A 36-year-old Ethiopian man presented to the study outpatient clinic with a history of loose stools that had lasted for 1 month. He reported noticing 1-millimeter-sized white fragments in his stool on one occasion. He had lived in Ethiopia until 3 months before presenting to the clinic and regularly consumed raw beef. As a Muslim, he had no history of pork consumption. His vital signs and physical examination results were unremarkable. Two stool examinations yielded negative results for helminth eggs but revealed Giardia cysts (Figure 1), and he was treated with metronidazole (1,500 mg/day for 7 days). His symptoms initially improved but recurred several weeks later. A repeat stool examination revealed an embryonated Taenia egg (Figure 2A), and he was admitted for treatment. After laxative preparation, he was administered praziquantel (1,200 mg), followed by polyethylene glycol. Subsequently, a 2.5-meter tapeworm lacking a scolex (Figure 2B) was expelled. Histopathology revealed a gravid proglottid densely filled with eggs (Supplemental Figure 1), and a restriction fragment length polymorphism analysis of a polymerase chain reaction-amplified cox1 fragment helped identify the parasite as Taenia saginata. Three months later, the patient remained asymptomatic.
Figure 1.
Giardia spp. cyst identified in a stool sample using Kohn staining. The staining highlights the typical oval morphology and internal structures, including axonemes and nuclei, aiding in microscopic identification. (original magnification: 400×).
Figure 2.
Stool and parasite specimens of Taenia saginata (T. saginata). (A) Repeat stool examination revealed an embryonated egg containing an oncosphere (original magnification: 400×). (B) A T. saginata specimen lacking a scolex was expelled from the patient after treatment with praziquantel.
Intestinal parasitic infections are uncommon in high-income countries but remain prevalent worldwide.1 They often cause nonspecific gastrointestinal symptoms, making accurate diagnosis difficult. Because a single stool examination may fail to result in the identification of pathogens, performing at least three stool examinations is recommended.2 Mixed infections have also been reported,3 indicating that gastrointestinal symptoms may involve multiple pathogens.
In the present case, repeated stool examination led to the diagnosis of a giardiasis and taeniasis coinfection, highlighting the importance of repeated testing when parasitic infection is suspected.
Supplemental Materials
ACKNOWLEDGMENTS
The authors gratefully acknowledge the invaluable assistance provided by the Departments of Pathology and Laboratory Medicine at Tokyo Metropolitan Toshima Hospital in the diagnostic workup of this case. They also wish to express appreciation to Dr. Yasuyuki Morishima of the Department of Parasitology, National Institute of Infectious Diseases, Japan Institute for Health Security, for conducting the polymerase chain reaction analysis that enabled definitive identification of the parasite.
Note: Supplemental materials appear at www.ajtmh.org.
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