| disease | Mumps |
| alias | Mumps, Mumps, Mumps, Epidemic Parotitis |
Mumps, also known as epidemic parotitis, is a common respiratory infectious disease among children and adolescents, and can also occur in adults. The disease is caused by the mumps virus, which primarily affects the parotid glands but can also invade various glandular tissues, the nervous system, and almost all organs such as the liver, kidneys, heart, and joints. Therefore, in addition to swelling and pain in the parotid glands, it can often cause symptoms such as meningitis, encephalitis, orchitis, pancreatitis, and oophoritis.
bubble_chart Epidemiology
Mumps is a common pestilence disease worldwide. It can occur throughout the year, with the highest incidence in spring and winter in temperate regions, and less in summer, but outbreaks can still occur. In tropical regions, there is no seasonal variation. It can occur in epidemics or sporadically. Outbreaks are prone to occur in children's collective institutions, military units, and crowded populations with poor sanitary conditions. Foreign literature has mentioned that before the widespread use of vaccines, the disease tended to have periodic pandemics every 7 to 8 years, which was clearly a consequence of the accumulation of susceptible populations. With continuous improvement in living conditions and planned preventive immunization for susceptible populations, such periodic epidemics can be prevented. Since the gradual expansion of mumps vaccination in the United States starting in December 1967, the incidence rate has significantly declined. Particularly, since 1980, it has been mandated that all susceptible children, adolescents, and adults, except those with contraindications, must receive immunization. However, the annual incidence rate of mumps in the United States in 1986 and 1987 increased threefold compared to the average incidence rate of the previous five years. In 1989, it was further mandated that children aged 4 to 6 years receive booster immunization. However, over the past decade, the incidence of mumps in China has continued to rise steadily.
From January 1982 to December 1993, the Pediatric Hospital of Shanghai Medical University recorded a total of 38,517 cases of mumps in its pestilence disease outpatient clinic, of which 1,763 cases were hospitalized due to severe illness (such as high fever, prolonged fever, etc.) or complications. The data also revealed a pattern where the epidemic peak lasted for 1 to 3 years, followed by a one-year low, and then rapidly entered the next higher peak. This pattern occurred three times over the 12-year period. The disease occurs throughout the year, with the epidemic peak occurring from April to July.The mumps virus (paramyxovirus parotitis) belongs to the paramyxovirus family, which includes viruses such as parainfluenza, Newcastle, measles, and respiratory syncytial virus. It is an RNA-type virus, first isolated from a patient's saliva in 1934, and successfully infected monkeys and "volunteers". The virus has a diameter of about 85-300nm, with an average of 140nm. It is highly sensitive to physical and chemical factors, and can be inactivated by 1% lysol, ethanol, 0.2% formalin, etc. within 2-5 minutes. It dies quickly when exposed to ultraviolet light, and its activity can be maintained for 2 months at 4℃, 24 hours at 37℃, and loses activity after 10-20 minutes when heated to 55-60℃. It can survive for several months to several years at -65℃. The virus is only found in humans, but can proliferate in monkeys, chicken embryo membranes, and various human and monkey tissue cultures. Monkeys are most susceptible to this disease. The virus has only one serotype.
The nucleocapsid protein of the mumps virus has a soluble antigen (S antigen), and its outer surface contains neuraminidase and a hemagglutinin glycoprotein with viral antigen (V antigen). Both S antigen and V antigen have their corresponding antibodies. S antibody appears on the 7th day after the onset of the disease and reaches its peak within two weeks, then gradually decreases and can be maintained for 6-12 months. It can be detected by the complement fixation method, but S antibody is not protective. V antibody appears later, and can be detected 2-3 days after the onset of the disease, reaching its peak 1-2 weeks later, but it exists for a long time. It can be detected by complement fixation, hemagglutination inhibition, and neutralization antibody methods, and is the best indicator for detecting immune response. V antibody has a protective effect. Whether or not the disease occurs after infection with the mumps virus, an immune response can be generated, and it is rare for the disease to occur again after re-infection.
In the early stage of the disease, the mumps virus can be isolated from saliva, blood, cerebrospinal fluid, urine, or thyroid. The virus rarely mutates, and the antigenicity between different strains is very close.It is widely believed that the virus first invades the oral mucosa and nasal mucosa, proliferates extensively in the epithelial tissue, and then enters the bloodstream (first viremia), spreading through the blood to affect the parotid gland and some tissues, where it further proliferates. It then re-enters the bloodstream (second viremia) and invades some organs that were not previously affected. In the early stages of the disease, the mumps virus can be isolated from oral and respiratory secretions, blood, urine, milk, cerebrospinal fluid, and other tissues. Some have isolated the virus from the placenta and fetus. The fact that some patients may never develop parotid swelling throughout the course of the disease, while conditions such as meningitis, encephalitis, and orchitis can appear before parotid swelling, also supports the view that the mumps virus first invades the oral and nasal mucosa and spreads through the bloodstream to affect various organs and tissues. Some also believe that the virus has a special affinity for the parotid gland, so after entering the oral cavity, it invades the parotid gland through the parotid duct, proliferates within the gland, and then enters the bloodstream, causing viremia and affecting other tissues.
Various glandular tissues such as the testes, ovaries, pancreas, intestinal serous enzyme-producing glands, thymus, and thyroid all have the potential to be invaded. The brain, meninges, liver, and myocardium are also often affected, leading to a wide range of clinical manifestations of mumps. Meningoencephalitis is a consequence of the virus directly invading the central nervous system, and the pathogen can be isolated from the cerebrospinal fluid.
The main pathological change in mumps is non-suppurative inflammation of the parotid gland, which becomes swollen and red, with exudate, hemorrhagic foci, and leukocyte infiltration. The parotid duct exhibits catarrhal inflammation, with serofibrinous exudate and lymphocyte infiltration around the duct and in the glandular interstitium. The duct is filled with cellular debris and a small number of neutrophils. The overlying skin shows edema, necrosis, and congestion of blood vessels between the acini. There is significant edema around the parotid gland, and nearby lymph nodes are congested and swollen. There is little change in the composition of saliva, but the secretion volume is reduced compared to normal.Due to partial obstruction of the parotid duct, the excretion of saliva is hindered, so consuming acidic foods can cause distending pain due to increased saliva secretion and retention. Saliva contains amylase, which can enter the bloodstream through the lymphatic system, leading to elevated blood amylase levels and excretion in the urine. The pancreas and intestinal serous enzyme-producing glands are also affected. The virus tends to invade mature testes, and orchitis is rare in young patients. The epithelium of the seminiferous tubules in the testes shows significant congestion, hemorrhagic spots, and lymphocyte infiltration, with edema and serofibrinous exudate in the interstitium. The pancreas exhibits congestion and edema, with grade I degeneration and fatty necrosis in the islets.
bubble_chart Clinical Manifestations
The incubation period is 8 to 30 days, with an average of 18 days. Most patients do not have prodromal symptoms, and the first sign of illness is swelling below the ear. A few cases may experience brief non-specific discomfort (lasting from a few hours to 2 days), with symptoms such as muscle soreness, loss of appetite, fatigue, headache, low-grade fever, conjunctivitis, and pharyngitis. Over the past decade, the severity of mumps in China has increased, characterized by longer fever duration, more complications, and a higher proportion of hospitalized children among outpatient cases.
The onset is mostly acute, with symptoms such as fever, chills, headache, loss of appetite, nausea, vomiting, and generalized pain. Swelling of the parotid gland becomes apparent within a few hours to 1-2 days. Fever ranges from 38 to 40°C, and the severity of symptoms varies widely, with adult patients generally experiencing more severe symptoms. The most characteristic feature is swelling of one parotid gland first, although both sides may swell simultaneously. The swelling typically centers around the earlobe, extending forward, backward, and downward, resembling a pear shape with a firm texture and indistinct edges. When the gland is significantly swollen, distending pain and sensory changes occur, worsening with mouth opening, chewing, or consuming acidic foods. The local skin becomes tight and shiny, with a burning sensation but usually no redness, and mild tenderness on touch. The surrounding connective tissue may also show edema, extending upward to the temporal region and zygomatic arch, downward to the jaw and neck, and occasionally involving the sternocleidomastoid muscle (rarely, edema may appear in front of the sternum), leading to facial distortion.
Usually, the swelling of one parotid gland is followed by involvement of the opposite side within 1-4 days (occasionally after 1 week), with bilateral swelling occurring in about 75% of cases. The submandibular or sublingual glands may also be affected simultaneously. Swelling of the submandibular gland causes noticeable neck swelling, with a soft, tender, oval-shaped gland palpable under the jaw. The sublingual gland may also be involved, causing swelling of the tongue and neck, along with difficulty swallowing.
The opening of the parotid duct (located on the buccal mucosa near the upper second molar) often shows redness and swelling in the early stages. Saliva secretion initially increases but then decreases due to retention, although dry mouth symptoms are generally not prominent.
Parotid gland swelling usually peaks within 1-3 days, persists for 4-5 days, and then gradually subsides, returning to normal. The entire course of the disease lasts about 10-14 days.
Atypical cases may present without parotid gland swelling, instead manifesting as simple orchitis or meningoencephalitis, or only showing swelling of the submandibular or sublingual glands.
bubble_chart Auxiliary Examination
1. Peripheral blood picture: The white blood cell count is mostly normal or slightly increased, with a relative increase in lymphocytes. In cases with complications, the white blood cell count may increase, and occasionally a leukemoid reaction may occur.
2. Serum and urine amylase measurement: In 90% of patients, serum amylase is mildly to moderately increased (grade II), and urine amylase is also increased, which aids in diagnosis. The degree of amylase increase often correlates with the degree of parotid gland swelling, but the increase may also be related to pancreatic and small intestine serous enzyme gland lesions.
3. Serological tests
(1) Neutralizing antibody test: A low titer such as 1:2 suggests current infection.
In recent years, the Hemolysis-in-Gel method has been used, which is consistent with the neutralization test but is simpler and faster than the detection of neutralizing antibodies, although the method still requires further improvement.
(2) Complement fixation test: This test has auxiliary diagnostic value for suspected cases. A fourfold or greater increase in titer between paired sera (early in the course of the disease and at 2-3 weeks) or a single serum titer of 1:64 is diagnostic. If conditions permit, both S and V antibodies should be measured. An increase in S antibody indicates recent infection, while an increase in V antibody without an increase in S antibody only indicates past infection.
(3) Hemagglutination inhibition test: The amniotic fluid and allantoic fluid of virus-infected chicken embryos can agglutinate chicken red blood cells. The serum of mumps patients in the convalescent stage has a strong agglutination inhibition effect, while the inhibition effect of early serum is weaker. A fourfold or greater difference in titer between two measurements is considered positive.
(4) Virus isolation: In early cases, mumps virus can be isolated from saliva, urine, blood, cerebrospinal fluid, and other tissues such as the brain and thyroid. The procedure is complex and is not widely available at present.
(5) When the kidneys are involved, proteinuria, red and white blood cells, and even changes similar to nephritis may appear in the urine. {|108|}
The diagnosis is not difficult based on the prevalence, contact history, and characteristics of parotid gland swelling. In cases of atypical or suspicious instances, further confirmation can be achieved through the aforementioned laboratory examination methods.
bubble_chart Treatment Measures
Isolate the patient and ensure bed rest until the swelling of the parotid gland completely subsides. Pay attention to oral hygiene, and the diet should preferably consist of fluids and soft foods, avoiding acidic foods, and ensuring adequate fluid intake.
General antibiotics and sulfonamide drugs are ineffective. Interferon has been tried and seems to have some therapeutic effect.
The efficacy of adrenal cortical hormone therapy is not yet confirmed, but it may be considered for short-term use in severe cases or when complications such as meningitis, encephalitis, or myocarditis occur.
Local helium-neon laser irradiation for the treatment of mumps has certain effects on pain relief and swelling reduction.
Symptomatic treatment, including dehydration agents, can be given for high fever, headache, vomiting, etc. Complications should be managed according to the condition.
For adult male patients, the early application of diethylstilbestrol, taken orally three times a day, 1mg each time, may have the effect of preventing orchitis.
Most cases are mild, but some are accompanied by severe complications. Serious conditions such as severe meningoencephalitis, myocarditis, and nephritis must be handled with caution and actively treated.
Isolate patients early until the swelling of the parotid gland completely subsides. Contacts generally do not necessarily require quarantine, but in collective children's institutions (including hospitals, schools), military units, etc., they should be kept under observation for 3 weeks. Suspected patients should be immediately and temporarily isolated.
Mumps attenuated live vaccine: Chicken embryo cell culture attenuated live vaccine, which has been widely used abroad since 1966, has an infection prevention effect of up to 97% in children and 93% in adults. The mumps live vaccine is used in combination with measles and rubella vaccines with satisfactory results, and there is no interference among the three. After immunization, the neutralizing antibodies of the mumps virus can be maintained for at least 9.5 years.
In addition to intradermal and subcutaneous injections, the mumps live vaccine can also be administered through nasal spray or aerosol inhalation (conducted in an aerosol chamber) with good results.
Materials from our country prove that six months after immunization (combined nasal spray and aerosol inhalation), the incidence rate in the children's immunization group (7.4%) is significantly lower than that in the corresponding control group (78.5%), and the incidence rate in the adult immunization group (0.33%) is also lower than that in the corresponding control group (4.6%), with no adverse reactions. Given the high incidence rate and severity of the disease in our country, the use of the mumps vaccine (including for adults) should be planned. Especially for new classes in kindergartens, universal immunization can significantly reduce the incidence. Currently, the application of this vaccine is gradually being promoted in our country.
The mumps live vaccine cannot be used in pregnant women (to prevent the virus from infecting the fetus through the placenta and causing adverse consequences), individuals with congenital or acquired immunodeficiency, and those allergic to egg protein (because the live vaccine is derived from chicken embryos).
General immune globulin, adult blood, or placental globulin do not have a preventive effect on this disease. The blood of patients in the convalescence stage and their immune globulin or specific high-titer immune globulin may be useful, but they are difficult to obtain, and the protection time after use is short, only 2-3 weeks, so they are not used much, and their effectiveness needs further study.
Mumps is actually a systemic infection, and the virus often involves the central nervous system or other glands or organs, leading to corresponding symptoms. Some complications are not only common but can also occur without the swelling of the parotid gland.
1. Neurological complications
(1) Aseptic meningitis, meningoencephalitis, encephalitis: These are common complications, especially in pediatric patients, with boys being more affected than girls.
The incidence of encephalitis in mumps is about 0.3% to 8.2%. Since not all mumps patients undergo cerebrospinal fluid examination, and some cases never show parotid gland swelling, it is difficult to calculate the exact incidence. It is said that in uncomplicated mumps, 30-50% or even 65% of patients have an increased white blood cell count in the cerebrospinal fluid, caused by the virus directly invading the central nervous system. Symptoms of meningoencephalitis can appear as early as 6 days before or up to 2 weeks after the parotid gland swelling, usually within 1 week after the swelling. The cerebrospinal fluid and symptoms are similar to other viral encephalitis, including headache, vomiting, etc., with acute cerebral edema being more pronounced. The EEG may show changes but not as obvious as in other viral encephalitis, and clinically, it mainly involves the meninges. The prognosis is generally good, although individual encephalitis cases can lead to death. There have been cases of mumps encephalitis confirmed by serology in China, where there was no parotid gland swelling or pain from beginning to end.
(2) Occasionally, multiple neuritis or myelitis may occur 1 to 3 weeks after mumps, with a generally good prognosis. The swollen parotid gland may compress the facial nerve, causing temporary facial paralysis. Sometimes, imbalance, trigeminal neuritis, hemiplegia, paraplegia, ascending paralysis, etc., may occur. Rarely, mumps can lead to hydrocephalus due to aqueductal stenosis.
(3) Deafness: Caused by involvement of the auditory nerve. Although the incidence is not high (about 1/15,000), it can result in permanent and complete deafness, but fortunately, 75% are unilateral, so the impact is not significant.
2. Reproductive system complications Mumps virus tends to invade mature reproductive glands, so it is more common in patients after puberty, and rare in children.
(1) Orchitis: The incidence is 14-35% in adult male patients, with reports of 9-year-old children also developing this condition. The incidence significantly increases after the age of 13-14. It usually occurs about 1 week after the parotid gland swelling starts to subside, with sudden high fever, shivering, testicular distending pain, accompanied by severe tenderness, varying in severity, and generally subsides in about 10 days. Scrotal skin edema is also significant, and there may be yellow fluid in the tunica vaginalis cavity. The condition mostly affects one side, and about 1/3 to 1/2 of cases experience varying degrees of testicular atrophy. Since the condition is often unilateral, even if bilateral, only part of the seminiferous tubules are involved, so it rarely leads to infertility. Epididymitis often occurs concurrently.
(2) Oophoritis: About 5-7% of adult female patients. The symptoms are mild and do not affect fertility, but may occasionally cause premature amenorrhea. Symptoms of oophoritis include lower back pain, mild lower abdominal tenderness, menstrual cycle disorders, and in severe cases, an enlarged ovary with tenderness can be palpated. So far, there have been no reports of infertility caused by this.
(3) Pancreatitis: Seen in about 5% of adult patients, rare in children. It usually occurs 3, 4 days to 1 week after parotid gland swelling, with severe pain and tenderness in the upper middle abdomen as the main symptoms. Accompanied by vomiting, fever, abdominal distension and fullness, diarrhea or constipation, etc., sometimes an enlarged pancreas can be palpated. Pancreatitis symptoms usually disappear within a week. Blood amylase is not suitable as a diagnostic basis, and a serum lipase value exceeding 1.5U/dl (normal 0.2-0.7U/dl) suggests recent pancreatitis. Lipase usually rises 72 hours after the onset, so it has little value in early diagnosis. In recent years, as the condition of pediatric patients has become more severe, the complication of pancreatitis has also increased. Among 1763 children hospitalized for complications at the Pediatric Hospital of Shanghai Medical University from 1982 to 1993, 43 cases were complicated by pancreatitis, ranking second only to meningoencephalitis.
⑷ Nephritis: In early cases, the mumps virus can be isolated from the urine in the vast majority of cases, suggesting that the virus can directly damage the kidneys. In mild cases, there may be a small amount of protein in the urine, while in severe cases, the urine routine and clinical manifestations resemble those of nephritis. In rare severe cases, acute renal failure may occur, leading to death. However, the prognosis is good for most patients.
⑸ Myocarditis: Approximately 4-5% of patients develop myocarditis. It is most commonly seen 5-10 days into the course of the disease and can occur simultaneously with parotid swelling or during the stage of convalescence. Manifestations include pale complexion, increased or decreased heart rate, muffled heart sounds, arrhythmia, temporary cardiac enlargement, and systolic murmurs. Electrocardiogram may show sinus arrest, atrioventricular block, ST segment depression, flat or inverted T waves, and premature beats. Severe cases can be fatal. Most cases only show ECG changes (3-15%) without obvious clinical symptoms, and pericarditis is occasionally seen.
⑹ Others: Mastitis (31% of female patients over 15 years old develop this condition), osteomyelitis, hepatitis, pneumonia, prostatitis, bartholinitis, thyroiditis, thymitis, thrombocytopenia, urticaria, acute follicular conjunctivitis, etc., are all rare. The incidence of arthritis is about 0.44%, mainly affecting large joints such as the elbows and knees, and can last from 2 days to 3 months, with complete recovery possible. It mostly occurs within 1-2 weeks after parotid swelling, but there are also cases without parotid swelling.
⑴ Suppurative parotitis: Often unilateral, with obvious local redness, swelling, and tenderness. In the advanced stage, there is a sense of fluctuation, and pus can be squeezed out from the parotid duct. The total white blood cell count and neutrophils are significantly increased in the blood count.
⑵ Cervical and preauricular lymphadenitis: The swelling is not centered around the earlobe, but is limited to the neck or preauricular area. It is nodular, relatively hard, with clear edges, obvious tenderness, and superficial mobility. Inflammation related to the cervical or preauricular lymph nodes can be found, such as pharyngitis, ear boils, etc. The total white blood cell count and neutrophils are increased.
⑶ Symptomatic parotid swelling: In diabetes, malnutrition, chronic liver disease, or the use of certain drugs such as iodides, oxyphenbutazone, isoproterenol, etc., can cause parotid swelling. It is symmetrical, without swelling or pain, and feels soft on palpation. Histological examination mainly shows fatty degeneration.
⑷ Parotitis caused by other viruses: It is known that parainfluenza virus types 1 and 3, influenza A virus, coxsackievirus A, herpes simplex virus, lymphocytic choriomeningitis virus, and cytomegalovirus can all cause parotid swelling and central nervous system symptoms. Etiological diagnosis is required.
⑸ Parotid swelling caused by other reasons: Allergic parotitis and parotid duct obstruction have a history of recurrent episodes, with sudden swelling and rapid resolution. Simple parotid swelling is more common in adolescent males, due to functional hypersecretion and compensatory parotid swelling, without other symptoms.
⑹ Meningoencephalitis caused by other viruses: Mumps meningoencephalitis can occur before parotid swelling (some cases never have parotid swelling), making it difficult to distinguish from those caused by other viruses. Diagnosis can be confirmed by the aforementioned serological tests, virus isolation, and epidemiological investigations. {|105|}
