Health officials are warning Americans about a rare insect-borne virus that has infected several travelers.
As of August 16, there have been 21 cases of Oropouche virus disease, sometimes called “sloth fever,” detected among U.S. travelers returning from Cuba, according to the Centers for Disease Control and Prevention (CDC). The CDC is urging clinicians and public health offices to be aware of the virus, test for suspected cases, and for travelers to protect themselves from insect bites.
What is ‘Sloth Fever’?
Oropouche virus is an arthropod-borne virus, meaning it is spread to people by the bite of infected arthropods, a group of insects. The virus is mainly spread to humans by infected Culicoides paraensis, a species of biting midges, although it can also be transmitted by certain mosquito species, according to the CDC.
The virus is sometimes called “sloth fever” because scientists first found it in a three-toed sloth, and the virus naturally lives in sloths, non-human primates, and birds. Dr. Chantal Vogels, an assistant professor of epidemiology at Yale School of Public Health, explained that this nickname likely stems from the role of sloths as hosts in the virus’s natural transmission cycle.
Oropouche virus is endemic to the Amazon basin, including Bolivia, Colombia, and Peru. It was first discovered in a human in 1955, in a febrile forest worker in a village in Trinidad and Tobago. Dr. Peter Hotez, co-director of the Texas Children’s Hospital Center for Vaccine Development, mentioned concerns about the virus spreading to Cuba and possibly elsewhere in the Caribbean, with imported cases already seen in the U.S. He noted that there is a possibility it could establish itself in the southern U.S., particularly in Gulf Coast states.
What Are the Symptoms?
The incubation period of Oropouche virus disease is three to 10 days and presents symptoms similar to other diseases like dengue, Zika, and chikungunya. Common symptoms include fever, headache, chills, muscle aches, and joint pain, typically lasting about two to seven days before disappearing.
Patients may also experience other symptoms such as nausea, vomiting, rash, sensitivity to light, dizziness, and pain behind the eyes. Dr. Michael Angarone, an infectious diseases specialist at Northwestern Medicine in Chicago, pointed out that about a week after initial symptoms, more than 50% of people may experience a recurrence of symptoms, which will last for another five to seven days before subsiding again.
How Is It Treated?
To diagnose Oropouche virus disease, a healthcare provider will need to order laboratory tests. There are no vaccines to prevent or medicines to treat Oropouche virus disease. Treatment mainly involves managing symptoms, including getting rest, preventing dehydration, and taking over-the-counter pain medicine, such as acetaminophen, according to the CDC.
The CDC advises against taking aspirin or other non-steroidal anti-inflammatory drugs until dengue can be ruled out to lower the risk of bleeding.
How Do I Prevent the Virus?
The best prevention method is to avoid bites from midges or mosquitoes. The CDC recommends using insect repellent, installing tight-fitting screens on windows and doors, wearing long-sleeve shirts and pants, and using a fan when outdoors. Currently, there is no evidence of local transmission in the U.S.; all cases have been travel-related.
Dr. Vogels emphasized that travelers should be alert, especially if traveling to areas where there is ongoing transmission. If symptoms appear upon returning to the U.S., they should seek medical attention.
There have also been recent reports of possible vertical transmission, where a pregnant person passes the infection to their baby in utero. This infection may result in adverse pregnancy outcomes, including fetal deaths and congenital malformations. While this has been demonstrated in South America, it is also being investigated in cases from Cuba. Dr. Angarone mentioned that descriptions of fetal demise, miscarriage, or premature labor, and congenital abnormalities have been reported, though not yet confirmed to be caused by the virus.
Experts recommend that travelers, especially those who are older or immunocompromised, take extra precautions to prevent infection. Pregnant individuals should reconsider nonessential travel to countries with an Oropouche virus Level 2 Travel Health Notice, as advised by the CDC.
