Tri-County Clinician Update: First Oregon measles case confirmed, linked to Clark County outbreak
This update includes information regarding the Clark County measles outbreak including:
- An update on the outbreak with links to where your patients may have been exposed
- Background information on measles
- Prevention, prophylaxis and timing of 2nd MMR
- Testing for measles
- Infection control
- Local health department contacts
- Additional FAQ’s for health care providers, adapted from Oregon Health Authority
31 young people from Clark County, Washington have confirmed measles, all either unvaccinated or vaccination unconfirmed. Use this link for updated information on the Clark County outbreak.
The first measles case in Oregon was confirmed on January 25 in Multnomah County. The case is directly linked to the Clark County outbreak. There were limited public exposures related to this case.
We may continue to see cases in our area through February 23, 2019 based on the most recent exposures; this date may be extended as additional cases are identified.
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 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, susceptible pregnant women and immunocompromised 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.
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 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 certain susceptible individuals who have been exposed to measles. Oregon recommendations 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)
Infants aged 6-12 months and other healthy contacts to measles cases are recommended to receive MMR vaccine as post-exposure prophylaxis if given within 72 hours of exposure. MMR provides permanent protection and may prevent disease if given within 72 hours of exposure. If MMR vaccine is not administered within 72 hours of exposure as post exposure prophylaxis, MMR vaccine may be offered at any time following exposure to the disease in order to offer protection from future exposures. 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 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. This test can be requested by contacting the local health department of the patient if evaluation shows:
- A compatible illness; AND
- susceptibility to measles; AND
- exposure to a known case or public exposure location; recent foreign travel
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 notes that the virus can live up to 2 hours in airspace where the infected person 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, consider whether they could have been exposed at the specified locations. Up-to-date vaccination status for age make measles much less likely. If a patient needs to be evaluated in-person, or arrives unexpectedly with symptoms compatible with measles, consult with your health system infection control program and consider these options to minimize exposure to others:
- If possible and appropriate, patient may be scheduled as the last patient of the day.
- If feasible, appropriate, and patient privacy can be protected, patient can be briefly evaluated outside, at least 30 feet away from others. Once mask is placed and a clear path to exam room prepared, patient can be escorted into the building.
- Whenever possible, patient should be escorted from a separate clinic entrance that allows them to access an exam room directly without exposing others.
- The number of health care workers interacting with the patient should be kept to a minimum.
- If the patient is already in the clinic, patient should be roomed immediately rather than allowed to wait in the lobby.
- The exam room door should remain closed at all times, and the patient should remain masked during the entire visit.
- All labs and clinical interventions should be done in the exam room.
- The exam room should not be used for 2 hours until after the patient has left.
- Any patient referred to an Emergency Department for evaluation should be placed immediately in a negative pressure room and seen by staff who are fully immunized against measles and wearing a fit-tested N-95 mask or powered air purifying respirator (PAPR).
Consider all relevant potential diagnoses; if measles is considered likely then specific testing can be facilitated by contacting the local health department. Patients who are likely to have measles but do not need inpatient admission should be instructed to isolate at home until measles is ruled out clinically or via testing.
Local Health Department Phone Numbers:
- Clackamas: 503-655-8411
- Clark: 360-397-8182
- Multnomah: 503-988-3406
- Washington: 503-846-3594
Health care provider FAQ - adapted from Oregon Health Authority
What are the criteria for testing at the Oregon State Public Health Lab (OSPHL)?
All patients with:
- Fever, at least one of the “3 C’s” (cough, conjunctivitis, coryza), with or without rash; AND
- Known high risk exposure to a person with measles or recent travel to measles endemic areas; AND
- No measles vaccination in the prior 45 days.
Providers should ask about exposure to infected individuals, travel (past month), and MMR vaccine history. This helps public health staff assess level of risk for infection, but providers should not rule-out a suspect diagnosis based on these factors alone. NOTE: All specimens tested through OSPHL must be approved through your local public health authority prior to submission. Providers also have the option of testing through commercial labs.
Can patients with recent MMR be tested for measles if they present with symptoms?
The MMR vaccine produces a measles-like rash about 5% of the time and should generate first an IgM and then an IgG antibody response. When a patient with suspected measles has been vaccinated 6-45 days prior to specimen collection, neither IgM nor IgG antibody responses can distinguish measles disease from the response to vaccination. Symptomatic patients with no known exposure and vaccine in the prior 45 days would be considered a vaccine-associated case. Vaccine-associated cases are thought to be non-infectious; however, home isolation is advised just to be safe.
When should measles IgM be ordered?
Please refer to the lab testing guidance posted here for more information on lab testing and specimen collection. Measles IgM is recommended to confirm suspected measles if the rash onset was at least 72 hours earlier. Measles IgM is insensitive earlier in disease.
Measles RT PCR is a sensitive test with a fast turnaround but can be falsely negative if done too early in the disease course. All requests for measles RT PCR must be approved by state and local public health before sending to the Oregon State Public Health Lab.
Can an asymptomatic patient who was exposed to measles go to a laboratory or healthcare facility to get vaccinated or have their blood drawn?
It is safe for a patient that was exposed to measles but not showing any signs or symptoms of measles (e.g., fever, cough, coryza, conjunctivitis, and rash) to go to a lab or a healthcare facility for services.
Who is considered immune to measles?
Oregon Health Authority considers individuals immune to measles if they have written documentation (records) showing at least one of the following:
- Birth before 1957 (but see below)Laboratory-confirmed disease
- Laboratory evidence of immunity (protective antibody titers); or
- Documentation of vaccination as follows:
- Pre-school children: 1 dose
- Children in grades K–12: 2 doses
- Women of childbearing age: 1 dose
- Healthcare personnel born during or after 1957: 2 doses
- Students at post-high-school educational institutions: 2 doses
- International travelers≥12 months of age: 2 doses
- Children 6–11 months: 1 dose
During an outbreak of measles, healthcare facilities serving the outbreak area should recommend 2 doses of MMR vaccine for unvaccinated personnel, including those born before 1957, who lack laboratory evidence of measles immunity or laboratory confirmation of disease.
Thank you for your partnership,
Sarah Present, MD, MPH Health Officer, Clackamas County
Jennifer Vines, MD, MPH Deputy Health Officer, Multnomah County
Christina Baumann, MD, MPH Health Officer, Washington County