An investigation into the mumps outbreak among students at the University of Iowa between July 2015 and May 2016 shows that complications from mumps, while reported less frequently due to widespread vaccine use, can still occur even in patients who have received recommended vaccination. 

To investigate these complications, health officials conducted an investigation via interviews, medical chart abstractions, and immunization record review. There were 287 students diagnosed with mumps for whom clinical data was available, of which 20 patients showed complications: 15 cases of orchitis,3 of transient hearing loss, 2 of mastitis, and 1 of meningitis. All 20 patients had a record of receiving at least 2 doses of measles-mumps-rubella vaccine.

The case series, published in this week’s Morbidity and Mortality Weekly Report (MMWR) describes these complications in 3 patients.

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Patient A was a 21-year-old male who developed right jaw pain and swelling. He was diagnosed with mumps parotitis 2 weeks after his roommate had been diagnosed with mumps. Nine days after symptom onset, the patient’s parotitis resolved but he continued to have a temperature of 101.0 degrees Fahrenheit. Two days later, he developed left testicular pain and swelling. After being diagnosed with orchitis, he was prescribed NSAIDs and ice packs with no additional follow-up care.

Patient B was a 21-year-old female who developed progressive right ear pain, cough, and shortness of breath. She was diagnosed with right otitis externa and left otitis media 2 days later, and was prescribed amoxicillin and analgesics. She experienced worsening respiratory symptoms later that day and was also found to have right bullous myringitis, right parotitis suspected to be mumps, and suspected pneumonia; she was prescribed azithromycin. A PCR test for mumps was negative but her symptoms and the ongoing outbreak matched the case definition for probable mumps. The next day, she had tinnitus and reduced hearing in her right ear and was later diagnosed with moderate right senorineural hearing loss (attributed to mumps) and conductive hearing loss. She was prescribed a 1-week course of prednisone and had symptom resolution by the 13th day after the onset of parotitis. 

Patient C was a 21-year-old male who developed left facial pain and swelling with a positive PCR test for mumps. He was treated for neck stiffness, fever, and tachycardia 22 days after the initial onset of symptoms. His Gram stain and bacterial cultures returned negative and the analysis was consistent with viral meningitis. This diagnosis was attributed to mumps due to the onset of meningitis ranging from four days before to 21 days after the onset of parotitis. He was discharged with symptomatic care and his meningneal symptoms resolved within a week.

Although these patients received the recommended 2 doses of measles-mumps-rubella vaccine, mumps complications may still occur. In addition, these complications may also occur at different times throughout the illness even without parotitis. Clinicians should carefully monitor for these complications and their attribution to mumps. If mumps is suspected, PCR testing should be done on a buccal swab specimen and serology testing on a serum specimen.

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Donahue M, Schneider A, Ukegbu U, et al. Notes from the field: complications of mumps during a university outbreak among students who had recieved 2 doses of measles-mumps-rubella vaccine – Iowa, July 2015-May 2016. MMWR Morb Mortal Wkly Rep. 2017;66:390-391. doi:

This article originally appeared on MPR