Health officials have issued an urgent warning after diagnosing 3 people in the United Kingdom with “Sloth Fever”—a tropical disease usually found only in Brazil. The disease, also known as the Oropouche virus (OROV), causes mild symptoms that typically disappear within a week.

Symptoms that may indicate infection include fever, headache, joint pain, muscle aches, chills, nausea, vomiting, rash, dizziness, light sensitivity, and pain behind the eyes. However, sometimes the virus can attack the brain, leading to meningitis or encephalitis, which can be fatal.

Fortunately, these neurological symptoms occur in only about 4% of infected patients. The virus is sometimes called “Sloth Fever” because it naturally occurs in sloths, as well as primates and birds.

New figures released yesterday by the UK’s National Health Service revealed 3 cases of the virus in Britain, with no deaths reported so far.

All three cases involved individuals who returned to the UK after traveling to Brazil.

The lesser-known tropical infection spreads through bites from small midges and some mosquitoes.

There is no treatment for the disease. About 60 to 70% of patients experience recurrence of the illness days to months after the initial infection. However, symptoms can be managed with rest, plenty of fluids, and over-the-counter medications like paracetamol.

The newspaper added that there is no vaccine, but travelers can take preventive measures such as wearing long-sleeved clothing and using insect repellents to protect against mosquitoes.

These repellents should contain 50% DEET—the active ingredient that repels pests like midges and mosquitoes. Other measures include staying in air-conditioned places or rooms with fine mesh window screens to prevent mosquito entry and using insecticide-treated mosquito nets.

Cases of this organ-damaging tropical virus among Britons have tripled. The first recorded deaths from the disease, which has been present since the 1950s, were two women in Brazil last year. So far this year, there have been over 12,000 confirmed cases worldwide.

The disease has also spread to other parts of South America, as well as the US and Canada, which have each reported one case. Since the beginning of the year, there have unfortunately been 5 deaths, all in Brazil.

In their latest warning, officials urged pregnant women traveling to Central and South America to be cautious because the virus is linked to miscarriage.

The UK’s National Health Service said: “If you are pregnant and considering travel to affected areas, it is important to discuss this with your doctor or travel clinic before going.

While we are still learning about the risks of the Oropouche virus (OROV) during pregnancy, the possibility of mother-to-child transmission and its impact on the fetus means caution is necessary.”