THE TELOSPORASIDA AND THE COCCIDIA PROPER 



239 



are found in the small intestine and cecum 

 from the second to fourth day after experi- 

 mental infection. They are ellipsoidal 

 and about 20 j^ long. They produce 40 to 

 60 merozoites according to Hitchcock, or 

 12 or less according to Lickfeld. These 

 merozoites are relatively large, measur- 

 ing 16 to 18.5 by 5 to 8 ju. 



The second generation schizonts are 

 found on the 5th and 6th days after infec- 

 tion in the small intestine and less com- 

 monly in the large intestine. According 

 to Hitchcock, they produce up to 24 mero- 

 zoites, but most contain 12 to 16; accord- 

 ing to Lickfeld there are 30 to more than 

 100 of these merozoites, and they measure 

 7. 5 by 2. 5jLt. 



The sexual stages are found on the 

 7th and 8th days after infection. They 

 occur in the small intestine and less com- 

 monly in the cecum. According to Hitch- 

 cock (1955), the macrogametes average 

 25 to 22 /J,, but other workers have re- 

 corded dimensions up to 56 by 48/j, . The 

 microgametocytes average 28 by 19jll 

 according to Hitchcock, but other workers 

 have recorded dimensions up to 50 by 30 ji , 

 and Lickfeld said that they are 73 jj, in 

 diameter in life. Well over 2000 spindle- 

 shaped, curved, biflagellate microgametes 

 are formed in each microgametocyte. The 

 oocyst wall is laid down following fertiliza- 

 tion while the zygotes are still within the 

 host cells. The young oocysts then break 

 out and are passed in the feces. The pre- 

 patent period was found by Hitchcock 

 (1955) to be 7 to 8 days. 



According to Walton (1959), the hap- 

 loid number of chromosomes in /. felis 

 is 2. Lickfeld (1959) described a cryp- 

 tomitotic type of schizogony, but saw no 

 chromosomes. 



Pathogenesis : This species is 

 slightly to moderately pathogenic, depend- 

 ing on the host species, age, degree of 

 infection, etc. It is less serious in cats 

 than in dogs. None of 18 four- to nine- 

 week-old kittens infected by Hitchcock 

 (1955) with 100,000 sporulated oocysts 

 showed signs of disease. Andrews (1926), 



however, observed enteritis, emaciation, 

 weakness, depression, dysentery and even 

 death in kittens and dogs experimentally 

 infected with I. felis. Hitchcock thought 

 that these signs and deaths in the kittens 

 might well have been due to feline dis- 

 temper. 



The gross pathologic lesions are 

 similar to those caused by /. bigemina. 

 There is hemorrhagic enteritis, frequently 

 with ulceration, thickened mucosa and 

 epithelial desquamation. 



Immunity : Animals which have re- 

 covered from I. felis infections are re- 

 sistant to reinfection. 



Cross Transmission : Lee (1934) in- 

 fected dogs with /. felis from the cat, and 

 a fox with /. felis from the dog. 



ISOSPORA RIVOLTA 



(GRASSl, 1879) 



Synonyms : Coccidiuni rivolta, 

 Lucetina rivoltai. 



Hosts : Dog, cat, dingo, and prob- 

 ably other wild carjiivores. 



Location: Small intestine. 



Geographic Distribution : Worldwide. 



Prevalence : This species is common 

 in dogs and cats. Gassner (1940) found it 

 in 20% of 320 dogs in Colorado. Catcott 

 (1946) found it in 4% of 113 dogs in Ohio. 

 Ehrenford (1953) found it in 72% of 377 

 dogs from Indiana and nearby states. 

 Choquette and Gelinas (1950) found it in 

 13. 5% of 155 dogs in Montreal. Hitchcock 

 (1953) found it in 13% of 147 kittens in 

 Michigan. 



Morphology : The oocysts are ovoid, 

 20 to 25 by 15 to 20 fi. The oocyst wall is 

 smooth, with a micropyle at the small 

 end. An oocyst polar granule and residuum 

 are absent. The sporocysts are 16 by 10 \i. 

 A sporocyst residuum is present. The 

 sporulation time is 4 days. 



