SARCOCYSTIS, TOXOPLASMA AND RELATED PROTOZOA 



329 



in 1 of 99 wild Norway rats in England. 

 Miller and Feldman (1953) found no posi- 

 tive dye test reactors among 54 albino 

 rats which they studied. 



Toxoplasma has been found in labor- 

 atory mice by Nicolau and Balmus (1934) 

 and Mooser (1950). Gibson and Eyles 

 (1957) found it by mouse inoculation of 

 brain tissue in 6% of 121 wild house mice 

 captured in the neighborhood of a house in 

 Memphis where a new-born infant had died 

 of congenital toxoplasmosis. Lainson 

 (1957) failed to find it in 399 wild house 

 mice in England. Makstenieks and Ver- 

 linde (1957) found that none of 4097 labor- 

 atory mice from animal dealers in the 

 Netherlands was positive to the dye test 

 even at a titer of 1:4. 



Toxoplasmosis is so common in voles 

 (J^icrotiis agrestis ) in England that it is 

 said to be a population-limiting factor 

 (Findlay and Middleton, 1934; Elton, Davis 

 and Findlay, 1935). 



Among other mammals, toxoplasmosis 

 has been reported in mink by Hulland (1956) 

 and Pridham and Belcher (1958) in Canada, 

 and by Momberg-J0rgensen (1956a) in 

 Norway. In the last case, a severe out- 

 break of distemper was also present. 

 Lainson (1957) found it in a weasel {Miis- 

 tela nivalis), a ferret, and 2 ferret-polecat 

 hybrids in England. Toxoplasma was re- 

 ported in 3 chinchillas in Washington by 

 Gorham and Farrell (1956), and in 3 chin- 

 chilla ranches in Canada by Hulland (1956). 



Among domestic birds, Toxoplasma 

 was found in a hen in Switzerland by Fank- 

 hauser (1951a), in a flock of chickens in 

 Norway by Erichsen and Harboe (1954), 

 and in 35 hens from 21 flocks in Denmark 

 by Biering-S0rensen (1956). 



Manwell and Drobeck (1951) isolated 

 T. gondii from a pigeon caught in Syracuse, 

 N. Y. , while Jacobs, Melton and Jones 

 (1952) isolated it from 4 of 80 wild pigeons 

 caught in Washington, D. C. ; the dye test 

 was positive in 7 of these birds, including 

 1 of those from which the organism was 

 isolated. 



Rosenbusch (1931) found T. gondii in 

 a canary in Argentina, and Sergent and 

 Poncet (1954) found it in one in Algeria. 

 Finlay and Manwell (1956) have reviewed 

 the literature on Toxoplasma in birds. 



Fig. 37. 



Toxoplasma gondii trophozoites 

 from mouse peritoneal exudate. 

 Giemsa stain. X 2800. (Original) 



Morphology : The trophozoites of T. 

 gondii are crescentic or banana-shaped, 

 with one end pointed and the other rounded, 

 and measure 4 to 8 by 2 to 4 (i. The nu- 

 cleus is vesicular and more or less central. 

 There are no flagella, cilia or pseudopods. 

 Locomotion is by body flexion whereby the 

 protozoa follow a corkscrew path, rotate 

 on their longitudinal axis or somersault 

 (Manwell and Drobeck, 1953), or by gliding. 



The morphology of the trophozoites 

 has been studied following silver protein 

 staining by Goldman, Carver and Sulzer 

 (1957, 1958) and with the electron micro- 

 scope by Gustafson, Agar and Cramer 

 (1954), Bringmann and Holz (1954), Ludvik 

 (1956) and Meyer and Mendonca (1957). 

 They resemble the trophozoites of Sarco- 

 cyslis in a number of ways. At the anterior 

 end within the pellicle is a short, truncate, 

 hollow cone 0.15 to 0.25/i in diameter and 

 0.2 to 0.3 ;i long, called a conoid. There 

 is sometimes a distinct, spike-like exten- 

 sion at the anterior end. A number of fine, 

 longitudinal fibrils run posteriorly in the 

 pellicle from the region of the conoid; they 

 extend for about 1/5 of the body length 

 according to Ludvik (1956) or 2/3 of it 

 according to Bringmann and Holz (1954). 

 Running longitudinally in the body from the 

 conoid are 5 to 18 cylindrical or club-shaped 

 structures known as toxonemes. They are 

 of variable length, some extending nearly 

 to the posterior end and others not reaching 

 the level of the nucleus; they become very 

 slender and tortuous as they approach the 

 conoid, and seem to enter its base. They 



