Nearly two dozen people in the United States have been confirmed to have contracted the Oropouche virus during travels outside the country this summer, the Centers for Disease Control and Prevention reported Tuesday. A previously little-known virus, Oropouche has garnered headlines in recent weeks with reports of a small number of deaths and a possible link to congenital malformations in babies infected in the womb.
All 21 cases — 20 from Florida and one from New York State — were in people who had traveled to Cuba, which is experiencing its first recorded outbreak of Oropouche, sometimes referred to as “sloth fever.” The report was written by public health scientists from Florida and New York and published in the CDC’s online journal Morbidity and Mortality Weekly Report.
“At this time, we’re currently recommending that pregnant women avoid all non-essential travel to areas with ongoing outbreaks,” Erin Staples, a medical epidemiologist in the CDC’s division of vector-borne diseases, told STAT.
Earlier this month, the CDC warned health care providers to be on the lookout for people with Oropouche infections, which have been spreading in several South American countries and Cuba. The European Centre for Disease Prevention and Control also warned doctors in Europe to think about Oropouche when faced with sick travelers, with Spain, Italy, and Germany reporting 19 cases in June and July.
Two deaths in Brazil — the first reported in conjunction with Oropouche fever — have been reported, in women in their early twenties. There have also been a handful of reports of the possible vertical transmission of the virus — when a virus is passed from a pregnant person to their fetus — resulting in stillbirths or spontaneous abortions and congenital malformations.
In particular, Brazil has reported several babies born with microcephaly — a condition in which the brain is underdeveloped — a finding that is reminiscent of the 2015-2016 Zika outbreak. Investigation of these events is ongoing, according to the Pan American Health Organization, the World Health Organization’s regional operation for the Americas.
In an Aug. 3 risk assessment on Oropouche, PAHO indicated it believes there is a high risk of additional spread of the virus, which has triggered a surge of activity in several South American countries so far this year.
“The risk of spread could increase due to significant population movements both within and between countries, as well as social, entomological, and environmental factors,” the PAHO assessment warned.
Until the events of this summer, Oropouche was an obscure virus, gaining little attention outside the areas where it circulates in a cycle that involves birds, sloths, biting insects, and occasionally people.
You probably have questions about the virus and the disease. STAT has some answers:
How is it pronounced?
Oro-pooosh. Think pooh, but with a “sh” sound tacked on the end.
What kind of illness does it trigger?
About 60% of people who become infected will develop symptoms, which could easily be mistaken for other insect-borne diseases like dengue fever, chikungunya, Zika, or malaria. People who contract Oropouche may experience fever, severe headache, chills, muscle aches, and joint pains. Some may develop sensitivity to light, dizziness, pain behind the eyes, nausea, vomiting, and rash, according to the CDC.
Staples said a small number of people who contract the virus will develop hemorrhagic symptoms — bleeding gums, for instance — or neuroinvasive illness like meningitis. “Less than 5% of people infected are believed to develop some of these more severe signs and symptoms,” Staples told STAT.
Symptoms typically last between two and seven days, but can reoccur after a period of a few days or even weeks, which differentiates Oropouche from some of the other diseases it resembles. Recovery can take days to about a month.
Is there a vaccine? Are there specific drugs?
In a word, no. The best way not to contract Oropouche is to avoid being bitten by insects.
The CDC told doctors in its alert that rest, fluids, and acetaminophen to control pain and fever can be used to mitigate symptoms. It stressed that aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) shouldn’t be used because they increase the risk of hemorrhagic symptoms.
When was it discovered?
The virus gets its name from the area on the island of Trinidad where it was first reported, in 1955.
Where is it typically found?
It is commonly reported in Brazil, especially in the Amazon region. By the end of July, PAHO had been informed of just over 8,000 confirmed cases so far this year, most from Brazil. Other countries that reported transmission included Colombia, Cuba, Bolivia, and Peru. Three-quarters of the cases in Brazil were reported from the Amazon region.
How is it transmitted? Like many of the illnesses it resembles, Oropouche is spread via biting insects — in this case, a species of midges called Culicoides paraensis and a type of mosquito known as Culex quinquefasciatus. Staples cautioned, though, that it’s unclear whether other midges or mosquitoes can transmit the virus, allowing it to take root in other places. What’s currently known about the virus is how it behaves in the places where it has been studied longest, like the Amazon.
For now, the CDC believes the risk that Oropouche could start to spread in the United States is low — but not zero. “We do know we have some of the same vectors in the Americas that have been described as transmitting it,” Staples said.
In fact, a study published in the journal Viruses in 2021 suggested that midges of a species called Culicoides sonorensis, which is found widely in the United States and parts of Canada, could transmit Oropouche if they became infected.
That said, North American lifestyles could lower the risk the virus poses, Staples said, noting that, during summer when biting insects flourish, people often move from air-conditioned homes to air-conditioned cars.
Like dengue or even West Nile virus, Oropouche virus circulates among some animals and humans. While all the animals that can be infected aren’t known, it’s clear birds, three-toed sloths, and some primates are part of the Oropouche cycle. When bitten by an infected insect, the virus replicates in their blood. When other insects feed on them, it amplifies the amount of virus in a location. At some point, the infection spills over into humans.