THE TRICHOMONADS 



85 



Morgan's (1946) review listed 447 refer- 

 ences, and many more papers have been 

 published since then. Among more recent 

 papers on its pathogenesis are those of 

 Morgan (1947), Bartlett (1947), Bartlett 

 and Dikmans (1949), Bartlett, Moist and 

 Spurrell (1953), Laing (1956) and Gabel 

 et al. (1956). 



Bovine trichomonosis is a venereal 

 disease, transmitted by coitus. It can 

 also be transmitted by artificial insemin- 

 ation. Non-venereal transmission is very 

 rare under natural conditions. After in- 

 fection of the female, the trichomonads 

 multiply at first in the vagina, causing a 

 vaginitis. They are most numerous here 

 14 to 18 days after infection (Hammond 

 and Bartlett, 1945). They invade the 

 uterus thru the cervix. They may disap- 

 pear from the vagina or they may remain 

 there, producing low-grade inflammation 

 and catarrh. 



Early abortion is characteristic of 

 bovine trichomonosis. Abortion usually 

 occurs 1 to 16 weeks after breeding. The 

 foetus is often so small that it is not ob- 

 served by the owner, and he does not 

 realize that abortion has occurred, be- 

 lieving that the animal failed to conceive 

 and that its heat periods are irregular. 

 Morgan and Hawkins (1952) knew of only 

 6 reports in the literature of abortion due 

 to T. foetus after 6 months gestation. 



If the placenta and fetal membranes 

 are completely eliminated following abor- 

 tion, the animal usually recovers spon- 

 taneously. This is the most common 

 course. If, however, part of the placenta 

 or membranes remain, a chronic catar- 

 rhal or purulent endometritis results which 

 which may cause permanent sterility. 



Sometimes the animal does not abort, 

 but the fetus dies and becomes macerated 

 in the uterus. Pyometra results, and the 

 uterus may contain several quarts of a 

 thin, greyish white fluid swarming with 

 trichomonads. In the absence of bacteria, 

 this fluid is almost odorless. The cervi- 

 cal seal may remain intact or it may allow 

 a small amount of fluid to escape when the 

 animal is lying down. Animals with pyo- 



metra seldom come in heat, and the owner 

 may believe them to be pregnant. In long- 

 standing cases, the trichomonads may 

 disappear from the uterine fluid. 



Occasionally normal gestation and 

 calving may occur in an infected animal, 

 but this is rare. 



In the bull, the most common site of 

 infection is the preputial cavity, altho the 

 testes, epididymis and seminal vesicles 

 may sometimes be involved. Spontaneous 

 recovery is rare; bulls remain infected 

 permanently unless treated. The numbers 

 of trichomonads fluctuate, the intervals 

 between peaks being 5 to 10 days according 

 to Hammond el al. (1950). 



Immunology: Cows or heifers which 

 recover from infection are usually rela- 

 tively immune, altho reinfections can occur. 



A number of investigators have studied 

 various immunological responses to trich- 

 omonad infection. Kerr and Robertson 

 (1945) showed that there is more than one 

 serological strain of T. foetus. McEnte- 

 gart (1956) found that T. foetus var. belfast 

 and T. foetus var. )uaiiley differed sero- 

 logically from each other and from T. 

 vaginalis. Menolasino and Hartman (1954) 

 were unable to distinguish T. foetus from 

 T. vaginalis serologically, but McDonald 

 and Tatum (1948) and Schoenherr (1956) 

 were able to do so. Both also found sero- 

 logical differences between T.foetus and 

 Pentatyicho>no)ias lioiiiiiiis, and the latter 

 between T. /oe/;(S and T richonionas gal- 

 liuae. Sanborn (1955) found that T. foetus 

 differed serologically from the large pig 

 cecal trichomonad, T. suis and from the 

 pig nasal trichomonad. 



Kerr and Robertson (1941, 1943) and 

 Pierce (1947) studied the agglutination test 

 in cattle, and Feinberg (1952) described a 

 capillary agglutination test. Kerr (1943) 

 felt that his test was positive in about 60% 

 of all infected cattle, but Morgan (1943a) 

 considered it impractical. The wide dis- 

 tribution in the animal kingdom of non- 

 specific antibodies against T. foetus was 

 brought out by Morgan (1944), who showed 

 that the sera of the carp, horned lizard 



