THE TELOSPORASIDA AND THE COCCIDIA PROPER 



177 



Location: Unknown. Oocysts found 



in feces. 



Geographic Distribution : India (Bom- 

 bay). 



Prevalence : Hiregaudar (1956) des- 

 cribed this species from a single calf. 



Morphology : The oocysts are ovoid, 

 36 to 38 by 25 to 28 ji . The oocyst wall is 

 0.3jn thick, slightly thicker toward micro- 

 pylar end, smooth, transparent, and pale 

 yellow or yellow. The micropyle is dis- 

 tinct, 0.5|j. in diameter. The sporocysts 

 are oval, 15 to 9 /j,, thinning at the pointed 

 end. The sporozoites are 4 to 6 by 1 to 3/1 

 and finely granular. An oocyst residuum 

 and polar granule are absent. A sporocyst 

 residuum is present. The sporulation 

 time is 1 to 2 days during the summer. 

 The extremely thin wall and the tiny, dis- 

 tinct micropyle may differentiate this 

 species from other bovine coccidia. How- 

 ever, the possibility must not be over- 

 looked that these oocysts may be those of 

 a species such as E. bukkliioiiensis from 

 which the thick, brittle outer wall has 

 cracked off. 



Life Cycle : Unknown. 



Pathogenesis: Unknown. 



COCCIDIOSIS IN CATTLE 



Epidemiology : Infections with a 

 single species of coccidium are rare in 

 nature; mixed infections are the rule. 

 Ei))ieria ziiynii and E. bovis are the most 

 pathogenic species, but E. auburnensis 

 and the other species may contribute to 

 the total disease picture, and some of 

 them may cause marked signs by them- 

 selves if they are present in large enough 

 numbers. 



Bovine coccidiosis is primarily a 

 disease of young animals. It ordinarily 

 occurs in calves 3 weeks to 6 months old. 

 Older calves and even adult animals may 

 be affected under conditions of gross con- 

 tamination, but they are usually symptom- 

 less carriers. 



Calves become infected by ingesting 

 oocysts along with their feed or water. 

 The severity of the disease depends upon 

 the number of oocysts they receive. If 

 they get only a few, there are no symptoms, 

 and repeated infections produce immunity 

 without disease. If they get more, the 

 disease may be mild and immunity may 

 also develop. It they get a large number, 

 severe disease and even death may result. 



Crowding and lack of sanitation greatly 

 increase the disease hazard. Successive 

 passage of coccidia from one animal to 

 another often builds up infection to a patho- 

 genic level, since in each passage the re- 

 cipient receives more oocysts than in the 

 previous one. This is the reason for the 

 common observation that calves placed in 

 a lot where others are already present may 

 suffer more from coccidiosis than those 

 which were there first. This successive 

 passage from a carrier to a symptomless 

 "multiplier" to a sub-clinical case to a 

 fatal case was described by Boughton 

 (1945) as typical of the transmission of 

 bovine coccidiosis. In addition, it is 

 likely that recycling by repeated infections 

 of a single individual may also play an im- 

 portant part. 



A little -understood type of bovine 

 coccidiosis is winter coccidiosis. This 

 occurs when it is so cold that oocyst spor- 

 ulation should be minimal if it occurs at 

 all. Presumably there is enough heat in 

 the bedding to permit sporulation. Another 

 explanation which has been advanced is 

 that the stress of winter conditions exacer- 

 bates a latent infection. This explanation 

 is not easy to validate, however, in view 

 of the self-limiting nature of coccidial 

 infections. 



Davis, Herlich and Bowman (1959, 

 1959a, 1960, 1960a) found that concurrent 

 infections of cattle with the nematodes, 

 Trichostrotigylus colubrifonnis or Coop- 

 eria punctata, exacerbated the effects of 

 coccidia in calves, but that Ostertagia 

 ostertagi and Strongyloides papillosus had 

 no such effect. 



Diagnosis : Bovine coccidiosis can 

 be diagnosed from a combination of history, 



