Cyclospora cayetanensis

Causative agent of cyclosporosis

Parasite and occurrence. Cyclospora cayetanensis was first identified as an apicomplexan parasite (family Eimeriidae) in 1994. The parasite occurs in various countries on all continents with generally low prevalences and with seasonal fluctuations, in children and adults, and also in AIDS patients.

Morphology and life cycle. Infection per os with sporulated oocysts in food or drinking water. Developmental stages in duodenal and jejunal enterocysts, probably two generations of schizonts; following gamogony formation of spherical oocysts 8-10 im in size. Prepatency about one week; oocysts are shed unsporulated in feces, then sporulate outside of host within five to 12 days to become infective. The sporulated oocysts contain two sporocysts with two sporozoites each (Fig. 9.11j, p. 504).

Clinical manifestations. Villus atrophy, cryptic hyperplasia, and inflammatory changes in the intestinal mucosa. Incubation about one week, self-limiting diarrhea in immunocompetent persons (lasts for about two to three weeks) with loss of appetite, flatulence, and malaise, usually nonfebrile; the diarrhea may persist for months in immunodeficient patients.

— Cyclospora and Cryptosporidium

— Cyclospora and Cryptosporidium

Cryptosporidium Parvum Carbol Fuchsin

Fig. 9.14 a Oocysts of Cyclospora cayetanensis in stool smear, modified Ziehl-Neelsen staining. b Oocysts of Cyclospora, unstained, after isolation from stool. c Oocysts from Cryptosporidium parvum in stool smear. Staining as in a. (b and c from: Bench Aids for the Diagnosis of Intestinal Parasites. Geneva: WHO; 1995.)

Fig. 9.14 a Oocysts of Cyclospora cayetanensis in stool smear, modified Ziehl-Neelsen staining. b Oocysts of Cyclospora, unstained, after isolation from stool. c Oocysts from Cryptosporidium parvum in stool smear. Staining as in a. (b and c from: Bench Aids for the Diagnosis of Intestinal Parasites. Geneva: WHO; 1995.)

Diagnosis and therapy. Detection of oocysts in stool specimens using concentration methods or in stained stool smears (for instance modified Ziehl-Neelsen staining or modified carbol-fuchsin staining). Cyclospora oocysts are easily confused with the oocysts of cryptosporidia (Fig. 9.14); they show autofluorescence in UV light and no reaction with monoclonal antibodies to Cryptosporidium. The drug of choice is cotrimoxazole.

Was this article helpful?

0 0
Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Post a comment