A) GENERAL GUIDELINES
1) SUMMARY: Transmission of multiple arborviruses in countries in the Americas can produce febrile illness with rash, myalgia, or arthralgia; therefore, laboratory testing should confirm the etiology of these diseases (ie, Zika, chikungunya and dengue virus). Laboratory testing usually includes serum testing to detect viral nucleic acid or virus-specific immunoglobulin (Ig) M and neutralizing antibodies. It has been determined that serological cross-reactivity is possible between Zika and dengue viruses so molecular detection is necessary in acute specimens (Centers for Disease Control and Prevention (CDC), 2016). It is anticipated that locally acquired mosquito borne cases will occur in some areas of the United States.
2) WHO SHOULD BE TESTED: Any patient who presents with an acute febrile illness, rash, myalgia, or arthralgia and have travelled recently (within the past 2 weeks) where there is ongoing infection of the Zika virus. Testing should include Zika, chikungunya and dengue virus infections (Centers for Disease Control and Prevention (CDC), 2016).
3) REPORTABLE DISEASE: As an arboviral disease, Zika virus infection is a nationally reportable disease (Staples et al, 2016).
4) LABORATORY SAFETY: Zika and dengue viruses are classified as biological safety level (BSL) 2 pathogens and chikungunya virus is classified as a BSL 3 agent and all should be handled appropriately with Biosafety in Microbiological and Biomedical Laboratories (BMBL) guidelines (Centers for Disease Control and Prevention (CDC), 2016).
5) DIAGNOSTIC TESTING: Beginning in 2016, the US FDA has issued an Emergency Use Authorization for several diagnostic tools that can be used for testing for the Zika virus. They include Trioplex Real Time RT-PCR assay and the Zika MAC-ELISA, which have been distributed to qualified laboratories in the US (Rabe et al, 2016).
6) BLOOD DONATION: As of late August, 2016 the US FDA has recommended that all blood donations (blood and blood components) collected in the US and US territories be tested for the Zika virus using an investigational individual donor nucleic acid test (ID-NAT). Donors that are reactive for Zika virus should be deferred from donating for 120 days from the date of the reactive test. Donors should also be counseled regarding a possible exposure/infection (http://www.fda.gove/downloads/biologiicsBloodvaccines/GuidanceComplianceRegulatoryInformation/Guidances/Blood/UCM518213.pdf).
a) Donation centers in Florida and Puerto Rico should begin testing immediately.
b) Donation centers in the following states: Alabama, Arizona, California, Georgia, Hawaii, Louisiana, Mississippi, New Mexico, New York, South Carolina and Texas should implement these recommendations as soon as possible but not later than 4 weeks after the guidance issue date (8/26/2016).
c) Donation centers in all other states and territories should implement the recommendations as soon as possible, but not later than 12 weeks after the issue date.
B) STAGE OF ILLNESS
1) Diagnosis of Zika virus can vary depending on the stage of illness (acute versus convalescent period). In the acute phase (first 7 days of illness), viral RNA can usually be identified in serum, and RT-PCR is preferred to test all 3 types (Zika, dengue, chikungunya) of viruses. In the convalescent period (serum collected more than 8 days after illness), patients should be tested by virus-specific IgM ELISA; positive results are confirmed by testing for neutralizing antibodies. For patients with a positive IgM (ie, dengue or Zika IgM ELISA), the results are considered indicative of a recent flavivirus infection; therefore, plaque-reduction neutralization tests should be performed to measure virus-specific neutralizing antibodies to possibly discriminate between cross-reacting antibodies in primary flavivirus infections (Centers for Disease Control and Prevention (CDC), 2016).
a) In patients with a primary flavivirus infection, a 4-fold or greater increase in virus-specific neutralizing antibodies between the acute- and convalescent phase serum specimens obtained 2 to 3 weeks apart can be used to confirm a recent infection (Centers for Disease Control and Prevention (CDC), 2016).
b) In patients previously immunized against (eg, Yellow fever or Japanese encephalitis vaccine) or previously infected with another flavivirus infection (eg, West Nile, St. Louis encephalitis virus), cross-reactive antibodies (ie, IgM, neutralizing antibody assays) make it difficult to diagnose the patient's current illness (Centers for Disease Control and Prevention (CDC), 2016).
C) SPECIMEN TESTING AND COLLECTION
1) Zika, chikungunya and dengue virus testing can be performed at the Centers for Disease Control (CDC) and some state health departments that already perform testing for the West Nile virus RT-PCR assay (Centers for Disease Control and Prevention (CDC), 2016; Centers for Disease Control and Prevention (CDC), 2016). Tests performed at the CDC include Zika, chikungunya and dengue virus RT-PCR, IgM ELISA, and plaque reduction neutralization tests (PRNT). If testing is needed, contact your state health department for further information (Centers for Disease Control and Prevention (CDC), 2016).
2) Commercial diagnostic assays or testing kits for the Zika virus are NOT currently available (Centers for Disease Control and Prevention (CDC), 2016).
3) Results are usually available 4 to 14 days after receipt of the specimen. Once testing is completed, ALL results will be sent to the appropriate state health department. In addition, state health departments should be notified of any direct submissions to the CDC (Centers for Disease Control and Prevention (CDC), 2016)
4) For additional assistance in collecting or sending laboratory samples to CDC, contact the Arboviral Diseases Branch on-call epidemiologist at 970-221-6400 or contact them at http://www.cdc.gov/ncezid/dvbd/specimensub/arboviral-shipping.html (Centers for Disease Control and Prevention (CDC), 2016).
5) Within Puerto Rico, please call 787-706-2399 for further questions about testing (Centers for Disease Control and Prevention (CDC), 2016).
D) PREGNANT WOMEN
1) All pregnant women in the United States and US territories should be assessed for possible Zika virus exposure during each prenatal visit (Oduyebo et al, 2016).
2) CDC recommends that pregnant women not travel to an area with active Zika virus transmission. Pregnant women who must travel to one of these areas should strictly follow steps to prevent mosquito bites (Oduyebo et al, 2016).
3) SYMPTOMATIC PREGNANT WOMEN
a) Pregnant women who report signs or symptoms consistent with Zika virus exposure (ie, acute onset of fever, rash, arthralgia, conjunctivitis) should be tested for the virus (Oduyebo et al, 2016).
b) Maternal testing includes the same studies as the general population (Petersen et al, 2016); however, the type of testing recommended can vary depending on the time of evaluation relative to symptom onset (Oduyebo et al, 2016).
1) rRT-PCR testing of serum and urine should be performed in women that seek care less than 2 weeks after symptom onset. A positive result confirms the diagnosis of recent maternal Zika virus infection (Oduyebo et al, 2016).
2) Symptomatic pregnant women with a negative result should have Zika virus IgM and dengue virus IgM antibody testing performed. If either test are positive or equivocal results, PRNT should be performed on the same IgM-tested sample to rule out a false-positive result (Oduyebo et al, 2016).
3) Symptomatic pregnant women who seek care 2 to 12 weeks after symptom onset should initially have Zika virus and dengue virus IgM antibody testing done. Positive or equivocal results require rRT-PCR testing that should be performed on the same sample to evaluate whether Zika virus RNA is present; a positive result confirms recent maternal Zika virus infection. However, if the rRT-PCR is negative and there is a positive or equivocal Zika virus IgM antibody, a PRNT should be performed. Likewise, if a patient has a positive or equivocal dengue IgM antibody test result with a negative Zika virus IgM antibody, the test should also be confirmed by PRNT (Oduyebo et al, 2016).
4) SYMPTOMATIC AND ASYMPTOMATIC PREGNANT WOMEN WHO SEEK CARE AFTER 12 WEEKS
a) In symptomatic and asymptomatic pregnant women with possible Zika virus exposure who seek care greater than 12 weeks after symptom onset or possible exposure, IgM antibody testing should be considered. If there is evidence of fetal abnormalities, rRT-PCR testing should be done on maternal serum and urine. However, a negative IgM antibody or rRT-PCR obtained greater than 12 weeks after symptoms does NOT rule out recent Zika virus infection. Because of the limitations of testing beyond 12 weeks, serial fetal ultrasounds should be considered (Oduyebo et al, 2016)
5) ASYMPTOMATIC PREGNANT WOMEN
a) Testing of asymptomatic pregnant women differs depending on the possible circumstances of exposure (Oduyebo et al, 2016):
1) Asymptomatic and NOT living in an area with active Zika virus transmission less than 2 weeks after possible exposure: Perform rRT-PCR (serum and urine) testing (Oduyebo et al, 2016):
1) If negative, obtain Zika virus IgM antibody testing 2 to 12 weeks after possible exposure. If both, Zika virus and dengue virus IgM are negative - No recent Zika virus infection (Oduyebo et al, 2016).
2) Asymptomatic and NOT living in an area with active Zika virus transmission 2 to 12 weeks after possible exposure OR asymptomatic and living in an area with active Zika transmission (includes first and second trimester): Obtain Zika and dengue IgM (serum) (Oduyebo et al, 2016).
1) If Zika virus IgM positive or equivocal and any results on dengue virus IgM: Presumptive recent Zika or flavivirus infection. Follow with rRT-PCR testing (serum); a positive result indicates recent Zika virus infection. A negative finding requires PRNT testing. The test results are as follows (Oduyebo et al, 2016):
a) A Zika virus PRNT greater or equal to 10 and dengue virus PRNT of less than 10: Recent Zika virus infection.
b) A Zika virus PRNT greater or equal to 10 and dengue virus PRNT greater or equal to 10: Recent flavivirus infection, however, a specific virus cannot be identified.
c) A Zika virus PRNT of less than 10: NO recent evidence of Zika virus infection.
2) If Zika and dengue IgM are negative: No recent Zika virus infection (Oduyebo et al, 2016).
3) If dengue virus IgM positive or equivocal and Zika IgM virus is negative: Presumptive dengue virus infection. Obtain PRNT to confirm findings (Oduyebo et al, 2016).
6) PRENATAL MONITORING OF PREGNANT WOMEN
a) POSITIVE LABORATORY EVIDENCE OF CONFIRMED OR POSSIBLE CASES
1) RECENT ZIKA VIRUS INFECTION: Consider serial ultrasounds every 3 to 4 weeks to follow fetal anatomy and growth. Amniocentesis is based on individual clinical circumstances (Oduyebo et al, 2016).
2) PRESUMPTIVE RECENT ZIKA VIRUS INFECTION: Consider serial ultrasounds every 3 to 4 weeks to follow fetal anatomy and growth. Amniocentesis is based on individual clinical circumstances (Oduyebo et al, 2016).
3) NO EVIDENCE OF ZIKA VIRUS OR DENGUE VIRUS INFECTION: Prenatal ultrasound to evaluate for fetal abnormalities consistent with congenital Zika virus syndrome. If fetal abnormalities are present, repeat Zika virus rRT-PCR and IgM testing. Clinical management should be based on laboratory results. If fetal abnormalities are absent, prenatal care should be based on the potential ongoing risk of Zika virus exposure in pregnant women (Oduyebo et al, 2016).
7) AMNIOTIC FLUID TESTING
a) Amniotic fluid can be tested for the virus by RT-PCR. At present, the sensitivity and specificity to detect congenital infection remains unknown. It is also unknown if a positive test is predictive of a fetal abnormality (Petersen et al, 2016).
E) POSTNATAL MONITORING OF WOMEN
1) SUMMARY: Infants born to women that had tested positive for the Zika virus or possibly have the infection should be evaluated for congenital Zika virus infection. Zika virus testing is recommended for these infants regardless of the presence or absence of phenotypic abnormalities (Oduyebo et al, 2016).
F) INFANTS
1) BACKGROUND: The Zika virus infection has been transmitted through both intrauterine transmission (congenital) and intrapartum transmission from a viremic pregnant woman to her newborn. It has also been detected in breast milk (Zika virus RNA); however, transmission through breastfeeding has not been reported (Staples et al, 2016).
2) Due to concerns about microencephaly associated with maternal exposure to the Zika virus, fetuses and infants of women infected should be evaluated for congenital exposure and possible neurologic abnormalities (Centers for Disease Control and Prevention (CDC), 2016). Currently, molecular and serologic testing are recommended by the CDC to diagnose congenital infection because of the uncertainty in determining which method is most reliable in this age group (Staples et al, 2016).
3) In the US, interim guidelines have been established by the CDC for healthcare providers who care for infants born to women who may have been potentially exposed to the Zika virus either through travel or living in an area with Zika transmission during pregnancy (Staples et al, 2016). The following guidelines are recommended (Staples et al, 2016):
a) Pediatricians should work closely with obstetricians to identify pregnant women or new mothers that were potentially exposed to the Zika virus.
b) Fetal ultrasounds and maternal testing for Zika should be reviewed.
4) Infants should be tested for Zika virus based on the following (Staples et al, 2016):
1) Infants with microcephaly or intracranial calcifications born to women who traveled to or resided in an area with Zika virus transmission.
2) Infants born to mothers with a positive or inconclusive laboratory testing for Zika virus.
3) Infants with possible laboratory evidence of congenital Zika virus exposure should receive further clinical evaluation and treatment as indicated.
4) Providers should contact their local state health department to coordinate testing of an infant (as an arboviral disease it is a reportable disease).
5) METHOD OF COLLECTION
a) RT-PCR TESTING: Obtain serum specimens from the umbilical cord or directly from the infant within 2 days of birth (Staples et al, 2016).
b) OTHER STUDIES: Samples should also be collected and tested from the placenta at the time of delivery or CSF fluid (if collected for another reason) and include RT-PCR, IgM ELISA for Zika and dengue viruses on infant and maternal serum. In some cases, cross-reactivity may produce a false-positive result; therefore, further testing using the plaque reduction neutralization tests (PRNT) method can measure virus-specific neutralizing antibodies to rule out cross-reactivity antibodies from closely related flaviviruses (eg, dengue or yellow fever viruses) (Staples et al, 2016).
c) IMMUNOHISTOCHEMICAL STAINING: This method may be considered to detect the Zika virus antigen on fixed placenta and umbilical cord tissues (Staples et al, 2016).
6) RESULTS OF TESTING
a) POSITIVE CONGENITAL INFECTION: The infant is considered congenitally infected with the virus, if Zika virus RNA or viral antigen are present in a sample (ie, amniotic fluid, placenta, umbilical cord). A positive finding also includes, Zika virus IgM antibodies with confirmatory neutralizing antibody titers that are greater than or equal to 4-fold higher than dengue virus neutralizing antibody titers in the infant serum or cerebrospinal fluid (Staples et al, 2016).
1) A positive rRT-PCR or immunohistochemical staining on the placenta indicates the presence of maternal infection (Oduyebo et al, 2016).
b) INCONCLUSIVE FINDINGS: Results are inconclusive if the Zika virus neutralizing antibody titers are less than 4-fold higher than the dengue virus (Staples et al, 2016).
c) Positive and inconclusive test results should be reported to state and local health department for ongoing follow-up. Testing should also include a repeat hearing test at 6 months even if the initial study was normal (Staples et al, 2016).
7) OTHER STUDIES
a) Perform a retinal exam within the first month in infants with a possible congenital Zika virus infection (Staples et al, 2016).