Which statement is true regarding laboratory testing for mumps?

• A. RT-PCR is recommended as the primary diagnostic test
• B. Serology is necessary for confirmation of a suspected clinical case
• C. IgM tests for mumps are highly specific
• D. An acute infection must be confirmed by a four-fold rise in IgG titer

Answer: (A)

Detecting the virus itself with a nucleic acid test is the most reliable way to confirm an active mumps infection. RT-PCR on specimens like a buccal or throat swab (or saliva) directly identifies mumps virus RNA and is highly sensitive during the early phase when the virus is shed, making it the preferred diagnostic approach for acute illness. Serology isn’t the best first-line tool because IgM responses can be delayed, absent in some vaccinated or partially immune individuals, or cross-react with related viruses, leading to false positives or negatives. Asking for a fourfold rise in IgG requires paired samples collected weeks apart, which isn’t practical for diagnosing an acute case or guiding immediate public health actions. So, RT-PCR is the most appropriate primary diagnostic test for suspected mumps.