Zika Testing and Mosquito Activity

Philadelphia Zika Testing
Confirmed and Probable Cases: 59
*A revised case definition was implemented on 9/26/2016.
Unspecified flavivirus infections were re-classified as probable Zika cases.

Last Updated (11/10/2017)
Philadelphia Mosquito Activity
Number of traps with Aedes aegypti Mosquitoes: 0
Number of traps with Aedes albopictus Mosquitoes:1162

Last Updated (11/10/2017)

Latest Updates to Zika Guidance

  • On February 28, 2019, CDC updated their travel recommendations. The updated guidance recommends that pregnant women and couples planning to become pregnant within 3 months talk to their healthcare providers to carefully consider the risks and possible consequences of travel to areas with risk of Zika. CDC continues to recommend that pregnant women not travel to any area experiencing a current Zika outbreak. For CDC Zika Travel Information: https://wwwnc.cdc.gov/travel/page/zika-travel-information
  • On Tuesday, October 30, 2018, PDPH updated the Zika guidance for preconception counseling and prevention of sexual transmission of Zika for men. See the Guidelines for Management and Control Section.

Health Alerts, Advisories, Notifications, and Updates


Vaccine Information

  • No vaccines are currently available for Zika virus.

Diagnostics and Treatment

Clinical Characteristics

Zika virus is primarily spread by the bite of infected Aedes spp. mosquitoes. Other less common modes of transmission include maternal-fetal transmission, sexual transmission, transfusion-associated infection or theoretically transplant-associated infection. A summary of clinical characteristics follows.

Table 1: Zika Clinical Characteristics
Average Incubation (Range) % with Symptoms Symptoms Outcome
Zika 2–7 days
(2–12 days)
18-25% Mild illness with low-grade fever, maculopapular rash, conjunctivitis, or arthralgia. Other symptoms may include myalgia, headache, or retro-orbital pain. Rarely fatal; resolves in <1 week

Infections during pregnancy can result in microcephaly, sensory deficits, fetal loss, or other birth defects

Rare neurologic complications--Guillain-Barre syndrome, encephalitis, meningitis and myelitis


Philadelphia-area healthcare providers are encouraged to utilize commercial laboratories when ordering Zika virus testing for exposed, symptomatic persons with health insurance. PDPH will continue to coordinate approval and testing at the Pennsylvania Department of Health (PADOH) Bureau of Laboratories for the following patients regardless of insurance status(Click here for the PADOH laboratory testing form ):

  1. Uninsured or under-insured symptomatic patients
  2. Any exposed, pregnant woman with a fetal loss or ultrasound abnormality
  3. Newborns with possible Zika-related birth defects or those born to mothers with evidence of Zika infection during pregnancy
See our specimen submission guidance for additional information. Contact PDPH at (215) 685-6742 for testing requests and to report suspected Zika cases who have had testing ordered.

For symptomatic patients, it is important for providers to place separate testing orders for other arbovirus testing (dengue and chikungunya). If IgM testing for dengue and chikungunya is indicated, commercial laboratory testing should be pursued. While the PADOH laboratory can conduct PCR testing for dengue and chikungunya, they do not offer dengue and chikungunya IgM testing.

The type of assay(s) that should be performed will depend on the specimen type and time from illness onset to specimen collection.

  • Collect at least 6 milliliters (ml) of blood in a blood tube (red top, serum separator tube, tiger top, speckle top, gold top)
  • Centrifuge the blood tube within 6 hours of collection and using sterile technique, transfer the serum to a separate, labeled sterile tube (at least 3 ml serum required) Seal the sterile serum tubes with paraffin film. If a centrifuge is not available on site, pack tubes on cold packs and arrange for transport to a laboratory within 6 hours of collection.
  • For symptomatic persons, test for Zika, chikungunya, and dengue.
    • Day 1 to 3 of illness: Order PCR
    • Day 4 to 13 of illness: Order PCR, IgM, & IgG
    • Day 14 and after: Order IgM, & IgG
  • *Note: IgG testing is not available for Zika.

  • Collect 3 mL in a sterile container with a tight fitting screw cap and secure with parafilm.
  • Day 1 to 14 of illness: Order PCR
  • *Note: PCR testing of urine is only recommended for Zika. A serum specimen must be submitted with the urine specimen or testing will not be performed.

The following laboratory results can help confirm diagnosis:

  • Positive virus-specific PCR
  • *Note: Negative PCR results do not exclude Zika infection. Additional serum collected on or after day 14 of illness should be submitted for IgM testing.
  • Positive virus-specific IgM titer with evidence of virus-specific neutralizing antibodies
    • Plaque-reduction neutralization tests (PRNT) that help differentiate flavivirus infections (e.g., Zika, dengue, West Nile, yellow fever, and Japanese encephalitis viruses) are only available through public health laboratories.
    • Results of IgM testing may be falsely negative if the specimen is collected during the first week of illness. Consider collecting an additional serum specimen 2 weeks after the initial specimen for testing.
    • Positive IgM results in patients who resided in an affected area or had another ongoing exposure should be interpreted with caution. Evidence that the Zika IgM response can be prolonged has been documented, making it difficult to determine when infection was acquired for these patients.
  • 4-fold change in virus-specific PRNT or IgG titers (dengue and chikungunya) from paired sera collected 2 or more weeks apart

Pregnant Women

At each prenatal care visit, the provider should assess the pregnant patient for travel to areas with active Zika transmission or have another possible exposure (e.g., unprotected sex with a returning traveler or partner who resides in an affected area). As of January 1, 2018, Zika testing is no longer recommended for exposed, asymptomatic pregnant women with healthy pregnancies. Zika testing should continue for the following exposed, pregnant women:

  • Pregnant women who develop Zika-specific symptoms (mild fever, rash, arthralgia, or conjunctivitis) during or within 2 weeks of a possible Zika exposure
  • Exposed, pregnant women (symptomatic and asymptomatic) who have a fetal loss or prenatal ultrasound findings consistent with congenital Zika virus syndrome (i.e., intracranial calcifications, microcephaly)
As of January 1, 2018, Zika testing is no longer recommended for exposed, asymptomatic pregnant women with healthy pregnancies. Zika testing should continue for the following exposed, pregnant women:
  • Day 1 to 13: serum and urine rRT-PCR testing
    • Negative PCR results do not exclude Zika infection. Serum collected on or after day 14 of illness or following exposure (asymptomatic pregnant women) should be submitted for IgM testing.
  • Day 14 to Week 12: serum IgM testing
    • If IgM positive, PCR testing will be performed and if PCR negative, PRNT testing will follow.

      Note: For pregnant exposed women, the PADOH laboratory is performing PCR and IgM testing on all serum specimens regardless of timing of specimen collection.

Contact PDPH at (215) 685-6742 for testing requests after the 12-week time frame. For more information, see the CDC testing algorithm for pregnant women exposed to Zika.

For any pregnant woman who has a positive or inconclusive Zika testing result, serial fetal ultrasounds to detect microcephaly, intracranial calcifications, or other abnormalities related to Zika are recommended along with consideration of amniocentesis for Zika testing. For further information, see CDC’s guidance for clinical management of pregnant women with suspected Zika infections.

Figure 1. CDC Testing Algorithm for Pregnant Women Exposed to Zika

Zika-specific testing of serum and urine at the time of birth should be performed for infants with possible congenital Zika infection:

  • Infants with microcephaly or intracranial calcifications born to women exposed to Zika virus while pregnant (i.e., travel or residence in an area with Zika virus transmission, sexual contact with an infected partner)
  • Infants born to mothers with positive or inconclusive test results for Zika virus infection

Thorough clinical evaluation and laboratory testing for infants with possible congenital Zika virus infection are also indicated, including testing to rule out other congenital infections for infants with microcephaly and long-term follow up for infants without microcephaly born to mothers who have positive or inconclusive Zika test results during pregnancy. See CDC’s guidance for congenital Zika infections for more information.


  • Patients with Zika should be managed as dengue with acetaminophen recommended for initial treatment.
  • If dengue, which causes hemorrhagic complications, has been ruled out, NSAIDS may be considered to manage fever.

Reporting to PDPH

To arrange for testing and report suspected Zika cases including possible congenital infections, neurologic complications, and Guillain-Barre syndrome post-infection, contact PDPH by calling 215-685-6742 during business hours.

Health Educational Materials

Links and Resources

Guidelines for Management and Control

Zika Virus Guidelines
Prevention for Travelers
Mosquito Bite Prevention for Returning Travelers
  • Advise patients with suspected Zika infections to stay indoors and avoid mosquito bites for the first 7 days of illness to prevent local transmission.
  • During mosquito season in Philadelphia (April to October), encourage travelers returning from areas with Zika outbreaks who are asymptomatic to continue to take steps to avoid mosquitoes especially during the 3 weeks following their return to Philadelphia.
    • use repellent when outdoors
    • wear long sleeves and pants when weather permits
    • remove sources of standing water around their home a few times a week
    • keep screens on doors and windows in good repair
Clinical Guidelines for Zika
Prevention of Sexual Transmission and Family Planning Considerations for Returning Travelers Since sexual transmission of Zika virus is possible and Zika virus may persist in semen longer than blood, providers should counsel individuals who traveled to a country with Zika transmission and their partners on the prevention of sexual transmission. This guidance also extends to conception planning if the patient or their partner has traveled to or resides in a Zika-affected area. Duration of precautions (abstinence, condom use, wait time to attempt conception) will vary depending on which partner traveled and whether s/he developed symptoms (See Table 3 at the bottom of this page).

As part of family planning counseling, healthcare providers should provide information on available strategies to prevent unintended pregnancy, including use of the most effective contraceptive methods that can be used correctly and consistently by the patient. In addition, patients should be counseled that correct and consistent use of condoms reduces the risk for sexually transmitted infections including Zika.

Table 3: Prevention of Sexual Transmission of Zika Virus and Family Planning Considerations (Updated: 10/30/18)
Patient Gender Patient Zika Symptoms/Exposure
(travel to or residence in an affected area)
Patient Pregnancy Status
(females only)
Partner Characteristics
Zika Symptoms/ Exposure (travel to or residence in an affected area) /
and Pregnancy Status
Duration of Precautions
(abstinence/condom use and wait time for conception)
Symptomatic or asymptomatic with exposure to Zika -- Pregnant partner duration of pregnancy
Symptomatic or asymptomatic with exposure to Zika -- Non-pregnant partner regardless of gender 3 months
No symptoms or exposure -- Symptomatic male or asymptomatic male with exposure to Zika 3 months
No symptoms or exposure -- Symptomatic female or asymptomatic female partner with exposure to Zika 8 weeks
Regardless of symptoms or exposure pregnant Symptomatic male or asymptomatic partner (male or female) with exposure to Zika duration of pregnancy
Symptomatic or asymptomatic with exposure to Zika not pregnant No symptoms or exposure 8 weeks
No symptoms or exposure not pregnant Symptomatic male or asymptomatic male with exposure to Zika 3 months
No symptoms or exposure not pregnant Symptomatic female or asymptomatic female with exposure to Zika 8 weeks

Updated: 12/11/2019 2:00pm