Mumps

Key Features

Essentials of Diagnosis

• Exposure 12–25 days before onset

• Painful, swollen salivary glands, usually parotid

• Frequent involvement of testes, pancreas, and meninges in unvaccinated individuals

• Mumps can occur in appropriately vaccinated persons in highly vaccinated communities

General Considerations

• Children are most commonly affected

• Mumps is more serious in adults than in children

• Appears to occur more commonly in males

• However, in outbreaks, infection can affect patients in their second or third decades of life

• Factors that contribute to outbreaks include

  • Efficacy of vaccines

  • Waning individual immunity

  • Crowded conditions

• Incubation period: 12–25 days (average, 16–18 days)

• Transmission

  • Direct contact with respiratory secretions or saliva or infected surfaces

  • Can also be airborne or via droplets

  • Subclinical infection, which is still transmissible, is present in up to one-third of affected individuals

Demographics

• Since the measles, mumps, and rubella (MMR) vaccine was introduced in 1989, the mumps case rate has decreased by more than 99%, with only a few hundred cases reported most years

• In 2020 the number of cases decreased: data reported to the CDC showed 616 cases of mumps in 2020 compared to 3474 in 2019

Clinical Findings

Symptoms and Signs

• Parotid tenderness and overlying facial edema

  • Most common physical findings

  • Typically develop within 48 hours of the prodromal symptoms

  • Usually, one parotid gland enlarges before the other, but unilateral parotitis occurs in 25% of patients

  • The parotid duct (orifice of Stensen) may be red and swollen

  • Trismus may result from parotitis

• High fever, testicular swelling, and tenderness (unilateral in 75% of cases)

  • Denote orchitis

  • Usually develops 7–10 days after the onset of parotitis

Differential Diagnosis

• Calculi in the parotid ducts

• Tumors

• Cysts

• Sarcoidosis

• Cirrhosis

• Diabetes

• Bulimia

• Pilocarpine usage

• Sjögren syndrome

• Parotitis may be produced by

  • Pyogenic organisms (eg, S aureus, gram-negative organisms [particularly in debilitated individuals with poor oral intake])

  • Drug reaction (phenothiazines, propylthiouracil)

  • Other viruses (HIV, influenza A, parainfluenza, EBV infection, coxsackieviruses, adenoviruses, HHV-6)

• Inflammation of the lymph nodes

Diagnosis

• Characteristic clinical picture usually suffices for diagnosis

Laboratory Findings

• Mild leukopenia with relative lymphocytosis may be present

• Elevated serum amylase usually reflects salivary gland involvement rather than pancreatitis

• Mild acute kidney injury is found in up to 60% of patients

• An elevated serum IgM is considered diagnostic

  • Repeat testing 2–3 weeks after the onset of symptoms is recommended if the first assay is negative because the rise in IgM may be delayed, especially in vaccinated persons

• A fourfold rise in complement-fixing antibodies to mumps virus in paired acute and convalescent serum IgG specimens also confirms infection

• Anti-mumps IgM ...