Mumps or epidemic parotitis is a viral disease of humans. Prior to the development of vaccination and the introduction of a vaccine, it was a common childhood disease worldwide, and is still a significant threat to health in the third world.Painful swelling of the salivary glands (classically the parotid gland) and fever is the most typical presentation. Painful testicular swelling and rash may also occur. While symptoms are generally not severe in children, the symptoms in teenagers and adults can be more severe and complications such as infertility or subfertility are relatively common, although still rare in absolute terms. The disease is generally self-limited, running its course before waning, with no specific treatment apart from controlling the symptoms with painkillers.
Signs and Symptoms
The more common symptoms of mumps are:
· Swelling of the parotid gland (or parotitis) in more than 90% of patients on one side (unilateral) or both sides (bilateral), and pain behind the lower jaw when chewing.
· Fever
· Headache
· Sore throat
· Orchitis, referring to painful inflammation of the testicle. Males past puberty who develop mumps have a 30 percent risk of orchitis.
Other symptoms of mumps can include, sore face and/or ears and occasionally in more serious cases, loss of voice.
Fever and headache can occur already as prodromal symptoms of mumps, together with malaise and anorexia.
Causative Agent
The Mumps Virus, a RNA virus belonging to the Paramyxovirdae Family, is the causative agent for the mumps disease.
Mode of Transmission
The mode of transmission is through direct contact and airborne droplets.
Diagnosis
Serologic antibody testing can verify the diagnosis when parotid or other salivary gland enlargement is absent. If comparison between a blood specimen obtained during the acute phase of the illness and another specimen obtained three weeks later shows a fourfold rise in antibody titer, the patient most likely has mumps.
Incubation Period
The incubation period is usually 14 to 25 days, but may range from as few as 12 to as many as 35 days.
Pathogenesis
Mumps is transmitted by droplet spread or by direct contact. The primary site of viral replication of the epithelium of the upper respiratory or the GI tract or eye. The virus quickly spreads to the local lymphoid tissue and a primary viremia ensues, whereby the virus spreads to distant sites in the body. The parotid gland is usually involved but so may the CNS, testis or epididymis, pancreas and ovary. A few days after the onset of illness, virus can again be isolated from the blood, indicating that virus multiplication in target organs leads to a secondary viremia Parotitis is the most frequent presentation, occurring in 95% of those with clinical symptoms. Occasionally, meningitis may precede parotitis by a week. Virus is excreted in the urine in infectious form during the 2 weeks following the onset of clinical illness. It is not known whether virus actually multiplies in renal tissues or whether the virus is of hematogenous origin. Life-long immunity is the rule after natural infection, but reinfections can occur and 1 - 2% of all cases are thought to be reinfections.
Pathophysiology
After the initial entry into the respiratory system, the virus replicates locally, then follows with a viremic dissemination to target tissues, such as the central nervous system (CNS) and salivary glands, particularly the parotid glands. This fact was a significant contribution from an experimentally induced mumps infection by Henly et al in 1948.
A secondary phase of viremia, found before the immune response, is the result of replication of the virus at the target organs. Viruria is common, via blood transmission of the virus into the kidneys, where active replication occurs. Therefore, impairment of renal function may occur.
Cell necrosis and inflammation with mononuclear cell infiltration is the tissue response. Salivary glands show edema and desquamation of necrotic epithelial cell lining the ducts. Focal hemorrhage and destruction of germinal epithelium may occur, leading to duct plugging.
Prevention
The most common preventative measure against mumps is immunization with a mumps vaccine. The vaccine may be given separately or as part of the MMR immunization vaccine which also protects against measles and rubella. In the US, MMR is now being supplanted by MMRV, which adds protection against Chickenpox. The WHO recommends the use of mumps vaccines in all countries with well-functioning childhood vaccination programs. In the United Kingdom it is routinely given to children at age 15 months. The American Academy of Pediatrics recommends the routine administration of MMR vaccine at ages 12-15 months and at 4-6 years. In some locations, the vaccine is given again between 4 to 6 years of age, or between 11 and 12 years of age if not previously given. Efficacy of the vaccine depends on the strain of the vaccine, but is usually around 80%. The Jeryl Lynn strain is most commonly used in developed countries, but has been shown to have reduced efficacy in epidemic situations. The Leningrad-Zagreb strain is commonly used in developing countries, but appears to have superior efficacy in epidemic situations.
Some anti-vaccine activists protest against the administration of a vaccine against mumps, claiming that the attenuated vaccine strain is harmful, and/or that the wild disease is beneficial. Disagreeing, the WHO, the American Academy of Pediatrics, the Advisory Committee on Immunization Practices of the Centers for Disease Control and Prevention, the American Academy of Family Physicians, the British Medical Association and the Royal Pharmaceutical Society of Great Britain currently recommend routine vaccination of children against mumps. The British Medical Association and Royal Pharmaceutical Society of Great Britain had previously recommended against general mumps vaccination, changing that recommendation in 1987. In 1988 it became United Kingdom government policy to introduce mass child mumps vaccination programs with the MMR vaccine, and MMR vaccine is now routinely administered in the UK.
Before the introduction of the mumps vaccine, the mumps virus was the leading cause of viral meningoencephalitis in the United States. However, encephalitis occurs rarely (less than 2 per 100,000). In one of the largest studies in the literature, the most common symptoms of mumps meningoencephalitis were found to be fever (97%), vomiting (94%) and headache (88.8%). The mumps vaccine was introduced into the United States in December 1967: since its introduction there has been a steady decrease in the incidence of mumps and mumps virus infection. There were 151,209 cases of mumps reported in 1968; in 1998 there were only 666 cases reported.
Treatment
There is no specific treatment for mumps. Symptoms may be relieved by the application of intermittent ice or heat to the affected neck area and by Acetaminophen/Paracetamol (Tylenol) for pain relief. Aspirin use is discouraged in young children because of studies showing an increased risk of Reye's syndrome. Warm salt water gargles, soft foods, and extra fluids may also help relieve symptoms.
Patients are advised to avoid fruit juice or any acidic foods, since these stimulate the salivary glands, which can be painful.
Complications
Known complications of mumps include:
· Infection of other organ systems
· Sterility in men (this is quite rare, and mostly occurs in older men)
· Mild forms of meningitis (rare, 40% of cases occur without parotid swelling)
· Encephalitis (very rare, rarely fatal)
· Profound (91 dB or more) but rare sensorineural hearing loss, uni- or bilateral
References
http://www.wikipedia.org
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http://www.emedicine.com
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http://www.healthscout.com
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http://ehs.ucdavis.edu
Served as reference.
http://virology-online.com
Source for Pathogenesis.
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