Clinician Alert: Measles cases in Southwest Washington

Offered by

Note: January 12, 2024 - The Testing section of this alert was updated to clarify that Clark County in Washington does not require approval for testing sent to a state lab.

This alert is a notification that measles has been identified in Southwest Washington. The Health Advisory for Region 4 Washington Counties (Clark, Skamania, Wahkiakum, and Cowlitz) can be found here.

While there are no defined public exposures at this time, we request that area clinicians:

  • Keep measles on the differential for patients who present with compatible symptoms, especially if they report an exposure and/or are unvaccinated for measles.
  • Immediately notify the public health department where the patient lives if you suspect measles. See 24-hour contact information under the Resources section below.
  • Encourage vaccination in individuals 12 months and older who have not started or completed measles vaccination. See full vaccination recommendations, including contraindications such as pregnancy, here.
  • Distribute this notification to clinicians in your organization and networks.

Background

As of January 6, there have been six epidemiologically-connected cases of measles identified by the Clark County and Wahkiakum County public health departments. The onset of illness for these cases was in mid to late December. Clark County is not aware of any public exposures. Based on the information they have so far, they believe the risk to the public is low. All six cases are unvaccinated.

Measles is a highly contagious virus that passes from an infected person to another through coughing or sneezing and is considered to have both droplet and airborne transmission. Common complications from measles include otitis media, bronchopneumonia, laryngotracheobronchitis, and diarrhea. Even in previously healthy children, measles can cause serious illness requiring hospitalization, including encephalitis, and more rarely delayed complications such as subacute sclerosing panencephalitis.

Measles can be prevented with the MMR (measles, mumps, rubella) vaccine. In our region, MMR vaccination rates for 2-year-olds have slowly and steadily declined since 2019, and are below the 95% goal for herd immunity, so this is a good opportunity to discuss immunization with your patients.

While there are no known cases of measles and no known exposures in Oregon at this time, we are watching the situation closely and staying in close contact with our colleagues across the river. We are also sharing the following guidance out of an abundance of caution, and to streamline case identification and optimize both patient care and infection prevention should a case be identified in the metro area.

Testing

Timely laboratory confirmation of measles is critical to tracking the spread and prioritizing prevention efforts. Tests for measles can be ordered from most commercial labs or through the Oregon State Public Health Laboratory (OSPHL). Testing through the OSPHL is preferred, since it typically has a much faster turnaround time (within 3 days of specimen receipt), but approval is required from the local health department of residence of the patient. Please refer to this set of instructions which has a link to the OSPHL Virology/Immunology Test Request Form.

Please see below for Specimen Collection Guidance. Call the appropriate health department immediately if you suspect a measles infection. These tests should be ordered for patients who may have been exposed if their evaluation shows:

  1. A compatible illness; AND
  2. Likely susceptibility to measles

Oregon County Health department approval is required for PCR testing sent to OSPHL, which is the recommended lab for testing measles suspects. County health departments may be reached 24 hours a day to report suspect cases and discuss testing:

  • Multnomah County Public Health: 503-988-3406
  • Washington County Public Health: 503-846-3594
  • Clackamas County Public Health: 503-655-8411

Collect ALL of the following specimens:

  1. Nasopharyngeal (NP) swab for measles PCR (This is the preferred test for diagnosis given it’s sensitivity and reliability early in disease.):
    1. NP swab should be collected 0-5 days after rash onset; after 5 days, NP swab should be accompanied by urine.
    2. Throat swab is also acceptable.
  2. Urine for measles PCR:
    1. Urine PCR test is most sensitive between ≥72 hours and 10 days after rash onset.
  3. Serum for measles IgM and IgG testing:
    1. Measles specific IgM antibody may not be present until ≥72 hours after rash onset but persists for about 30 days after rash onset.
    2. A positive IgG early in illness may suggest prior immunity

Healthcare Infection Control

Measles primarily spreads to close and household contacts through large droplets, but can also be transmitted through the airborne route. According to the CDC, the virus can be transmitted through the latter route up to 2 hours after a contagious patient coughed or sneezed. Preventing healthcare exposures is critical to keep high-risk groups safe. When possible, use phone triage and assessment to determine if patients who might have measles need to be seen in-person.

If patients or caregivers are concerned about measles, inquire whether they know of any exposure to an identified case. Up-to-date vaccination status makes measles much less likely.

Please implement these interventions in your clinical settings to minimize exposure to others:

  • If a patient with possible measles arrives unexpectedly, require the patient to mask and room them promptly (negative pressure room if available) keeping the door closed.
  • Report any possible measles cases immediately to the health department of the county where the patient resides (see phone numbers under Resources below).
  • If feasible and appropriate, schedule possible measles patients as the last patient of the day.
  • If feasible and appropriate, consider patient evaluation outdoors at least 30 feet away from others.
  • If possible, suspected measles patients should be escorted into the building via an entrance that allows them to access an exam room without exposing others.
  • Minimize the number of health care workers interacting with the patient. Caregivers should have documented immunity to measles and wear an N-95 mask or PAPR.
  • Perform all labs and clinical interventions in the exam room if possible.
  • The exam room should not be used for 2 hours after the patient has left.
  • Patients who are under evaluation for measles should isolate at home until the diagnosis is clarified.
  • Be aware that unvaccinated or undervaccinated children and staff can be excluded from school during their incubation period, and ensure your patients know that Public Health will follow up with any confirmed cases.

Prevention

Measles is best prevented by 2 doses of MMR or MMRV. In normal circumstances, the first dose is recommended between 12-15 months of age to avoid interference from the maternal antibody. The definitive resource on the timing of the second dose is the CDC Pink Book which states:

The second dose of MMR may be administered as soon as 4 weeks (28 days) after the first dose. Children who have already received two doses of MMR vaccine at least 4 weeks apart, with the first dose administered no earlier than the first birthday, do not need an additional dose when they enter school.

Post-exposure prophylaxis with IV immunoglobulin within 6 days after exposure is recommended for certain susceptible individuals who have been exposed to measles. Oregon recommendations for post-exposure prophylaxis are available here. In general, immunoglobulin is prioritized for susceptible individuals at risk for severe disease including:

  • Infants under age 12 months (intramuscular IG 0.5 mL/kg, max 15 mL)
  • Pregnant women without evidence of immunity (400 mg/kg IVIG)
  • Severely immunocompromised persons regardless of vaccination history (400 mg/kg IVIG)

Unvaccinated eligible children and adults who were exposed to measles should only receive a post-exposure prophylaxis vaccine within 72 hours of exposure (usually this is difficult given how long it takes to identify, diagnose, and report) and should NOT receive the vaccine before the end of the incubation period because of the 5% chance of a vaccine rash—which could be confused with measles. The MMR vaccine should not be used in pregnant women or severely immunocompromised patients.

Resources

Patients or clinicians may call their respective County Health Department Communicable Disease team if they would like to talk through their situation and get recommendations for next steps. Suspected measles cases may also be reported 24 hours a day via these same channels.

Thank you for your partnership,

Christina Baumann, MD, MPH, Health Officer, Washington County

Richard Bruno, MD, MPH, Health Officer, Multnomah County Health Department

Teresa Everson, MD, MPH, CPH, Deputy Health Officer, Multnomah County Health Department

Sarah Present, MD, MPH, Health Officer, Clackamas County