Health Officials Warn of ‘Sloth Fever’ After Cases in UK

Health authorities in the United Kingdom have issued a critical alert regarding the detection of the tropical illness known as ‘sloth fever’ or Oropouche virus (OROV). This warning follows the diagnosis of three individuals who recently returned from Brazil, where the virus is prevalent. Although the disease typically manifests with mild symptoms, it can escalate to severe conditions in some cases.

The UK Health Security Agency (UKHSA) released a statement on August 14, 2023, confirming the cases. While no fatalities have been reported in the UK, the situation remains serious, particularly given that Brazil has recorded five deaths attributed to the virus in 2025.

Symptoms and Transmission Risks

Individuals infected with Oropouche virus often experience mild to moderate symptoms, including headache, joint pain, fever, muscle aches, and chills. In some cases, symptoms may also include nausea, vomiting, a rash, dizziness, sensitivity to light, and pain behind the eyes. The virus is named ‘sloth fever’ due to its presence in sloths, but it is also commonly found in birds.

Although most symptoms resolve within a few days to a week, there is a risk of neurological complications, such as meningitis or encephalitis, in approximately 4% of infected individuals. The illness spreads primarily through mosquito and midge bites, and there are concerns regarding potential sexual transmission, although this has not been confirmed.

Precautions for Travelers and Pregnant Women

Given the potential risks, particularly for pregnant women, the UKHSA has advised caution for those traveling to Central and South America. The virus has been linked to miscarriage, leading health officials to recommend that pregnant individuals consult with their general practitioners or travel clinics before embarking on trips to affected areas.

The UKHSA stated, “While we are still learning about the risks of OROV during pregnancy, the potential for mother-to-child transmission—and impact on the fetus—means caution is necessary.”

In addition to medical advice, individuals traveling to risk areas are encouraged to take preventive measures. This includes wearing long-sleeved clothing, applying insect repellents containing DEET, and using air conditioning or window screens to minimize exposure to bites.

Currently, over 12,000 confirmed cases of the virus have been reported this year, with Brazil accounting for the majority at 11,888 cases. Additionally, both the United States and Canada have reported isolated instances of the virus recently, highlighting the need for awareness and preventive measures among travelers.

As health officials continue to monitor the situation, the public is urged to remain vigilant and informed about the symptoms and risks associated with Oropouche virus.