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The infectious agent is Cyclospora cayetanensis. Newly recognized as a protozoan parasite causing illness in humans, although earlier reports had suggested other
Identities for this pathogen, including blue-green algae (eg, Cyanobacteria-like bodies) or other protozoan forms.
Parasite is widely distributed geographically, including the U.S., Latin America and Asia.
Waterborne transmission and food-borne transmission bacterial pathogens occur; whether other modes of transmission exist remains to be defined. Oocysts, when passed in stool, are not immediately infectious and require sporulation over days to weeks. Consequently, direct person-to-person spread of infection is not likely. In US associated with widespread outbreaks of diarrheal illness due to contaminated raspberries imported from Guatemala.
Parasite invades epithelial cells as detectable in small bowel biopsies.
Mechanism of pathogenesis not understood, but the absence of fecal leukocytes and blood suggests that disease is due to a noninvasive mechanism.
Immunocompetent hosts: Incubation period is usually about seven days. Patients experience diarrhea, flu-like symptoms and symptoms common to other small bowel pathogens, such as flatulence and burping. May have a single self-limited episode, but prolonged diarrhea, anorexia and upper GI symptoms often occur. Pronounced fatigue and malaise have been frequent symptoms with weight loss experienced by some.
Immunocompromised hosts: Recognized in ADS, but nature of intestinal illness due to Cyclospora in immunocompromised hosts not yet defined.
Oocysts in stool (8-10 µm in diameter) are acid-fast and can be detected with acid-fast stains of stool. Thus, must be distinguished from Cryptosporidium, Cyclospora oocysts are not found on routine stool O + P exams; rather specific acid-fast stains must be requested.
Trimethoprim-sulfamethoxazole 1 double strength tablet bid for 7 days is effective. Alternative therapies for those unable to take TMP-SMX are not