THE TELOSPORASIDA AND THE COCCIDIA PROPER 



241 



Prevention : Sanitation and isolation 

 are effective in preventing coccidiosis. 

 Animal quarters should be cleaned daily. 

 Runways should be concrete. Ordinary 

 disinfectants are ineffective against coc- 

 cidian oocysts, but boiling water, if it is 

 still boiling when it reaches the oocysts, 

 will kill them. 



ISOSPORA BELLI 

 WENYON, 1923 



Host : Man. 



Location : Presumably small intes- 

 tine. Elsdon-Dew, Roach and Freedman 

 (1953) found oocysts in material from a 

 duodenal intubation. 



Geographic Distribution : Presumably 

 worldwide, but more common in the trop- 

 ics than in the temperate zone. 



Prevalence : This species is quite 

 rare in man. However, Elsdon-Dew and 

 Freedman (1953) found it in 32 persons in 

 Natal, and considered that it was often 

 missed because it was not looked for. 



Pathogenesis : Most infections with 

 /. belli appear to be subclinical and self- 

 limiting. However, it may cause a mu- 

 cous diarrhea. In 31 of the 33 cases of 

 Isospora infection studied by Barksdale 

 and Routh (1948), anorexia, nausea, ab- 

 dominal pain and diarrhea were present. 

 Matsubayashi and Nozawa (1948) reported 

 that symptoms appeared 1 week after ex- 

 perimental infection of 2 human volunteers, 

 presumably with /. belli, and that oocysts 

 appeared in the feces 10 days after infec- 

 tion and persisted for a month. 



Cross-Transmission Studies : Jeffery 

 (1956) failed to transmit /. belli from man 

 to 2 monkeys, 2 dogs, 2 pigs, 12 mice, 4 

 rats, a guinea pig and a rabbit. Robin and 

 Fondimare (1960) were unable to transmit 

 it from man to the guinea pig, rabbit, 

 mouse or rat. 



ISOSPORA HOMINIS 

 (RAILLIET AND LUCET, 1891) 

 WENYON, 1923 



Synonyms : Coccidiiun bigeminum 

 var. hominis, Lucetina hominis. 



Morphology : This species has often 

 been confused with /. hominis (see Elsdon- 

 Dew and Freedman, 1953), but is clearly 

 different. The oocysts are elongate el- 

 lipsoidal, 20 to 33 by 10 to 19 fi (mean, 

 30 by 12 fi according to Elsdon-Dew and 

 Freedman, 1953). One or both ends of 

 the oocyst may be somewhat narrow. The 

 oocyst wall is smooth, thin, and colorless. 

 A very small micropyle is sometimes 

 visible. An oocyst polar granule may be 

 present in young, incompletely sporulated 

 oocysts, but quickly disappears. An 

 oocyst residuum is absent. The sporo- 

 cysts are subspherical to ellipsoidal, with- 

 out a Stieda body, 12 to 14 by 7 to 9 fi 

 (mean 11 by 9fi according to Elsdon-Dew 

 and Freedman, 1953). A sporocyst resi- 

 duum is present. The sporozoites are 

 slender, somewhat crescent-shaped, with 

 the nucleus at one end. Both immature 

 and mature oocysts may be passed in the 

 feces. The sporulation time is up to 5 

 days. 



Life Cycle : Unknown. 



Host: Man. 



Location: Small intestine. 



Geographic Distribution : Worldwide, 

 but more common in the tropics than in 

 the temperate zone. 



Prevalen ce: 

 rare in man. 

 Freedman 



Natal, and thought that it was often missed 

 because people did not look for it. 



This species is quite 

 However, Elsdon-Dew and 

 (1953) found it in 23 persons in 



Morphology : The oocysts are spor- 

 ulated when passed. The oocyst wall is 

 very thin, stretched around the sporocysts 

 and usually constricted between them, and 

 sometimes not visible. It is often rup- 

 tured, releasing the sporocysts. The 

 oocysts are about 20 by 15|j.. Micropyle, 

 oocyst polar granule and residuum are 

 absent. The sporocysts are ellipsoidal or 

 with one side flattened, about 15 by 10 /i, 

 without a Stieda body. A sporocyst resi- 

 duum is present. 



