Purpose:Trichuris trichiura is the third most common roundworm worldwide, with more than one fourth of the world's population carrying this parasite. The diagnosis is made primarily by stool examination for eggs. Colonoscopic diagnosis is rare, with less than 20 cases reported in the literature.
Case: A 73 year Nepalese male presented to the outpatient endoscopy unit for evaluation of nonspecific generalized abdominal pain and normocytic anemia. He had no associated nausea, vomiting, weight loss or change in bowel pattern. The patient had immigrated to the United States about one year earlier. His laboratory data was significant for normocytic anemia without eosinophilia. Upper endoscopy revealed chronic gastritis but was otherwise unremarkable. Colonoscopy revealed a solitary worm, found in the cecum, with ova characteristic of Trichuris trichiura. The patient was treated with albendazole 400mg daily for three days. Follow-up two months after treatment revealed improvement in symptoms.
Discussion:Trichuris trichiura affects more than 800 million people worldwide. The majority of cases in the United States are found within the immigrant population. The mode of transmission is primarily fecal-oral or accidental ingestion of eggs, which are usually found on dry goods such as beans, rice or grains. Upon ingestion of eggs, larvae hatch and develop in the small intestine and then migrate into the right colon. Adult worms live in the cecum and ascending colon. The anterior portion of the adult worm embeds in the mucosa, whilst the posterior portion hangs in the lumen and mates with neighboring worms. It takes approximately 60 days for a gravid female worm to shed eggs. Female worms in the cecum shed between 3,000 and 20,000 eggs per day. The lifespan of adult worms is between 1-3 years. Diagnosis is primarily by stool examination; however it is important to note that stool analysis can be negative if examined within 2-3 months of acquiring infection. Clinical presentations can include non-specific abdominal pain, colonic obstruction, perforation, gastrointestinal hemorrhage or rectal prolapse, with laboratory findings of anemia or eosinophilia. Patients with light infestation can be asymptomatic. Colonoscopic findings of worms in the right colon (cecum and ascending colon) generally reflect a light burden, while worms found in the left colon (descending, sigmoid colon and rectum) reflect heavy burden. Irrespective of infection burden, treatment is recommended. The treatment options are albendazole 400mg once daily for 3 days, or mebendazole 100mg twice daily for 3 days.