How do most adults acquire cytomegalovirus (CMV), and is the incidence higher among homeless individuals or people who inject drugs?

How Most Adults Acquire CMV and Incidence in Homeless/Drug-Using Populations

Among adolescents and adults, sexual transmission is the major mode of CMV acquisition, with the virus shed in semen, cervical secretions, and saliva 1. Contrary to what might be expected, people who inject drugs actually have higher rates of CMV seropositivity and are not considered a low-risk group for CMV infection 2.

Primary Transmission Routes in Adults

The evidence clearly delineates how adults acquire CMV:

• Sexual contact is the predominant route among adolescents and adults, with transmission occurring through exposure to infected semen, cervical secretions, and saliva 1, 3
• Contact with infected saliva or urine from young children, particularly for adults working in or having children in childcare facilities 2, 3
• Blood transfusion of cellular blood products from infected donors 1, 4
• Organ transplantation from CMV-positive donors 4, 5

Risk Groups and Prevalence Patterns

The guidelines specifically identify risk stratification based on behavioral factors:

Higher CMV seropositivity rates occur in:

• Individuals who have had male homosexual contact 2, 6
• People who use injection drugs 2, 6
• Those in lower socioeconomic strata (50-80% prevalence in women of childbearing age, with highest rates in lower socioeconomic groups) 1
• Adults working in childcare settings 2, 3

Lower CMV seropositivity rates occur in:

• Patients who have not had male homosexual contact AND have not used injection drugs 2, 6

Direct Answer to Your Question

Yes, incidence is higher in people who inject drugs. The guidelines explicitly state that patients who have used injection drugs have relatively high rates of CMV seropositivity and therefore can be presumed to be seropositive 2, 6. This is the opposite of low-risk groups.

While the evidence doesn't specifically address homeless populations as a distinct category, the association with lower socioeconomic status (which correlates with higher CMV prevalence) 1 and the overlap with injection drug use suggests elevated risk in this population as well.

Clinical Implications

The practical significance is that:

• HIV-infected persons who belong to groups with low CMV seropositivity (those without history of male homosexual contact or injection drug use) should be tested for CMV antibody 2
• Those with injection drug use history can generally be presumed CMV seropositive
• Prevention counseling should emphasize that latex condoms must always be used during sexual contact to reduce CMV exposure risk 2, 3
• Good hygiene practices, particularly handwashing, can diminish CMV acquisition risk 2, 3