How Mumps Is Diagnosed

Mumps is diagnosed based on clinical symptoms, particularly the swelling of the neck and lower face region, which is a trademark of mumps infection.

Additionally, there are some tests that can help confirm the diagnosis. Samples of saliva or cells obtained from inside your mouth can detect evidence of the virus or the immune cells that fight it. Imaging tests can identify some of the complications of mumps.

Self-Checks/At-Home Testing

If you or your child has not received the immunization for mumps, there is a risk of becoming sick with the infection. And sometimes people who have been vaccinated can be at risk of contracting the infection if they become immunocompromised.

These can include fever, headaches, swollen neck, muscle aches, pain when eating or swallowing, or just generally feeling run down.

Labs and Tests

There are several tests that can help in the diagnosis of mumps infection.

Reverse Transcription Polymerase Chain Reaction (RT-PCR)

An RT-PCR test can detect the presence of viral RNA, which is the genetic material of the mumps virus. A buccal swab is a scraping of tissue from inside your cheeks. A PCR can be done on this sample, a saliva sample, or a blood sample (and rarely a urine sample).

Antibody Tests

The body forms antibodies in response to infection. Because mumps immunization triggers antibody formation, you may have antibodies to the mumps virus if you have been immunized or if you have had the infection and successfully fought it off.

A blood test can detect the antibodies in your blood and can also help differentiate whether you are immune to the virus or whether you have an active infection.

• If you have serum IgG antibodies present in your blood, this indicates you had a previous infection or were vaccinated against the mumps.
• If you have an active infection, your tests would show IgM antibodies.

However, people with a history of mumps vaccination may not have detectable mumps IgM antibodies, so false-negative tests can occur.

Culture

A culture is a test in which a sample is taken to a lab to evaluate for viral growth. The same sample that's used for an RT-PCR test can be used for the viral culture.

It takes time for a virus to grow in a culture, and it may take two to three weeks for your test to become positive. In the meantime, it's important to avoid infecting others while you are awaiting results.

Spinal Fluid Sample and Culture

If you or your child has possible meningitis or encephalitis due to mumps, your medical team may need to do a lumbar puncture to collect a sample of cerebrospinal fluid (CSF), the fluid that surrounds the brain.

A lumbar puncture, also called a spinal tap, is a test in which your healthcare provider inserts a needle into an area of your back, between the vertebral bodies, to collect a sample of the fluid that surrounds your brain and spinal cord. This fluid may show increased white blood cells and protein, and sometimes a decrease in glucose. These signs are indicative of an infection, but they do not specifically mean that you have mumps.

If the mumps virus grows in a CSF culture, this means that that you have meningitis or encephalitis due to mumps.

Pancreatic Enzyme Testing

If you have pancreatitis as a complication of mumps, your blood tests may show an elevation of amylase and lipase, which are pancreatic enzymes. These results are not specific for mumps, and there are many other causes of pancreatitis besides mumps.

Mumps Healthcare Provider Discussion Guide

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Imaging

In general, imaging studies are not part of the routine diagnosis of mumps. However, this infection can cause clinical signs that require imaging evaluation. And imaging studies may be helpful for evaluating the extent of complications.

Neck CT

If the cause of your neck swelling is unclear, you might need a CT scan of your neck to identify other possible causes of neck swelling, such as trauma, abscesses, or cancer.

Brain CT or MRI

If you have encephalitis due to mumps, you could have serious symptoms, such as seizures, that require further evaluation with brain imaging. If you have neurological symptoms, your healthcare provider may need to see a CT scan of your brain prior to doing a lumbar puncture. 

Abdominal CT or Ultrasound

If you have signs or symptoms of pancreatitis, your healthcare provider may need to order an abdominal CT or ultrasound to better evaluate your condition and to see if you have evidence of other abdominal inflammation or disease. 

Testicular Ultrasound

If you have testicular swelling, one of the complications of mumps infection, your healthcare provider might order an imaging test to determine whether there is another problem causing the swelling and whether you need any medical or surgical intervention.

Differential Diagnosis

Mumps causes a number of symptoms that are similar to those of other conditions. Because mumps is relatively uncommon, your healthcare provider is likely to consider other causes for your symptoms.

Viral Infection

Many viral infections cause headaches, fevers, fatigue, and muscle aches. Swelling of the parotid glands is a characteristic of mumps, but other viral infections can cause swelling of the lymph nodes in the neck and the armpits as well.

In general, the swelling caused by most viral infections is not as prominent as that of mumps. An antibody test, PCR test, and culture can help differentiate one virus from another.

Bacterial Infection

Most bacterial infections that affect the respiratory tract can cause the same symptoms as mumps, and they often cause lymph node enlargements as well. However, bacterial infections usually can be treated with antibiotics, so your healthcare provider is likely to run tests to identify the bacteria if your infection is considered highly likely to be a bacterial infection.

Abscess

An abscess is an enclosed infection that can develop due to trauma, a bacterial infection, and rarely from a viral infection. The swelling and pain of mumps, along with the fever, can mimic an abscess. A physical examination or an imaging test can help clarify the difference.

Neck Trauma

The swelling of the neck that occurs with mumps can look like swelling after a traumatic injury. If you cannot tell whether your child has been injured or has an infection, there are a few ways that your child’s healthcare providers will know the difference.

The medical history can be helpful, but sometimes very active children cannot remember falling or hurting themselves. The presence of fever, headaches, fatigue, and generalized muscle aches suggests that your child may have mumps. If there is excessive pain in the swollen area, bruising, or signs of injuries elsewhere on the body, this suggests that trauma may be the cause of the swelling.

Cancer

The swelling of mumps may be asymmetric, and swelling can be the first sign of cancer. Your healthcare provider may order imaging tests and possibly a biopsy to clarify the cause of your swelling. Don't be alarmed if these tests are ordered though—if anything, they'll help rule out a cancer diagnosis.

Testicular Torsion

Testicular swelling and inflammation may require urgent medical treatment. Testicular torsion, which is anatomical twisting or obstruction of the spermatic cord, is a dangerous condition that cuts off the testicle's blood supply and causes sudden pain and swelling.

The signs and symptoms of testicular torsion may appear similar to that of the testicular swelling caused by mumps. If your healthcare provider is concerned that the cause of your testicular swelling is something besides mumps, you may need an imaging test to differentiate the cause and to determine whether you need urgent treatment.