An interim case definition has been published by the WHO for the purpose of global standardization of classification and reporting. [176]
Suspected case:
A person presenting with rash and/or fever and at least one of the following signs or symptoms:
Arthralgia
Arthritis
Conjunctivitis (nonpurulent/hyperemic).
Probable case:
A suspected case with the presence of IgM antibodies against Zika virus and no evidence of infection with other flaviviruses, plus an epidemiologic link (i.e., contact with a confirmed case, or a history of residence in or traveling to an area with local transmission of Zika virus within 2 weeks prior to onset of symptoms).
Confirmed case:
A person with laboratory confirmation of recent Zika virus infection:
Presence of Zika virus RNA or antigen in serum or other samples (e.g., saliva, tissues, urine, whole blood)
IgM antibody against Zika virus is positive and plaque reduction neutralization test (PRNT) for Zika virus with titer ≥20 and Zika virus PRNT titer ratio ≥4 compared with other flaviviruses.
WHO: Zika virus disease - interim case definition
An interim case definition has been published by the PAHO. [155]
Suspected case:
Patient with rash (usually pruritic and maculopapular) plus 2 or more of the following:
Fever (usually <101.3°F [<38.5°C])
Conjunctivitis (nonpurulent/hyperemic)
Arthralgia
Myalgia
Periarticular edema
In geographic areas without autochthonous transmission and where there are no vectors present, patients who meet the criteria above and who:
in the 2 weeks prior to onset, traveled to/resided in a geographic area where there is known local transmission of the Zika virus or there is known vector presence; or
had unprotected sex in the 2 weeks prior to onset with a person who traveled in the previous 8 weeks to a geographic area with known local transmission of the Zika virus or an area with known vector presence.
Probable case:
Patient who meets the criteria of a suspected case and has Zika IgM antibodies with no evidence of infection with other flaviviruses.
Confirmed case:
Patient who meets the criteria of a suspected case and has laboratory confirmation of recent Zika virus infection:
RNA or Zika virus antigen in any specimen (i.e., serum, urine, saliva, tissue, or whole blood); or
Positive Zika IgM antibodies and PRNT for Zika virus titers ≥20 and 4 or more times greater than the titers for other flaviviruses, as well as exclusion of other flaviruses; or
Detection of viral genome (in fresh or paraffin tissue) in autopsy specimens by molecular techniques, or detection by immunochemistry.
PAHO have also published case definitions for Guillain-Barre syndrome or a congenital syndrome associated with Zika virus, as well as definitions for Zika virus-associated abortion or still birth and vertical transmission (without congenital syndrome).
Pan American Health Organization: case definitions
The CDC includes Zika virus infection in their arboviral diseases (neuroinvasive and non-neuroinvasive) case definition:
CDC: arboviral diseases, neuroinvasive and non-neuroinvasive 2015 case definition
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