Case definitions for public health surveillance

Overview

Suspected case

Any person with acute onset of fever, with jaundice appearing within 14 days of onset of the first symptoms.

Probable case

A suspected case; and one of the following:

• presence of yellow fever IgM antibody in the absence of yellow fever immunization within 30 days before onset of illness; or
• positive postmortem liver histopathology; or
• epidemiological link to a confirmed case or an outbreak.

Confirmed case

A probable case; and

Absence of yellow fever immunization within 30 days before onset of illness; and one of the following:

• detection of yellow fever-specific* IgM; or
• detection of fourfold increase in yellow fever IgM, or IgG antibody titres between acute and convalescent serum samples, or both; or
• detection of yellow fever-specific* neutralizing antibodies.

or

Absence of yellow fever immunization within 14 days before onset of illness; and one of the following:

• detection of yellow fever virus genome in blood or other organs by PCR; or
• detection of yellow fever antigen in blood, liver or other organs by immunoassay; or
• isolation of yellow fever virus.

Notes

* Yellow fever-specific means that the results of antibody tests (such as IgM or neutralizing antibody) for other prevalent flaviviruses are negative or not significant. Testing should include at least IgM for dengue fever and West Nile virus but may include other flaviviruses according to local epidemiology (for example, Zika virus).