As of February 2024, the Pan-American Health Organization has been reporting that Oropouche virus (OROV) infections have been on the rise in Brazil, Ecuador, French Guiana, Panama, Peru, and Trinidad and Tobago. This may in part be due to changes in how the government of Brazil has been testing and tracking OROV infections. In a worrying development, according to a technical note published by the Ministério da Saúde Secretaria de Vigilância em Saúde e Ambiente, Brazil’s ministry of health, on the 12th of July, there are mounting concerns about the effects of OROV during pregnancy. Early reports describe microcephaly in infants testing positive for Oropouche antibodies, suggesting that Oropouche virus could cause birth defects.
Oropouche Fever
Since the 1950s OROV has been circulating in Latin America and the Caribbean causing Oropouche fever. Oropouche fever is similar to yellow fever and dengue in that it is primarily spread by mosquitoes and midges and causes fever, chills, body pains, head aches and vomiting and in some cases haemorrhagic signs or meningitis like symptoms. Most people will recover within five to seven days with no long-term after effects.
Until recently medics believed that OROV was spread only by insect bites with no reports of human-human transmission. However, in their technical note, Brazilian Health officials express concern that OROV is now being vertically transmitted. That is, passed from mother to fetus during pregnancy.
Early Warning
Other viruses in the same simbu virus family as Oropouche can hop across the placenta, for example Akabane virus (AKAV) and Schmallenberg virus (SBV). Akabane and Schmallenberg infections have caused miscarriages and fetal abnormalities in the young of infected animals. Scientists worry that Oropouche virus could have similar effects. With very little data to go on, researchers are tentatively warning prospective parents to take precautions against insect bites.
In June 2024, an investigation by Instituto Evandro Chagas (SEARB/IEC/SVSA/MS) discovered traces of OROV infection in the cerebral spinal fluid or plasma of four children born with microcephaly. What’s more, in July 2024, a SEARB/IEC/SVSA/MS lab probe into a miscarriage at 30 weeks showed the presence of OROV in umbilical cord blood, placenta and various fetal organs, demonstrating clear evidence of vertical transmission. While as yet scientists cannot link OROV directly to fetal abnormalities or spontaneous abortion, the authors of the note urge a ‘better safe than sorry approach’.
Beating the Bugs
Late in June 2024, the United States Centres for Disease Control (CDC) raised concerns about the spread of Oropouche virus in the Americas, warning that travellers should take precautions against mosquito and midge bites.
Presently there is no specific treatment for Oropouche fever and no vaccine. Health officials advise people travelling to the affected areas to avoid insect bites by using insect repellent, avoiding areas with high concentrations of midges and mosquitoes, using mosquito nets and insect screens and by covering up exposed skin.
References
Calado AM, Seixas F, Dos Anjos Pires M. Virus as Teratogenic Agents. Methods Mol Biol. 2024;2753:105-142. doi:10.1007/978-1-0716-3625-1_4
Epidemiological Alert – Oropouche in the Region of the Americas – 2 February 2024 – PAHO/WHO | Pan-American Health Organization. Published February 2, 2024. Accessed July 24, 2024. https://www.paho.org/en/documents/epidemiological-alert-oropouche-region-americas-2-february-2024
Oropouche virus disease – French Guiana, France. Accessed July 24, 2024. https://www.who.int/emergencies/disease-outbreak-news/item/oropouche-virus-disease—french-guiana-france
Sakkas H, Bozidis P, Franks A, Papadopoulou C. Oropouche Fever: A Review. Viruses. 2018;10(4):175. doi:10.3390/v10040175
Technical Note No. 15/2024-SVSA/MS — Ministry of Health. Accessed July 24, 2024. https://www.gov.br/saude/pt-br/centrais-de-conteudo/publicacoes/notas-tecnicas/2024/nota-tecnica-no-15-2024-svsa-ms.pdf/view
Wesselmann KM, Postigo-Hidalgo I, Pezzi L, et al. Emergence of Oropouche fever in Latin America: a narrative review. The Lancet Infectious Diseases. 2024;24(7):e439-e452. doi:10.1016/S1473-3099(23)00740-5