Slow clearance of measles virus RNA after acute infection

Background: Measles virus (MV) RNA was detected 1 month after hospitalization with measles in more than half of Zambian children but the duration of detectable RNA was not determined. Objectives: To characterize the time course of MV clearance and identify factors associated with presence of viral RNA at late times after clinical recovery from infection. Study design: Blood, urine and nasopharyngeal specimens from 49 Zambian children with laboratory-confirmed measles were collected a median of 100 days (range 65-118) after rash onset. Samples were assayed for MV nucleocapsid and hemagglutinin RNA by reverse transcriptase-polymerase chain reaction. Amplified products were sequenced. Selected immunologic studies were performed. Results: MV RNA was detected in at least one specimen from 18 children (37%). Eighteen percent of 44 blood mononuclear cell, 23% of 30 nasopharyngeal and 50% of 6 urine specimens were positive. Detection was not associated with HIV-1 infection, % CD4⁺ T lymphocytes, plasma interleukin-10 levels or persistent MV-specific IgM. The MV genotype was D2 and sequences of late specimens were the same as specimens collected during acute illness. Conclusions: Presence of viral RNA at multiple sites more than 3 months after acute disease suggests that clearance of MV-infected cells occurs over many months.