Parotitis (Mumps)

Mumps (medically known as parotitis) is a viral disease that causes swelling of the parotid glands on either side of the ears, which pushes them out making them look bigger. The disease is usually benign in children, but can cause serious complications in adults.

CAUSES

The infectious agent that causes the disease is the parotitic virus. It belongs to the family Paramyxoviridae, subfamily Paramyxovirinae, of the genus Rubulavirus. It was first isolated in 1934, by Goodpasture and Johnson.

It is a single-stranded, negative-sense, enveloped RNA virus with a diameter of 100 to 300 nm. The virus encodes several genes, including hemagglutinin-neurominidase (HN) protein, fusion (F) protein and a matrix (M) protein.

TRANSMISSION

Measles is an airborne disease that is mainly transmitted via respiratory droplets (small particles emitted from the respiratory system when someone coughs, sneezes or talks). The virus is also eliminated in the urine and can be transmitted transplacentally, without causing malformations in the foetus.

Usually, the affected patient is contagious for 6-7 days before the salivary glands start to swell, and up to 9 days after. Maximum contagiousness occurs in the 48 hours prior to the onset of these symptoms.

GEOGRAPHICAL DISTRIBUTION

Mumps, together with measles and rubella, are defined as endemic-epidemic disease, which means they are periodically and constantly present within the population.

Prior to the discovery of a vaccine, mumps pandemics occurred every 2 to 5 years, predominantly affecting children under 9 years of age. People who catch the disease develop lasting immunity.

Mumps outbreaks are generally observed during the winter and spring, especially in closed environments or communities.

Since the introduction of the combined trivalent vaccine (for measles, mumps, and rubella), cases have declined sharply. However, low vaccination coverage in different parts of the world still leads to frequent outbreaks.

In the United States, several mumps cases, which occurred within families, schools, universities, and other meeting places, were reported between 2015 and 2017. From January 2016 to June 2017, 150 outbreaks were recorded, causing a total of 9,200 cases.

According to the latest data published on the ECDC website, 13,693 cases were reported by various European states in the year 2017. Complications due to mumps are rare and affect approx. 5-7% of cases.

80% of cases were reported in the Czech Republic, Poland, Spain, and the United Kingdom. The disease has a higher prevalence among males, and affects the younger age groups (an average age range of 10 to 19 years), even in individuals who have been vaccinated at least once.

These data bring to light the fundamental importance of active immunisation in the prevention of mumps outbreaks.

SYMPTOMS

Mumps infection usually takes an asymptomatic course, or presents with mild respiratory symptoms in 50% of cases. In the rest of the cases, the initial symptoms start to appear after an incubation period of approx. 2 to 3 week, following the last contact with the infected person.

The onset of the disease is characterised by fever, headache, myalgias (muscle aches), chills, otalgia (ear ache), anorexia (loss of appetite), and generalised malaise. After about 24 hours, there is enlargement of the parotid glands, which are located in the retromandibular region (on either side of the ears), but the submandibular and sublingual glands may also be affected. The swelling of these areas is the origin of the popular name for the disease, "mumps”. Mumps is painful to the touch, and also painful when chewing and swallowing.

In children, the condition usually takes a benign course, without causing any particular harm. However, some complications can occur, especially after puberty, including: orchitis, oophoritis, meningitis or encephalitis, and pancreatitis.

• Orchitis is an infection of the testicles, that presents with pain, edema, erythema, and a hot sensation and tenderness in the scrotum. This condition occurs in 30 to 40% of mumps cases in males. It can lead to infertility, although cases are rare.
• Oophoritis is a less frequent condition than orchitis, which affects the female gonads, and does not have any affect on fertility.
• Meningitis, on the other hand, occurs in 4% to 6% of cases, and presents with headache, vomiting, neck stiffness, and general malaise. Encephalitis, which is even less frequent, can cause drowsiness, seizures, and coma.
• Pancreatitis presents with sudden and severe nausea, vomiting, and epigastric pain. Normally, symptoms regress within a week.

Other complications that may be related to mumps, include: prostatitis, nephritis, myocarditis, hepatitis, mastitis, polyarthritis, and sensorineural deafness due to the direct action of the virus on inner ear, however, these are very rare.

During the gestational period, mumps infection during the first trimester of pregnancy is associated with increased miscarriage. The virus can pass through the placental membrane and infect the foetus, but it does not cause congenital malformations.

DIAGNOSIS

Diagnosis is made on the basis of the patient’s history and clinical examination, which is relatively easy to carry out, due to the characteristic symptoms of the disease. In the absence of complications, laboratory tests do not reveal any specific data, other than an increase in white blood cell count due to infection.

TREATMENT

There is no specific treatment for mumps. In mild cases, rest is sufficient, with avoidance of solid or sour foods in the acute phase, which can cause pain due to the inflamed parotids. Otherwise, medications aimed at symptom control, such as antipyretics for fever (in children under 12 years of age, paracetamol is advised as acetylsalicylic acid is not recommended) and pain relief medication may be prescribed.

PREVENTION

The only effective tool for preventing the disease is vaccination.

The vaccine is mandatory and is administered in the form of a combined trivalent or tetravalent vaccine. The trivalent MPR vaccine prevents measles, mumps and rubella infections, while the quadrivalent MPRV vaccine prevents measles, mumps, rubella and varicella (chicken pox).