THE TRICHOMONADS 



87 



They survive in some media but not in 

 others. Rapid freezing and high salt con- 

 centration are deleterious (Levine and 

 Marquardt, 1955; Levine, Mizell and 

 Houlahan, 1958). The stage of the popu- 

 lation growth curve is important, the pro- 

 tozoa being much more sensitive to injury 

 when frozen during the initial and logarith- 

 mic phases than at the peak of the curve 

 and for some time thereafter (Levine, 

 McCaul and Mizell, 1959). Temperature 

 fluctuation during storage is deleterious 

 (Fitzgerald and Levine, 1961). 



A particularly interesting fact is that 

 glycerol appears to be toxic at refrigerator 

 temperatures but not at either sub-freezing 

 or incubator (37° C) temperatures (Joyner, 

 1954; Joyner and Bennett, 1956; Fitzgerald 

 and Levine, 1961). It may be possible to 

 develop a technic for freezing semen which 

 would be sure to kill the protozoa, but at 

 present the use of frozen semen from in- 

 fected bulls cannot be recommended. 



Many different laboratory animals 

 can be infected experimentally in various 

 ways with T. foetus (see Morgan, 1946 for 

 review). Leaving aside other routes of 

 infection, successful vaginal infections 

 with T. foetus have been established in 

 the rabbit by Witte (1933) and others, in 

 the guinea pig by Riedmuller (1928) and 

 several others, in the golden hamster by 

 Kradolfer (1954) and Uhlenhuth and 

 Schoenherr (1955), in the dog by Trussell 

 and McNutt (1941), in the goat by Wittfogel 

 (1935) and Hammond and Leidl (1957), in 

 the sheep by Wittfogel (1935) and Andrews 

 and Rees (1936), and in the pig by Ham- 

 mond and Leidl (1957). The golden ham- 

 ster is the laboratory animal of choice for 

 experimental vaginal infections. Abortions 

 were produced in some of the infected 

 guinea pigs. Laboratory mice and rats 

 are refractory to vaginal infection. 



Kijst (1936) found trichomonads simi- 

 lar to T. foetus in the genital tract and 

 aborted fetuses of swine and horses in 

 Germany. Petersen (1937) cultured trich- 

 omonads resembling T. foetus from the 

 genital tracts of 13 mares with pyometra. 

 He also found an infected stallion which 

 had transmitted trichomonads to mares. 



Schoop and Oehlkers (1939) also found 

 trichomonads in the genital tract of horses. 

 Schoop and Stolz (1939) found trichomonads 

 resembling T. foetus in the uteri of 4 out 

 of 5 roe deer in Germany. The infections 

 were associated with sterility, and the 

 trichomonads produced vaginitis in guinea 

 pigs. Schoop (1940) suggested that if the 

 trichomonads from deer were T. foetus, 

 deer might be a source of infection for 

 cattle. 



The relation of T. foetus to the trich- 

 omonads of swine still remains to be elu- 

 cidated. The pig nasal trichomonad, 

 TritricJioiuoiias suis, greatly resembles 

 T. foetus morphologically (Buttrey, 1956) 

 and in metabolic characteristics (Doran, 

 1957, 1959), and vaginal infections were 

 readily established in cattle with it by 

 Switzer (1951) and Fitzgerald et at. (1958). 

 The infection reported by Switzer lasted 3 

 weeks and was accompanied by a mild 

 catarrhal vaginitis. Those reported by 

 Fitzgerald et al. lasted 46 to 133 days, 

 and some infections appeared to interfere 

 with breeding efficiency. 



Vaginal infections of cattle with trich- 

 omonads from the cecum and stomach of 

 swine have also been readily established 

 (Switzer, 1951; Hammond and Leidl, 

 1957a; Fitzgerald e/ aZ. , 1958), and the 

 latter two authors reported that bulls be- 

 came infected by breeding infected heifers 

 and then transmitted their infections to 

 other heifers. The bulls later recovered 

 spontaneously in both studies. Kerr (1958), 

 too, infected heifers intravaginally with 

 trichomonad from swine, using both strains 

 obtained from Hammond and a strain of 

 T. suis isolated in England. He found that 

 the vaginal mucus agglutination test of 

 heifers infected with porcine trichomonads 

 was positive with T. suis and Belfast strain 

 T. foetus antigens but not with Manley 

 strain T. foetus antigen. 



In the other direction, Fitzgerald et al. 

 (1958) produced cecal infections with T. 

 foetus in young pigs. 



Robertson (1960) made a serologic 

 comparison of the Belfast and Manley 

 strains of T. foetus and Strains S2 and 414 



