Mumps virus IgG

Laboratory confirmation of mumps in previously vaccinated or previously infected individuals is challenging, and failure to detect mumps IgM in previously vaccinated persons has been well documented.People with a history of mumps vaccination may not have detectable mumps IgM antibody regardless of timing of specimen collection.The ability to detect IgM varies by vaccination status and is highest in unvaccinated persons (80%–100%) (Sakata et al. 1985, Rota et al, 2016), intermediate in one-dose vaccine recipients (60%–80%) (Briss et al. 1994; Narita et al. 1998), and lowest in two-dose vaccine recipients (13%–14%) (Bitsko et al. 2008; Rota et al. 2009).

Mumps exposure history	IgM	IgG	Comments	References
Unvaccinated; no history of mumps	+ or −	IgM may be detected for weeks to months, 80 – 100% of serum samples IgM positive; low levels of IgG may be present at symptom onset.	Meurman et al. 1982; Sakata et al. 1985, Rota et al. 2016
1–dose vaccine history	+ or −	Likely +	Approximately 50% of serum samples collected 1–10 days after symptom onset were IgM-positive; 50%–80% of serum samples collected >10 days after symptom onset were IgM-positive	Narita et al. 1998; Jin et al. 2004; Krause et al. 2007, Rota et al. 2016
2–dose vaccine history	13%–46% of serum samples collected less than 3 days after symptom onset were IgM-positive. 71% of serum samples collected >3 days were IgM positive.	Bitsko et al. 2008; Rota et al. 2009

Q: What type of serologic assay is recommended for mumps IgM testing?

A: Both EIA and IFA assays can perform well for diagnosis of primary mumps infection. Acute-phase mumps specimens may contain significant levels of mumps IgG, especially among persons with a history of 1 or 2 doses of MMR. The IFA format is particularly susceptible to interference by high levels of mumps IgG. Treatment of serum with an agent to remove human IgG antibody, such as Gullsorb or a similar IgG inactivation reagent, is necessary to avoid false-positive IgM test results.