Measles outbreak is threat to workplace

Check employee's vaccine records

Your nursing staff, already stretched thin, is about to take a hit. A measles outbreak has sickened a dozen people in your city, one of whom came into your ED before he was symptomatic. In an avoidable complication, several members of your staff whose measles vaccines were not up to date or effective now must stay home from work for 20 days.

This was the story at one Boston hospital in the spring, when a single measles case — a worker from India who came to work at a bank in the city's landmark John Hancock Tower — touched off an outbreak that felled 15 people across the city before waning in late June.

Highly disruptive to the hospital staff, yet highly avoidable if employees' vaccination histories were flagged.

"People were surprised that we had to isolate them from the 5th to 25th days of exposure, and it put some real strain on the emergency rooms and health departments [where they worked]," says Anita Barry, MD, director of communicable disease control for the Boston Public Health Commission. "But one guy was seen in two different hospitals. The first hospital didn't suspect measles, so when it was confirmed — even before the lab confirmation, when the physical findings suggested measles — the first hospital had people who had been exposed and had to be taken out of work. They had to do it, and it was a burden."

Measles not an eradicated threat

The rarity of measles outbreaks, coupled by the nearly universal vaccination of children in the United States, has led many to assume the threat of measles is almost non-existent. But global travel and the fact that measles is common in other countries means the disease should not be taken for granted.

The Boston outbreak was initiated by an asymptomatic single young man who flew to the city from India, and within a period of hours had unwittingly exposed a dozen coworkers. It's a threat that could easily be repeated, as workers coming into the United States on temporary work assignments are not required to prove they are vaccinated against diseases.

"There is a cohort of people in the United States who are susceptible to measles — people born too late to get the natural disease (before 1957), and people who were children when the vaccine was given in a way that was ineffective (1963-1967, roughly)," says Barry. Those born before 1957 were probably exposed to the disease naturally, had a mild outbreak, and are immune; children born after 1957 and through 1962 received vaccine that was effective; and children vaccinated since 1967 also received effective vaccine.

"Those who received the vaccine from 1963 through 1967 think they're protected, but they're probably not," she adds. During that time, some children received a killed-virus vaccine, rather than the live virus that is in effective vaccine. Also, immunoglobulin was given along with live-virus vaccines during that time, rendering the vaccine ineffective.

Occupational health nurses, Barry says, "might have a susceptible cohort [at their worksites] and not know it."

Susceptible cohorts were at work at the Boston bank and hospital; consequently, hundreds of people were forced to stay home until the incubation period passed or they were proved to not be susceptible.

"We had an unfortunate confluence of events," says Barry. "We had someone coming from outside the United States from an area where measles occur, working in a place where people work relatively close together, and having a susceptible cohort who thought they were vaccinated for measles. Introduction from outside the U.S., which is common, plus environment, plus a susceptible pool in one place."

Employees in 30s and 40s susceptible

Health officials are warning that anyone born after January 1, 1957, should have two valid doses of a measles-containing vaccine that they received after they were at least 12 months old. Children immunized before their first birthday might not be protected, as maternal antibodies could neutralize the vaccine.

"If someone in your workplace can't produce ecords [showing they are protected], they need to be revaccinated," says Barry. That means two doses of measles vaccine for those born after 1957, and anyone born outside the United States who has not been vaccinated.

People born before January 1957 should have serology documenting that they are immune — either by exposure or vaccine —or should have at least one dose of vaccine, Barry says.

"It's surprising to people," she points out. "Many of our cases are in their 30s and 40s, and they had had their shots. But they got the ineffective vaccine."

Especially in the health care setting, but also in any workplace, if someone comes in with the symptoms of measles, isolation and protection measures must be taken immediately, and completely. (See Symptoms of measles in box below.)

Symptoms of measles

Measles is the most infectious human disease; infectious particles can remain suspended in the air for up to two hours. The average incubation period from exposure to rash onset is 14 days (range 7-18 days. Symptoms include:
  • Fever (as high as 103-105°F)
  • Cough
  • Conjunctivitis
  • Coryza
  • Erythematous maculopapular rash (maculopapular eruption, often begins on face and spreads to the trunk and extremities, lasts 5-6 days)
  • Mouth lesions (Koplik spots, characteristic but not always present)
  • Average incubation from exposure to rash is 14 days (range 7 to 18 days)
  • Infectious particles can remain suspended in air for up to two hours

  • Also:
  • Loss of appetite
  • Diarrhea (especially in infants)
  • Generalized lymphadenopathy
  • Source: Centers for Disease Control and Prevention, Atlanta, GA.

    "We had a number of cases where people came into a health care facility and they were masked, but then they sat in a waiting room with other patients," Barry relates. "Measles is airborne. When someone comes in with suspected measles, you need to have a system where the person is immediately masked and put in an airborne isolation room. You have to remember that second step of getting them into an airborne infection isolation room."

    The good news, Barry points out, is that people can protect themselves against measles. (See Immunization guidelines in box below.)

    Measles immunization guidelines

    The Centers for Disease Control and Prevention and the Massachusetts Department of Public Health recommend:
  • Carefully assess all patients presenting with febrile rash illnesses and report such cases to their local Board of Health; and
  • Ensure that all staff and patients are up to date with their measles, mumps, rubella (MMR) immunizations;
  • All children <12 months of age are encouraged to get their first dose of MMR vaccine as soon as possible;
  • All individuals born in and after 1957 should have two doses of MMR vaccine (regardless of country of birth);
  • Individuals born in the United States before 1957 are usually considered immune — but, they may wish to receive a single dose of MMR vaccine to increase their likelihood of protection against measles (Exception: Health care workers born before 1957 should have one dose of MMR vaccine);
  • Individuals born outside the United States before 1957 should have one dose of MMR.
  • Source: Massachusetts Department of Public Health, Boston.

    Occupational health nurses "need to make sure their current and new staff are protected against measles," she urges. "Another story we heard, not uncommonly, from the health care facilities here is that they know about their new employees, but their veteran employees don't know their status. So they had to come out of work, and that was hard on the facility. So think about your current people."

    [For more information, contact:

    Anita Barry, MD, director of communicable disease control, Boston Public Health Commission. Phone: (617) 534-5611.]