Peggy Weintrub
This year, the Midwest has seen an outbreak of mumps, a disease that most think of as a problem eliminated by vaccination.
According to the
US Centers for Disease Control and Prevention, since 2001 an annual average of 265 mumps cases has been reported nationwide. But as of May 4, more than 2,869 cases have been reported in 13 states -- more than 10 times the national average. Of these, 1,552 are confirmed, probable or suspected cases in Iowa.
In addition, there are 1,305 probable and confirmed cases in seven other states: Nebraska, Kansas, Illinois, Wisconsin, Missouri, Pennsylvania and South Dakota. Five states report cases linked to travelers from Iowa: Colorado, Minnesota, Mississippi, Indiana and New York.
So far, there are no cases that have been associated with the Midwest outbreak in California, according to Peggy Weintrub, MD, clinical professor of pediatrics at UCSF Children's Hospital and chief of the Division of Pediatric Infectious Diseases. But since the mumps outbreak is in the news, we asked Weintrub to tell us more about this infectious disease.
Q: First of all, what is mumps?
A: Mumps is an acute viral infection spread primarily by coughing and sneezing. Some people with mumps are almost asymptomatic or have a mild infection that resembles any other upper respiratory tract infection. In "classic" mumps, the most common symptoms are fever, headache and swollen salivary glands.
Generally, it's a more serious illness in adults than in children. Most people who get mumps do not experience serious complications, though occasionally we see encephalitis (inflammation of the brain), mastitis or oophoritis (inflammation of the breast or ovaries), and orchitis (inflammation of the testes). These problems can lead to permanent hearing loss and male infertility.
Q: You said it is spread by coughing and sneezing. So, the disease is airborne?
A: You can get it from someone actually coughing in your face, but you can also get it from droplets in the room. You can also touch a surface which an infected person recently touched (such as toys, public areas, etc.) and inoculate yourself by touching your eyes, nose or mouth.
Q: How long does it take to get sick from the point at which you're first infected?
A: The usual incubation period from the time you are exposed to the virus until the time you have symptoms is from 16 to 18 days, but the shortest is 11 or 12 days, and it can be up to 25 days. Most people are contagious from about three days before to nine days after the swelling of the glands.
Q: Why has mumps reemerged now? The disease seemed to have been all but eradicated.
A: The mumps vaccine was introduced in 1967 and recommended for universal use in 1977. In the US, we typically assume that people who have had mumps were born before the 1960s. After the vaccine was introduced, the incidence of mumps declined markedly.
Q: We know that the "serotype" of the outbreak virus is serotype G, the same one that has been circulating in the United Kingdom. Do we think it was brought here from the UK?
A: In truth, we don't really know how this started. The UK has had recent outbreaks of mumps, though we do not know if this is linked to the cases here in the US.
Q: Then why are we seeing a significant outbreak of mumps in 2006?
A: Remember that vaccination is not 100 percent effective. One dose of the vaccine confers about 80 percent immunity; a second dose confers about 90 percent immunity. That means that in a 100 percent vaccinated population, 10 percent of the people still won't be immune. That's generally acceptable and results in only sporadic cases.
However, when you have a group of people living together in close quarters for an extended period of time (like in the military or a college dorm), there is a higher probability of infection. This appears to be the case in the Midwest, where it began on a college campus and most of the cases are between 18 and 25 years old. If the population hadn't been vaccinated, we wouldn't be talking about 1,100 cases, but many more.
Q: Have there been any cases in California or the Bay Area?
A: We always have sporadic cases. There are somewhere in the neighborhood of 250 cases of mumps per year in the country, so some will be in California. But we haven't had any cases that are linked to the outbreak.
Q: What should parents who might be concerned about their children getting the mumps do?
A: Parents should make sure that all their children of any age are fully immunized for this and other vaccine-preventable diseases.
Links:
Centers for Disease Control and Prevention: Mumps
