STEVEN M. GORDON, MD Dr. Gordon is the hospital epidemiologist and a staff physician in the Department of Infectious Disease at the Cleveland Clinic. KARIM A. ADAL, MD, MS Dr. Adal is a staff physician in the Department of Infectious Disease at the Cleveland Clinic. Cyclospora: update on an emerging pathogen • • Cyclospora cayetanensis, an emerging Cyclospora is usually transmitted pathogen with worldwide distribution, causes diarrhea in by contaminated water, but may be both immunocompetent and HIV-infected patients. We food-borne (eg, raspberries). review the epidemiology of Cyclospora infection and how to diagnose and treat it. Persons returning from or residing in endemic areas are at high risk , rmn^ , r , , , , r ,. , , for infection n e summer 19yo, several food-borne outbreaks of diarrheal disease caused by Cyclospora cayetanensis occurred in the United . , . , States and Canada and involved over 1000 persons1-2; this The diarrhea is usually se f-limited pathogen had caused only three previous outbreaks of human but may last up to 6 weeks and be j[ mfection m the Umted States 3 Alth h CyclosPora is not a associated with profound fatigue. w orggnism) it is now recognized as a cause of diarrhea and as an . Li- u j u -J" emerging pathogen that has invaded the food supply.4 This article Diagnosis is established by direct describes the diagnosis and treatment of Cyclospora infection, examination of fresh stool specimens in a laboratory with A TYPICAL CASE personnel experienced in identifying Cyclospora. ^ 38-year-old housewife from northeastern Ohio presented to the out- patient clinic at the Cleveland Clinic in June 1996 with a 3-week his- Treatment with oral trimethoprim tory of nonbloody diarrhea, abdominal cramps, a 15-pound weight sulfamethoxazole is effective. loss, and severe fatigue. Of note, she had consumed waffles topped with fresh raspberries over the Memorial Day weekend. Her husband, mother, father, and aunt, who also ate the raspberry-laden waffles, all developed a similar diarrheal illness. There was no history of travel outside of Ohio. Her physical examination disclosed nothing abnormal. A modi- fied acid-fast smear of a fresh stool specimen showed oocysts consis- tent with C cayetanensis (FIGURE). Bacterial cultures for enteric pathogens were negative, and examination of her stool revealed no other ova or parasites. Stool specimens from the patient's father and mother also contained Cyclospora. All the patients were treated with oral trimethoprim-sulfamethoxazole, and their symptoms resolved completely. CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 64 • NUMBER 6 JUNE 199 7 3 1 3 Downloaded from www.ccjm.org on September 29, 2021. For personal use only. All other uses require permission. CYCLOSPORIASIS • GUMBO AND ASSOCIATES ic.6~9 Cyclosporiasis appears to be seasonal, with peak incidence during the rainy seasons (from April to June in Peru and May to September in Nepal).7'10 Although all age groups can acquire the disease, the highest attack rates occur among children older than 18 months.11 There is no apparent immunity to infection, and reinfection can occur at all ages.12 Cyclospora is an increasingly recognized cause of traveler's diarrhea, causing up to 11% to 20% of cases of diarrhea in studies of expa- triates in Nepal.6-10'11 Documentation of infection acquired in the United States is also increasing. The earliest recorded outbreak of diarrheal disease associated with Cyclospora in Modified acid-fast stain of stool showing Cyclospora cayetanensis oocyst (x 1000). the United States occurred in 21 resident The oocyst measures approximately 8 |im; in contrast, Cryptosporidium oocysts are physicians in a Chicago hospital in 1990 and half as large. was epidemiologically linked to a contaminat- ed water supply.5 Subsequently, more than • WHAT IS CYCLOSPORA? 1000 confirmed cases in the United States and Canada were reported to the Centers for Cyclospora is a protozoan parasite in the same Disease Control and Prevention in the sum- Acid-fast suborder as four other human pathogens: mer of 1996.1.2 staining of Cryptosporidium, Isospora, Toxoplasma, and stool Sarcocystis. Cyclospora oocysts are 8 to 10 |im • HOW IS CYCLOSPORA TRANSMITTED? samples is in diameter (almost twice the size of the gold Cryptosporidium) and are often referred to as Cyclospora oocysts are excreted unsporulated standard for "Cryptosporidium grande." Within each oocyst in the stool and require a period of time diagnosis are two sporocysts, each containing two before they become infective; therefore, sporozoites. In the past the parasite was direct transmission from an infected patient referred to as "Cyanobacterium-like bodies" to another person is unlikely. The infective (CLBs). dose necessary to cause disease in man is Cyclospora was first described as an unknown. enteric pathogen of moles in 1870; the first Cyclospora infection occurs most common- report of an infection in man (in Papua New ly via contaminated water.3>4,!3 Cyclospora, like Guinea) was published more than 100 years Cryptosporidium, is resistant to chlorination later.5 Reported cases have increased since and is not readily detected by methods that are the mid-1980s, in part because of the avail- currently used to assure the safety of drinking ability of better techniques for detecting the water. There is also epidemiologic evidence of parasite in stool and because of increasing transmission by contaminated food. In the recognition of the parasite as a cause of diar- multistate Cyclospora outbreak of 1996, rasp- rhea.4 berries grown in Guatemala were served at the events related to clusters of Cyclospora ill- • WHO IS AT RISK FOR INFECTION? ness.1'2 Further studies are underway to identify Although Cyclospora infections have been which populations are at highest risk for documented worldwide, most of our epidemi- Cyclospora infection and to delineate further ologic knowledge comes from studies in the modes of transmission of this emerging Nepal, Haiti, and Peru, where it is endem- pathogen. 300 CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 64 • NUMBER 6 JUNE 1997 Downloaded from www.ccjm.org on September 29, 2021. For personal use only. All other uses require permission. CLINICAL FEATURES OF CYCLOSPORIASIS techniques commonly used for the laboratory diagnosis of C cayetanensis infection, using the Infection by C cayetanensis can be asympto- modified acid-fast stain as the gold standard. matic, cause a self-limited diarrhea, or cause The wet-mount technique had a sensitivity of chronic diarrhea. Cyclospora has an incubation 75%, safranin O staining had a sensitivity of period of 2 to 10 days (median 7 days).4 The 30%, and auramine rhodamine staining had a diarrhea is usually watery and nonbloody, clin- sensitivity of 23%. Physicians should notify ically indistinguishable from other types of the laboratory when Cyclospora is suspected, so noninvasive or secretory infectious diarrhea. that a combination of a wet-mount study and There are often accompanying abdominal a modified acid-fast staining study will be per- cramps, and patients may report a rapid loss of formed. weight. The clinical picture may sometimes be Under modified acid-fast staining the dominated by severe fatigue and, at times, organism varies from dark red to transparent fever, anorexia, and chills.4.14 These nonspe- (FIGURE). Of note, the diagnostic yield corre- cific symptoms often lead to delay in diagnosis lates with the experience of the laboratory while the practitioner pursues other possible personnel—the false-negative rate is high in causes of fatigue. There are no specific findings laboratories where technicians are not on physical examination. A more chronic specifically trained to look for this pathogen. clinical course with biliary disease has been Methods based on the polymerase chain described in patients with HIV infection.15 reaction are being developed and have a Upper endoscopic studies of the small reported sensitivity of 62% and specificity of bowel in patients with cyclosporiasis have 100%. 16 shown erythema of the distal duodenum, and duodenal biopsies have shown a loss of brush • TREATMENT Give border and changes consistent with epithelial trimethoprim injury, blunting and severe partial atrophy of Trimethoprim-sulfamethoxazole is the only 160 mg and villi, crypt hyperplasia, and both acute and drug that has shown efficacy so far against C sulfamethox- chronic inflammation in the lamina propria.12 cayetanensis. Two prospective trials have doc- azole 800 mg umented the efficacy of this oral preparation twice daily for • DIAGNOSING CYCLOSPORIASIS (160 mg of trimethoprim and 800 mg of sul- 7 days famethoxazole twice daily for 7 days) in treat- The diagnosis of cyclosporiasis is made by ing cyclosporiasis.8'17 • direct examination of stool samples. In a study of HIV-infected patients, Pape and coworkers8 ACKNOWLEDGMENTS: We would like to thank Dr. J.W. Tomford for his clinical acumen in helping to establish the diagnosis and Dr. Molly compared the sensitivities of various staining Eaton for providing the photomicrograph. • REFERENCES 1. Colley DG. Widespread foodborne cyclosporiasis outbreaks present 11 • Hoge CW, Echeverría P, Rajah R, et al. Prevalence of Cyclospora major challenges (letter). Emerging Infectious Diseases 1996; species and other enteric pathogens among children less than 5 years 2:354-356. of age in Nepal. J Clin Microbiol 1995; 33:3058-3060. 2. Centers for Disease Control and Prevention (CDC). Update: 12. Connor BA, Shlim DR, Scholes JV, et al. Pathologic changes in the Outbreaks of Cyclospora cayetanensis infection—United States and small bowel in nine patients with diarrhea associated with a coccidian- Canada. MMWR 1996; 45:611-612. like body. Ann Intern Med 1993; 119:377-382. 3. Huang P, Weber J, Sosin DM, et al. The first reported outbreak of diar- 13. Rabold JG, Hoge CW, Shlim DR, et al. Cyclospora outbreak associated rheal illness associated with Cyclospora in the United States. Ann with chlorinated drinking water (letter). Lancet 1994; 344:1360-1361.