These interim case definitions have been developed for the purpose of providing global standardization for classification and reporting of Zika virus cases. WHO guidance for the surveillance of Zika virus disease is currently being developed.

WHO will periodically review these interim case definitions and update them as new information becomes available.

Suspected case

A person presenting with rash and/or fever and at least one of the following signs or symptoms:

arthralgia; or

arthritis; or

conjunctivitis (non-purulent/hyperaemic).

Probable case

A suspected case with presence of IgM antibody against Zika virus1 and an epidemiological link2

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); or

IgM antibody against Zika virus positive and PRNT90 for Zika virus with titre ≥20 and Zika virus PRNT90 titre ratio ≥ 4 compared to other flaviviruses; and exclusion of other flaviviruses

Notes

1 With no evidence of infection with other flaviviruses

2 Contact with a confirmed case, or a history of residing in or travelling to an area with local transmission of Zika virus within two weeks prior to onset of symptoms.