United States: Researchers have confirmed the first case of the Oropouche virus being passed from a mother to her baby. This type of transmission is called “vertical transmission.” A team of 23 scientists from eight different institutions made this important discovery.
This ORVO which is a zoonotic arbovirus, and it was first isolated from the blood of the charcoal worker with a high fever in 1955 on the Caribbean Island of Trinidad. Outbreaks have hereby typically occurred south of the Amazon and isolated within the Amazonian villages.
As reported by the Medical Xpress, in 2024, OROV infections emerged in regions that were previously reported to be non-endemic in all the five regions across Brazil. These extensions into areas not earlier impacted include new virus strains originating from diverse gene segment reassortment.
New England Journal of Medicine Letter to the editor titled “A Case of Vertical Transmission of Oropouche Virus in Brazil” October 30, 2024, there is report up on case from Ceará, a state previously free from infection with OROV, the first discovery of which occurred via laboratory surveillance.
Further inquiries estimated the number of cases at 171, the great majority of which were in the Baturité Massif’s rural valleys. Natural land-use practices in this area are well suited to the Culicoides paraensis a small to medium biting fly also known as no-see-ums. Culicoides from which transmission to human is contracted is the primary vector of OROV.
One of the most shocking scenarios cited was of a 40-year-old pregnant woman in 30 weeks who complained of fever, chills, muscle aches, a severe headache. Previous prenatal care had diagnosed gestational diabetes treated with metformin and four ultrasounds done as a part of the prenatal care.
Medical assessment on July 27th there was light spotting of vaginal bleeding and dark colored discharge, while the use of ultrasonography showed that the fetus had attained macrosomic size.
Further deterioration of the clients’ condition and reduced fetal movements by August 5th indicated fetal death.
Laboratory test revealed acute OROV infection and thereby excludes the possibility of dengue, Zika, chikungunya, and Mayaro viruses. During autopsies of this stillborn infant employing MITE, OROV RNA was detected in several fetal organs thereby confirming vertical transmission.
Molecular characterization by maximum-likelihood phylogenetic analysis placed the virus on branch OROVBR-2019-2024 that is in association with the strains belonging to the current outbreak. These findings connect the stillbirth to the current OROV contamination in Brazil and shown that the virus is dangerous during pregnancy.
This report should be a wake-up call for health care providers to look at OROV infection in pregnant women with fever and associated symptoms in regions where the virus is known to be in circulation or obtaining ground.