CDC Updates Its Zika Testing Guidelines

CDC Updates Its Zika Testing Guidelines

Since the 2016 Zika virus outbreak, there has been a drastic decline in the number of them being reported in the Americas.

Based on information from the U.S. Centers for Disease Control and Prevention (CDC), March 2018 was the last confirmed case of locally-acquired Zika in the U.S.

However, there have been travel-related Zika cases in the U.S. during 2019 – Florida had 36 cases, and California had 30.

The Pan American Health Organization said there were nearly 4,300 Zika virus cases noted in the Americas this year.

There is also a risk of catching Zika was traveling to Europe too.

French authorities noted a third case of autochthonous Zika in the Var department in October. The virus can also cause both fetal and adult abnormalities like Guillain-Barre Syndrome and microcephaly.

This virus is transmitted to people mainly through bites of infected mosquitos such as the Aedes aegypti or Aedes albopictus mosquitos. The CDC also discovered that Zika is also sexually transmitted.

The CDC, in response to the current worldwide arboviral epidemiological circumstances, improved its Zika testing guidelines in November 2019 to include the following:

Asymptomatic Pregnant Women

  • Testing not recommend on asymptomatic pregnant women living in or traveled recently to the U.S. and any of its territories.
  • Testing not routinely recommended for Zika virus on asymptomatic pregnant women who live in or have traveled to areas where Zika is prevalent. However, NAAT testing is still an option.
  • Zika virus serologic testing should not be done on asymptomatic pregnant women because the antibodies could last for years, giving a false-positive result.
  • Researchers have found a notable cross-reactivity between Zika IgM and dengue IgM antibodies in serologic tests, and the antibodies of a recent dengue infection could lead to a false positive in Zika IgM.

Symptomatic Pregnant Women

  • Specimens need to be collected immediately to determine the symptom onset for these women who live or travel to areas where Zika is a risk.
  • Diagnostic testing must be done concurrently, such as a Zika virus NAAT on urine specimens and serum specimens.
  • Symptomatic pregnant women should not undergo Zika virus IgM testing.
  • If a woman tests positive for Zika NAAT on one specimen, repeated tests should be done on other extracted RNA to ensure it was not a false positive.

Pregnant Women With Prenatal Ultrasound Findings of Congenital Zika

  • NAAT and IgM Testing must be carried out on both maternal serum and urine.
  • If the NAAT test is negative and the IgM test is positive, a PRNT confirmation must be done against both dengue and Zika.
  • Should an amniocentesis be done during clinical care, a NAAT testing of the amniocentesis specimen must be done.

Tests on both fetal and placental tissues should be considered.

Symptomatic Patients Not Pregnant

  • Zika testing not needed for this group based on current virus epidemiology.
  • No need to test non-pregnant patients for either Zika or dengue.
  • Testing does not need to be carried out in a preconception screening.

As the CDC gets more information about Zika, the agency will update its testing guidelines using that information.

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