22889 Mumps Virus Antibody, IgG and IgM, (MMPGM)

Serum specimens obtained during the acute phase of infection or soon after vaccination may be negative for IgM- or IgG-class antibodies by serological tests.

All positive IgM results must be interpreted cautiously as some false-positive results or heterotypical responses of the IgM have been seen in the serum of pregnant women or in patients with an acute infection caused by cytomegalovirus, herpes simplex virus, measles, rubella, or parvovirus. 

Testing for IgM-class antibodies to mumps virus should be limited to patients with a clinically compatible disease.

Mumps virus shares antigenic relationships with other viruses of the paramyxovirus group; therefore serologic cross-reactions are possible, but uncommon with this test procedure.

IgG-class antibodies to mumps virus may be present in serum specimens from individuals who have received blood products within the past several months, but have not been immunized or experienced past infection with this virus.

​​The mumps virus is a member of the Paramyxoviridae family of viruses, which include parainfluenza virus serotypes 1-4, measles, respiratory syncytial virus, and metapneumovirus. Mumps is highly infectious among unvaccinated individuals and is typically transmitted through inhalation of infected respiratory droplets or secretions. Following an approximate 2-week incubation period, symptom onset is typically acute with a prodrome of low-grade fever, headache, and malaise. Painful enlargement of the salivary glands, the hallmark of mumps, occurs in approximately 60% to 70% of infections and in 95% of patients with symptoms. Testicular pain (orchitis) occurs in approximately 15% to 30% of postpubertal men and abdominal pain (oophoritis) is found in 5% of postpubertal women. Other complications include mumps-associated pancreatitis (<5% of cases) and central nervous system disease (meningitis <10% and encephalitis <1%).​

Widespread routine immunization of infants with attenuated mumps virus has dramatically decreased the number of reported mumps cases in the United States. However, outbreaks continue to occur, indicating persistence of the virus in the general population.

Laboratory diagnosis of mumps is typically accomplished by detection of IgM- and IgG-class antibodies to the mumps virus. However, due to the widespread mumps vaccination program, in clinically suspected cases of acute mumps infection, serologic testing should be supplemented with virus isolation in culture or detection of viral nucleic acid by polymerase chain reaction testing in throat, saliva, or urine specimens.

IgM:

Negative: Index value 0.00-0.79

Reference values apply to all ages.

IgG:

Vaccinated: Positive (> or =1.1 AI)

Unvaccinated: Negative (< or =0.8 AI)

Reference values apply to all ages.

A positive IgG result coupled with a positive IgM result suggests recent infection with mumps virus. This result should not be used alone to diagnose mumps infection and should be interpreted in the context of clinical presentation.

A positive IgG result coupled with a negative IgM result indicates previous vaccination to or infection with mumps virus. These individuals are considered to have protective immunity to reinfection.

A negative IgG result coupled with a negative IgM result indicates the absence of prior exposure to mumps virus and nonimmunity. However, a negative result does not rule-out mumps infection or response to vaccination. The specimen may have been collected before the appearance of detectable antibodies. Negative results in suspected early mumps infection or within a week following vaccination should be followed by testing a new serum specimen in 2 to 3 weeks.

Equivocal results should be followed up with testing of a new serum specimen within 10 to 14 days.