This year’s unprecedentedly large Oropouche virus epidemic marked the first known cases of human vertical transmission of the virus, causing miscarriage and birth defects. In addition to the first two reported cases, four likely cases were retrospectively identified from a microcephaly biobank, and a number of additional potential cases in Brazil remain under investigation. Other countries affected by the epidemic have not reported finding – or investigating – such incidents.

While many closely related orthobunyaviruses cause neurological birth defects and spontaneous abortion in other animals, and preliminary studies have suggested that similar issues may occur in humans, I wasn’t aware of any prior work on this for Oropouche virus, so I was surprised that the July PAHO Epi Alert of the incident referenced a prior study:

In 1982, IEC (Instituto Evandro Chagas) professionals together with the Institute of Tropical Medicine of Manaus and the University of Manaus, Brazil reported the occurrence of nine cases of OROV infection in pregnant women. Among these cases, two, who were in the second month of gestation, resulted in spontaneous abortion. Although the technique used for diagnosis in pregnant women was a serological test (due to the unavailability of molecular tests at the time), this finding is suggestive of vertical transmission, and was recorded as part of the characterization of the first outbreak of Oropouche in the state of Amazonas, Brazil between 1980 and 1981.

After a bit of digging, I found the source cited: a 1982 study by Borborema et al. In its discussion of patient symptom profiles, it does, in fact, note: