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The 2014 Ohio Mumps Outbreak

As I write this post, a large outbreak of mumps is ongoing in Columbus, Ohio. The city, which on average sees a single case each year, has seen over 250 since February. To put things in further perspective, only about 440 cases are normally diagnosed in the entire United States annually. The outbreak began on the campus of Ohio State University, where about 150 cases have been identified, but no information about the index case has been reported thus far.

Although the current outbreak will likely smolder for months, the total number of cases thus far is considerably fewer than the worst of the past decade. A 2009-2010 outbreak in New York and New Jersey ended up affecting about 3,000 people. In 2006, about 6,500 college students throughout the Midwest were infected. It is unlikely we will see these kinds of numbers in Ohio, but even our worst in recent years pale in comparison to those that have occurred in England over the past decade, where there was a peak of about 56,000 documented cases in 2005.

The diagnosis of only a few hundred cases per year is a clear victory of the mumps vaccination program, which started in 1967. Prior to the widespread adoption of the vaccine, 186,000 cases were seen in the United States annually. That works out to a decrease in cases of over 99%. This reduction didn’t occur because of improved sanitation, cleaner water, or even sunspots. It occurred because of the hard work and dedication of vaccine researchers, medical professionals and the widespread public acceptance of a safe and effective vaccine.

Mumps doesn’t get the kind of press that measles outbreaks do. There are a number of reasons why this is true and reasonable. I will get into more detail, but essentially mumps, although it can result in significant morbidity, just isn’t as sexy and it isn’t a good candidate for anti-anti-vaccine poster child. Measles wins in that regard, and let’s hope it stays that way. I am terrified at the thought of HiB meningitis returning. But that doesn’t mean that mumps outbreaks can’t serve as fodder for educating the public on vaccines. First though, a primer on mumps.

What is mumps?

Mumps, like measles, is a viral infection for which humans are the only natural host. The single-stranded RNA mumps virus is, also like measles, a member of the Paramyxovirus family of viruses, which is quite an interesting group. This family of viruses also includes respiratory syncitial virus (RSV), which is the major cause of respiratory infection in young children and the most common illness leading to hospitalization in kids under 2 years of age. Croup, another classic pediatric illness, is also caused by a Paramyxovirus, as is canine distemper virus and a morbillivirus that infects dolphins.

Historically, young school-age children were the most likely to be diagnosed, but that changed after vaccination efforts took hold. Over time, an evolution in the epidemiology occurred. After the mumps vaccine was in widespread use, initially the bulk of cases were diagnosed in unimmunized children and adolescents, with 1 out of 10 cases being seen in adults who were born prior to the vaccine becoming available or mandatory for school entry. This led to the current recommendations of a dose of MMR (measles-mumps-rubella) at 12 to 15 months and again at 4 to 6 years of age, as well as documentation of vaccination for college students, although that is only required in 25 states.

As mentioned above, there have been several outbreaks in recent years. Although there have been instances where pockets of children who were not vaccinated have become ill, the majority of cases these days occur in the partially- and even fully-immunized. The most important factor in these outbreaks has been close proximity. Schools, camps and military posts have all been the site of case clusters.

Patients, while still predominantly young, now skew a bit older, in part because of being crammed together in dorms, for instance, but also because of shortcomings in the available vaccine. While the measles component of the MMR is upwards of 99% effective after two doses, the mumps counterpart is only about 80 to 90% effective. So mumps outbreaks, although rendered infrequent and less severe by our vaccine strategy, will likely continue to occur.

Anyone who is susceptible, whether immunized or not and regardless of age, can become ill when exposed to the virus. The mumps virus is very infectious and easily moves from one susceptible person to another, particularly if they are living in close quarters. The virus is spread suspended in respiratory droplets but can also be transferred by direct contact with an infected person or with a virus-carrying fomite. Once infected, the virus usually builds up for a couple of weeks before causing symptoms, but it can be shed in secretions for a few days before the first sign of illness and for several days after.

What does mumps do?

In many people infected with mumps, there are no apparent symptoms. As many as 15 to 20% will be completely asymptomatic in fact. And we think that roughly half of those infected will only have nonspecific respiratory complaints that are indistinguishable from the common cold. Although likely not to the same degree as those with more classic mumps, these lucky individuals still are capable of spreading the infection.

Classic mumps typically also involves some initial nonspecific symptoms, including mild fever, loss of energy and appetite and generalized body aches. What happens next in about 95% of patients is what makes mumps so recognizable to the public. Within a couple of days of the onset of symptoms, both parotid glands (in most cases although not always at the same time) become inflamed, swollen and very tender. This often causes the angle of the jaw to be completely hidden by the swollen tissue and it can last up to 10 days. The one case of mumps I’ve seen, which I diagnosed during a small outbreak in Louisiana in 2010, fit this description.

Although the classic presentation is uncomfortable for patients, it isn’t deadly and there are no long-term problems that result. Unfortunately, mumps is known to cause more serious complications in other areas of the body. Orchitis, inflammation of the testicles, is the most common of these when the patient is a postpubertal male, occurring in about a third of patients. This can result in testicular atrophy and impaired fertility. Sterility is rare but can occur when both testes are involved. A similar phenomenon, oophoritis or inflammation of the ovaries, can occur in postpubertal women although it is much less common.

The most common complication of mumps after involvement of the parotid glands, however, is meningitis. Luckily, it is often mild, perhaps only causing headache, but it can be more significant in 4-6% of cases. The prognosis is excellent with full neurologic recovery expected. Mumps can also cause encephalitis, which is widespread inflammation of the brain itself rather than just the outer covering as with meningitis. Before the vaccine, mumps encephalitis was the most common viral cause of the condition, occurring in about 1 out of every 6,000 cases. Mumps encephalitis causes fever and changes in mental status (by definition), and can result in seizures, weakness and even transient paralysis. Like viral meningitis, recovery tends to be complete.

Prior to the mumps vaccine, many children suffered hearing loss because of the infection. It typically only involved one ear, and the degree of hearing loss was variable. But cases of permanent bilateral deafness were known to happen.

There are more associated complications, such as Guillain-Barre syndrome and facial palsy. There have also been reports of arthritis, pancreatitis and even fatal inflammation of the heart, but these are considered to be rare. One very good bit of news is that mumps, as opposed to rubella (also included in the MMR vaccine) is not associated with birth defects when a pregnant woman is infected. Congenital rubella is an awful syndrome, much worse than mumps and even measles, and has become extremely rare because of the vaccine.

What do we do about mumps?

There is no specific treatment for mumps. The general approach is to reduce symptoms with medicines for fever, if the patient is uncomfortable, pain and inflammation. Often this can be accomplished with the same medicine, ibuprofen being a good choice. Some patients find the use of warm and/or cold packs helpful in dealing with a tender and swollen parotid gland. Ice, and elevation of the swollen scrotum, along with ibuprofen, can ease symptoms of patients with orchitis.

Hospitalization is rarely necessary, but may be warranted in cases of meningitis, encephalitis, or pancreatitis. The case I admitted back in 2010 was initially misdiagnosed in the emergency department as having a bacterial infection of the parotid gland, something which would be extremely rare in a child. But then again, so is mumps. And we weren’t aware of the small cluster of cases at the time.

The most important aspect of managing mumps is preventing spread to others. Isolation is often recommended for up to 5 days after onset of symptoms. Vaccination of susceptible individuals exposed to a patient with mumps is also recommended, although to date there are no studies supporting its efficacy in preventing symptoms from that exposure. The goal of this CDC recommendation is primarily to prevent infection from a new exposure during a current outbreak or from one in the future.

What the CDC Advisory Committee on Immunization Practices (ACIP) considers to be an adequate immunization status changed after the 2006 outbreak. Instead of one dose of MMR for children in kindergarten through 12th grade being considered adequate, they now require two. This is also true for high-risk adults, which includes those who work in healthcare facilities, travelers to mumps-endemic regions and college students. During an outbreak, they recommend giving a 2nd dose early to children aged 1 to 4 years and all adults. There is some evidence from the 2009 outbreak to support that offering a third dose might be helpful in decreasing spread of the infection, although this has yet to be replicated.

So why all the mumps?

The vaccine for mumps is a component of the MMR (technically also the MMRV, which includes varicella), the same MMR that has been the focus of controversy manufactured by a vocal minority of anti-vaccine celebrities, politicians and pseudoskeptical researchers over the past several years. The anti-vaccine movement, particularly in the UK, is clearly linked to an increase in vaccine-preventable illnesses and many experts are worried that we haven’t seen the worst yet. This has been covered extensively on Science-Based Medicine in the past.

The mumps component of the MMR, just like the measles vaccine, contains a weakened but live virus that has been processed using animal cells. Since 1978, the Jeryl Lynn vaccine strains have been used to make all mumps vaccine in the United States. This combination of two strains was cultured from the throat of Jeryl Lynn Hilleman, daughter of mumps vaccine developer Maurice Hilleman, in 1963. Hilleman developed eight of the current vaccines in use and is credited as saving more lives than any other scientist in the 20th century, although Norman Borlaug fans may not agree.

Where the similarity between the mumps and measles vaccines ends is when we look at effectiveness. We know that the mumps vaccine works pretty well. There is simply no other explanation for the dramatic decreases in incidence after it came on the scene. But continued sporadic and sometimes significant outbreaks speak to the fact that we certainly wish it worked better. The measles vaccine, after two doses, results in roughly 99% of people being protected from disease if exposed. With mumps, even with two doses, that drops to somewhere around 85%, with a range of 60-90%. That difference is especially meaningful considering that even if there was 100% uptake of the vaccine, herd immunity for mumps kicks in when about 92% of the population is immune.

When studies have compared the percentage of individuals becoming infected after exposure in unvaccinated and vaccinated populations during actual outbreaks, the effectiveness of the vaccine hasn’t matched the results of clinical trials. Not that the benefit isn’t significant though. With two doses of MMR, only 2 to 4% were infected while a little more than a third of those having received zero doses became ill. It’s a good vaccine, but 4% of thousands can add up. And because most people are vaccinated, at least in the United States, so are most people infected with mumps.

Some outbreaks, the one is 2006 that involved the United States, Canada and the UK being the prime example, involved a serotype that differed from the one used in the MMR vaccine. Differences were found in immune response in vitro, although vaccine-induced antibodies obtained even from serum 11 years after vaccination still appeared to work against the outbreak strain. But researchers remain uncertain about differences of effectiveness in natural infections. Half the amount of neutralizing antibodies may be enough in vitro but not in the real world. The question of waning immunity has been raised as well. So far the evidence is mixed, and there does not appear to be much talk of adding a third dose during adolescence or early adulthood.

Conclusion

At one point, there was a goal of eradicating mumps in the United States by 2010. Sadly, this didn’t happen and probably can’t be accomplished given the less-than-ideal effectiveness of the vaccine currently available and the ease of bringing mumps back into the country after visiting areas with higher prevalence. Recent mumps outbreaks, unlike those involving measles infections, are not a result of vaccine refusal, although that certainly may change if the number of vaccinated people were to continue to decrease.

Mumps isn’t the worst of the vaccine-preventable illnesses by a wide margin. But it can cause significant morbidity, including deafness and impaired fertility, and the symptoms of classic mumps can be extremely uncomfortable even if they won’t kill you. The MMR vaccine is extremely safe and is pretty good at decreasing your risk of becoming infected if exposed. It’s even better at protecting you from measles and rubella. So there is just no excuse unless you have a true medical contraindication. And even if you become infected after vaccination, your illness may be less severe than it might have been otherwise.

Posted in: Epidemiology, Vaccines

Leave a Comment (23) ↓

23 thoughts on “The 2014 Ohio Mumps Outbreak

  1. Viking Moose says:

    So maddening to see. And kinda scary.

    Besides normal hygiene procedures, what are precautions one can take? For example, an immunocompromised person – HIV infected, transplant recipient, person on suppressing meds?

    the “arguments” that really irk me are the ones involving “health ‘freedom’” or “you know who else ‘coerced’ people into medical procedures…”

    That boob at the Cato institute, Singer, has an antivax screed going on (surprisingly, Ron Bailey at Reason is on the side of science!). h/t to W on the “debate” at R e a s o n dot com

    But go there and read the comments if you want your head to explode.

    Today, it’s a nice break from the shrill fire alarm tests…

    Happy Friday, all.

  2. goodnight irene says:

    Oddly enough, mumps was the one disease that prompted many parents to get kids vaccinated–the fear of sons becoming sterile was the motivator. It seems after reading this to have been somewhat exaggerated. My mother (and her friends) were all absolutely hysterical about this possibility. My brother and I both got mumps in the late 50’s and while I was treated roughly the same, my brother was the subject of intensive pampering and (radical at the time) the doctor was even called.

    I am so grateful for this blog, as without it I might be prone to falling into “I had it and survived, so what’s the big deal about vaccinating” thinking. I did have all the childhood diseases with no complications other than a chicken pox mark or two. I had a nasty scar from smallpox vaccination for many years, but it went away eventually.

  3. ChristineRose says:

    I’ve been trying to restrain myself from commenting on this because I really don’t have anything mature and lucid to say, but the need to rant has overtaken me. I had a horrid case of mumps at age four which lasted for weeks and ruined my fifth birthday. All data is long gone, but I think I must have had some combination of encephalitis and/or meningitis as I suffered hearing loss, extreme weakness, and apparently lost around 30% of my bodyweight (again, no hard numbers but there is photographic evidence).

    It really drives me crazy when the antivax types refer to this disease as something akin to going camping and cooking without an oven and using latrine toilets. No, it isn’t. It’s a terrible idea, and today’s children do not and should not have to learn this the hard way.

  4. mouse says:

    My nephew had mumps a few years ago. I think he was about 10-12. His parents vaccinate, so I kinda wondered what was up, because while he was not dangerously ill, he was very sick and out of school for a week or more. I had thought mumps would be more like chicken pox, where vaccinated kids who are exposed to the disease might get a very mild case. Interesting to see an answer.

    I must protest though, It’s friday and I can’t find any way to work in a beer, wine, whiskey or even sherry reference. Sad face.

    1. Chris says:

      When I last got mumps in 1968 my mother was very surprised because I apparently had had it before. Though we did get stories that it must have occurred on one side only, or some such (both sides of my face was swollen, I could barely open my mouth to sip fluids). It some kind of reasoning since the people around us knew others who got mumps a second time around.

      It seems that this is a case where even getting the disease does not confer perfect immunity. Especially since 1968 was an epidemic year for mumps. And with so much of the virus floating around, what immunity those of us who had it before was overwhelmed.

      So if getting the disease provides only imperfect immunity, then it is no surprise that it is the same with the vaccine.

      1. irenegoodnight says:

        I had the mumps twice as well! I didn’t say so because whenever I mention this, I am usually told that that is not possible and as I don’t like to push ideas for which I have no proof, I quit mentioning it. I also had frequent strep infections before having my tonsils out at age 16, so my neck area was swollen and painful much of the time. I hate that younger parents who never had any of this think it’s okay to let kids go through having these illnesses.

        1. Sullivanthepoop says:

          A retrospective study of natural measles infections done in the 1990s showed that some 5% of people got measles more than once. I thought that was fascinating since 5% of people are not protected from measles after MMR. I have known at least 1 person to get chickenpox twice.

          1. Chris says:

            This is why I hate the claim that “natural” immunity is better.

            Along with the Nirvana Fallacy that a vaccine is only good if it is 100% effective. It is the height of foolishness to think that a vaccine should confer better immunity than the actual disease.

          2. Calli Arcale says:

            Want to meet another? I had chickenpox as a toddler, so I was a natural choice to babysit some neighbor kids who had come down with chickenpox. A while later, coincidentally while babysitting them again, I started feeling really tired and had a bit of a headache. I took it easy, and within a day or so was feeling fine. Then, Easter Sunday. I have a vivid memory of unbutton my nightgown to pull it off and get dressed in my Easter finery to go off to church, and noticing that I had some zits I hadn’t noticed before on my chest. Three. No, four. Five. Seven. Ten. They were literally appearing before my eyes — each time I looked at my chest, I found more, and of course they weren’t really zits. They were pox. I was stuck at home for the next couple of weeks. Unfortunately, I had already passed it to my brothers, who had passed it to their classes, so a lot of kids got chickenpox that month.

            My kids got the varicella vaccine, for sure. ;-)

  5. MTDoc says:

    Just returned from a state sponsored immunization conference. Since it has been many years since I was in the game, I was amazed at how complex the process of immunization has become. In fact most of the conference wasn’t about the many vaccines, but how to master an appropriate administration schedule. If I was still in practice, this is definitely something I would delegate to a specially trained staff member. When I practiced most of my medicine, we had the DPT, the MMR, and the OPV. By way of historical context, I charged two dollars for the DPT, and three dollars for the live virus products, service and vaccine included. And in twenty years, never had anyone question the necessity of vaccination. It’s probably a good thing I’ve been put out to pasture.

  6. Windriven says:

    “. It’s probably a good thing I’ve been put out to pasture.”

    Better for you than for your patients, I’m thinking.

    1. mouse says:

      But, their loss is our gain. I always enjoy MTDoc’s comments.

    2. MTDoc says:

      Thanks for the kind thoughts. I take some comfort in thinking that might be true!

      1. Andrey Pavlov says:

        I don’t recall having said it before, so I will will take the opportunity now to third that sentiment. Thank you for taking the time to post here MTDoc! From your comments I think windriven and mouse are correct in their assessment.

  7. squirrelelite says:

    It’s about pertussis, not mumps, but I thought this news was of interest.
    http://www.npr.org/blogs/health/2014/04/25/306845814/family-tree-of-pertussis-worked-out-could-prompt-better-vaccine

    1. MTDoc says:

      Since this reply is two days after the fact, you will probably never see it, but I wanted to thank you for the link anyway. Yesterday morning I was confronted with a neighbor’s problem regarding possible exposure to an active case of pertussis. The local health dept. wants to put every possible contact on antibiotics (PEP) or “post exposure prophylaxis”. Since her kids just had Tdap boosters three months ago, are in excellent health, and were only in the same room as the index case, she asks my advice. (Old doctors do die, but never stop practicing medicine). The CDC would not recommend PEP in this situation, but the local HD does. I did not, so now I sit with my fingers crossed for the next three weeks! Thanks again for the link. For me at least it was on thread.

  8. Roman Korol says:

    “. It’s probably a good thing I’ve been put out to pasture.”

    Better for you than for your patients, I’m thinking.

    How elegantly put, Windriven! Tip of the hat! I am going to have to steal that compliment of yours, as regards a doctor that *I* know!

  9. Max says:

    The outbreak in New York was mainly among yeshiva students.
    Vaccination status was known for 91% of patients 18 and under. Among patients aged 7-18 years, the age group with the majority of cases, 93% had received at least 1 dose of the MMR vaccine, and 85% had received 2 doses.

    I was just reading about this in the NEJM.
    “Although intense exposures within households, and especially within yeshivas, may have facilitated this outbreak, other factors may also have played a role. Results from outbreak settings suggest that vaccine-induced protection against mumps may wane. Another possible factor is reduced vaccine effectiveness against the outbreak genotype. Nonetheless, neither waning nor reduced heterotypic protection alone would explain why an outbreak would affect particular communities while sparing broader adjacent communities. The high rate of infection among females in dormitories during the mumps outbreaks in 2006 and the high proportion of cases among males attending yeshivas in this study suggest that a high-density setting, in which there are certain behaviors that facilitate transmission of the virus, may overwhelm existing antibody levels.”

    1. WilliamLawrenceUtridge says:

      If this is the same situation I read about at some point in the past, in yeshivas, instruction consists of hours spent face to face chanting versus of the Torah (or other written part of Judaism). Simply spending that much time, that close, to someone breathing that many viral particles directly into your respiratory tract, overcomes immunity and you actually go on to develop the disease, despite appropriate immunization and antibody titres.

      It proves, once again, that reality is complicated, more complicated than anything we might think to be firm facts.

  10. Flower says:

    What do we do about mumps?

    Since risk factors for severe measles and its complications include the following:

    Malnutrition[21][22]
    Underlying immunodeficiency[21]
    Vitamin A deficiency[21][24]

    I’d say, administer adequate amounts of vitamins and minerals which boost immunity and provide an overall good diet.

    1. Chris says:

      A better way to improve immunity to mumps is making sure anyone who can gets an MMR vaccine.

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