Slow clearance of measles virus RNA after acute infection

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.

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.

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.

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.

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.