Infectious diseases affecting the small bowel - what not to miss.

PURPOSE OF REVIEW: This review summarizes infectious diseases involving the small bowel (SB) with a focus on recent literature related to diagnosis and pathophysiology. RECENT FINDINGS: Typical symptom for SB infections is diarrhea, mostly self-limiting. Pathogens include bacteria, viruses, fungi, protozoan parasites, and helminths. Host-pathogen interaction is of special interest in infections with potentially severe or prolonged course. Research uses increasingly enterocyte cell culture systems. SARS-CoV2 can also infect enterocytes via angiotensin converting enzyme 2 (ACE2) receptor and causes gastrointestinal complaints in some patients. Chronic SB infections as tuberculosis, Cytomegalovirus, or Epstein-Barr virus have to be differentiated from Crohn's and other diseases. Severe rare fungal and protozoan parasitic infections can cause relevant morbidity in immunocompromised patients. Soil-transmitted helminthic infections are a special issue in endemic areas. SUMMARY: Many infections involve the SB, typically causing mild and self-limiting diarrhea. Symptomatic therapy, hygiene, and isolation are the mainstay of management. However, some patients develop severe or chronic disease. Immunosuppression is a major cause for severe, but also for rare opportunistic systemic infections that can also affect the SB.