This summer has been quite a doozy in terms of health news. A quick recap: COVID cases and hospitalizations are on the rise, the U.S. is dealing with concerns about bird flu, and there are new reports of West Nile. And now, unfortunately, there’s another insect-borne virus we need to be wary of: Oropouche, also known as “sloth fever.” Symptoms of the potentially deadly disease pose a threatening risk to pregnant people, the elderly, and immunocompromised, in particular—and with infections steadily on the rise, the Centers for Disease Control and Prevention (CDC) has issued an emergency health alert and travel notice.
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So far, in 2024, the CDC has received more than 8,000 reports of the Oropouche virus globally. The virus isn't new; it was first detected in South America in 1955, and most of the recent reports are from that area, namely from Brazil, Bolivia, Peru, Colombia, and Cuba. As of this writing, two people have died from Oropouche this year.
However, with the summer travel season coming to a close, more cases of Oropouche have been cropping up in both the U.S. and Europe. As of Aug. 16, a total of 21 Americans have been infected with sloth fever, the CDC announced in a press release. All infected patients were returning from trips to Cuba, including 20 Florida residents and one person living in New York.
According to the CDC, humans contract Oropouche virus after being bitten by an infected midge (a very small fly) or mosquito. Infected insects can also pass the virus onto sloths, birds, and rodents. According to the Associated Press, the virus received the nickname "sloth fever" because scientists initially found it in a three-toed sloth, which was then thought to be an important part of the transmission process between insects and animals. While human-to-human transmission hasn’t been reported, health officials have raised concerns about the disease being transmitted from a pregnant person to the fetus.
According to the agency, approximately 60 percent of people infected with Oropouche experience symptoms. Symptoms such as fever, chills, headache, muscle aches, and joint pain can develop in up to 10 days. Additionally, sloth fever can cause eye pain, light sensitivity, nausea, vomiting, diarrhea, fatigue, abdominal pain, and skin rash.
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A vaccine or antiviral treatment for Oropouche doesn’t exist, but the CDC says symptoms typically resolve on their own within a few days. However, it isn’t unusual for symptoms to return days to weeks later. In more advanced (and rare) cases, Oropouche can affect the nervous system and even cause death.
“As we see more people becoming infected, we can see rare and unusual occurrences of clinical symptoms or death,” Erin Staples, PhD, a medical epidemiologist with the CDC’s Division of Vector-Borne Diseases, told CNN. “But these are all things that CDC is currently working with our partners to learn more about.”
Those sick with sloth fever are advised to rest and stay hydrated. Acetaminophen is approved to help with fever and pain, but the CDC strongly urges patients to avoid non-steroidal anti-inflammatory drugs (NSAIDs) like Aspirin, which can increase the risk of hemorrhage.
The CDC is asking travelers to exercise extreme caution, especially when visiting areas experiencing Oropouche virus outbreaks. The agency is also urging pregnant people to reconsider their travel plans.
“This is a good time to think about mosquito bite prevention,” Janet Hamilton, MPH, executive director of the Council of State and Territorial Epidemiologists, told CNN. “Avoid going out at dawn and dusk, when mosquitoes are most likely to be biting; dress appropriately to protect your skin from bites from mosquitoes and other insects, and to use a mosquito repellent that is effective at preventing infections.”