xiii, b, 2 Haughwout: Infections with Coccidium 83 



accompanied by more urgent symptoms, is frequently treated 

 lightly by the sufferers themselves. It seems from what we 

 know of the self-limitation of many coccidial infections in the 

 lower animals that the same thing may occur in man and pass 

 almost unnoticed, especially in countries where routine exami- 

 nations of stools are seldom made. Furthermore coccidial cysts 

 are frequently mistaken for the eggs of helminths and vice versa 

 by the inexperienced microscopist. 



It may be urged that the very similar life cycle of the malarial 

 parasite and the tendency of old malarial cases to relapse ap- 

 parently contradict this theory of self-limitation, but I should 

 like to point out that in Coccidium and Isospora gametogony is 

 completed and sporogony starts and is carried on to an advanced 

 stage in the original host. There is encystment, and the cysts 

 pass out and complete their development before it is possible 

 for them to infect a new or the same host. 



In Plasmodium, however, we have an alternation of hosts, spo- 

 rogony being completed within the body of the mosquito. The 

 sexual cycle in man is carried to the gametocyte stage only, 

 and we have no evidence that this stage is infective to the orig- 

 inal host. We are left here to speculate as to whether relapses 

 of malarial fever are due to the presence of a relatively small 

 number of trophozoites, which lie dormant in the spleen or 

 bone marrow or which may even be free in erythrocytes in 

 the circulation, or to some autogamous, parthenogenetic, or sim- 

 ilar process, as Schaudinn and others have suggested. 



It must not be inferred from this that all coccidial infections 

 of this type tend toward spontaneous recovery. In many in- 

 stances the infections are rapidly fatal. Cyclospora karyolytica 

 gives rise to an enteritis in the ground mole, which may bring 

 about a fatal termination in forty-eight hours, the intestinal 

 discharges consisting almost entirely of desquemated epithelium 

 and parasites. Young animals are prone to succumb quickly, 

 and this should make us especially watchful in the case of chil- 

 dren, who ordinarily come in closer contact with animals that 

 may harbor parasites than do adults. 



The most reliable information regarding coccidial infections 

 in man comes to us from the British workers in the war zone, 

 although Wenyon and O'Connor (23) mention human infections 

 with Isospora in Egypt. Fantham (5) reports four cases of 

 coccidial infection, "apparently Isospora type," found during 

 the examination of the stools of 1,305 British soldiers in the 

 various hospitals in the western command. These cases were 

 all dysenteries who had become infected chiefly in Gallipoli, al- 



