336 



SARCOCYSTIS, TOXOPLASMA AND RELATED PROTOZOA 



The antigen for this test may be pre- 

 pared from protozoa in chicken embryos, 

 mouse brain, peritoneal exudate or tissue 

 cultures, Eichenwald (1956) preferred 

 chorioallantoic membrane or tissue cul- 

 ture because peritoneal exudate has a 

 strong anticomplementary activity. 



Jacobs and Lunde (1957) and Lunde and 

 Jacobs (1958) reported on a hemagglutina- 

 tion test for toxoplasmosis. It agreed 

 very closely with the dye test in a survey 

 of 12 human serum specimens from Trin- 

 idad; 54. 5% were positive by both tests. 

 They considered that the hemagglutination 

 test was adequate for survey purposes but 

 that more work must be done to determine 

 its usefulness in the diagnosis of acute in- 

 fections. 



A skin test using "toxoplasmin" was 

 developed by Frenkel (1948, 1949). Pos- 

 itive reactions appear in man, rhesus 

 monkeys and guinea pigs 3 to 4 weeks 

 after infection. However, they do not 

 appear in about 10% of the individuals, 

 and the test remains negative in most in- 

 fected rodents and in humans with highly 

 active disease. 



Hook and Faber (1957) found that anti- 

 genic activity in both the dye and comple- 

 ment fixation tests is associated with a 

 protein component of sonically fragmented 

 T. gondii which was precipitated by 30% 

 saturated ammonium sulfate at pH 7. 



Diagnosis : The most certain method 

 of diagnosis of toxoplasmosis is by isola- 

 tion of the parasites themselves by inocu- 

 lation of experimental animals. Eichen- 

 wald (1956) considered mice, hamsters 

 and guinea pigs the most sensitive ani- 

 mals in his experience, and recommended 

 the administration of cortisone to the test 

 animals for 3 to 5 days before inoculation 

 in order to increase the chance of isolating 

 the organisms. Jones el al. (1958), how- 

 ever, found no advantage in using cortisone. 

 They recommended intraperitoneal inocu- 

 lation of mice. Simitch, Petrovitch and 

 Brodjochki (1956) considered the ground 

 squirrel, Citellus cilelliis, to be the ani- 

 mal of choice, while Lainson (1957) found 

 that the multimammate rat (Mastoniys 

 coucha) is more susceptible than the house 



mouse and suggested that it might prove 

 more suitable. After isolation, the or- 

 ganism should be identified serologically. 



Despite the disadvantages discussed 

 above, the dye test still appears to be the 

 most satisfactory serological test avail- 

 able at present. Eichenwald (1956) con- 

 sidered the complement fixation test useful 

 only as an adjunct to it, and the hemagglu- 

 tination test requires further study. A 

 neutralization test was introduced by Sabin 

 and Ruchman (1942). It is now carried out 

 chiefly in tissue cultures. However, ac- 

 cording to Eichenwald (1956), it is of use 

 primarily as a research tool to study cell- 

 parasite relationships. 



Serologic studies with fluorescein- 

 labelled Toxoplasma antibody have also 

 been carried out (Goldman, Carver and 

 Sulzer, 1957). This technic shows prom- 

 ise. The antibody does not agglutinate 

 Besnoitia. 



Toxoplasma can also be found in 

 stained smears and sections of tissues and 

 exudates. It must be differentiated from 

 similar organisms, including Sarcocystis, 

 Besnoitia and Enceplialitozoon, and this is 

 not always possible on morphological 

 grounds alone. 



Cultivation : Toxoplasma grows 

 reaily in chicken embryos and tissue cul- 

 ture. It was first cultivated in both by 

 Levaditi el al. (1929). Cook and Jacobs 

 (1958) cultivated it in a wide variety of 

 mammalian and avian tissue cultures, in- 

 cluding various human, monkey, mouse, 

 rabbit, guinea pig, rat, ox and chick nor- 

 mal tissues, and in human and mouse can- 

 cer cells. They also reviewed the litera- 

 ture on the subject. 



Eyles, Coleman and Cavanaugh (1956) 

 preserved T. gondii for as long as 209 

 days by freezing it in the presence of 5% 

 glycerol and storing it at -70° C. They 

 used the technic routinely for preservation 

 of their strains. 



Treatment : No satisfactory treatment 

 for toxoplasmosis is known. Promising 

 results have been obtained by the use of 

 pyrimethamine and sulfonamides simul- 



