Buccal/throat swabs. Massage the parotid (salivary) glands for 30 seconds. Swab the buccal cavity, which is the space near the upper rear molars between the cheek and teeth; Stensen's duct drains into this space. Immediately place the swab into a tube of viral transport medium (VTM). Urine and blood specimens should also be routinely collected and submitted for testing to enhance the likelihood of detecting mumps virus RNA by real-time PCR. For suspected mumps cases complicated by meningitis or encephalitis, a CSF sample should be submitted along with the other sample types mentioned above.
Keep specimen at 4C
Labile. It is recommended that all specimens for molecular testing be stored at 4C immediately after collection and then promptly sent to the laboratory for appropriate processing and storage for testing. This is critical to ensure the stability and amplification of nucleic acids, particularly for the detection of RNA viruses since RNA is unstable and easily degraded by RNAses from the surrounding environment.
For delays of more than 24-48 hours (e.g., when shipping specimens from an outside facility), specimens should be processed as needed and rapidly frozen to -70C and then transported to the laboratory on dry ice.
Specimens for molecular testing should not be stored at room temperature or frozen at -20C. Swab specimens not received in viral transport medium or received in bacteriological transport medium are discouraged. DO NOT USE CALCIUM ALGINATE OR WOODEN SHAFT SWABS FOR COLLECTION OF SPECIMENS; ONLY USE DACRON OR RAYON TIPPED SWABS ON PLASTIC OR METAL SHAFTS.
Specimens should be transported to the laboratory as quickly as possible after collection. When immediate transport is not possible, refrigerate the specimens or keep them on wet ice.
Amplification and detection of mumps virus RNA using real-time TaqMan PCR and nucleic acid primer/probe pairs specific for conserved regions of the mumps virus genome. This test is performed pursuant to an agreement with Roche Molecular Systems, Inc.
Following an incubation period of 14-18 days, mumps begins with a nonspecific prodrome of low-grade fever, headache, respiratory symptoms, malaise, and myalgia. Most common feature is swelling of salivary glands in 30-40%, particularly the parotid glands. Swelling is usually bilateral; unilateral in 25% of cases. Severe illness with complications more likely in adults. The virus is transmitted from person to person through respiratory secretions and is quite contagious. Greatest communicability is 1-2 days before to 5 days after onset of parotid gland swelling. Illness lasts a week to 10 days. Complications include orchitis in 20-30% of infected postpubescent males, oophoritis and mastitis in 5% of postpubertal females; sterility and impaired fertility are uncommon. Mumps can also be complicated by meningitis and encephalitis.
Clinical diagnosis of mumps is unreliable; requires laboratory confirmation. Although once a common disease in children, fewer physicians now recognize the clinical features of mumps. Also, many viruses, including parainfluenza virus, enteroviruses, EBV, CMV, HIV, and influenza virus, can cause acute parotitis. Mumps virus PCR is most useful in detecting mumps virus RNA from buccal/throat swabs, urine, blood, and CSF (for meningitis/encephalitis) specimens to diagnose acute disease in unvaccinated or previously vaccinated individuals. Outbreaks of mumps still occur in the United States despite high coverage rates with vaccine. The disease is normally imported from abroad or associated with importation from other countries and outbreaks arise in people who have not been immunized and as a result of two-dose vaccine failure. Therefore, both unvaccinated and vaccinated persons are at risk for acquiring mumps themselves and transmitting the virus to others. Living in closed communities in crowded conditions is a contributing factor in the spread of the virus.
Detection of mumps virus RNA by PCR, mumps virus antigens by immunofluorescence, or growth of mumps virus in culture is diagnostic evidence for acute or very recent infection in a person with a suspected mumps illness. Confirmation of mumps virus infection by IgG- or IgM-based serology is confounded by cross-reactivity with related viruses such as the parainfluenza viruses. Also, IgM responses in previously vaccinated persons are highly variable and may be negative in up to 50-60%. It also may not be possible to demonstrate a 4-fold rise in mumps-specific IgG between paired sera in cases with a history of 1 or 2 doses of mumps vaccine.
Negative or no mumps virus RNA detected
The laboratory diagnosis of mumps virus can be made by isolation of the virus in cell culture, observing a significant rise in mumps-specific IgG antibody between acute- and convalescent-phase sera collected at least two weeks apart, finding mumps-specific IgM antibody in a single acute-phase serum collected within 5-10 days of disease onset, direct detection of mumps antigen by immunofluorescence antibody staining of respiratory cells, or by amplification of mumps virus RNA by PCR of clinical specimens. PCR is rapid and the most sensitive method and is the preferred test in the Clinical Virology Laboratory for diagnosis of acute mumps illness.