A refresher on recognizing and treating measles

In late February, Canada’s Chief Public Health Officer raised the alarm about the global surge in measles activity. This increase, combined with spring break travel and a decline in measles vaccine coverage among school-aged children in Canada, could lead to an increase in imported measles cases and potential transmission among unvaccinated or undervaccinated people in Canada.1 As of March 11, 2024, six laboratory-confirmed cases of measles had been reported in Ontario in 2024. Five cases were associated with travel (i.e., acquisition of measles outside of Canada) and one case occurred in an individual with no known source of exposure (i.e., no history of travel and no epidemiological link with a confirmed case).2 Some of these cases required hospitalization.1 Nationally, as outlined in Canada’s Measles & Rubella Weekly Monitoring Report, seven cases of measles had been reported in Canada in 2024 (as of February 18–24, 2024).3Measles is a highly contagious airborne virus. More than 90% of people who come into contact with the virus and who are not immune to measles will become infected. Measles infection can lead to severe complications, including deafness, brain inflammation leading to brain damage, and death. People at higher risk of complications from measles include children less than five years of age, adults older than 20 years of age, pregnant people and individuals who are immunocompromised.1Measles infection and transmission can be prevented by ensuring high rates of measles vaccine coverage, ensuring measles protection through vaccination prior to travel and the prompt isolation of suspected measles cases. The following information is intended to help healthcare providers prevent measles, and promptly recognize and manage patients with suspected measles. These are general guidelines that healthcare providers can follow; consult available guidelines from your province or territory for more specific information.PreventionVaccination provides the best protection against measles. Two doses of a measles-containing vaccine (measles/mumps/rubella [MMR] or measles/mumps/rubella/varicella [MMRV]) are almost 100% effective at preventing measles infection.1,4 The 2021 childhood National Immunization Coverage Survey showed that 91.6% of two-year-olds in Canada had received at least one dose of a vaccine against measles, but only 79.2% of seven-year-olds had received two doses.1 The first dose of a measles-containing vaccine is usually given to children at 12–15 months of age. The second dose is usually given at 18 months of age or between four and six years of age (before school entry).1,4 It is important to ensure that school-aged children who were due for their second dose of measles-containing vaccine during the COVID-19 pandemic receive this dose as soon as possible, as it may have been missed due to disruptions in immunization services during the pandemic.5MMR vaccine can be given throughout the lifespan in people that have not received all their scheduled vaccinations. MMRV vaccine is only authorized for individuals 12 months to less than 13 years of age.4Being up to date with measles vaccinations before travelling internationally is important.1,6Ensure that children and adolescents have received both doses of a measles-containing vaccine before travel.1If travelling to a high-risk area, infants between six months and less than 12 months of age should receive a dose of measles-containing vaccine.1 In these situations, the routine two-dose series should be restarted on or after the first birthday (i.e., a total of 3 doses).6Before travel, ensure adults have received two doses of a measles-containing vaccine if they were born in 1970 or later. Adults born before 1970 should have received one dose of a measles-containing vaccine or have lab evidence of immunity (e.g., through blood testing); alternatively, they are considered immune if they have a history of laboratory-confirmed measles disease.1,6If an individual’s immunization records are unavailable, immunization with measles-containing vaccine is generally preferable to ordering serology to determine immune status. There is no harm in giving a measles-containing vaccine to an individual who is already immune.5Pharmacists are permitted to administer measles/mumps/rubella vaccine (with certain age restrictions) in several Canadian jurisdictions (not Ontario, Northwest Territories or Nunavut).7 Full details on measles vaccination are available in the Canadian Immunization Guide.8 Other preventive measures include washing hands frequently with soap and water or alcohol-based hand sanitizer, and practising proper cough and sneeze etiquette.6 Individuals should also be vigilant in monitoring for symptoms of measles (discussed below).1 Prompt recognitionSymptoms Prodromal symptoms begin seven to 21 days after infection. They include fever, malaise and the three “Cs”—Cough, Coryza (runny nose) and Conjunctivitis (nonpurulent).White spots on the buccal mucosa, known as Koplik spots, are highly characteristic of measles and may appear in the prodromal stage or two to three days after symptoms begin.A generalized maculopapular rash usually appears about 14 days after infection, or about three to seven days after prodromal symptoms begin. It typically starts on the face, advances to the trunk of the body and then to the arms and legs. It lasts four to seven days.Healthcare providers should suspect measles if a patient presents with a febrile illness and rash, and a history suggesting that they are not immune to measles, are unvaccinated, partially vaccinated or immunocompromised, particularly if the individual has travelled or is known to be linked to a measles case or outbreak.4,5 ManagementThere is no specific antiviral treatment for measles infection, which is why prevention with vaccination is so important. Medical management is supportive and aimed at symptom relief and management of complications. This can include rehydration and management of secondary complications of measles, such as bacterial pneumonia.4 Self-isolationIndividuals with measles are considered infectious from four days prior to rash onset through to four days after rash onset (9 days total). Immunocompromised individuals may be infectious for longer and should be advised to isolate for the duration of illness. Patients should be advised to self-isolate from all public places (e.g., child care settings, schools, work places, places of worship, sporting events, health care and other group settings). They should also avoid contact with nonhousehold individuals, as well as high-risk individuals (e.g., pregnant people, infants < 12 months of age, immunocompromised individuals).5Infection prevention and control precautionsBefore seeking medical attention, individuals with suspected measles should be advised to contact their healthcare provider or the healthcare facility before their arrival so that appropriate infection prevention and control precautions can be implemented to prevent the spread of measles.5If a patient presents to a physician’s office or pharmacy with a suspected measles infection, follow these steps (where appropriate):Provide the patient with a medical mask (if able to tolerate use and no contraindications)Promptly isolate the patient in a negative pressure room, if available (if not available, place in a single patient room with the door closedObtain specimens for testingContact your local public health unit immediately to report the case (do not wait for laboratory confirmation) and to receive additional guidanceProvide isolation guidance (see above) to the patient while results are pending.5Case follow-upThe local public health unit is generally responsible for the follow-up of any measles case, including contact identification and management, which may include recommendations for post-exposure prophylaxis.5 All contacts of a person who may be infected with measles should be identified and classified as susceptible or nonsusceptible. MMR vaccine or immunoglobulin may be used for measles post-exposure management in persons who are susceptible, depending on the time since exposure and the risks of the individual who was exposed. Immunoglobulin provides only short-term protection and requires postponing the administration of MMR vaccine. Long-term protection against measles is only achievable with immunization (MMR or MMRV vaccine), or infection with the measles virus.4Educate patients about why measles outbreaks can happen in CanadaIt is important for healthcare providers to educate the public about why measles outbreaks can happen in Canada. Explain that measles is no longer consistently present in Canada due to the introduction of routine childhood measles vaccination programs. Before the introduction routine measles immunization, measles was a common childhood illness that infected most individuals before the age of 20 years and caused over two million deaths each year worldwide.4,5 Outbreaks can happen in Canada when a person who is unvaccinated or nonimmune travels to a country where measles is circulating and becomes infected with measles; they are then infectious to others when they return home to Canada. The risk of measles spreading is highest when there are a lot of unvaccinated or nonimmune people clustered together in particular regions or communities. Vaccination rates in Canada, while high, are currently below the necessary level for community immunity in some places. Importation of measles by travel to other countries and local transmission has led to measles outbreaks in Canada.4SummaryMeasles infection and transmission can be prevented by ensuring high rates of measles vaccine coverage, ensuring measles protection through vaccination prior to travel and the prompt isolation of individuals with suspected measles.References:Public Health Agency of Canada. Statement from the Chief Public Health Officer of Canada on global increase in measles and risk to Canada. February 23, 2024. (accessed March 13, 2024).Public Health Ontario. Measles. (accessed March 13, 2024).Government of Canada. Measles & rubella weekly monitoring report – week 8: February 18 to February 24, 2024. https://www.canada.ca/en/public-health/services/publications/diseases-conditions/measles-rubella-surveillance/2024/week-8.html (accessed March 13, 2024).Government of Canada. Measles: for health professionals. (accessed March 13, 2024).Public Health Ontario. Measles: information for health care providers. 1st Edition: March 2024. (accessed March 13, 2024).Government of Canada. Global measles notice. Updated: August 31, 2023. (accessed March 13, 2024).Canadian Pharmacists Association. Injection authority and vaccine administration in pharmacies across Canada. February 2024. (accessed March 13, 2024).Government of Canada. Measles vaccines: Canadian Immunization Guide. (accessed March 13, 2024).

A refresher on recognizing and treating measles

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