Serological Testing - PowerPoint Presentation

Slide1

Serological Testing

Serum specimens should be tested by an IgM assay**

Test appropriate specimen by Zika

RNA

PCR/NAT

Dengue

Chikungunya

Specimen positive for RNA patient POSITIVE for dengue virus

Specimen negative for dengue virus RNA

Specimen positive for chikungunya virus – patient POSITIVE for chikungunya virus

Specimen negative for chikungunya virus RNA

Any Specimen positive for Zika virus RNA is POSITIVE for Zika virus

Specimen negative for Zika virus RNA

Zika, dengue & chikungunya IgM ELISA interpreted as presumptive positive, equivocal, or indeterminate. Proceed to PRNT

PRNTFinal interpretation is made bythe lab conducting the PRNT

2017 Zika Response: Algorithm for US Testing of SYMPTOMATIC NON-PREGNANT IndividualsSpecimens collected <14 days Following Symptom Onset

Results should be considered in the context of symptoms, exposure risk, and time point of specimen collection. **Antibody cross-reactivity to other flaviviruses complicates interpretation of the current anti-Zika IgM tests. Dengue IgM testing should be conducted for individuals with a potential dengue exposure and when a presumptive other flavivirus result is obtained.When testing urine and amniotic fluid with the CDC Trioplex assay, only report the Zika result.PRNT confirmation is not routinely recommended for Puerto Rico. Revised 8/9/17.

All tests

NEGATIVE

Reported as

No evidence of recent infection

Fig. 1Slide2

Dengue**

Chikungunya

Specimen positive, equivocal or presumptive dengue infection –

Forward for confirmation by

PRNT

Specimen negative for dengue IgM:

Patient

NEGATIVE for dengue infection

Specimen positive or presumptive chikungunya infection –Forward for confirmation by PRNT

Specimen negative for chikungunya IgM:Patient NEGATIVE for chikungunya infection

Specimen negative for

Zika IgM: Patient NEGATIVE for Zika infection

PRNTFinal interpretation is made by

the lab conducting the PRNT2017 Zika Response: Algorithm for US Testing of

SYMPTOMATIC NON-PREGNANT IndividualsSpecimens Collected <12 weeks Following Symptom Onset

Results should be considered in the context of symptoms, exposure risk, and time point of specimen collection.** Note antibody cross-reactivity to other flaviviruses complicates interpretation of the current anti-Zika IgM tests. Dengue IgM testing should be conducted for individuals with a potential dengue exposure and when a presumptive other flavivirus result is obtained.

PRNT confirmation is not routinely recommended for Puerto Rico. Revised 8/9/17.

**

Zika

IgM ELISA interpreted as presumptive positive, equivocal, or indeterminate.

Serological Testing

Serum specimens should be tested by an anti-Zika IgM assay

Test available and appropriate specimens by RNA NAT for ZIKV only

Any specimen Zika RNA positive: patient

POSITIVE

for Zika virus infection

Zika RNA not detected in any specimens.

Forward specimens for confirmation of Zika IgM by PRNT

Fig. 2Slide3

NOTE

:

For asymptomatic pregnant women with possible ongoing exposure through travel or unprotected sex, PCR NAT testing should be run three times during pregnancy, unless PCR or PRNT results are positive at any time before or during pregnancy.

NOTE: Pregnant women with possible exposure to Zika virus and who have a fetus with prenatal ultrasound findings consistent with congenital Zika virus infection should be tested. NAT and IgM testing should be performed on maternal serum and urine following the algorithm for symptomatic pregnant women. If amniocentesis is being performed as part of clinical care, NAT testing of amniocentesis specimens should also be performed. Testing of placental and fetal tissues may also be considered

. See this link for additional information for assessing epidemiologic risk:

http://www.cdc.gov/zika/geo/index.html

Revised 8/9/17.

2017 Zika Response: Algorithm for Testing of

SYMPTOMATIC PREGNANT Women Meeting Epidemiologic Criteria

If testing for asymptomatic pregnant women (with recent but no ongoing exposure) is requested, algorithm for symptomatic pregnant women will be followed Specimens collected <12 weeks

after return from travel or exposure

Test urine and serum by Zika RNA NAT and serum by Zika, dengue and chikungunya IgM serology.(Serum PCR for dengue and chikungunya will be performed on serum collected <14 days)

PCR is negative on both sample sources and IgM ELISA is indeterminate,

equivocal, or presumptive positiveby IgM serology.Forward serum for confirmation by PRNT

Fig. 3

Suggests acute infection: Repeat PCR on the original positive specimen source

Specimen repeats positive. Result as:

Virus

Detected

Zika

PCR is positive on 2 specimen sources, or PCR is positive on 1 specimen source and

Zika

IgM is positive

Specimen repeats negative: Result

as

: Virus Not Detected

and repeat IgM on a second serum collected in 2 weeks. Add comment: Discordant PCR results obtained; please submit a second serum specimen collected in 2 weeks for IgM serology to determine final interpretation.

If second specimen is IgM negative: Interpret as:

No Evidence of

Zika Virus Infection

Result as:

Virus Detected

Zika

virus PRNT >10 and dengue virus PRNT >10.

Flavivirus Infection: Specific Virus and Timing of infection cannot be determined.

For pregnant women without Zika virus exposure before the current pregnancy, positive IgM represents recent unspecified

flavivirus infectionZika, dengue & chikungunya virus PRNT <10. No evidence of

viral infection

Zika

PCR

is positive on one

specimen

source, but negative on the other and serum IgM

is negative

All specimens

negative (PCR dengue and chikungunya DOC

<

14 days of exposure):

Patient

negative for

all viruses

Recommend collection of

a convalescent serum

for additional

Zika

testing if second specimen will be collected

within 12 weeks

of exposure

for

Zika

IgM

If second specimen is IgM positive, interpret as:

Evidence of Acute

Zika

Infection

PCR is positive for chikungunya or dengue on serum (Serum DOC is

<

14 days of exposure), result as:

Virus Detected

Zika

, dengue or CHIK

virus PRNT

>

10, other viruses PRNT <10.

Z

ika

, Dengue, or Chikungunya Virus

Infection: Timing of infection cannot be determined.

For pregnant women without

Zika

, dengue or CHIK virus

exposure before the current pregnancy,

positive IgM represents

recent virus

infection