Millie Long, MD, on Understanding Infection Risk in IBD
Millie D. Long, MD, MPH, FACG, presented a comprehensive review of infection risk in inflammatory bowel disease (IBD) at the 2025 Advances in IBD annual meeting, emphasizing the need for proactive prevention, medication stewardship, and early recognition of high-risk scenarios. Her session underscored that patients with IBD face elevated rates of common, serious, and opportunistic infections and that immunosuppressive therapy—particularly corticosteroids—remains a major modifiable contributor.
Dr Long is professor of medicine, vice chief of education and director of the fellowship program in the Division of Gastroenterology and Hepatology at the University of North Carolina at Chapel Hill.
She began by clarifying terminology essential for clinical decision-making. Serious infections, she noted, are those requiring hospitalization or intravenous antibiotics and “may be life-threatening, in contrast to common infections.” Opportunistic infections were defined as infections caused by organisms that pose little risk to immunocompetent individuals but become dangerous when host defenses are impaired.
Evidence from population-based cohorts demonstrates that infection risk is meaningfully higher in IBD. In a matched UK primary care cohort, 46% of patients with IBD developed a common infection compared with 37% of controls, with Crohn’s disease showing an incidence of 17.4 per 100 person-years. Viral and gastrointestinal infections were similarly increased. The presence of corticosteroids, immunomodulators, or biologics further heightened risk.
A detailed assessment of respiratory syncytial virus (RSV) outcomes highlighted how underlying IBD and recent corticosteroid exposure compound vulnerability. In a large administrative dataset, patients with IBD and RSV infection had higher hospitalization risk (adjusted odds ratio 1.30), and recent systemic corticosteroid use within 3 months raised that risk further (aOR 1.86). Dr Long emphasized that corticosteroids create a dose-dependent susceptibility due to broad immunosuppressive effects: they inhibit cytokines, chemokines, adhesion molecules, and arachidonic acid pathways. “This shotgun approach…causes a dose-dependent risk of infections,” she said. Dose, duration, age, and comorbidities all influence risk.
Anti-TNF therapy also carries documented infectious risks due to its central role in pathogen defense. Viral infections account for most incidents (40%), followed by bacterial, fungal, and parasitic infections. Tuberculosis and hepatitis B reactivation require ongoing attention. Independent risk factors include malnutrition, diabetes, older age, and use of combination therapy, Dr Long noted.
JAK inhibitors elevate risk of serious infection to approximately 3.1 per 100 person-years and show strong associations with herpes zoster and tuberculosis. Again, age ≥65 years, higher JAK inhibitor doses, diabetes, and prednisolone ≥7.5 mg increase vulnerability. In contrast, she explained, ustekinumab demonstrated low rates of serious infection—1.1 per 100 person-years in a large prospective cohort—and rare opportunistic infections.
A comparison of medication classes in a Veterans Affairs cohort of more than 14,000 patients found no significant differences in serious infection risk across classes when evaluated against anti-TNF plus thiopurine therapy. Across all therapies, age, diabetes, heart failure, COPD, prednisone use, and opioid use were key contributors to serious infection.
Preventive strategies remain essential, particularly in endemic regions where fungal or mycobacterial diseases elevate opportunistic infection risk. Vaccination provides meaningful protection: pneumococcal vaccination decreased severe disease 5-fold, with PCV-13 and PPSV-23 offering strong benefit. Prophylaxis for Pneumocystis jirovecii pneumonia (PJP) is recommended for patients on triple immunosuppression and should be considered in select patients on dual immunosuppression; TMP-SMZ reduced PJP occurrence by 91%.
Dr Long closed with two central directives: “Avoid/reduce steroids” and “Control IBD to prevent infectious complications.” For practicing gastroenterologists, the session reinforced that infection prevention begins with thoughtful medication choices, risk stratification, vaccination, and minimizing corticosteroid exposure whenever possible.
Reference
Long M. Infection in a patient with IBD. Presented at: 2025 AIBD Annual Meeting. December 8-10, 2025.
