coccidia: cross infection 



Pons' cases, and 30 days in cats and dogs; (3) no re- 

 lapses were reported. The literature contains descrip- 

 tions of a number of other cases of human coccidiosis 

 accompanied by symptoms, for example, Haughwout 

 (1921) in an American in the Philippines who was suf- 

 fering from occasional watery diarrhea, Boon van 

 Ostade (1923) in a Malay who acquired it in Java or 

 Sumatra and had chronic diarrhea, Petzetakis (1925) in 

 a case of acute dysentery, and Leger ( 1926), also a dys- 

 enteric case, in Annam. 



III. Host-Parasite Specificity 



Cross-infection experiments. The results of recent 

 investigations, especially those of Andrews (1927), in- 

 dicate that the coccidia of mammals are very rigidly 

 host-specific. According to Andrews, attempts had pre- 

 viously been made to infect kittens, mice and rats with 

 oocysts from man; horses, pigs, sheep, rabbits, guinea- 

 pigs, and rats with oocysts from cattle ; man, kittens and 

 rats with oocysts from dogs; dogs and rats with 

 oocysts from cats ; and cattle with oocysts from rabbits. 

 These experiments were all unsuccessful except those 

 of Fantham (1917), who claims to have infected kittens 

 with oocysts from man. Fantham's work is open to 

 question since no details are given and his experimental 

 animals may already have been infected with their 

 natural coccidial parasites. Andrews (1927) attempted 

 to infect dogs, cats, skunks and opossums with oocysts 

 from rabbits ; dogs with oocysts from skunks ; and cats 

 with oocysts from pigs, prairie-dogs and skunks but 



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