Zika Virus Infection

Important information

  • Pregnant women in any trimester should consider postponing travel to areas with ongoing Zika virus transmission.
  • Travelers, including pregnant women who do travel, should strictly follow steps to avoid mosquito bites.
  • It is recommended that providers routinely check the Centers for Disease Control (CDC) webpages for up to date information on affected geographic areas, travel and clinical guidance. Important changes will be communicated via LAHAN.
  • Pregnant women who have returned from an affected area should be tested for Zika virus infection if they have had symptoms suggestive of Zika virus infection during or within 2 weeks of travel, or if their fetus/infant has evidence of microcephaly or intracranial calcifications.
  • In Los Angeles County (LAC), all requests for Zika virus testing must be made by calling the Acute Communicable Disease Control Program (ACDC) at 213-240-7941.
  • Providers must report all suspected cases of Zika virus infection in Los Angeles County to ACDC.
  • All children diagnosed with microcephaly whose mothers were pregnant while in a Zika-affected area since March 2015 also should be reported to ACDC.

Actions requested of providers

  • Advise pregnant women to postpone travel to areas of ongoing Zika virus transmission.
  • Advise all persons traveling to Zika-affected areas how to prevent mosquito bites (see Prevention of Zika Virus Infection and Mosquito Bites).
  • Contact ACDC at (213) 240-7941 to report all suspect cases and to coordinate Zika testing for patients with suspect infection.

In 2015, Brazil, the site of a large Zika virus outbreak, has reported a substantial increase in the number of babies born with microcephaly. Zika virus was identified in tissue specimens and amniotic fluid from several infants born with microcephaly and in early fetal losses. The incidence of microcephaly associated with congenital Zika virus infection, the spectrum of possible congenital defects, and the causal link between Zika virus infection and adverse pregnancy outcomes is unknown.

Currently, local transmission of Zika virus has not been reported in the continental United States. However, as the number of infections among U.S. travelers is expected to increase, viral introduction and local spread via Aedes mosquitos within the U.S. is possible.

The CDC recently issued travel alerts, a health advisory, and interim guidance documents: Interim Guidelines for Pregnant Women During a Zika Virus Outbreak – United States, 2016 and Interim Guidelines for the Evaluation and Testing of Infants with Possible Congenital Zika Virus Infection — United States, 2016.

Clinical Presentation and Treatment

About 1 in 5 people infected with Zika virus become symptomatic. Characteristic clinical findings are acute onset of fever with maculopapular rash, arthralgia, or conjunctivitis. Other commonly reported symptoms include myalgia and headache. Clinical illness is usually mild with symptoms lasting for several days to a week.

No specific antiviral treatment is available for Zika virus disease. Treatment is supportive. Because of similar geographic distribution and symptoms, patients with suspected Zika virus infections also should be evaluated for possible dengue or Chikungunya virus infection. Aspirin and other non-steroidal antiinflammatory drugs (NSAIDs) should be avoided until dengue can be ruled out to reduce the risk of hemorrhage. People infected with Zika, Chikungunya, or dengue virus should be protected from mosquito exposure while ill to reduce the risk of local transmission.

Prevention of Zika Virus Infection and Mosquito Bites

Zika virus infection is prevented by avoiding being bitten by an infected mosquito. The mosquitoes that transmit Zika, dengue, and Chikungunya viruses are aggressive and are present during the daytime and early evening. The best way to prevent infection with Zika virus is to avoid traveling to areas with high rates of transmission. If patients do travel, they should follow all precautions to avoid mosquito bites including the following:

  • Use insect repellents containing DEET, picaridin, and IR3535. If sunscreen is being used it should be applied before insect repellent. Insect repellant should be reapplied as directed on the product label.
  • Providers should specifically communicate to pregnant women that, when used as directed on the product label, EPA-registered insect repellents can be used safely during pregnancy.
  • Other precautions include covering exposed skin, staying in rooms with screens or air conditioning, and treating clothing with permethrin.
Testing for Zika Virus in Los Angeles County

Testing is recommended for the following situations:

  • Pregnant women with a history of travel to a Zika-affected area and:
    • Compatible symptoms (two or more of the following: fever, maculopapular rash, arthralgia, or non-purulent conjunctivitis) during or within 2 weeks of travel or
    • Presence of fetal microcephaly or intracranial calcifications on ultrasound.
  • Children with microcephaly whose mothers were in an affected area during their pregnancy since the outbreak began in March 2015.
  • Infants born to mothers with positive or inconclusive test results for Zika virus infection.
  • Non-pregnant patients with compatible symptoms and history of travel to a Zika-affected area. Note: because laboratory testing capacity is limited, priority will be given to specimens from pregnant women and infants with microcephaly.

Testing should be considered for the following situation:

  • Patients diagnosed with Guillain-Barre Syndrome (GBS) with a history of travel to a Zika-affected area may be tested. There have been reports of GBS in patients following suspected Zika virus infection in other countries, however the relationship between Zika virus infection and GBS is currently unknown.

Testing is not recommended for asymptomatic persons.

  • CDC does not currently recommend testing for Zika virus in asymptomatic pregnant women with a travel history unless there is fetal ultrasound finding of microcephaly or intracranial calcifications because of concerns about test accuracy. However, serial ultrasound evaluation for microcephaly or intracranial calcifications may be considered, per CDC.

At this time, testing is only available at the CDC. All Zika virus testing must be coordinated and approved by ACDC which will provide the test submission form and advice on specimen collection, storage and shipping. Providers should have the following information ready before contacting ACDC:

  • Symptoms; date of onset
  • Dates of travel and country/countries of travel
  • If pregnant, gestational age
  • History of previous infection with dengue, Chikungunya or West Nile virus, and history of vaccination for Yellow Fever or Japanese encephalitis

Note: test results may be delayed due to the volume of requests.

Evaluation for Dengue or Chikungunya

Patient with suspected Zika should also be evaluated for dengue and Chikungunya virus infections. Specimens should be sent to a commercial laboratory to test for these viruses.