Cases of measles diagnosed by late May 2017 (90 cases by week ending May 20, 2017) have surpassed the total number of cases of measles during all of 2016 (83 cases). Although a significant outbreak has been occurring among the Somali community in Minnesota, cases are not limited to that geographic region. At least 11 states have had cases of measles diagnosed thus far in 2017. With summer travel underway and the ease with which measles can spread, it is important to consider measles as a possible diagnosis if a patient presents with fever and rash.
Are you ready? See if you know the answers to these questions about measles:
- How is measles transmitted?
- How contagious is measles?
- How long is the incubation period for measles?
- What symptoms might be present?
- What are the possible complications?
- Is measles a reportable condition?
- Who should get vaccinated against measles?
Answers are in the article that follows.
Measles transmission and contagiousness
Measles virus spreads primarily through large respiratory droplets, but can also be spread for up to two hours by aerosolized droplets that remain in closed areas after the infected person vacates the area, such as an exam room or elevator. The virus is highly contagious and can be expected to infect up to 100 percent of susceptible individuals following exposure. For these reasons, people suspected of having measles should not share waiting rooms with others who might be susceptible. Transmission of the virus in waiting rooms has been documented.
Incubation period, symptoms and complications
The incubation period for onset of early symptoms is typically 10 to 12 days. Because rash onset typically follows a two- to four-day prodromal period, incubation from exposure to development of rash is about two weeks after exposure, but can occur up to three weeks later.
- Typically lasts two to four days, but can range from one to seven days.
- Fever — typically increases stepwise and can get as high as 103 to 105 degrees Fahrenheit.
- Cough, coryza, conjunctivitis.
- Koplik spots — blue-white spots on mucous membranes, particularly the buccal mucosa; typically appear one to two days before the rash and lasts until a day or two after the rash appears.
- Lasts about five to six days.
- Starts around the hairline and on face and neck and proceeds downward and outward to cover the body.
- Typically appears over about three days; lesions blanch with fingertip pressure. Blanching does not tend to occur later in the rash period.
- Rash fades in order of first appearance.
- Rash is typically maculopapular with flat red bumps.
- Occur in about 3 of 10 cases.
- Most likely in infected children younger than 5 years or adults 20 years or older as well as in pregnant women and those with suppressed immune systems, such as from leukemia or HIV.
- Most common complications include diarrhea (8 percent), otitis media (7 percent), and pneumonia (6 percent). Pneumonia can be caused by either measles virus or by a bacterial superinfection and is the most common cause of measles-related deaths (60 percent). Children are most likely to succumb to pneumonia, whereas adults are more likely to die from acute encephalitis.
- Rare complications can include encephalitis (0.1 percent), seizures (0.6 to 0.7 percent) and death (0.2 percent).
- Subacute sclerosing panencephalitis (SSPE) can occur following measles infection. This uniformly fatal neurodegenerative disorder can occur within one month of infection or up to 27 years later. The average time until appearance is about seven years.
- Measles is a known immunosuppressive infection. A paper published in 2015 by M.J. Mina and colleagues found that this immunosuppression following measles infection can last for years. Dr. Offit discussed this paper in a previous issue of Vaccine Update.
What to do if measles is diagnosed in your practice
Given its contagiousness, measles can spread rapidly through a community and is, therefore, a reportable condition. If you suspect measles:
- Collect a serum sample as well as a throat (or nasopharyngeal) swab. If possible, also collect a urine sample. Work with local health department officials to arrange expedited testing.
- Isolate individuals suspected of being infected with measles, preferably in an airborne infection isolation room. Do not have them wait in the waiting room, if possible, and provide them a mask.
- Ensure that only staff with immunity are in contact with the patient, and if available, have staff use N95 respirators.
- Do not use a regular exam room that had someone with a suspected measles infection for at least one hour after the patient left.
- Contact your local health department within 24 hours if you did not previously contact them related to sample testing.
- Identify others who may have been exposed and work with the department of health to ensure they are notified of the potential exposure, screened for prior proof of immunity, and provided with post-exposure prophylaxis and quarantine or other instructions as needed.
Measles vaccine is a live, weakened virus administered as part of the MMR vaccine. Vaccination is recommended at 12 to 15 months of age with a second dose between 4 and 6 years of age.
Unvaccinated students attending college or traveling internationally should get two doses of MMR separated by at least 28 days.
Adults born before 1957 are considered immune due to the prevalence of disease during their childhood. Adults born during or after 1957 who do not have evidence of immunity should get at least one dose of MMR vaccine, and if they are traveling internationally, they should get two doses.
Infants as young as 6 months of age who will be traveling internationally can be immunized before travel. For those between 6 and 11 months of age, one dose should be administered. For those 12 months or older, two doses separated by at least 28 days should be given.
For a series of resources, visit the EZIZ measles webpage. EZIZ is an e-learning and resource website for California’s VFC program.