HomeMy WebLinkAboutacphd-measles-testing-specimen-routing-procedures-adaAlameda County Public Health Department
Measles Testing & Specimen Routing Procedures
Background
Alameda County Public Health Laboratory (ACPHL) now has the capacity to
conduct rubeola (measles) nucleic acid amplification testing by polymerase chain
reaction (PCR) on upper respiratory specimens and urine specimens. Measles PCR
testing is highly sensitive if oropharyngeal (OP) swab and urine specimens are
collected within 3 days of rash onset, though detection may be successful as late
as 10- 14 days after rash onset. If a case is identified later in their disease course
(i.e., more than 7 days after rash onset) serologic testing for rubeola IgM should be
pursued in addition to PCR testing of OP swab, NP swab and urine specimens. At
present, ACPHL is not offering serologic testing for rubeola IgM or rubeola IgG.
Serologic testing for persons suspected of having measles must be performed by
the Viral and Rickettsial Diseases Laboratory (VRDL) at the California Department
of Public Health (CDPH) in Richmond. Rubeola IgG testing of contacts of confirmed
measles cases may be performed at a commercial or hospital laboratory if there is
a need to establish evidence of immunity.
Purpose
These procedures should be used by healthcare providers and clinical labs in
healthcare facilities pursuing testing for measles to determine which specimens
should be routed to the ACPHL and which should be routed directly to the CDPH
VRDL. Please note that testing for measles must be approved by Alameda
County Public Health Department prior to specimen collection and routing. For
testing approval, call (510) 267-3250 (option 2) M-F 8:30-5PM. After hours and on
weekends, please call the Alameda County Fire Dispatch at (925) 422-7595 and ask
to speak with the Public Health Duty Officer on call.
Specimen Collection
Throat (Oropharyngeal/OP) and NP Swabs (OP/throat swab is the preferred
respiratory specimen):
•OP swab: Use a sterile synthetic swab (e.g., Dacron) and vigorously swab
tonsillar areas with sterile Dacron swab
•NP swab: Firmly rub posterior nasopharynx with sterile Dacron swab
•Place OP and NP swabs into separate tubes with liquid viral or universal
transport media. Do not use bacterial transport media.
Urine:
•Collect 10-50 ml urine in a sterile container
•Collect from the first part of the urine stream. The first morning void is ideal.
•Process the urine: Centrifuge at 500-600 x g for 10 minutes at 4°C.
Resuspend the pellet in 2-3 ml of viral transport medium. If processing is
not possible, store and ship the sample at 2°- 8°C within 24 hours.
Alameda County Public Health Department
Serum IgM or IgG testing:
•Collect 7-10 ml of blood in a red top or serum separator tube.
•Capillary blood (finger or heel stick) can be used for pediatric patients, if
necessary; at least 3-5 capillary tubes are needed.
•The optimal time for collecting acute blood is at least 72 hours after rash
onset. Serum collected before then may be falsely negative but can be
tested.
•If initial IgM testing is negative in an unvaccinated person and measles
is strongly suspected, a second serum sample and specimens for
PCR should be collected.
•IgG testing can be done on case contacts to determine prior exposure to the virus.
Specimen storage and shipping
Store all specimens at 4°C. For storage longer than 24 hours, process serum
and urine. Ship all specimens on cold pack within 24 to 72 hours.
Samples for Measles
Testing
Testing
laboratory
Shipping Instructions
OP swab, NP swab, urine ACPHL Ship approved specimens to: ACPHL
2901 Peralta Oaks Ct #206 San
Leandro, CA 94577
Hours of operation: M-F, 8:30 am –
5:00 pm
Samples must arrive with completed
ACPHL specimen submittal form at
specimen receiving window at or
before 4:30 pm, M-F.
Serum (Measles IgM and
IgG)
CDPH-VRDL Ship approved specimens to:
Specimen Receiving CDPH VRDL
850 Marina Bay Parkway Richmond,
CA 94804
Samples must arrive with completed
VRDL specimen submittal form and
be received by 4 pm, M-F.
References
1.CDPH VRDL Measles Laboratory Testing Guidance