Mumps Case File

Mumps Case File

Eugene C.Toy, MD, Cynthia Debord, PHD, Audrey Wanger, PHD, Gilbert Castro, PHD, James D. Kettering, PHD, Donald Briscoe, MD

CASE 32

A 6-year-old boy is brought to your office for evaluation of fever, ear pain, and swollen cheeks. His mother reports that he’s had 3 or 4 days of low-grade fever and seemed tired. Yesterday he developed the sudden onset of ear pain and swelling of the cheeks along with a higher fever. He is an only child, and neither of the parents has been ill recently. He has had no significant medical illnesses in his life, but his parents decided not to give him the measles, mumps, rubella (MMR) vaccine because they read that it could cause autism. On examination, his temperature is 38.6°C (101.5°F), and his pulse is 105 beats per minute. He has swollen parotid glands bilaterally to the point that his earlobes are pushed up, and the angle of his mandible is indistinct. His tympanic membranes appear normal. Opening his mouth causes pain, but the posterior pharynx appears normal. You do note some erythema and swelling of Stensen duct. He has bilateral cervical adenopathy.

◆ What is the cause of this child’s illness?

◆ What factor has reduced the incidence of this disease by over 99 percent in the United States?

ANSWERS TO CASE 32: MUMPS

Summary: A 6-year-old boy has tender inflammation of the parotid glands (parotitis) and fever.

◆ Most likely cause of this child’s disease: Mumps virus

◆ Factor decreasing disease incidence by over 99 percent in the United States: Routine vaccination with live, attenuated mumps virus

CLINICAL CORRELATION

The mumps virus is primarily a childhood disease that causes acute, painful swelling of the parotids and other glands. It is a highly communicable disease that has one known serotype and infects only humans. Mumps is endemic around the world, with approximately 90 percent of children being infected by the age of 15. It is now an uncommon illness in countries such as the United States, where a live attenuated vaccine is widely used. The MMR vaccine, a combination vaccine of measles, mumps, and rubella, has resulted in a greater than 99 percent reduction in the incidence of mumps. Almost all cases of mumps now seen are in the unvaccinated or in persons with depressed cellular immunity.

APPROACH TO SUSPECTED MUMPS VIRUS INFECTION

Objectives

1. Be able to describe the characteristics of the mumps virus.
2. Be able to describe the strategies for prevention and treatment of the infection.

Definitions

Parotitis: Inflammation of the parotids; large salivary glands located on each side of the face below and in front of the ear.

Hemagglutinin-neuraminidase protein: A viral capsid glycoprotein involved with viral attachment, fusion, and enzymatic hydrolysis of various proteins; also produces nonspecific agglutination of red blood cells used for diagnostic assay.

Orchitis: Inflammation of the testes.

Oophoritis: Inflammation of one or both ovaries.

DISCUSSION

Characteristics of the Mumps Virus That Impact Transmission The mumps virus is a member of the family Paramyxoviridae. As a paramyxovirus, it is an enveloped, virus with a single-stranded, negative-sense RNA genome. The viral envelope contains two glycoproteins: a hemagglutininneuraminidase protein involved in attachment and a membrane fusion protein. The mumps virus is transmitted to epithelial cells of the mouth or nose via direct contact with contaminated respiratory droplets or saliva or via fomites. The virus then fuses with the host cell membrane via the specific viral attachment and surface fusion proteins, which results in binding to sialic acid on the target cell membrane. Transcription, replication, protein synthesis, and assembly occur in the cytoplasm of the host cell. Newly formed virions acquire their outer envelope by budding through the host cell membrane and are released to infect other host cells. After initial infection and replication in the nasal or upper respiratory tract, viral infection spreads to the salivary glands. Virus infects the parotids or other salivary glands either by ascending infection into the gland through Stensen duct or by viremia. Viral particles are also transmitted to distant organs, such as the kidneys, testes, ovaries, and central nervous system (CNS) through viremic spread.

The symptoms of mumps are often the result of the inflammatory response of the host immune system. Many mumps infections are subclinical, and this, along with the fact that infected persons are contagious even 1–2 weeks prior to developing symptoms, promotes person-to-person spread of the disease. The cell-mediated immune system is responsible for defense against this infection and acquired immunity is lifelong. Passive immunity is transferred from mothers to newborns, and thus, mumps is rarely seen in infants less than 6 months old.

Diagnosis

Cases of mumps are now relatively uncommon, but can be diagnosed primarily by clinical presentation along with a patient history that lacks mumps virus immunization. Clinical symptoms include acute onset of fever and malaise, followed with painful bilateral or unilateral swelling of the parotid or other salivary glands. Ten to twenty percent of cases may progress to more severe infections with CNS involvement, resulting in aseptic meningitis or meningoencephalitis. In adolescent children and adults, additional complications may occur including: orchitis, oophoritis, and pancreatitis. These more severe symptoms are rarer and occur primarily in immunocompromised hosts.

Laboratory diagnosis is not typically required; however, rapid confirmation of mumps infection can be obtained through direct viral antigen detection via immunofluorescence analysis. Appropriate clinical samples for analysis include saliva, CSF, and urine. Alternately, serology can be used to detect a fourfold rise in mumps-specific IgM or IgG antibody in clinical samples. Also, clinical specimens can be cultured in cells for observation of cytopathic effects such as cell rounding and syncytia formation.

Treatment and Prevention

Though mumps is usually self-limiting, it is treated with supportive care: fluids, rest, anti-inflammatories. Patients with mumps or suspected mumps should be isolated for up to a week after symptoms begin or until infection is ruled out. There is no specific antiviral therapy for mumps. However, immunization with the live attenuated mumps virus vaccine provides effective protection against infection.

COMPREHENSION QUESTIONS

[32.1] A 6-year-old child presents to their pediatrician with symptoms of fever, fatigue, and swollen glands. Which of the following patient information would confirm a diagnosis of infection with the mumps virus?

A. A history of exposure to mumps

B. Clinical evidence of orchitis

C. Detection of mumps-specific IgM antibody

D. Resolution of fever followed by signs of encephalitis

[32.2] Which of the following statement regarding infection with the mumps virus is correct?

A. After initial replication, viremic spread can occur to various organs.

B. Diagnosis is made solely on symptoms, as virus cannot be cultured.

C. Passive immunization is the only means of preventing infection.

D. Reinfection is possible, because of the presence of two viral serotypes.

E. Virus is transmitted via the fecal-oral route.

[32.3] Which of the following organs would most commonly exhibit signs of mumps infection?

A. CNS

B. Ovaries

C. Pancreas

D. Parotids

E. Testes

Answers

[32.1] C. The detection of mumps-specific IgM antibody indicates active mumps virus infection; answers A, B, D, and E are incorrect; (A) exposure to mumps does not necessarily cause infection, particularly if the child has been immunized; (B) symptoms of orchitis because of mumps infection occurs only in adolescent males; (D) encephalitis is a more rare complication of mumps infection and is not specific to the mumps virus.

[32.2] A. After initial replication in the upper respiratory tract and salivary glands, viral particles are also transmitted to distant organs such as the kidneys, testes, ovaries, and CNS through viremic spread; answers B, C, D and E are incorrect.

[32.3] D. Swollen parotid glands are a common symptom during infection with the mumps virus; answers A, B, C, and E are possible complications of infection with the mumps virus, but are less commonly occurring.

MICROBIOLOGY PEARLS ❖ Nearly all cases of mumps are seen in unvaccinated children or persons with depressed cellular immunity. ❖ Clinical manifestations: acute fever and painful swelling of the parotids and other glands. ❖ Immunization with a live attenuated mumps virus vaccine has resulted in nearly 100 percent reduction in the incidence of infection.

REFERENCES

Brooks GF, Butel JS, Morse SA. Jawetz, Melnick, & Adelberg’s Medical Microbiology, 23rd ed. New York: McGraw-Hill, 2004:560–2. 

Ryan JR, Ray CG. Sherris Medical Microbiology, 4th ed. New York: McGraw-Hill, 2004:513. 

Centers For Disease Control and Prevention. Vaccines and preventable diseases: mumps vaccines. http://www.cdc.gov/vaccines/vpd-vac/mumps/default.htm.

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