Real-time PCR for mumps diagnosis on clinical specimens--comparison with results of conventional methods of virus detection and nested PCR.
Since November 2003, the UK has seen a dramatic rise in the number of mumps cases, resulting in increasing demands on virology laboratories to confirm mumps infection in a timely and efficient manner. Traditional mumps virus detection methods are often insensitive, lengthy, and cumbersome. Some laboratories in the UK now use molecular methods that are based on nested polymerase chain reaction (PCR). Early serological diagnosis often relies on detection of anti-mumps IgM, which may be absent in the first 10 days of illness. We compared a one-step real-time RT-PCR with an established nested PCR (SH-PCR) and virus detection by culture and antigen detection, and assessed the clinical usefulness of mumps real-time PCR for diagnosis from CSF. In total, 280 clinical samples were investigated by real-time PCR, nested PCR and a combination of traditional virus detection methods (antigen detection on oral samples, cell culture on all samples). Furthermore, 88 CSF samples submitted for diagnosis of possible viral meningitis were analysed by real-time PCR. The real-time PCR detected the highest number of positive oral samples (119/180) compared to SH-PCR (92/180) and combined virus culture and antigen detection procedures (90/180). Sensitivity of mumps virus detection in urine was poor for all three methods: 34.0% (traditional detection), 29.8% (real-time PCR) and 2.1% (SH-PCR), respectively. Real-time PCR on 88 CSF samples identified five patients with mumps meningitis, significantly increasing viral diagnosis in this cohort. Real-time PCR on oral samples is the investigation of choice for mumps infection. Mumps virus detection in urine by any of the PCRs used was clearly less successful. Real-time PCR on CSF samples seems a promising adjunct for diagnosis of mumps meningitis, especially in an age group with high incidence of mumps.