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Once virtually eradicated through routine immunization, measles and mumps are making a striking comeback in the U.S. in 2014 with a record number of post-vaccination era measles cases and several large mumps outbreaks on college campuses.
The reemergence of these once-common childhood diseases presents an unwelcome new challenge for infection preventionists, as the introduction of even a single undiagnosed case can set off a laborious and expensive follow-up of exposed patients and health care workers. For example, a single imported case of measles once cost two Arizona hospitals some $800,000, with much of the expense related to ensuring the immunity of employees and furloughing workers.1 Similarly, a mumps outbreak in a Chicago hospital in 2006 racked up a bill of $262,788 or $29,199 per case.2
Within the first six months of 2014 there were a record 500 confirmed cases of measles, including more than 400 in Ohio, reports the Centers for Disease Control and Prevention. The previous record year for measles was 2011 with more than 200 cases, so at the current pace 2014 is heading into uncharted misery. Patients with reported measles cases in 2014 range in age from 2 weeks to 65 years, with 48% under age 20. In addition, in the first half of the year some 800 people were reported to have mumps in the U.S., with more than half of the cases occurring in Ohio. The CDC reported that mumps outbreaks have occurred this year at Ohio State University in Columbus, Fordham University in New York City, the University of Wisconsin-Madison and the University of Illinois at Urbana-Champaign. Mumps outbreaks can spread quickly in confined settings like college dorm rooms. For comparison, in 2013 there were 438 mumps cases and fewer than 200 measles infections.
The CDC reports that close to 70% of the people who had confirmed measles in 2014 were unvaccinated, and nearly all of the cases originated in one of 18 countries, including the Philippines, which is experiencing a large, ongoing measles outbreak that has infected more than 6,000 people this year.3
In that regard, while measles elimination in the U.S. was declared in 2000, there are about 20 million cases of measles each year globally. The US has greater than 90% MMR vaccine coverage among children aged 19-35 months and adolescents, but the anti-vaccine movement has contributed to pockets of vulnerability in some communities.
Indeed, while there can be vaccine breakthrough infections and enhanced transmission in crowded settings for mumps, the measles vaccine is considered highly effective. Thus there is little doubt that some of the infections and outbreaks can be traced to the influence of a high profile anti-vaccine movement that cites discredited research in falsely linking the MMR vaccine to autism. (See related story p. 80).
"That’s all new parents needed to hear, and soon some were not vaccinating according to the guidelines, or they were spacing out their vaccines — which leaves a young toddler susceptible," says Susan P. Hanrahan, MS, CIC, manager of infection control at Jersey Shore University Medical Center in Neptune, NJ. "It took years to discredit [false] research, but the damage was already done. Compounding the public’s mistrust of vaccine efficacy are high-end celebrities like Jenny McCarthy advocating not following the American Academy of Pediatric recommendations to follow the evidence-based schedule."
Childhood preventable diseases will inevitably circulate in communities if the current climate of vaccine non-compliance continues, she adds.
"Healthcare professionals need to be prepared for community outbreaks and have in place a system that addresses how their facility will respond, so patients and staff are not inadvertently exposed to suspect patients in waiting rooms and examination rooms," Hanrahan says.
In Monmouth County New Jersey, Hanrahan, clinical colleagues and public health officials dealt with a four-week mumps outbreak that began last August.
"We had young individuals in their mid-20’s present with symptoms clinically significant for mumps, although not all were blaringly obvious and [some] had a subclinical presentation," she says.
One patient had visited a general practitioner who recognized his symptoms as mumps and obtained the buccal swab culture, which is the gold standard for laboratory confirmed diagnosis, she notes.
"In any community outbreak it’s not just one individual," she says. "The patient had roommates and people he worked with who were directly affected. They in turn had secondary contacts and so the virus kept perpetuating. Prolonged close contact with these individuals increased the mechanism of droplet transmission so that mumps passed around in the community pretty quickly."
Hanrahan and colleagues created a line list that included patients presenting to the facility with fever, parotid gland swelling, malaise, jaw pain, arthralgia, and complications such as orchitis, mastitis, pancreatitis, hearing loss, encephalitis and aseptic meningitis.
Culture confirmations were crucial to getting public health agencies involved in the outbreak. Having culture confirmation impacts how quickly officials speak with the infected patients’ friends and family to identify additional cases and officially announce to the public that the disease is present in the community, she says. The public needs to be informed so they are educated regarding disease prevention strategies and what to do if mumps is suspected.
"The more lab confirmed cases you have the stronger the argument is that it’s an outbreak," she explains. "A lot of times people have signs and symptoms but they’re termed probable’ or suspect’ cases."
Among the mumps cases, some had received the full two doses of the MMR vaccine whereas some had only one dose of the vaccine, Hanrahan recalls.
Studies suggest that the mumps vaccine is 80% to 90% effective, leaving a significant portion of people vulnerable to infection even though they have received the recommended two-doses of MMR.
Though the CDC continues to recommend mumps vaccination using the current MMR shot, there has been some speculation that transmission is continuing because the attenuated mumps virus in the vaccine does not match the currently circulating strain. In a news release regarding a mumps outbreak on campus, the McKinley Health Center at the University of Illinois stated, "Some theorize that the current strain of the virus may be a new strain. Occasionally, slightly shifted strains of the mumps virus circulate in the United States. Because these new strains vary slightly from the strain originally used in the vaccinations provided to people during their childhood, it could explain some of the failure of the vaccine this year."
The measles vaccine is effective, but does little good if people who refuse vaccination travel to areas of measles outbreaks and bring the highly contagious disease home, where transmission can explode in groups that have foregone immunization. Even a single case walking into a hospital can cause considerable chaos, particularly in areas that have not seen a measles case since the last century.
"Dallas County had not seen a case of the measles since 1997," says Sharon Holmes, MPH (ASCP), CIC, director of infection prevention and control at Children’s Medical Center Dallas, TX.
That changed last year, when a 14-month old unvaccinated girl who returned from travel to Ethiopia was admitted to Children’s with a persistent fever, rash, cough, and coryza.4 The patient was placed in contact and droplet isolation precautions for the first five days of admission.
The baby recovered, and certainly didn’t seem as sick as a child with measles, but an alert hospitalist noticed a gap in vaccination records. (The first dose of MMR is recommended at 12 to 15 months.) A Rubeola IgM test was ordered and the positive results came back in a few days. The hospital’s lab calls the infection preventionists if they have a positive result. When results for the baby with measles came in at 11 p.m., infection control specialists were paged at 8 a.m. the next day. One improvement suggested in the aftermath of the measles case was to have the hospital’s electronic medical record automatically send a notice to the infection control department when a measles test is ordered, Holmes says.
"When we discovered it was measles — knowing that measles is so contagious that anyone sharing the same airspace could be infected — we considered everyone on the unit to be infectious," Holmes says. "We screened to make sure they had the vaccination, and, if not, we did titers to see if they were immune."
Hospital officials were not quite as worried about the staff becoming infected because all employees are required to have up-to-date immunizations, she notes. "This was more of an issue for patients sharing the same air space, who may not have a vaccine history or who are immune incompetent," Holmes says.
Of course, the patient was upgraded to airborne precautions as soon as the measles diagnosis was known. "The patient was originally on contact droplet precautions because she had a history of sore throat and fever," Holmes says. "When the floor was notified of her positive measles results they moved her into a negative pressure room."
In all, 28 patients were subject to follow-up investigation. Three were post-renal transplant patients, so they were given prophylactic immunoglobulin from the state health department.1 There was one measles case treated at an ancillary clinic that was likely linked to the hospital’s case, she adds. "The key was to involve our local health department, who guided us towards notification to families who had been on the unit," Holmes says.
Shortly after the Dallas measles case, there was an outbreak at a large church in an adjacent county, but it was not connected to the hospital case. It goes without saying that the index of suspicion for measles will remain high for some time.
"We see a lot more testing for measles whenever there’s a rash and persistent fever," Holmes says.
Providers — many of whom may have never seen these childhood infections — should be aware that the CDC recommends they consider measles when patients have a fever and rash and clinically compatible symptoms. However, since the vast majority of the population has been immunized the likelihood is still much greater that a suspect case will not be measles. Physicians can ask for a vaccine history or vaccination records from families, but obtaining this information can be difficult.
"Generally, people don’t carry around their child’s immunization records, so if they go to the emergency department and are asked if the child’s vaccines are up to date, most people will say, Yes,’" Holmes says.
A better solution would be for states to develop immunization tracking histories that hospitals and community providers can access. Texas has such a voluntary program, she says. Parents enroll their child in the program, giving health providers the right to send information to their child’s pediatrician and other health care facilities.