Cytomegalovirus (CMV) infection occurs frequently in young children, who are then a major source of transmission. Oral CMV shedding by 14 infants with primary infection was comprehensively characterized using quantitative PCR weekly for >9 months. Three phases of oral shedding were identified: expansion, transition, and clearance. Viral expansion occurred over a median of 7 weeks, with a median doubling time of 3 days. During the transition phase, expansion slowed over a median of 6 weeks before reaching peak viral load. Clearance was slow (22-day median half-life) and shedding did not resolve during observation for any infant. Mathematical modeling demonstrated that prolonged oral CMV expansion is explained by a low within-host reproduction number (median 1.63) and a delayed immune response that only decreases the infected cell half-life by 44%. Thus, the prolonged oral CMV shedding observed during primary infection can be explained by slow viral expansion and inefficient immunologic control.
Dynamics of persistent oral cytomegalovirus shedding during primary infection in Ugandan infants.