Parotitis overview

# Overview
Parotitis is the inflammation of the parotid glands, represented by a visible swelling in the back of the mouth behind the ears. Parotitis can come from a variety of sources; the pathogenesis of parotitis is dependent on the pathophysiology of the causative agent. Parotitis was first discovered by Hippocrates in the 5th century B.C.E. Claude D. Johnson M.D. and Ernest W. Goodpasture M.D. discovered the mumps virus, the most common cause of parotitis. The mumps virus was first isolated in 1945 by K. Habel and John Enders, leading to the first clinical trials to develop vaccinations. The mumps vaccine was developed by Maurice Hilleman and colleagues in December 1967, immunizing against the most common parotitis cause. The most common causes of parotitis are infectious, including mumps viral infections as well as infection due to Staphylococcus aureus bacteria. It can also develop as a symptom of blockages, such as salivary gland stones and benign or malignant neoplasia, as well as from autoimmune conditions (such as Sjogren's syndrome) and in recurrent forms from unknown etiologies. Symptoms of parotitis include abnormal tastes,difficulty opening mouth, dry mouth, fever, mouth or facial pain (particularly when chewing or swallowing), reddening of the face or upper neck, and facial swelling in front of the ears. The presence of swollen parotid glands, unilaterally or bilaterally, is diagnostic of parotitis. Parotitis must be differentiated from other diseases that present edematous swelling in the throat and neck. These diseases include retropharyngeal abscess, angioneurotic edema, salivary gland neoplasia, Sjogren's syndrome, and sialolithiasis and sialadenitis of the submandibular glands. Parotitis is most commonly seen in children and young adults that have not received the mumps vaccine, but can also be seen in perimenopausal women aged 40 and older. It is more common to see parotitis in developing countries due to the lower prevalence of the mumps vaccine. Common risk factors for developing parotitis are being between 6 months and 30 years old, lacking the mumps vaccine, lacking natural exposure to the mumps virus, being over 40 years old and perimenopausal if a woman, traveling to developing countries, malnutrition, immunosuppression, poor oral and external hygiene, and a reduced salivary flow rate. Parotitis is a self-limited condition that will usually resolve itself without treatment. The duration of parotitis in a patient depends on the cause. Parotitis occurrences usually last between 3 and 7 days, rarely persisting for up to 2-3 weeks at a time. Recurrent parotitis is usually self-limited, usually subsiding between the ages 10-15 and resolved by age 22. More severe cases may not resolve themselves and require more intensive intervention, such as parotidectomy. An abscess of the parotid gland is a complication of infectious parotitis. Prognosis is good, with the majority of parotitis patients recovering fully with or without symptomatic treatment due to the self-limited nature of the disease. Parotitis therapy is primarily supportive and symptomatic: Common therapies include analgesics for pain, warm salt water rinses, lemon drops and lozenges to stimulate saliva flow to relieve pain. Other therapies are used to target the potential cause of the parotitis, including antiretroviral medication, antimicrobial therapy, anti-tuberculosis therapy, and sialendoscopy and parotid gland surgery. Effective preventative measures for parotitis include the mumps vaccine, maintaining personal hygiene and limiting proximal contact with mumps or Staphyloccocus aureus infected individuals, limiting sexual contact with HIV-infected individuals and using condoms during sexual intercourse, and the Bacillus Calmette-Guerin vaccine to prevent extrapulmonary tuberculosis. Preventative measures for obstruction-based parotitis include reducing risk factors for salivary gland stones and parotid gland neoplasia.

# Historical Perspective
Parotitis was first discovered by Hippocrates in the 5th century B.C.E. Claude D. Johnson M.D. and Ernest W. Goodpasture M.D. discovered the mumps virus, the most common cause of parotitis. The mumps virus was first isolated in 1945 by K. Habel and John Enders, leading to the first clinical trials to develop vaccinations. The mumps vaccine was developed by Maurice Hilleman and colleagues in December 1967, immunizing against the most common parotitis cause.

# Pathophysiology
The pathophysiology of parotitis is dependent upon the cause. Viral parotitis is caused by the infiltration of respiratory droplets containing the mumps virus. The mumps HN and F glycoproteins reach the surface of the infected host cell through the endoplasmic reticulum and Golgi complex. Virions emerge from the infected cells due to the M protein facilitating the localization of the viral ribonucleic proteins onto the host cell membrane. Both HN and F glycoproteins mediate the fusion of virus and host cell, as well as cell and cell-membrane fusion, to perpetuate the spread of the virus throughout the host. The virus replicates in the nasopharynx and regional lymph nodes. Upon replication, viremia occurs for three to five days, spreading to the salivary glands. Parotitis results from the inflammatory response tp the presence of mumps virus in the parotid salivary gland. Bacterial parotitis is most commonly caused by Staphylococcus aureus.

# Causes
Parotitis is most commonly caused by viral or bacterial infections, but can also result from autoimmune syndromes, parotid gland blockages, and from diseases with uncertain etiologies.

# Differentiating Parotitis from Other Diseases
Parotitis must be differentiated from other diseases that present edematous swelling in the throat and neck. Diseases include retropharyngeal abscess, angioneurotic edema, salivary gland neoplasia, Sjogren's syndrome, and sialolithiasis and sialadenitis of the submandibular glands.

# Epidemiology and Demographics
The epidemiology and demographics of parotitis varies due to the multiple causes of the disease. The global incidence of mumps, viral parotitis, in 2014 was 0.24 per 100,000 individuals. The prevalence of parotitis from Sjogrens syndrome, as of 2015, is 1000 per 100,000 individuals in the United States. Parotitis is most commonly found in children without the first or follow-up administration of the mumps vaccine. Mumps outbreaks, and resultant parotitis, are also seen in young adults between 20-30 years old that were too old to be vaccinated as children, yet too young to have experienced a natural exposure to infection. Sjogrens syndrome is primarily found in women at the perimenopausal age. Parotitis from Sjogrens syndrome is 9 times more likely to affect females than males. Juvenile recurrent parotitis is more commonly found in male children. Parotitis from mumps is rare in developed countries due to widespread administration of the vaccination. Developed countries with parotitis epidemics through mumps are usually due to a lack of the follow-up administration of mumps vaccine, non-vaccinated children not developing a resistance to the infection due to lack of natural exposure, or a viral strain that has developed resistance to the vaccine. Parotitis is more common in developing countries due to the lower vaccinated population.

# Risk Factors
Common risk factors for developing parotitis are being between 6 months and 30 years old, lacking the mumps vaccine, lacking natural exposure to the mumps virus, being over 40 years old and perimenopausal if a woman, traveling to developing countries, malnutrition, immunosuppression, poor oral and external hygiene, and a reduced salivary flow rate.

# Natural History, Complications, and Prognosis
Parotitis is a self-limited condition that will usually resolve itself without treatment. The duration of parotitis in a patient depends on the cause. Infectious parotitis, most commonly from mumps virus, will incubate for 15 to 24 days before symptoms manifest in an infected individual. Parotitis will gradually develop over 2-3 days after mumps symptoms manifest, usually remaining for 7 days. Parotitis will usually resolve itself without treatment within 10 days of manifestation. Juvenile recurrent parotitis usually manifests in children around 5 years old, but children from 3 months to 16 years old have been reported to begin experiencing symptoms as well. Parotitis occurrences usually last between 3 and 7 days, rarely persisting for up to 2-3 weeks at a time. Recurrent parotitis is usually self-limited, usually subsiding between the ages 10-15 and resolved by age 22. More severe cases may not resolve themselves and require more intensive intervention, such as parotidectomy. An abscess of the parotid gland is a complication of infectious parotitis. Prognosis is good, with the majority of parotitis patients recovering fully with or without symptomatic treatment due to the self-limited nature of the disease.

# Diagnosis

## History and Symptoms
Symptoms of parotitis include abnormal tastes,difficulty opening mouth, dry mouth, fever, mouth or facial pain (particularly when chewing or swallowing), reddening of the face or upper neck, and facial swelling in front of the ears. There may be a history of smoking, chronic illness, or poor oral hygiene in parotitis patients.

## Physical Examination
The presence of swollen parotid glands, unilaterally or bilaterally, is diagnostic of parotitis. Patients may also present erythema in the neck or side of the face, radiating from the swollen parotid gland. Parotitis patients are usually ill-appearing if the cause is infectious due to other symptoms of the cause, such as low-grade fever or malaise. Patients with recurrent parotitis that is not from an infection may appear well if there is no fever present.

## CT Scan or MRI
CT Findings in Parotitis are dependent on the cause. They can include salivary duct stones, parotid gland swelling, malignant or benign neoplasia, markers of inflammation, parotid gland abscess, and lymphadenopathy. MRI images of parotitis reveal an enlarged parotid gland. The T2 signal is usually high for acute parotitis, but can vary between low-intermediate for recurrent parotitis depending on presence of fibrosis.

# Treatment

## Medical Therapy
Parotitis therapy is primarily supportive and symptomatic. Common therapies include analgesics, such as paracetemol and diclofenac, and other measures to relieve pain, including heat massages and warm saltwater mouth rinses. Therapy that increases saliva flow is also used, including extra fluids and foods that stimulate saliva flow, including lemon drops and vitamin C lozenges. Other therapies are used to target the potential cause of the parotitis, including antiretroviral medication, antimicrobial therapy, anti-tuberculosis therapy, and sialendoscopy and parotid gland surgery.

## Surgery
Surgery is recommended for parotitis caused by salivary duct stones, abscess from bacterial infection, parotid gland neoplasia, and recurrent parotitis of unknown etiology of which non-surgical therapies fail to resolve the disease. Sialendoscopy is preferred to relieve salivary duct stone-based parotitis due to the minimally-invasive nature of the procedure. Abscess drainage is performed by superficial incision. Partial or total parotidectomy is performed to remove neoplasia and when recurrent parotitis does not respond to non-surgical therapy. It is not recommended unless necessary due to the likelihood of complications.

## Primary Prevention
Effective preventative measures for parotitis include the mumps vaccine, maintaining personal hygiene and limiting proximal contact with mumps or Staphyloccocus aureus infected individuals, limiting sexual contact with HIV-infected individuals and using condoms during sexual intercourse, and the Bacillus Calmette-Guerin vaccine to prevent extrapulmonary tuberculosis. Preventative measures for obstruction-based parotitis include reducing risk factors for salivary gland stones and parotid gland neoplasia.