Non-congenital Oropouche virus disease
2026 Case Definition

Clinical Criteria

A person with one of the following not explained by another etiology:

• Acute onset of fever (measured or reported) or chills, OR
• Acute onset of two or more of the following: headache, myalgia, arthralgia, retro-orbital pain, or generalized rash, OR
• Meningitis, encephalitis, acute flaccid paralysis, Guillain-Barré syndrome, or other acute sign of central or peripheral neurologic dysfunction (e.g., altered mental status, ataxia, paresis, seizures), as documented by a physician, OR
• Loss of a fetus at greater or equal to 20 weeks gestation.

Laboratory Criteria

Confirmatory Laboratory Evidence:

• Detection of Oropouche virus, viral antigen, or viral RNA in a body fluid or tissue^**, OR
• Four-fold or greater change in OROV-specific neutralizing antibody titers in paired acute and convalescent blood specimens collected optimally ≥ 2 weeks apart, OR
• Detection of OROV-specific IgM antibodies in blood or CSF with positive OROV-specific neutralizing antibodies in the same or a later specimen.

Presumptive Laboratory Evidence:

• Detection of OROV-specific IgM or neutralizing antibodies in blood or CSF.

Note: The categorical labels used here to stratify laboratory evidence are intended to support the standardization of case classifications for public health surveillance. The categorical labels should not be used to interpret the utility or validity of any laboratory test methodology.

^** This includes pregnancy-related specimens such as amniotic fluid, placenta, or products of conception.

Probable

• Meets clinical criteria AND presumptive laboratory evidence for non-congenital OROV disease AND meets epidemiologic linkage criteria.

Confirmed

• Meets clinical criteria AND confirmatory laboratory evidence for non-congenital OROV disease AND meets epidemiologic linkage criteria.

• Oropouche virus disease | 2026 Case Definition
• Oropouche virus disease | 2025 Interim Case Definition, Approved March 7, 2025