A 50-year-old female was referred for colonoscopy via the UK Bowel Cancer Screening Programme. Six months earlier, after travel to India, she developed lethargy, nausea, and severe bloody diarrhoea. Symptoms began two weeks after returning to the UK. She denied abdominal pain, weight loss or red-flag features. Past history included unilateral nephrectomy, no regular medications and no family history of IBD or GI malignancy.

Initial investigations included stool PCR, Clostridioides difficile testing, ova/cysts/parasites examination and blood cultures. She tested positive for Giardia lamblia and completed a 7-day course of metronidazole. Her systemic symptoms improved, but loose stools and rectal bleeding persisted. During this period, she completed the home FIT test, which was positive, prompting BCSP referral.

Colonoscopy revealed marked ulceration localised to the caecum. Biopsies were taken for histology and mycobacterial culture. Histopathology demonstrated trophozoites of Entamoeba histolytica, confirming amoebic colitis.The patient was treated with a 1-week course of paromomycin for luminal eradication, resulting in complete symptom resolution.

Amoebic colitis is uncommon in the UK but remains a significant differential diagnosis in patients with persistent gastrointestinal symptoms following travel to endemic regions. Surveillance data indicates approximately 100 laboratory-reported cases in the UK annually, the vast majority occurring in returning travellers from endemic regions¹. E. histolytica often mimics IBD or colorectal cancer, both clinically and endoscopically, with caecal involvement being most typical^2,3. Delayed or missed diagnosis is well documented, especially when co-infection with other parasites, such as Giardia, creates diagnostic anchoring bias.

Literature also emphasises that FIT positivity is not specific for neoplasia and can occur in a range of inflammatory and infectious conditions, including amoebiasis ⁴. E. histolytica associated ulceration can produce bleeding significant enough to trigger FIT positivity, leading to endoscopic identification.

Inadequate treatment is a recognised pitfall: while nitroimidazoles, such as Metronidazole, treat invasive disease, luminal agents such as paromomycin are required to prevent relapse or chronic carriage. Partial treatment, or treatment directed only at co-infecting organisms, can result in persistent symptoms and late diagnosis.

Clinicians should consider amoebic colitis in returning travellers with ongoing gastrointestinal symptoms, even when an initial pathogen has been identified. It also demonstrates how FIT-based screening may reveal non-neoplastic but clinically significant pathology. Awareness of travel-related infectious mimics is essential to avoid misdiagnosis, ensure appropriate therapy and prevent complications.