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Zika Virus Disease, Non-congenital Infection and Zika Virus, Congenital Infection
2016 Interim Case Definition, Approved February 26, 2016

CSTE Position Statement(s)

  • 16-ID-01 Interim

Subtype(s)

  • Zika virus disease, non-congenital infection
  • Zika virus, congenital infection

Background

Zika virus (ZIKV) is an emerging infection spread by mosquito vectors and whose incidence and prevalence has exploded in the Americas in 2015. Preliminary investigations demonstrate vertical transmission of ZIKV to the fetus in pregnant women. These in utero infections have been associated with the potential for devastating outcomes including microcephaly and spontaneous abortions. There is also an association with ZIKV infection and post-infectious Guillain-Barré syndrome (GBS) under investigation. Because of these epidemiological and clinical features, the World Health Organization declared ZIKV disease a Public Health Emergency of International Concern under the International Health Regulations 2005 on February 1, 2016.

ZIKV, a flavivirus transmitted by Aedes spp. mosquitoes, was discovered in the Zika Forest by the Virus Research Institute in Uganda in a non-human primate in 1947 and from Aedes africanus mosquitoes in 1948. In May 2015, the Pan American Health Organization issued an alert regarding the first confirmed ZIKV infection in Brazil. Since that time, local transmission has been reported in many other countries and territories in Latin America and the Caribbean. Brazil reported widespread ZIKV disease in adults and children, and a concomitant and significant rise in the number of infants born with microcephaly, as well as increases in miscarriages.

Subtype(s) Case Definition  

Zika virus disease, non-congenital infection

Clinical Criteria

A person with one or more of the following:

  • acute onset of fever (measured or reported)
  • maculopapular rash
  • arthralgia
  • conjunctivitis
  • complication of pregnancy
    • fetal loss in a mother with compatible illness and/or epidemiologic risk factors; OR
    • in utero findings of microcephaly and/or intracranial calcifications with maternal risk factors
  • Guillain-Barré syndrome not known to be associated with another diagnosed etiology.

Epidemiologic Linkage

  • Travel to a country or region with known ZIKV transmission, OR
  • Sexual contact with a laboratory confirmed case of ZIKV infection, OR
  • Receipt of blood or blood products within 30 days of symptom onset; OR
  • Organ transplant recipient within 30 days of symptom onset; OR
  • Association in time and place with a confirmed or probable case.

Case Classification

Probable

Meets clinical criteria AND

  • resides in or has recently traveled to an area with ongoing ZIKV transmission, OR
  • has direct epidemiologic linkage to a person with laboratory evidence of recent ZIKV infection (e.g. sexual contact, in utero or perinatal transmission, blood transfusion, organ transplantation), OR
  • association in time and place with a confirmed or probable case.

AND meets the following laboratory criteria:
  • positive ZIKV-specific immunoglobulin M (IgM) antibodies in serum or cerebrospinal fluid (CSF); AND
  • negative dengue virus-specific IgM antibodies; AND
    • No neutralizing antibody testing performed; OR
    • Less than four-fold difference in neutralizing antibody titers between ZIKV and dengue or other flaviviruses endemic to the region where exposure occurred.

Confirmed

Meets clinical criteria AND
Has laboratory evidence of recent ZIKV infection by:

  • Detection of ZIKV by culture, viral antigen or viral ribonucleic acid (RNA) in serum, CSF, tissue, or other specimen (e.g. amniotic fluid, urine, semen, saliva); OR
  • ZIKV IgM antibodies in serum or CSF with ZIKV neutralizing antibody titers 4-fold or greater than neutralizing antibody titers against dengue or other flaviviruses endemic to the region where exposure occurred.

Zika virus, congenital infection

Clinical Criteria

An infant with microcephaly or intracranial calcifications or central nervous system abnormalities.

Case Classification

Probable

An infant meets the clinical criteria AND:

  • Mother lived in or traveled to a country or area with ongoing ZIKV transmission during the pregnancy; OR
  • Mother has laboratory evidence of ZIKV or unspecified flavivirus infection during pregnancy;

AND the infant meets the following laboratory criteria:
  • ZIKV IgM antibodies detected in serum or CSF; AND
  • Tests negative for dengue or other endemic flavivirus-specific IgM antibodies; AND
    • No neutralizing antibody testing performed; OR
    • Less than four-fold difference in neutralizing antibody titers between ZIKV and dengue or other flaviviruses endemic to the region where exposure occurred.

Confirmed

An infant meets the clinical criteria AND meets one of the following laboratory criteria:

  • ZIKV detection by culture, antigen test, or polymerase chain reaction (PCR) in serum, CSF, amniotic fluid, urine, placenta, umbilical cord, or fetal tissue; OR
  • ZIKV IgM antibodies present in serum or CSF with ZIKV neutralizing antibody titers 4-fold or greater than neutralizing antibodies against dengue or other flaviviruses endemic to the region where exposure occurred.

Comments

Office of Management and Budget approval of the NNDSS Revision, 0920-0728 on January 21, 2016, authorized CDC to receive case notifications for Zika virus disease, non-congenital infection and Zika virus, congenital infection.

The ‘Zika virus disease, non-congenital infection’ and ‘Zika virus, congenital infection’ case definitions are based on CSTE Interim Position Statement 16-ID-01, which was approved by the CSTE Executive Board in February 2016. This Interim case definition was revised and replaced with a new case definition CSTE approved in June 2016.



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