Cryptosporidium diarrhea in costarican children

Abstract

Coccidian parasites of the genus Cryptosporidium cause acute diarrhea in many vertebrates, including man. Recent reviews on the subject [1-5] were stimulated by demonstration of a chronic, debilitating and generally fatal diarrhea in immunodeficient and immunosuppressed individuals, and in persons with acquired immunodeficiency syndrome (AIDS) [6-16]. Additional interest arose after finding that cryptosporidiosis is not rare among immunocompetent or otherwise healthy children and adults, who suffer from acute diarrheal disease in industrialized and less developed countries [17, 18]. The first Cryptosporidium species (C. muris) was described by Tyzzer in 1907 [19], who found the parasite in gastric glands of the domestic mouse. Tyzzer described oocysts measuring 5-6 x7 pm, with 4 sporozoites of about 12-14 p.m after excystation [19, 20]. He attempted transmission of the coccidium to the white rat, without success. Later, Tyzzer described another species, C. parvum, with considerably smaller oocysts measuring 3.0-3.3 X 4.0-4.5 p.m; excisted sporozoites measured 5.5-6.0 p.m [21]. This species was found in the small intestine of the laboratory mouse, rabbit and chicken [33], Cryptosporidium is currently placed in Apicomplexa, Sporozoea, Coccidia, Eucoccidiida, Eimeriina, and Cryptosporidiidae [22]. Many years after description of these species, additional "species" were named according to the vertebrate hosts in which they were found [22]. Most authors regard these species unjustified for several reasons. Oocysts found in different vertebrates are of similar size and morphology as those of C. parvum [23]. Infection and cross-infection occurs with oocysts of C. parvum-like strains in several vertebrate species and in man. Antibodies to one particular strain of Cryptosporidrum have been detected in sera from diverse vertebrate hosts [24]. On the basis of this information, one single species was proposed [24], in analogy with Toxoplasma, although one expert proposed one species for each of the four groups of vertebrates harboring parasites [25].