What are the risk factors for cytomegalovirus infection?

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Last updated: February 26, 2026 • View editorial policy

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Risk Factors for Cytomegalovirus Infection

CMV infection risk is primarily determined by recipient serostatus, donor serostatus, degree of immunosuppression, and exposure to young children or bodily fluids in specific populations.

General Population Risk Factors

Transmission Routes and High-Risk Exposures

  • Direct contact with bodily fluids (saliva, urine, semen, cervical secretions, breast milk) from infected individuals is the primary transmission mechanism 1
  • Young children aged 1-2 years represent the highest transmission risk, with peak shedding prevalence at this age 2
  • Childcare workers have 3.4 times higher risk of primary CMV infection compared to controls, with pooled seroprevalence of 59.3% 3
  • Healthcare workers show no significantly increased risk compared to controls (RR 1.3, not statistically significant) 3
  • Having one or more children at home significantly increases CMV seropositivity risk in both childcare and healthcare workers 3
  • Sexual transmission occurs through contact with infected semen or cervical secretions, particularly among sexually active individuals 1

Pregnancy-Specific Risk Factors

  • Primary CMV infection during pregnancy carries 30-40% fetal transmission risk 1
  • Recurrent infection or reactivation during pregnancy has lower transmission risk (0.15-1.0%) 1
  • HIV-infected pregnant women have 90% CMV coinfection rate with higher cervical shedding (52-59% vs 14-35% in HIV-negative women) 1
  • Lower socioeconomic status correlates with higher CMV prevalence (50-80% overall in women of childbearing age) 1

Transplant Recipients: Major Risk Factors

Stem Cell Transplantation

Three major risk factors for CMV reactivation and disease post-allogeneic stem cell transplant (SCT) are 1, 4:

  1. CMV-seronegative donor with CMV-seropositive recipient (D-/R+): Highest risk category with 45-86% reactivation risk and 20-30% CMV disease risk without prevention 1
  2. Acute or chronic graft-versus-host disease (GVHD): Particularly chronic GVHD requiring prolonged immunosuppression 1, 4
  3. Unrelated or HLA-mismatched donor transplants: Increases immunological disparity and infection risk 1, 4

Additional Transplant-Related Risk Factors

  • T-cell depletion (ex vivo or in vivo with antithymocyte globulin) significantly increases risk 1
  • Intensive glucocorticoid therapy or systemic steroid administration accounts for over one-third of CMV infections post-transplant 1, 5
  • Umbilical cord blood grafts have highest cumulative incidence at 65% with longest treatment duration (median 36 days) 5
  • Peripheral blood stem cell grafts have lowest incidence at 26% with shortest treatment duration (median 21 days) 5
  • CMV-seropositive donor carries 20-40% transmission risk 1

Kidney Transplant Risk Factors

  • Older recipient age independently increases CMV infection risk 6
  • Deceased donor transplant versus living donor 6
  • Rituximab administration for desensitization 6
  • Anti-thymocyte globulin use 6
  • Immunologically incompatible transplantation (ABO or HLA incompatible) increases risk in context of intensified immunosuppression 6

HIV-Infected Population

  • HIV-infected children have higher CMV acquisition rates during first 12 months of life and through age 4 years compared to HIV-uninfected children 1
  • Symptomatic HIV-infected children with CMV coinfection have up to 60% CMV shedding rate (versus <15% in non-HIV-exposed infants) 1
  • CD4+ T-lymphocyte count <200 cells/mm³ increases susceptibility to CMV disease 1
  • CMV causes 8-10% of pediatric AIDS-defining illness with 9% prevalence of symptomatic CMV disease 1

Inflammatory Bowel Disease Patients

  • Purine analogues are an independent risk factor for CMV reactivation 1
  • Moderate to severe active IBD requiring hospitalization increases risk 1
  • Steroid-refractory disease correlates with 10-30% CMV presence 1
  • Use of biologics increases C. difficile risk, which may complicate CMV detection 1

Timing Considerations

  • Early reactivation (first 100 days post-SCT) occurs mainly in patients without CMV prophylaxis 1, 4
  • Late reactivation (beyond 100 days) occurs in patients who completed prophylaxis or were on preemptive therapy, particularly with chronic GVHD or prolonged immunosuppression 1
  • First 6 months post-SCT represents highest morbidity risk period 1

Protective Factors

  • Mammalian target of rapamycin (mTOR) inhibitor use in kidney transplant recipients is protective against CMV infection 6
  • CMV-seronegative recipient with CMV-seronegative donor (D-/R-) has lowest risk when receiving CMV-negative or leukocyte-reduced blood products 1, 7

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

7
Guideline

Measures to Reduce Nosocomial CMV Transmission

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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