Oropouche Virus (OROV) and Breastfeeding Safety: Analysis of Related Orthobunyaviruses for Mother-Infant Vertical Transmission in Breast Milk.

The discovery that the Oropouche virus (OROV) can be transmitted vertically from an infected pregnant mother to the fetus, resulting in fetal and placental OROV infection, miscarriage, stillbirth, and congenital malformations including microcephaly, has emphasized its public health significance. Because of the importance of breastfeeding in those areas affected by the Oropouche fever outbreak, public health agencies have continued to encourage nursing among mothers who have had OROV infection or who reside or travel in endemic regions. However, the basis for this recommendation has not been stated. At the present time, there have been no reports of the OROV being transmitted from mothers having had Oropouche fever during pregnancy to their infants through breast milk. To further evaluate the potential risk of OROV transmission through breastfeeding, we have examined the peer-reviewed literature to determine if related Orthobunyavirus species infecting humans and animals are transmissible via breast milk. Bibliographic search engines, including PubMed, Scopus, and Google Scholar, were extensively reviewed using keywords, MeSH terms, and other sources cited in the articles examined. Studies investigating Orthobunyavirus species that infect humans and animals, including reassortant strains of OROV and viruses within the Simbu serogroup, were reviewed. We found that there have been no reported events of vertical transmission of any Orthobunyavirus through breast milk. Based on these results, we believe that the advantages of breastfeeding following maternal OROV infection outweigh any negligible risk for vertical transmission.