A herpes virus.
Everyone gets CMV, around half of Americans are seropositive. Well that's not everyone, but more than who vote for the President. There are race and age differences that put some groups more at risk:
"For example, of the ∼45% of non-Hispanic black women who are CMV seronegative during their teen years, nearly all (∼8 of 9) seroconvert by the time they are in their 30s. Approximately one-half of CMV-seronegative Mexican American women and one-fourth of CMV-seronegative non-Hispanic white women also seroconvert during the same period. This means that many women are at risk of experiencing a primary CMV infection during pregnancy (PubMed)."
In immunoincompetent patients, such as transplant patients and HIV, acute disease or reactivation can cause severe organ disease of virtually any organ.
Patients on temozolomide, an oral alkylating agent for glioblastoma multiforme and refractory anaplastic astrocytoma, can get CMV and Pneumocystis infections.
Dasatinib use is also a risk (a second-generation tyrosine kinase inhibitor) (PubMed).
Acute monospot negative "mono": fever, sore throat, tranaminitis, pancytopenia but tends to have fewer atypical lymphocytes and less adenopathy than EBV; there also tends to be no exudative pharyngitis.
Reinfection is possible with different strains and can lead to transmission during pregnancy (PubMed).
Retinitis, esophagitis/gastritis/colitis (in normal people (PubMed), neuritis are the important ones especially in HIV (CD4 <100 as a rule, but can be symptomatic with immune reconstitution syndrome) and pneumonia in transplant, especially bone marrow transplant, patients.
Quantitative PCR is the most helpful test on transplant patients to help make the diagnosis.
Colitis may be more common in normal people than what we suspect and prompt treatment may be helpful (PubMed).
Reactivation in the ICU is associated with increased death and length of hospitalization (PubMed). And not all studies demonstrate increased mortality and morbidity (PubMed). A nice systemic review. But. The one prophylaxis study shows INCREASED mortality in the treatment arm (PubMed).
And perhaps dementia (PubMed).
Prevention: tends to be protocol driven in transplant patients; given the superior bioavailability, valganciclovir should be used and longer is better than shorter (PubMed). It also prevents disease in HIV with CD4 under 100, but at the cost of neutropenia, prevention in this group is probably superseded by the effectiveness of HAART in preventing CMV.
For prophylaxis in allogeneic hematopoietic stem cell transplant patients there is also letermovir
Invasive disease is made on a basis of combination of histopathology, quantitative PCR, and, in the case of CNS disease in HIV, positive PCR in CSF.
CMV disease is a major reason for loss of transplant organs.
Secondary prophylaxis in solid organ transplants has benefit only as long as patients are on medication (PubMed).