Health Alerts, Advisories, Notifications, and Updates

Zika Virus Guidance

Local transmission of Zika virus has emerged throughout South/Central America, the Caribbean, and Mexico since 2015. With the recent outbreaks in the Americas, the number of Zika virus disease cases among travelers visiting or returning to the United States likely will increase.

Click the button below to view health alerts, surveillance data, health education materials, and guidelines for management and control specific to Zika Virus.


Vaccine Information

  • No vaccines are currently available for arborviruses.

Diagnostics and Treatment

West Nile Virus (WNV)

Clinical Characteristics:

  • Neuroinvasive WNV infection: meningitis, encephalitis or acute flaccid paralysis
    • <1% of infected individuals develop WNV neuroinvasive disease
    • May result in residual neurological deficits or death
    • Risk groups include:
      • adults > 50 years old
      • organ transplant recipients or immunocompromised patients
  • WNV Fever
    • 20% of infected individuals develop WNV fever
    • Fever accompanied by other symptoms, such as headache, body aches, joint pains, vomiting, diarrhea, or rash
    • Most recover completely, but fatigue and weakness can last for weeks or months

WNV Testing:

Between May and October, collect cerebrospinal fluid and serum for WNV IgM and IgG testing from patients who present with suspected WNV infections or unexplained encephalitis or meningitis. WNV-specific IgM in serum or CSF is preferred for laboratory confirmation. Consider the specimen type and timing of collection when ordering WNV-specific IgM testing.

  • Serum: Collect 8 to 14 days after illness onset. Draw and test additional serum if collected too early.
  • CSF: Collect within 8 days of illness onset. Polymerase Chain Reaction (PCR) or culture for other viral etiologies (i.e., herpes simplex virus, enterovirus, etc) should also be ordered.

A 4-fold increase in WNV-specific IgG titers from acute and convalescent serum collected at least 2-weeks apart can also confirm diagnosis. Contact the Division of Disease Control at (215) 685-6742 to help facilitate specimen submission to the PA Department of Health laboratory for confirmatory testing.

Chikungunya, Dengue, And Zika

Clinical Characteristics:

Average Incubation (Range) % with Symptoms Symptoms Blood Abnormalities Outcome
Chikungunya 3–7 days
(1–12 days)
72–97% Fever and polyarthalgia with headache, myalgia, arthritis, conjunctivitis, nausea/vomiting,or maculopapular rash Lymphopenia,thrombocytopenia, ↑ creatinine, ↑ LFTs Resolves in 7–10 days; some have relapsing arthralgia; rarely fatal
Dengue 4–7 days
(3–14 days)
25% Fever with headache, retroorbital pain, myalgia, arthralgia, rash, or minor hemorrhagic manifestations 5% develop shock, respiratory distress, severe bleeding, or organ failure Neutropenia, thrombocytopenia, ↑ hematocrit Fatal in up to 10% with severe infection
Zika 2–7 days
(2–12 days)
18-25% Mild illness with low-grade fever, maculopapular rash, arthralgia, arthritis, myalgia, headache, retroorbital pain, or conjunctivitis Rarely fatal; resolves in <1 week

Infections during pregnancy may lead to microcephaly or fetal loss

Guillain-Barre syndrome possible uncommon complication


If chikungunya, dengue, or Zika is suspected, collect serum and test for all three. Testing for all three pathogens is available through the PA Department of Health laboratory and PDPH should be contacted at (215) 685-6742 for testing requests (see specimen submission guidance). Commercial laboratories are offering arboviral testing, but assays available vary by laboratory, and providers will also need to place separate orders for each arbovirus (chikungunya, dengue, and Zika).

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

  • Day 1 to 3 of illness: Order polymerase chain reaction (PCR)
    *Note: Dengue PCR availability is limited
  • Day 4 to 7 of illness: Order PCR, IgM, & IgG
  • Day 8 and after: Order IgM, & IgG
For detailed information on screening and testing pregnant women and their infants for Zika, click here to view the Zika Virus Guidance page

The following laboratory results can help confirm diagnosis:

  • Positive virus-specific PCR
  • Positive virus-specific IgM titer with evidence of virus-specific neutralizing antibodies
    *Note: Neutralization tests that help differentiate arboviral pathogens are only available through public health laboratories
  • 4-fold change in virus-specific IgG titers from acute and convalescent serum (collected =2 weeks apart)


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

Reporting to PDPH

  • Report West Nile Virus cases immediately to PDPH by calling 215-685-6748 during business hours or calling 215-686-4514 after normal business hours.
  • To arrange for testing and report suspected Zika cases, contact to PDPH by calling 215-685-6742 during business hours
  • Report dengue and chikungunya cases within 5 days by calling 215-685-6748 or faxing a disease report form to 215-238-6947.

Health Educational Materials

Links and Resources

Guidelines for Management and Control

Arboviruses Guidelines
  • During warmer months (May-October) in Philadelphia and when traveling to areas with local transmission of chikungunya, dengue or Zika, encourage patients to take personal prevention measures :
    • use mosquito repellent
    • stay in well-screened, air-conditioned accommodations
    • wear long pants and sleeves when weather permits
  • Remove standing water outside their home twice a week
  • Pregnant women or women planning to become pregnant due to the risk of congenital infection along with adults > 65 years of age and persons with underlying conditions (e.g., hypertension, diabetes, etc) who are at risk for severe disease should consider not traveling to areas with ongoing chikungunya or Zika outbreaks
  • Advise patients with suspected chikungunya, dengue, or Zika infections to stay indoors and avoid mosquito bites for the first 7 days of illness to prevent local transmission
Prevention of Transmission for Returning Travelers
  • Advise patients with suspected Zika, dengue, or chikungunya infections to stay indoors and avoid mosquito bites for the first 7 days of illness to prevent local transmission
  • See the Zika Guidance page for information on the prevention ofsexual transmission of Zika and congenital Zika infections
Prevention of Sexual Transmission of Zika
  • Since sexual transmission of Zika virus is possible and Zika virus may persist in semen longer than blood, providers should provide counseling to prevent sexual transmission to men who traveled to a country with Zika transmission and their partners.
    • Those who have a pregnant partner should abstain from sexual activity or consistently and correctly use condoms during sex for the duration of the pregnancy
    • Those with non-pregnant partners might consider abstaining from sexual activity or using condoms consistently and correctly during sex
  • When more information on the duration seminal shedding becomes available, more definitive time frames for the prevention of sexual transmission will be provided
Clinical Guidelines for West Nile Virus
Clinical Guidelines for Chikungunya
Clinical Guidelines for Dengue
Clinical Guidelines for Zika

Updated: 04/06/2018 4:00pm