Mumps is back, not as a new agent, but because it outlasted our immunity. Mumps is defined as unilateral or bilateral parotid or other salivary gland swelling lasting two or more days without an apparent cause. The disease is usually benign and self-limited, although there are several rare complications, with approximately one-third of patients having subclinical infections.
Mumps is generally seen in school-aged children and teenagers. It is caused by the paramyxovirus, although parotiditis may be caused by a variety of infectious and non-infectious causes. (VPD Surveillance Manual, 3LK rd ed. 2002:1.) Mumps, however, is only caused by the paramyxovirus, and is epidemic in contrast to the many other causes.
Hippocrates first described its epidemic characteristics in the 5LK th century, and it wasn't until the middle of the 20LK th century that meaningful work studying the virus and developing an effective vaccine was done. The word mumps is attributed to several sources: the English noun means lump, and the verb which means sulky or the mumbling speech many patients develop. Mumps is reportable to the Centers for Disease Control and Prevention and to many if not all state health departments. A history of illness confers lifelong immunity. (Douglas and Bennett's Principles and Practice of Infectious Disease. 6LK ed. 2005: 2003. Accessed June 12, 2006.)
The disease, which begins after an incubation period of approximately 16 to 18 days, is characterized by the usual nonspecific viral symptoms of fever, malaise, headache, anorexia, and low-grade fever. Several days later, parotid gland swelling, usually bilateral, begins. This lasts for another seven to 10 days. On exam, the enlarged parotid will obscure the angle of the mandible and push the earlobe upward and outward. On intraoral exam, Stenson's duct will be enlarged and inflamed. There is often some degree of trismus, and citrus juice exacerbates the pain.
In approximately 10 percent of cases, other salivary glands such as the submandibular and submental are affected. Meningitis is the most common extra-glandular manifestation of the virus, with approximately 50 percent of patients having clinical or subclinical cerebrospinal fluid involvement. (Acta Med Scand 1943;113:487.)
Other nervous system involvement includes deafness (which begins with vertigo), ataxia, Guillain-Barre syndrome, and transverse myelitis. The most common complication outside the glandular system is epididymo-orchitis. This occurs in about one-third of post-pubertal men, and is usually unilateral, and begins with abrupt onset of fever, chills, nausea, vomiting, and testicular pain.
On exam, the testicle and scrotum are tender and swollen, and this lasts approximately one to two weeks. Interestingly, in about half the men with this complication, the affected testicle will show permanent atrophy. Mastitis has been reported in up to 30 percent of girls and women over 15 with mumps. (VPD Surveillance Manual, 3LK ed. 2002:1.)
Uncommon complications include arthritis, pancreatitis, prostatitis, hepatitis, and nephritis. In pregnant women who contract mumps, there is an increased risk of first trimester fetal demise but no increased risk of birth defects. (Douglas and Bennett's Principles and Practice of Infectious Disease. 6LK ed. 2005: 2003. Accessed June 12, 2006.) Overall, the patient should expect to feel ill for about a week with uncomplicated mumps. This disease is almost never fatal, and treatment is supportive.
The diagnosis is usually made clinically, especially in an epidemic situation (i.e., family members) by history and physical exam. One should ask a patient's immunization status, specifically whether he has had one or two measles-mumps-rubella (MMR) vaccinations. The white blood count is usually normal, but the serum amylase is almost always elevated, and will remain that way for two to three weeks. For confirmation (for epidemiological statistics or diagnostic uncertainty), there are two avenues: serum IgM (ELISA) or viral culture using saliva, cerebrospinal fluid, or urine. Few local laboratories do this culture, so serum studies are the method of choice. Convalescent IgG is the method for determining immunity.
The mumps vaccine was released in 1967, and since then incidence has declined drastically. Sporadic outbreaks occurred in the 1980s, and they were attributed to unvaccinated children and young adults. In 1989, after an outbreak of measles, the Centers for Disease Control and Prevention updated its vaccination recommendations for the MMR vaccine to include a second dose.
In the 1990s, mumps outbreaks occurred in highly vaccinated populations, and although most had had at least one MMR vaccine, more than half had had two immunizations. In 1998, the Advisory Committee on Immunization Practices (ACIP) recommended changing the age for primary immunizations, providing a second dose to school-aged children, establishing serological standards, and advising health care workers to document immunity (either by a second dose, history of infection, or serological studies). (MMWR June 9, 2006;55:629.)
The most recent outbreak began in Iowa last December, and as of this May, it had spread to 10 different states. (MMWR May 26, 2006;55:559.) The ACIP responded by changing the recommendations, and these are summarized in the table. Because many people born before 1957 had the disease (clinical or subclinical infection), being born before then is considered presumptive immunity. A study looking at second-dose immunity indicated an 88 percent effectiveness of two MMR vaccines versus 64 percent for one vaccine. (Vaccine 2005;23:4070.) In Finland, which has a two-dose vaccine program, mumps has been declared eliminated. (N Engl J Med 1994;331:1397.)
The bottom line is that we should be looking for this reemerging virus until the vast majority of the U.S. population receives a second MMR.
Key Changes to Recommendations on Mumps by the Advisory Committee on Immunization Practices
May 17, 2006
Acceptable Presumptive Evidence of Immunity
Documentation of adequate vaccination (2 doses) of live mumps virus for:
- Children from kindergarten through 12th grade.
- High-risk adults who work in health care, who travel internationally, and who attend post-high school education institutions.
Routine Vaccination for Health Care Workers
- Those born before or in 1957 without other evidence of immunity: Two doses of live mumps virus vaccine.
- Those born before 1957 without other evidence of immunity: Consider recommending one dose of a live mumps virus vaccine.
For Outbreak Settings
- Children 1–4 and adults at low-risk: If affected by the outbreak, consider a second dose of live mumps virus vaccine.*
- Health care workers born before 1957 without other evidence of immunity: Strongly consider two doses of live mumps virus vaccine.*
- Minimum interval between doses must be 28 days.
Source: MMWR June 9, 2006;55:629.