Gastrointestinal: Beef tapeworm (Taenia saginata)

Abstract

A 50-year-old Lebanese woman living in Australia was admitted to hospital with epigastric pain and melena. She had been taking warfarin for atrial fibrillation. Upper gastrointestinal endoscopy revealed a shallow ulcer, 6 mm in diameter, at the pylorus with no evidence of recent bleeding. She also had an unusual vascular lesion, 8 mm in diameter, in the second part of the duodenum that showed active bleeding, a fresh clot and a visible vessel (Figure 1). Hemostasis was achieved by the use of adrenaline injections and electrocautery. She also received an eradication regimen for Helicobacter pylori. Four weeks later, she was readmitted to hospital with melena and anemia (hemoglobin 96 g/l). Repeat upper gastrointestinal endoscopy was normal apart from scarring in the second part of the duodenum. Colonoscopy was also normal. Capsule endoscopy revealed a long, segmented tapeworm that extended from the mid-jejunum to the mid-ileum (Figure 2). Small erosions were seen near the proximal end of the tapeworm but there was no active bleeding. Fecal microscopy revealed Taenia eggs as well as cysts and trophozoites of Entameba hartmanni and Iodameba buschlii. She was treated with praziquantel, 600 mg bd for 2 days. She recalled having eaten raw beef in Lebanon in 2002. Approximately 50 million people are thought to be infected with Taenia saginata, largely in Africa, the Middle East and some parts of Europe. Infections are rare in countries such as the United States, Canada and Australia. Human infections are acquired by eating raw or semi-raw beef that contains the larval stage (cysticercus) of the parasite. The cysticercus is an oval bladder, approximately 8 mm × 5 mm, that is filled with fluid and contains the invaginated scolex of the tapeworm. In the human, the scolex attaches to jejunal mucosa and develops into an adult tapeworm, 4-10 meters in length, after 3-4 months. The majority of people have only a single tapeworm but these parasites can survive for up to 30 years. Symptoms include abdominal discomfort and nausea as well as perianal symptoms associated with the discharge of proglottids. On fecal microscopy, it is not possible to distinguish eggs from T. saginata from those of T. solium. However, differentiation may be possible with a careful examination of fecal proglottids. Effective drugs include praziquantel (as above) and niclosamide.