A clinically compatible case of yellow fever is defined as:
Acute illness with at least one of the following: fever, jaundice, or
elevated total bilirubin ≥ 3 mg/dl, AND
Absence of a more likely clinical explanation.
Laboratory Criteria
Confirmatory laboratory evidence
Isolation of yellow fever virus from, or demonstration of yellow fever
viral antigen or nucleic acid in, tissue, blood, CSF, or other body
fluid.
Four-fold or greater rise or fall in yellow fever virus-specific
neutralizing antibody titers in paired sera.
Yellow fever virus-specific IgM antibodies in CSF or serum with
confirmatory virus-specific neutralizing antibodies in the same or a later
specimen.
Presumptive laboratory evidence
Yellow fever virus-specific IgM antibodies in CSF or serum, and negative
IgM results for other arboviruses endemic to the region where exposure
occurred.
Epidemiologic Linkage
Epidemiologically linked to a confirmed yellow fever case, or visited or
resided in an area with a risk of yellow fever in the 2 weeks before onset of
illness.
Case classification
Confirmed
A case that meets the above clinical criteria and meets one or more of the
following:
Isolation of yellow fever virus from, or demonstration of yellow fever
viral antigen or nucleic acid in, tissue, blood, CSF, or other body fluid,
AND no history of yellow fever vaccination within 30 days before onset of
illness unless there is molecular evidence of infection with wild-type yellow
fever virus.
Four-fold or greater rise or fall in yellow fever virus-specific
neutralizing antibody titers in paired sera, AND no history of yellow fever
vaccination within 30 days before onset of illness.
Yellow fever virus-specific IgM antibodies in CSF or serum with
confirmatory virus-specific neutralizing antibodies in the same or a later
specimen, AND no history of yellow fever vaccination.
Probable
A case that meets the above clinical and epidemiologic linkage criteria,
and meets the following:
Yellow fever virus-specific IgM antibodies in CSF or serum, AND
negative IgM results for other arboviruses endemic to the region where
exposure occurred, AND no history of yellow fever vaccination.