Mumps (Parotitis)

Mump is a type of viral infection that is highly contagious, transmitted by and affecting only humans; the infection is one of the few epidemics that has plagued the world, it is also known as Parotitis.

Mumps viral infection mostly affects the parotid gland (a type of salivary gland) at the sides of the cheeks; many other linked organs may also suffer the effect of this infection.

The illness is of short duration, lasting between seven to ten days, it has no cure and resolves spontaneously. Before the discovery of mump vaccines, the highest rate of the disease outbreak was mostly reported in the late winter to early spring (that is between December to March).

Mumps spreads rapidly and can result in complications such as meningitis, pancreatitis, and inflammation of the heart, and even testicular/ovarian swelling, among so many others.

History of Mumps (Parotitis)

Medical historical records of Mump disease dates far back as to the Greco-Roman times; mumps was first observed and documented as parotitis by Hippocrates in the 5th century BC.

He was a father of medicine who described the outbreak of mumps on the Greek island of Thasos in around 410BC; which became a foundational brick of documentation for the disease, a passage from the documentation reads:

“Swellings appeared around the ears, in many on either side and in the greatest number on both sides, they were of a lax, large, diffused character, without inflammation or pain and they went away without any critical sign.”

Long later in the 19th century, its transmission capabilities were proven by Ernest Goodpasture and Claud Johnson; they showed that Mumps is caused by a virus in 1934.

Claud and Ernest went ahead to research and develop the disease by collecting saliva specimens from infected patients exhibiting early signs of mumps infection.

The saliva samples also contained the same virus found in infected rhesus monkeys in earlier research; they, therefore, drew the hypothesis that this virus was the causative agent of mumps.

This huge revelation was the foundation the birthed new avenues of research to be opened up, particularly into the development of a vaccine to stop the further spread of the disease.

Mumps Vaccine

In 1948, a vaccine for mumps infection was invented; a research that began three years before, to isolate the mumps virus. This first version of the mumps vaccine only had short-term effectiveness, because it utilizes a live virus that has been weakened instead of an inactivated variety.

Later in 1967, after series of developing research for an active and long-term vaccine, the US Food and Drug Administration (US-FDA) licensed Mumpsvax, a developed vaccine by Maurice Hilleman; an American microbiologist who led a team specialized in vaccinology, they developed over 40 vaccines (an unparalleled record of productivity) including the Mumps vaccine.

The Mumpsvax was created from the mumps virus infecting his five-year-old daughter, Jeryl Lynn Hilleman, it was recommended for routine use in the US in 1977.

Hilleman also developed the measles vaccines (MMR combination vaccine) in 1963 and an improved version in 1968 and a rubella vaccine while working at the Merck Institute of Therapeutic Research in Pennsylvania, USA.

The last outbreak of the mumps disease records was a 2016 outbreak in the US among populations that were already highly vaccinated against the disease.

Among the infected population already vaccinated 40 people of the Harvard University; this outbreak in the University unveiled the issue to the attention of Yonatan Grad, Harvard University assistant professor of immunology and infectious diseases, and Joseph Lewnard, his postdoctoral fellow, who in the third month of that same year reported on a resurgence of mumps among vaccinated young adults in the US.

Further studies on the mumps outbreak that year, carried out by Chan School of Public Health (a Teaching Hospital for Harvard) concluded the resurgence was likely due to waning vaccine-derived immunity.

The research by the Teaching Hospital revealed that the vaccine-derived immunity lasts an average of 27 years after the last dosage is administered.

This subsequently meaning, apart from the two doses administered during the childhood of a person, a third dose at the age of 18 may be required to maintained immunity into late adulthood.

Causes and Mode of Transmission of Mumps

Mumps is caused by a single stranded RNA virus contained inside a two-layered envelope cell wall (a paramyxovirus) that endows the virus its characteristic immune nature.

Unlike the viruses that cause common cold (which are of similar strands), only one type of the mump virus has been discovered and proven to exist. Though its potency of contamination highly exceeds the magnitude of both influenza and rubella (measles), it is, however, less contacted when compared to varicella (chickenpox).

When the virus is contracted, it replicates in the nasopharynx and regional lymph nodes. During a viremia (a medical situation where a virus enters the bloodstream and hence gains access to the rest of the body), the virus spreads to most tissues including the salivary glands, testes, ovaries, pancreas, and meninges.

Inflammation in infected tissues (reaction of the immune system trying to fight the virus as a foreign body) leads to featured symptoms of parotitis, aseptic meningitis, and orchitis.

The mumps virus is only transmitted from human to human and is most rapidly spread among individuals living in closed quarters and overcrowded settlements.

The virus most commonly is contaminated directly via respiratory droplets in the air; expelled during coughing and sneezing. However, less frequently, it can also be contaminated when a person comes across respiratory droplets that may land on clothing, pillows, and sheets.

Also, it is transmitted through saliva such as deep kissing an infected person, and by hand-to-mouth contact after touching items contaminated with this infected droplet.

It should also note that the mump virus is particular to humans, animals cannot contract or spread mumps, although rare cases have been cited in dogs.  

Symptoms of Mumps Infection

The incubation period of the mumps virus in the blood is about 16 to 25 days: the period between contracting the virus and onset of prodromal symptoms.

Viral shedding is short-lived, and an infected person should be isolated from other susceptible persons for the first week following the discovering of symptoms such as swelling of the salivary (parotid) glands.

Non-specific, prodromal symptoms may include:

  • Low-grade fever
  • Headaches
  • Myalgia
  • Loss of appetite
  • Malaise

One of the primary signs of mumps infection is the swelling of the parotid gland commonly known as the salivary gland, which is located anterior to the ears, just above the angle of the jaw.

The gland becomes inflamed (swollen and tender to touch) and referred pain to the ear may also be experienced, approximately 95% of infected individuals experience this symptom.

The inflammation of the parotid gland may last up to 10days and infected adults have been recorded to experience more severe symptoms than their young counterparts.

More than 50% of patients were discovered to experience a ‘respiratory-only’ or subclinical group of symptoms and among these numbers was mostly adults.

Symptoms of mumps are milder in vaccinated persons compared to unvaccinated persons and the disease has been discovered in some unvaccinated cases, about 15% to 24% to be asymptomatic (presenting no symptoms).

Risk Factors for Mumps

  • Non-completed vaccinated individuals (two separate doses), especially children are at a higher risk of contracting the virus when exposed to mumps than vaccinated persons.
  • Outbreaks of mumps are seasonal and are most likely to be during the winter/spring seasons.
  • Children between the ages of 2 to 12 years are at the highest risk of contracting mumps infection.
  • Individuals with weakened immune systems may be due to medications or other diseases (such as HIV/AIDS and cancer) are at risk of contracting the virus.
  • Some areas like Africa, Southeast Asia, and subcontinent regions are high-risk regions of the world as they have a very low rate of immunization. Travelers and tourists should take caution.
  • Another risk factor for the mumps infection is those born before 1956; generally, these persons are suspected to have experienced mumps infection during childhood. However, if not, they are at risk for adult mumps disease.

Diagnosis for Mumps

Laboratory studies are generally carried out to back up clinical impression.

The aim of these laboratory studies is to exclude other viral infections that may present similar infections and also rule out rare causes of similarly presenting parotid gland enlargements such as parotid cancer, IgG-4 related disease, or sarcoidosis.

Mumps is confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR) or viral culture from oral or urine specimens. A negative RT-PCR or viral culture in an individual with clinically compatible mumps symptoms does not rule out mumps as a diagnosis.

Acute mumps infection is also detected by a significant rise in IgG antibody titer between acute and convalescent-phase serum specimens, also known as IgG seroconversion.

However, this test cannot be used to confirm a diagnosis of mumps. False-positive results can occur in both vaccinated and unvaccinated because the test may be affected by other diagnostic entities that cause parotitis (inflammation of the parotid glands).

False results can also arise in vaccinated and unvaccinated persons, by the onset of symptoms in a person who is vaccinated or had the previous infection; the acute IgG levels may already be high and therefore a 4-fold rise cannot be detected when compared to the convalescent-phase serum sample.

Another diagnosis is the detection of the presence of IgM in serum mumps, but the test cannot be used to confirm a mump diagnosis because the IgM response mat is transient, delayed, or not detected.

This may be due of the previous contact with mumps virus either through vaccination or natural infection.

Complications of Mumps

Most complications that arise as a sub-result of mumps viral infection occur with or without parotitis, that is, the swelling of the salivary gland.

These complications that are common include:

  • Hearing loss
  • Orchitis: A painful inflammation of one or both testes
  • Meningitis: Inflammation of the meninges (the three membranes that envelops the brain and spinal cord).
  • Oophoritis: inflammation of the ovaries
  • Mastitis: Inflammation of the breast
  • Encephalitis: Inflammation of the brain
  • Pancreatitis: Inflammation of the pancreas 

Some other complications that are very rare but have also been reported include Nephritis, myocarditis, paralysis, seizures, cranial nerve palsies, and hydrocephalus.

These complications associated with mumps infection are more common in adults than children and likely to occur in unvaccinated persons infected persons.

Treatment of Mumps

VACCINATION: In children, Vaccines for mumps are available as MMR-II (Measles, Mumps and Rubella vaccine) and MMRV (Measles, Mumps, rubella and Varicella vaccine [ProQuad]).

Both vaccines contain live attenuated viruses. The MMR-II and MMRV have been recommended by the Advisory Committee on Immunization Practices (ACIP) to be used when any of the individual components of the vaccine is indicated; that is the vaccines can be implemented for the prevention of measles, mumps, rubella, and varicella. MMR is licensed for use in persons 12 months and above and MMRV for children age 1 to 12 years strictly.

For adults, according to the ACIP, certain persons without acceptable presumed immunity are to receive MMR vaccination of at least 1 dose of MMR for unvaccinated individuals, 2 doses of MMR for students entering colleges, technical/vocational schools, Universities, and other post-high-school educational institutions and 2 doses of MMR vaccines for measles and mumps and at least 1 dose MMR for rubella for healthcare personnel.

Pregnant women should seek personal counseling with doctors before taking a vaccine as pregnancy is a huge contraindication for MMR and MMRV vaccines.

Pregnancy would be recommended to be avoided for 4 weeks following vaccine administration. Non-immune women who contract mumps during the first trimester of their pregnancy have an increased rate of miscarriage, however, it is not advisable to terminate a pregnancy after a vaccine shot as the risk to the fetus appears to be extremely low.     

Most mumps infection cases are not with complications and so they can be supervised and treated by health clinicians like pediatricians or family practice doctors.

Although the attention of an infectious-disease specialist may need for unusual health circumstances or medical complications. Treatment focuses on the symptoms, to make the patient more comfortable during the infection.

The treatments include:

  • Take over-the-counter pain relievers, such as acetaminophen and ibuprofen, to reduce the fever.
  • Soothing swollen glands by applying ice packs.
  • Enough rest
  • Drink plenty of fluids to avoid dehydration due to fever.
  • Avoidance of acidic foods and beverages that may cause more pain in your salivary glands.
  • Eat a soft diet of soup, yogurt, and other foods that are not hard to chew (chewing may be painful when your glands are swollen).

Summary

  • Mumps is a highly contagious viral infection that can result in serious health complications such as encephalitis, deafness, orchitis, and meningitis.
  • There is no specific treatment for mumps. Warm or cold packs can be used on the parotid gland tenderness and swelling; this also helps with the pain, and also the use of acetaminophen and ibuprofen as pain relievers.
  • The Mumps vaccine is commonly administered as a part of a combination vaccine (MMR: Mumps Measles Rubella) also providing protection for the other diseases. MMR vaccines provide about 87% immunity against the infections, with the two first dosages administered 12-15 months with a booster at 4-6 years of age; a third dosage is also required at age 18.
  • Apart from individuals with low immunity, another very small population of people that should not get vaccinated with the MMR include; individuals with more than two continuous weeks of oral steroids, who are allergic to any components of the vaccines, including gelatin or neomycin. MMR vaccines are very unlikely to produce a severe reaction to those who are egg white allergy or in people involved in daily use of inhaled steroids (such as those used to control certain pulmonary diseases like asthma, COPD).

Sources

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