Cytomegalovirus Infection (CMV)

CMV-negative blood is the decision you actually own - Transfusion and transplanted organs transmit CMV. Centers reserve CMV-negative units for infants and immunocompromised recipients, and some maintain dedicated CMV-negative donor lists. Confirm the recipient's serostatus and what your blood bank is issuing before the case, not while the patient is bleeding.

Serostatus drives the transplant risk - Pre-transplant serology exists to risk-stratify donor-recipient pairs. A CMV-negative recipient of a CMV-positive organ gets valganciclovir or ganciclovir prophylaxis with serological monitoring, and knowing where your patient sits tells you how likely active disease is.

Check the counts before you dose - Myelosuppression is the principal side effect of ganciclovir and valganciclovir, so a recent CBC is the number you want. Anemia and thrombocytopenia also come from the infection itself. Review it alongside liver function tests, which CMV commonly disturbs.

Pneumonitis is the worst outcome - CMV pneumonia after marrow transplant carries high mortality when treatment is delayed, and patients who progress to needing ventilation do very badly. In a marrow transplant patient with new hypoxia this belongs on the differential, and their pulmonary reserve is not what their age suggests.

Colitis brings volume loss and blood loss - The colon is the most common gastrointestinal site, presenting with diarrhea, hematochezia, abdominal pain, fever, and weight loss. Expect a dry, anemic patient, and check a hemoglobin and basic metabolic panel rather than assuming.

Steroid-refractory colitis may be CMV - Reactivation is frequent in severe or corticosteroid-resistant ulcerative colitis, running 20% to 40% in that group. It matters when the plan is an urgent colectomy and everyone is calling it inflammatory bowel disease.

It is not only the obviously immunosuppressed - Recent ICU admission, hemodialysis, and exposure to antibiotics, antacids, corticosteroids, or red cell transfusion within the preceding month are all associated with CMV colitis in otherwise immunocompetent patients.

Relapse is the rule in transplant - Recurrence is common, and ganciclovir resistance is well described in transplant recipients who fail to respond to therapeutic doses or decline on therapy.

Cytomegalovirus (CMV) is human herpesvirus-5, a member of the Herpesviridae family. It spreads through blood products and transplanted organs, breastfeeding, close-contact shedding, perinatal transmission, and sexual contact. Roughly 70% of adults carry it latently, approaching 100% in poorer communities. Like the rest of its family it never clears: infection is followed by lifelong latency with intermittent reactivation.

In an immunocompetent host that reactivation is usually silent, or produces a mononucleosis-like illness without the pharyngeal exudate or heterophile antibodies of Epstein-Barr virus. What matters is what happens when T-cell control fails. In HIV with a CD4 count under 100/mm3, in solid organ transplant, and after bone marrow transplant, CMV becomes an aggressive opportunistic pathogen producing end-organ disease: pneumonitis, colitis, esophagitis, hepatitis, and retinitis.