Investigations

The diagnosis is usually clinical. If there is doubt then a rise in antibody titres, detection of viral RNA by reverse transcriptase-polymerase chain reaction (RT-PCR) techniques or viral culture from saliva, urine or CSF is diagnostic. The excretion of virus persists longer in the urine than in the saliva; it can be cultured from urine in 70% of cases.

Serum

• IgM can be detected as early 11 days after exposure
• the optimal time for detection is around 7–10 days after the development symptoms (1).

Saliva

• can use both IgM and RT-PCR tests (if salivary IgM is negative) to detect mumps in saliva
• the salivary IgM test has high specificity (98%), and its sensitivity increases from 75% in the first week after symptoms appear to 100% thereafter. (1).

Urine

• viral culture and RNA detection in urine can be done during the first 2 weeks of illness (2).

CSF

• CSF shows lymphocytosis, an elevated protein and a normal opening pressure, serum glucose ratio (< 50%) in up to a quarter of cases
• mumps RNA (up to 96% of cases) and specific antibody tests – IgG (in half of cases ) and IgM (in one third of cases) can be used to detect mumps in CSF (1).

Reference

• Senanayake S.N. Mumps: a resurgent disease with protean manifestations. MJA 2008; 189 (8): 456-459
• Gupta R.K et al. Mumps and the UK epidemic 2005. BMJ. 2005;330(7500):1132–1135