Congenital Oropouche virus disease
2026 Case Definition

Clinical Criteria

A liveborn infant without an identified genetic or other cause for the findings, including a positive test for another more likely etiology^§, and one or more of the following congenital anomalies typically identifiable in the neonatal period:

• Microcephaly (defined as head circumference measurement >2 standard deviations below the average [or <3rd percentile] for the same age and sex, notation of microcephaly in the medical record, or diagnostic code of microcephaly [e.g., ICD-10 code Q02]), OR
• Structural brain anomaly (e.g., ventriculomegaly, cortical hypoplasia, abnormal gyral patterns such as lissencephaly, corpus callosum abnormalities), OR
• Structural eye anomaly (e.g., microphthalmia, chorioretinal atrophy, optic nerve hypoplasia), OR
• Congenital contractures of major joints (arthrogryposis).

§ Other infectious etiologies (e.g., Zika virus, cytomegalovirus, rubella virus, varicella zoster virus, herpes simplex virus, lymphocytic choriomeningitis virus, Toxoplasma gondii, or Treponema pallidum) may have similar clinical findings, and testing for these infections should be considered as part of the complete evaluation for congenital disease.

Laboratory Criteria

Confirmatory Laboratory Evidence^¶:

• Detection of Oropouche virus, viral antigen, or viral ribonucleic acid (RNA) in the infant’s body fluid or tissue, OR
• Detection of OROV-specific immunoglobulin M (IgM) antibodies in infant blood or cerebrospinal fluid (CSF) with positive OROV-specific neutralizing antibody titers.

Presumptive Laboratory Evidence^¶:

• Detection of Oropouche virus, viral antigen, or viral RNA in amniotic fluid, placenta, umbilical cord, or cord blood^#, OR
• Detection of OROV-specific IgM antibodies in infant 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.

¶To prevent misclassifying postnatal OROV disease as congenital cases, in OROV endemic areas, specimens should be collected within 4 weeks after birth.

# Positive laboratory findings in amniotic fluid, placenta, umbilical cord, or cord blood are considered presumptive evidence of congenital OROV disease since they may detect infection in the mother in the absence of congenital infection.

Suspect

• Infant meets the clinical criteria for congenital OROV disease, AND
• Infant has no laboratory testing performed, or IgM testing was not performed and there is no detection of Oropouche virus, viral antigen, or viral RNA in any specimen, AND
• Infant’s mother meets confirmatory or presumptive laboratory criteria for non-congenital OROV disease during this pregnancy.

Probable

• Infant meets the clinical criteria for congenital OROV disease, AND
• Infant meets the presumptive laboratory criteria for congenital OROV disease, AND
• Infant’s mother meets:
  • Epidemiologic linkage criteria, OR
  • Confirmatory or presumptive laboratory criteria for non-congenital OROV disease during this pregnancy.

Confirmed

• Infant meets the clinical criteria for congenital OROV disease, AND
• Infant meets the confirmatory laboratory criteria for congenital OROV disease, AND
• Infant’s mother meets:
  • Epidemiologic linkage criteria, OR
  • Confirmatory or presumptive laboratory criteria for non-congenital OROV disease during this pregnancy.

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