Mumps is a contagious viral infection primarily affecting the salivary glands, particularly the parotid glands located near the sides of the face.

It remains a significant public health concern worldwide, despite vaccination efforts, due to its highly infectious nature and potential for complications.

Causative Agent and Transmission

Mumps is caused by the mumps virus, an enveloped RNA virus belonging to the Paramyxoviridae family. Humans serve as the only natural reservoir for this virus. Transmission occurs predominantly through respiratory droplets expelled during coughing, sneezing, or close contact with an infected individual’s saliva. The virus can also spread via fomites contaminated with respiratory secretions.

The incubation period ranges from 16 to 18 days on average, but it can range from 12 to 25 days. Infectiousness starts approximately one week before symptom onset and extends to about eight days afterward, facilitating significant viral spread, especially in densely populated or communal settings such as schools and colleges.

Clinical Presentation and Symptoms

Mumps typically presents with a prodromal phase characterized by nonspecific symptoms including low-grade fever, headache, malaise, muscle aches, anorexia, and sore throat. The hallmark clinical sign is parotitis—painful swelling of one or both parotid salivary glands occurring in approximately 90% of symptomatic infections.

The swelling can last from a few days to over a week and, in some cases, may be unilateral or bilateral. Less commonly, other salivary glands such as the submandibular or sublingual glands may be involved. Mumps can occasionally manifest without parotitis, presenting solely with respiratory symptoms or even remain asymptomatic in about 20 to 40% of infections.

Complications and Risks

While most individuals recover fully, mumps may lead to serious complications. Viral meningitis affects approximately 10 to 15% of cases, presenting with headache, neck stiffness, and photophobia. Encephalitis, though rarer, can cause neurological impairments.

Diagnosis

Diagnosis of mumps is often clinical, especially during outbreaks or in regions where the disease is common. The presence of parotitis in conjunction with the prodromal symptoms strongly suggests mumps. However, laboratory confirmation is essential in settings with low disease prevalence or unclear clinical presentation.

Laboratory tests include detection of mumps-specific IgM antibodies, viral RNA via real-time reverse transcription polymerase chain reaction (RT-PCR) from saliva or cerebrospinal fluid, and viral culture. Serological testing aids in diagnosing past infection or immunity status, which is critical for outbreak management.

Prevention and Vaccination

The measles-mumps-rubella (MMR) vaccine is the mainstay for mumps prevention and has substantially decreased disease incidence since its introduction. Two doses of the MMR vaccine confer about 88% effectiveness against mumps, reducing both infection and severity of symptoms. Despite vaccination, outbreaks still occur, particularly in close-contact environments, partly due to waning immunity over time.

Dr. Rob Van Binnendijk, a recognized expert involved in studying the mumps vaccine effectiveness in the Netherlands: "Our observations that orchitis was the most frequently reported complication, and that previous MMR vaccination considerably reduced the risk of orchitis among cases of mumps, are important to justify recommending mumps vaccination to unvaccinated persons."

Mumps is a viral infection marked by painful swelling of the salivary glands with varied clinical severity ranging from asymptomatic to serious neurological and reproductive complications. Accurate diagnosis, vigilant surveillance, and timely preventive measures are critical to managing this once widespread disease and minimizing its public health impact.