Ascaris lumbricoides has been estimated to affect up to 1.5 billion people, largely in tropical and subtropical countries. The term. âlumbricoidesâ reflects the ...
doi:10.1111/j.1440-1746.2008.05662.x
E D U C AT I O N A N D I M A G I N G
Gastrointestinal: Ascariasis
Ascaris lumbricoides has been estimated to affect up to 1.5 billion people, largely in tropical and subtropical countries. The term “lumbricoides” reflects the resemblance of adult worms to earthworms (Lumbricus sp). Infection is acquired by ingesting food, water or soil contaminated with embryonated eggs. These embryonated eggs release larvae in the duodenum that migrate through the liver and the right side of the heart into capillaries in the lungs. They then break into the alveoli, ascend the bronchial tree and return to the small intestine with swallowing of bronchial secretions. Subsequently, they develop into adult worms that survive in the intestine for 6-18 months. After mating, the females produce approximately 200 000 eggs each day. The majority of patients with ascariasis are asymptomatic. However, a minority have pulmonary symptoms during the lung phase of larval migration or gastrointestinal symptoms because of the presence of adult worms. In relation to the latter, heavy infections have been associated with abdominal pain and obstructive symptoms, sometimes with intussusception or volvulus. Worms can also enter the biliary system and provoke biliary pain, cholangitis or pancreatitis. In the patient illustrated below, ascariasis was a possible cause for gastrointestinal bleeding. The patient was a 76-year-old man from the Philippines who was investigated because of abdominal pain and melena. He was
anemic with a hemoglobin of 8.6 g/dL. Investigations including upper gastrointestinal endoscopy, colonoscopy and a computed tomography scan were normal. Small bowel enteroclysis revealed a round worm in the jejunum (Figure 1). He was treated with pyrantel pamoate (5 g) and, after 2 days, a worm was isolated from a fecal specimen (Figure 2). The worm was 20 cm in length and was identified as a female. Subsequently, his hemoglobin returned to normal. Gastrointestinal bleeding appears to be uncommon with ascariasis but might develop as a result of chemical irritation by secretions or by mechanical trauma. Adult worms do not have suckers but maintain position in the small bowel using spiral motility and bracing against the intestinal wall. The diagnosis is usually made by the identification of eggs on stool microscopy. Treatment with albendazole is an alternative to pyrantel pamoate.
Figure 1
Figure 2
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Contributed by A Suzuki, Y Yabushita, H Takahashi, M Inamori, S Nakao, K Suzuki, H Iida, H Endo, T Akiyama, T Ikeda, Y Sakamoto, K Fujita, M Yoneda, A Goto, Y Abe, H Kirikoshi, N Kobayashi, K Kubota, S Saito & A Nakajima Gastroenterology Division, Yokohama City University School of Medicine, Yokohama, Japan
Journal of Gastroenterology and Hepatology 23 (2008) 1770 © 2008 The Authors Journal compilation © 2008 Journal of Gastroenterology and Hepatology Foundation and Blackwell Publishing Asia Pty Ltd
