemotherapy. Emetine- 

 hydrochloride is injected subcutaneously or intramuscularly, the former 

 method being less painful. The effectiveness of emetine in liver abscess 

 apparently depends upon the rapid concentration and prolonged reten- 

 tion of the drug in the liver following the usual injection (129). Un- 

 fortunately, emetine-hydrochloride is highly toxic and its effects are 

 cumulative, so that cautious administration is essential. 



The search for new amoebacidal drugs. The need for more effective 

 drugs has led to the testing of many new compounds. Preliminary screen- 

 ing has involved two general procedures: tests for amoebacidal activity 

 in cultures, and tests for therapeutic value in infected laboratory animals. 

 Until pure cultures are available, the results obtained with cultures must 

 be interpreted cautiously. If culture tubes are plugged with cotton, the 

 failure of E. histolytica to grow in the presence of a drug might reflect 

 nothing more than a rise in oxidation-reduction potential of the medium 

 following bacteriostasis. Therefore, petrolatum seals, or other devices for 

 maintaining anaerobic conditions, are essential in such tests (28). The 

 use of monkeys (25, 89) in testing amoebicidal drugs has the advantage 

 that these animals often have natural infections with E. histolytica. How- 

 ever, E. polecki, which also occurs in Macaca mulatta, must not be con- 

 fused with E. histolytica in the interpretation of results (88). Dogs 

 maintained on a fish diet are susceptible to experimental infection with 



