Chapter 93: Mumps

INTRODUCTION

Mumps disease was described in the literature as early as fifth century BC by Hippocrates. The etiologic agent was identified as a virus in 1934 by Johnson and Goodpasture who demonstrated transmission to rhesus monkeys¹; propagation of the virus ultimately led to the development of vaccines by the late 1960s.² Mumps vaccine has resulted in dramatic decreases in the incidence and associated morbidity in the United States and in other countries that have introduced the vaccine in their routine childhood immunization programs. However, starting in the mid-2000s, mumps epidemics have occurred in countries with high mumps vaccination coverage, with the majority of cases occurring among persons who previously received two doses of mumps vaccine.^3-7 Still, incidence remains much higher in countries where there is no routine vaccination for mumps.⁸

CLINICAL DESCRIPTION

Mumps is an acute viral infection that typically presents as parotitis or other salivary gland swelling, and may be proceeded by a prodrome characterized by fever, headache, malaise, myalgias, anorexia, and fatigue.⁹ Infection may be asymptomatic in approximately 15–24% of unvaccinated persons.^10-12 The frequency of subclinical or asymptomatic infection in vaccinated persons is unknown, but mumps symptoms are usually milder among vaccinated persons.^13-19

Uncomplicated mumps illness typically resolves within 10 days. Mumps reinfection or recurrent mumps (parotid swelling resolves on one side and then weeks to months later occurs on the other side) can occur.^20-24

COMPLICATIONS

Complications associated with mumps infection are usually more severe in adults than children,^12,19 and are less common in vaccinated persons.^13-19 Orchitis is the most frequently reported complication and occurs in about 30% of unvaccinated and 6% of vaccinated postpubertal men.^16,18 About half of patients with mumps orchitis develop testicular atrophy of the affected testicles.^25,26 While orchitis and testicular atrophy from mumps can cause oligospermia, azoospermia, asthenospermia, no studies have documented cases of or assessed risk for sterility. Oophoritis and mastitis have been reported to occur in 7–30% of unvaccinated postpubertal women during outbreaks,^10,11,16,18 and in < 1% of vaccinated postpubertal women with mumps in population-based studies.^16,27,28 Sensorineural deafness associated with mumps infection can occur in up to 4% of unvaccinated patients and may result in permanent hearing loss.^29,30 Pancreatitis occurs in up to 4% of unvaccinated patients and is usually mild.¹² Hearing loss and pancreatitis occur in < 1% of vaccinated mumps patients.^{4,13,16,19,27,31,32}

Aseptic meningitis is the most common CNS complication and is typically mild or subclinical.²⁶ In studies involving vaccinated and unvaccinated cases, clinically apparent meningitis and encephalitis occurred in ≤ 1% of mumps cases.^{4,13,16,19,27,32} Nephritis, myocarditis, and other sequelae, including paralysis, seizures, cranial nerve palsies, and hydrocephalus, in mumps patients have also been reported. Mumps infection during pregnancy has not been associated with congenital malformations³³ but first-trimester infections may ...