Identification of Cyclospora and Isospora from Diarrheic Patients in the Philippines


Corazon C. Buerano1,2, Catherine B. Lago1, Ronald R. Matias1,
Blanquita B. de Guzman1, Shinji Izumiyama3, Kenji Yagita3, and
Filipinas F. Natividad1*

1Research and Biotechnology Division, St. Luke’s Medical Center
279 E. Rodriguez Sr. Ave., Quezon City 1102, Philippines
2Institute of Biology, University of the Philippines
Diliman, Quezon City 1101, Philippines
3Department of Parasitology, National Institute of Infectious Diseases
Toyama 1-23-1, Shinjuku-ku, Tokyo 162-8640, Japan

*corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.



In recent years, Cyclospora cayetanensis and Isospora belli have been recognized as causative organisms in cases of chronic diarrhea. The aim of this study was undertaken to determine the prevalence of enteric protozoa among diarrhea patients in the Philippines. Stools were collected and from 3456 samples examined, only one sample each was found positive for oocysts of Cyclospora cayetanensis and Isospora belli. Identification was based on autofluorescence of the oocysts with a 365 nm ultraviolet excitation filter. Both samples were obtained from male patients (18 and 73 years old, respectively) living in Iloilo province in the western islands of Visayas, Philippines. Both patients obtained their drinking water from deep wells. The identification of these two emerging pathogens, which are easily overlooked by less-trained technical staff, highlights the increasing awareness and technical capability on detecting these parasites in the Philippines.


Both Cyclospora and Isospora belongs to family Eimeridae, subphylum apicomplexa, which are closely related to cryptosporidium. Like the latter, both are implicated as etiologic agents of diarrhea in immunocompromised persons, particularly patients with acquired immune deficiency syndrome (AIDS). Cyclospora, first observed in humans in Papua New Guinea (Ashford 1979), has been isolated from humans worldwide since 1985 with increasing frequency (Marshall et al. 1997). Isospora belli was first described in 1915 (Marshall et al. 1997) and is the only species of Isospora known to infect humans. It has been reported in tropical areas of south America and southeast Asia (Wittner et al. 1993), and has also been associated with diarrhea outbreaks in mental wards and day care centers (Marshall et al. 1997).





ASHFORD RW 1979. Occurrence of an undescribed coccidian in man in Papua New Guinea. Ann Trop Med Parasitol 73: 497-500.

FAUST E, GIRALDO L, CACIEDO G, BONFANTE R. 1961. Human isosporiasis in the western hemisphere. Am J Trop Med Hyg 10: 343-49.

JUECO NL, DE LEON WU, FERNANDEZ EO. 1984. Parasitic infections diagnosed in the Department of Parasitology for the period 1978 to 1983. Acta Med Philipp 20 (4): 134-137.

MARKELL EK, MULLINGER PE, SCHNEIDER DJ. 1947. Intestinal parasitic infections in naval personnel. Am J Trop Med 27: 63-65.

MARSHALL MM, NAUMOVITZ D, ORTEGA Y, STERLING CR. 1997. Waterborne protozoan pathogens. Clin Microbiol Rev 10: 67-85.

OHNISHI K, KATO Y, ISEKI M. 2002. An imported case of cyclosporiasis in Japan. Kansen shogaku Zasshi 76: 118-120.

WITTNER M, TANOWITZ HB, WEISS LM. 1993. Parasitic infections in AIDS patients. Cryptosporidiosis, isosporiasis, microsporidiosis, cyclosporiasis. Infect Dis Clin North Am 7: 569-586.