The parotid glands are located on either side of the face, and are our largest salivary glands. We don’t tend to notice them unless they become enlarged, usually due to a bacterial or viral infection.
The classic cause of parotitis is the mumps virus, but other viruses (EBV & HIV), along with acute bacterial parotitis or Extrapulmonary Tuberculosis can cause inflammation of these glands, as well as some autoimmune diseases.
And sometimes, the etiology is unknown.
One common disease that isn’t usually associated with parotitis is influenza, although a few cases have been reported in the past (see Clinical Infectious Diseases Diagnosing Mumps: Don't Be So Sure).
A few weeks ago, the Chicago Department of Public Health issued an alert to local doctors to test for both influenza, and mumps, when diagnosing parotitis, as several unusual influenza-related cases had surfaced.
Several Midwest state health departments, including Illinois, have received reports of parotitis in persons with lab-confirmed influenza. Parotitis is inflammation of one or both of the parotid glands, the major salivary glands in the oral cavity, and is an uncommon complication of influenza. The Illinois Department of Public Health (IDPH) is working with other states and the Centers for Disease Control and Prevention (CDC) in conducting an investigation into such reports. Information about persons with lab-confirmed influenza who are diagnosed with parotitis is needed to understand the occurrence and further explore characteristics of such cases.
Last night the CDC published an overview of the 2014-15 flu season, with the following comment on these parotitis cases.
Is there any unusual disease activity going on this season?
Since December 2014, multiple states have notified CDC of laboratory-confirmed influenza infections in persons who have swelling of their salivary glands (a condition called ‘parotitis’). Of the cases of influenza infection with parotitis that have been reported to CDC, the majority have occurred in children with influenza A (H3) infection, and have resulted in mild illness. No deaths have been reported. CDC is currently investigating the situation in order to understand the characteristics of patients and the occurrence of parotitis.
Parotitis is not a common symptom of influenza infection, although cases of parotitis with influenza infection have been reported in the past. Parotitis is much more commonly seen following infection with other pathogens such as the mumps virus. Symptoms of influenza infection include fever, chills, cough, sore throat, runny or stuffy nose, muscle or body aches, headache, fatigue (tiredness), and sometimes vomiting and diarrhea (more common in children than adults).
As with several dozen EV-D68 related paralysis cases last year (see CIDRAP: Likely That Polio-like Illness & EV-D68 Are Linked), and a handful of reported Pediatric Neurological Complications during the 2009 H1N1 pandemic, this appears to be an infrequent (but far more benign) atypical side effect of infection.
A medical mystery for now, but one we’ll keep an eye on going forward.