The correct answer is Schistosoma haematobium infection. Congratulations to Kornilia Nikaki from Bristol and Christos Tzivinikos from London for getting the correct answer.
At colonoscopy, patchy cobblestone mucosal inflammation was seen in the rectum with no further mucosal abnormalities found at the terminal ileum and remaining parts of the colon. Histopathology demonstrated moderate chronic inflammation of the rectum and schistosome ova infiltration in the lamina propria . Travel history revealed that the patient swam in a fresh water lake in Brazil 6 months before presentation. On Ziehl–Neelson staining, the ova were demonstrated not to be acid fast, hence suggesting infection with S haematobium being the most likely causative organism. In the acute phase of infection, ova can be visualized on urine microscopy. In resource-poor settings, this is a fast, inexpensive way of diagnosis. Serologic tests are also available in cases of difficult microscopic detection. The treatment is an anti-helmintic. This patient has responded well to treatment.
More details and resources for further reading
Infection with S haematobia occurs through fresh water contact, typically leading to hematuria, which is caused by granulomatous reactions in the bladder wall, secondary to egg release from female worms residing in the pelvic veins and vesicle plexus. Hundreds to thousands of eggs can be released per day, which contain ciliated miracidia that secrete proteolytic enzymes for migration into mucosal surfaces. The eggs can locally parasitize genital organs, including the seminal vesicles. However, pathologic intestinal involvement is not a typical feature of S haematobium; it is more commonly associated with other species of schistosomiasis, such as S mansoni. Nevertheless, to a lesser extent, distant spread can occur when ova of S haematobia are carried from its usual site into the inferior mesenteric veins and subsequently invade the appendix, colon, and rectum. Rectal involvement in S haematobium can be a common finding in endemic areas and may be utilized as a diagnostic site, where rectal biopsies compared with urinary cytology have been demonstrated to be more sensitive in chronic infections.
- Gryseels, B., Polman, K., Clerinx, J. et al. Human schistosomiasis. Lancet. 2006; 368: 1106–1118
- Badran, A., El-Alfi, O., Pfischner, W.C. et al. The value of routine rectal biopsy in the diagnosis of schistosomiasis. Am J Trop Med Hyg. 1955; 4: 1068–1071