Portland Tri-County Clinician Update: Clark County Measles Outbreak
Please distribute widely to clinicians in your organization and networks. This update includes information regarding the Clark County measles outbreak including:
- An update on the outbreak
- Background information on measles
- Prevention, prophylaxis and timing of 2nd MMR
- Testing for measles
- Infection control
- List of locations where your patients could have been exposed
Outbreak Update: Sixteen children from Clark County, Washington developed lab-confirmed measles with rash onsets from 12/31/18 to 1/13/19; most were unvaccinated. Clark County is also investigating at least 5 additional suspected cases. Use this link for updated information on the Clark County investigation. One confirmed and one suspect patient required hospitalization. Based on this information, new cases could become ill with measles from roughly January 7th through February 3rd; this period may lengthen if more cases are detected.
Your patients may be at risk from multiple public and healthcare exposures in Portland, Oregon and Clark County Washington (see below for current list). We are aware that Costco contacted many shoppers directly about the exposure at the NE 138th Ave, Portland location on January 8th.
Measles is a highly contagious, severe, febrile viral respiratory illness that is preventable by vaccination. In addition to prominent respiratory symptoms and malaise, measles is characterized by a cough, conjunctivitis and an extensive rash that typically begins the 2nd to 4th day of illness. Measles frequently causes diarrhea, ear infection, and pneumonia; in recent years, approximately 30% of Oregon cases required hospitalization. Less frequent but feared complications include keratitis, corneal ulceration, blindness, encephalitis, and death. Infants, the elderly, pregnant women, and compromised hosts may be at greater risk for serious complications of measles. Measles spreads easily in healthcare settings; your diligence and awareness will help prevent additional cases and prolongation of the outbreak.
Prevention/Vaccination: 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 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 immunoglobulin within 6 days after exposure is recommended for susceptible people who have been exposed to measles. Oregon recommendations are available here. In general, immunoglobulin is recommended, and 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)
Infants aged 6-12 months and other healthy patients may receive MMR vaccine as post-exposure prophylaxis IF given within 72 hours of exposure. MMR should not be used in pregnant women or severely immunocompromised patients.
Testing for measles: Laboratory confirmation of measles is critical to track the course of the outbreak and to prioritize prevention and prophylaxis efforts. Traditional measles IgM has poor sensitivity early in the illness and is only considered reliable if obtained 72 or more hours after rash onset. The Oregon State Public Health Laboratory (OSPHL) uses a highly sensitive RT-PCR test that is more reliable, especially early in the illness. This test can be requested by contacting the local health department of the patient if the evaluation shows:
- A compatible illness
- susceptibility to measles, and
- exposure to a case or a location/time listed below
- Note: Health department approval is required for this test.
Healthcare Infection Control: Measles primarily spreads to close and household contacts through large droplets but can also be transmitted through the airborne route, even after the patient is no longer present- CDC advises that after 30 minutes there is little risk. 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, consider whether they could have been exposed at the locations based on the most recent information. Up-to-date vaccination status for age makes measles much less likely. If a patient needs to be evaluated in-person or arrives unexpectedly with symptoms compatible with measles, then follow these recommendations:
Be prepared to evaluate patients in airborne precautions (N-95/PAPR respirator) by fully immunized staff
Immediately mask the patient, and place in a room with the door closed
Perform evaluation in a negative pressure room, if possible
Consider all relevant potential diagnoses; if measles is still suspected then specific testing can be facilitated by contacting the local health department
Instruct the patient to self-isolate at home if measles is possible
If the patient does not need immediate medical evaluation, then contact the local health department of the patient’s residence to obtain advice on specific testing if measles is plausible.
Local Health Department Phone Numbers
- Multnomah County Public Health: 503-988-3406
- Washington County Public Health: 503-846-3594
- Clackamas County Public Health: 503-655-8411
- Clark County Public Health: 564.397.8182