Interim Clinical Considerations for Pregnant People with Confirmed or Probable Oropouche Virus Disease

Manifestations and clinical management of pregnant people

The data on Oropouche disease manifestation in pregnancy are limited to case reports. It is not known if Oropouche virus infection is more severe during pregnancy. Signs and symptoms are expected to be the same for pregnant people as non-pregnant people (e.g., acute onset of fever, chills, headache, myalgia, arthralgia). At present, the clinical management of the acute illness for pregnant people is expected to be the same as non-pregnant people.

Impact on pregnancy and infants

Based on limited data from Brazil, vertical transmission of Oropouche virus is possible. However, it is not known how frequent vertical transmission occurs during pregnancy and if the timing of Oropouche virus disease (Oropouche) during pregnancy increases the risk of an adverse outcome.

Case report descriptions

One pregnant woman reported symptoms and had laboratory evidence of Oropouche virus infection at six weeks gestation; the pregnancy resulted in a miscarriage at eight weeks gestation. However, it is unknown if the miscarriage was related to the disease, and no testing was available on the products of conception.

Another pregnant woman who had symptoms of Oropouche at 30 weeks gestation sought medical care 2 weeks after her illness onset because of a lack of fetal movement; the pregnancy resulted in fetal demise. Oropouche virus was detected in the fetal brain, liver, kidneys, lungs, heart, spleen, cerebrospinal fluid, as well as the placenta and umbilical cord.

The Brazil Ministry of Health has also reported several newborns with microcephaly who were found to have IgM antibodies against Oropouche virus based on testing of serum and cerebrospinal fluid. For one case where more clinical details were reported, the pregnant woman had symptoms consistent with Oropouche during her second month of pregnancy. A fetal ultrasound performed at 33 weeks gestation was abnormal, and a fetal magnetic resonance imaging (MRI) found evidence of oligohydramnios, microcephaly, and thinning of the brain parenchyma with severe ventriculomegaly, among other abnormalities. When the infant was born at 36 weeks gestation, microcephaly was confirmed with similar findings on head computerized tomography as the fetal MRI, and multiple joint contractures were noted. Testing was negative for evidence of several congenital infections; the infant was found to be positive for IgM antibodies against Oropouche virus. The infant died at 47 days of age and several tissues (brain, lung, kidney) and fluids (cerebrospinal and pleural fluids) were found to be RT-PCR positive for Oropouche viral RNA.

Fetal screening and detection considerations

Insufficient data are available to define the optimal timing of initial fetal ultrasound following Oropouche virus disease in a pregnant person. Similar to other viruses, for pregnant people with confirmed or probable Oropouche virus disease, serial fetal ultrasounds (every 4 weeks) should be considered to assess fetal anatomy and to monitor growth. Detailed fetal anatomy, with attention to neuroanatomy, may detect brain or associated structural abnormalities that might precede development of microcephaly.

In one reported case for which additional details were reported, first trimester infection was associated with detection of abnormalities in the third trimester. In the absence of additional data, timing and frequency of ultrasounds can be individualized based on clinical judgement and patient circumstances; however, fetal findings may take time to manifest after infection.

The sensitivity and accuracy of prenatal ultrasound for detection of microcephaly and brain abnormalities depends on a range of factors. These can include timing of screening, severity of microcephaly, expertise of the person performing the ultrasound, and patient factors. Limited data in other congenital infections indicate that ultrasound abnormalities identified in the prenatal period correlate with reported structural abnormalities in neonates at birth, and Oropouche virus disease during pregnancy may follow this same trend. A consultation with a high-risk prenatal care provider or obstetrician with expertise in congenital infections should be considered, if available.

The role of amniocentesis for the detection of Oropouche genetic material or Oropouche virus disease is unknown. Amniocentesis has been used in the evaluation of other congenital infections. However, amniotic fluid testing is not currently available for Oropouche virus.

At present, there is no specific antiviral treatment or vaccine available for Oropouche virus disease or associated vertical transmission and potential congenital abnormalities.

References

1. Pan American Health Organization / World Health Organization. Epidemiological Alert: Oropouche in the Region of the Americas: vertical transmission event under investigation in Brazil, 17 July 2024. Washington, D.C.: PAHO/WHO; 2024.
2. Pan American Health Organization / World Health Organization. Epidemiological Alert: Oropouche in the Region of the Americas, 1 August 2024. Washington, D.C.: PAHO/WHO; 2024.
3. Pan American Health Organization / World Health Organization. Public Health Risk Assessment related to Oropouche Virus (OROV) in the Region of the Americas, 3 August 2024. Washington, D.C.: PAHO/WHO; 2024.
4. Brazil Ministry of Health. Nota Técnica Conjunta nº 135/2024-SVSA/SAPS/SAES/MS — Ministério da Saúde (www.gov.br) 14 August 2024.
5. Clinical Overview of Oropouche Virus Disease | Oropouche | CDC
6. Oropouche fever: Latin America on high alert for virus that can cause stillbirths | The BMJ