#oropouche

Transmission of Oropouche to the womb means it has a feature in common with Zika and dengue

A virus that caused a large outbreak in Brazil this year can spread from a pregnant woman to the fetus. The confirmation of several cases of transmission to the womb means that the virus, called Oropouche, has a feature in common with two other insect-borne viruses, Zika and dengue.

A 40-year-old woman’s stillbirth this summer in Brazil was linked to transmission of the virus from the woman to the fetus, researchers report October 30 in the New England Journal of Medicine. (The World Health Organization defines a stillbirth as the death of a fetus after 28 weeks of pregnancy.) The Brazilian Ministry of Health has also confirmed two other deaths due to the spread of Oropouche virus to the womb: a stillbirth to a 28-year-old woman and a baby born with congenital anomalies who died after 47 days. There are other potential cases of transmission to the womb being investigated.

As of mid-October, Brazil has reported more than 8,000 cases of Oropouche fever since the beginning of the year. It’s the largest outbreak in the Americas this year; some of the other countries with cases include Peru, with more than 900, and Cuba, with more than 500. Infections can cause fever, chills, joint pain and severe headaches, among other symptoms. The virus is spread mainly by the bite of Culicoides paraensis midges, which are very small flies, and sometimes by mosquitoes. As with Zika, there aren’t any medicines to treat Oropouche fever or vaccines that target the virus.

Of the 27 Brazilian states, only the Federal District, Goiás, Paraná, Rio Grande do Norte, and Rio Grande do Sul have not reported cases of Oropouche fever in 2024.

Data from the Arbovirus Monitoring Panel indicates that, as of the beginning of the week, Brazil had recorded 7,653 cases of the disease and two deaths.

The state of Amazonas leads the ranking of Oropouche fever infections with 3,228 cases, followed by the states of Rondônia (1,710 cases), Bahia (844 cases), Espírito Santo (441 cases), and Acre (270 cases).

Immune response of already infected people proved limited

A study conducted by researchers from Fiocruz Amazon (Oswaldo Cruz Foundation) and Unicamp (University of Campinas) indicates that a new variant of the virus that transmits Oropouche fever (Orov) replicated about a hundred times more in mammalian cells compared to the original strain.

The article, in its initial version for publication, also states that the new virus has the ability to evade the immunity of previously infected individuals, potentially allowing reinfection.

The current outbreak of oropouche fever is caused by a novel variant of the arbovirus (OROV) that can replicate up to 100 times more than the original while also evading the victim’s immune response, according to an article published as a preprint (not yet peer-reviewed) on medRxiv.

Oropouche fever is a neglected tropical disease endemic to Latin America and the Caribbean. It is transmitted by mosquitoes and Culicoides midges. The main symptoms are headache, joint and muscle pain, nausea, vomiting, fever, chills, and photophobia. Some patients may manifest more severe symptoms, such as bleeding, as well as complications including meningitis and meningoencephalitis.

Although the disease has been documented in South America since the 1950s, the number of cases increased sharply between November 2023 and June 2024 in Brazil, Bolivia, Colombia and Peru. Autochthonous infections were detected in previously non-endemic areas throughout Brazil, with reports of cases in 21 states and a nearly 200-fold increase in incidence compared with the 2010s.

To investigate the virological factors that have contributed to this heightened spreading of oropouche fever, researchers at the State University of Campinas (UNICAMP), the University of São Paulo (USP) and the Federal University of Manaus (UFAM) in Brazil, collaborating with colleagues at the University of Kentucky in the United States, analyzed genomic, molecular and serological OROV data for the period between January 1, 2015, and June 29, 2024. They also characterized the variant in vitro and in vivo. The research was funded by FAPESP (projects 18/14389-0, 2022/00723-1, 2022/10408-6 and 2023/11521-3).

There is no evidence that it is more infectious; two have died from the disease

A study conducted by Brazilian researchers suggests that the emergence of a new lineage of the Oropouche virus (Orov) may be related to the outbreak of Oropouche fever in the Amazon region that has been occurring since 2022.

According to the researchers, 382 genomic analyses in patients revealed that the recent increase in cases coincides with the emergence of a new viral lineage that likely arose in the state between 2010 and 2014 and spread silently during the second half of the 2010s.

The paper, in an initial version for publication, was signed by researchers from Fiocruz (Oswaldo Cruz Institute) and the central public health laboratories of Roraima, Amazonas, Rondônia, Acre, Paraná, among other institutes.

Research conducted on mice has identified that the rapid response of a specific type of defense cell is essential for controlling Oropouche virus infections and preventing serious neurological damage. Without treatment, “Oropouche fever” causes symptoms including headaches, muscle and joint pain, skin rashes, and vomiting. In severe cases, it can lead to meningitis and encephalitis. Pregnant…

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