Crohn's disease is a chronic inflammatory condition that affects the gastrointestinal tract. It can cause lesions from mouth to anus and may result in extraintestinal complications. The prevalence of Crohn's disease is increasing in adults and children. Genetic predispositions to Crohn's disease have been identified, and specific environmental factors have been associated with its development. Common presenting symptoms include diarrhea, abdominal pain, rectal bleeding, fever, weight loss, and fatigue. Physical examination should identify unstable patients requiring immediate care, include an anorectal examination, and look for extraintestinal complications. Initial laboratory evaluation identifies inflammation and screens for alternative diagnoses. Measurement of fecal calprotectin has value to rule out disease in adults and children. Endoscopy and cross-sectional imaging are used to confirm the diagnosis and determine the extent of disease. Treatment decisions are guided by disease severity and risk of poor outcomes. Patients commonly receive corticosteroids to treat symptom flare-ups. Patients with higher-risk disease are given biologics, with or without immunomodulators, to induce and maintain remission. For children, enteral nutrition is an option for induction therapy. All patients with Crohn's disease should be counseled on smoking avoidance or cessation. Patients with Crohn's disease are at increased risk of cancer, osteoporosis, anemia, nutritional deficiencies, depression, infection, and thrombotic events. Maximizing prevention measures is essential in caring for these patients.

Chlamydia trachomatis is frequently detected in anorectal specimens from men and women. A recent hypothesis suggests that C. trachomatis is a natural commensal organism asymptomatically colonizing the gastrointestinal tract. In this study, we investigated the presence of chlamydial DNA and antigen in intestinal biopsy samples taken during colonoscopy. Cases (n = 32) were patients whose histopathology reports included the term 'chlamydia', suggesting a possible history of infection. Control patients (n = 234) did not have chlamydia mentioned in their histopathology report and all tested negative for Chlamydiaceae DNA by 23S ribosomal RNA-based real-time PCR. Amongst the cases, C. trachomatis DNA was detected in the appendix and colon of two female and one male patients. Chlamydia abortus DNA was present in the colon of a fourth female patient. Thus, chlamydial DNA could be demonstrated in intestinal biopsy samples proximal to the anorectal site and inclusions were identified in rectum or appendix of two of these patients by immunohistochemistry. However, the findings in two cases were compatible with sexually acquired C. trachomatis. The identification of C. trachomatis DNA/antigen does not prove the presence of active infection with replicating bacteria. Larger prospective studies on fresh tissue samples are required to confirm the data obtained in this study.

In the last years, there was a rising in the incidence of sexually transmitted infections, including proctitis. Infectious proctitis (IP), mainly caused by agents like Neisseria gonorrhea and Chlamydia trachomatis, is an entity that should be considered when patients with suspected inflammatory bowel disease (IBD) are approached, mainly if they have risk factors such as anal intercourse.

Rectal ulcerations are an uncommon presentation of a primary syphilis infection. Anorectal syphilis is difficult to diagnose because of its often asymptomatic or atypical clinical presentation. It is important to consider sexually transmitted diseases (STD) in all patients presenting with rectal symptoms. A history of anal sexual intercourse should be made, especially in men having sex with men (MSM). Moreover, the possibility of a primary syphilis infection of the rectum should be considered. Endoscopic findings might be diverse, whereas a typical chancre can present as an anorectal ulcer associated with regional lymphadenopathy. It is important to consider other causes of anorectal ulcers, like other STD, inflammatory bowel disease (IBD) or even malignant causes. The diagnosis of anorectal syphilis is based on the combination of the clinical presentation, serology tests, endoscopic findings and biopsies. The cornerstone of the treatment is based on an intramuscularly administration of a long-acting preparation of penicillin (benzathine penicillin G).

Zika virus (ZIKV) has elicited global concern due to its unique biological features, unusual transmission routes, and unexpected clinical outcomes. Although ZIKV transmission through anal intercourse has been reported in humans, it remains unclear if ZIKV is detectable in the stool, if it can infect the host through the anal canal mucosa, and what the pathogenesis of such a route of infection might be in the mouse model. Herein, we demonstrate that ZIKV RNA can be recovered from stools in multiple mouse models, as well as from the stool of a ZIKV patient. Remarkably, intra-anal (i.a.) inoculation with ZIKV leads to efficient infection in both Ifnar1-/- and immunocompetent mice, characterized by extensive viral replication in the blood and multiple organs, including the brain, small intestine, testes, and rectum, as well as robust humoral and innate immune responses. Moreover, i.a. inoculation of ZIKV in pregnant mice resulted in transplacental infection and delayed fetal development. Overall, our results identify the anorectal mucosa as a potential site of ZIKV infection in mice, reveal the associated pathogenesis of i.a. infection, and highlight the complexity of ZIKV transmission through anal intercourse.