Cases of the oropouche virus, unofficially known as sloth fever or sloth virus, have been found in Europe amid outbreaks in South America.
There have been more than 10,000 cases reported this year, with 19 in Europe, and the first two deaths caused by the disease have been confirmed in Brazil. So what do we know about the virus, how it got to Europe, and what the risks are?
Oropouche virus is a zoonotic disease mainly transmitted to humans as a result of being bitten by infected midges, though some mosquitoes can also carry and spread it.
It was first discovered in Trinidad and Tobago in 1955, on the Oropouche River – which is where its name derives from.
It has been circulating in Latin America and the Caribbean since then, with sporadic outbreaks in countries such as Brazil and Peru. There have been around 500,000 recorded cases since the disease was discovered, according to The Lancet Infectious Diseases journal.
Oropouche has been colloquially referred to as sloth virus or sloth fever because the disease is believed to have a reservoir in pale-throated sloths, along with non-human primates and rodents, meaning they are natural hosts to the virus and carry it.
The virus is also being found in areas where sloths, which carry a range of parasites and pathogens, are present, says Carolina Goncalves, superintendent pharmacist at Pharmica.
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“However, the name is relatively misleading as it is spread by insect bites, not by direct contact with sloths,” she adds.
First deaths from virus spark concern
The virus has become more prevalent recently, with more than 10,000 cases reported this year amid outbreaks in Brazil, Bolivia, Colombia, Peru, and more recently Cuba, where there had never been an outbreak before, according to the Pan American Health Organisation.
The Brazilian Ministry of Health has reported two young Brazilian women with no other known conditions died during the outbreak – the first known fatalities ever caused by oropouche – and highlighted concerns about the disease passing from mother to child during pregnancy.
The ministry reported six possible cases of it being passed in childbirth, and says investigations are ongoing regarding infections during pregnancy, potential birth defects, and stillbirths associated with the virus.
“There is much we still do not know about the oropouche virus but one of the main concerns arising from the current outbreak in South America is its potential harmful effects on unborn foetuses,” says Dr Enny Paixao, associate professor at the London School of Hygiene and Tropical Medicine.
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“Some very limited studies have suggested that antibodies against the virus have been found in children born with microencephaly and that there may be a link between infection, miscarriage, and foetal deaths in Brazil, but further research is needed to investigate a potential causal link,” says Dr Paixao.
Experts say there is a lot still not known about oropouche as a whole and that more research is needed across the board.
How has the oropouche spread got worse?
Several factors may explain the recent outbreak, Dr Paixao says, including “enhanced surveillance, climate and environmental changes, and potential changes to the virus”.
“Changes to temperature and precipitation can affect transmission, for example, rising temperatures can enhance the rate of development of culicoides midges, one of the virus’ main transmission vectors in South America alongside mosquitoes,” she says.
The factors driving the recent increase in cases needs further investigation, Dr Paixao continues, adding: “Until advancements are made in vaccine development or mosquito and midge control, or until natural immunity within the population in Brazil [and other affected countries] increases, the challenge posed by this neglected tropical disease will persist.”
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Cases in Europe for the first time – could there be an outbreak here?
Nineteen cases of oropouche were reported in Europe for the first time in June and July, according to the European Centre for Disease Prevention and Control (ECDC) – with 12 in Spain, five in Italy and two in Germany.
But these cases were imported into Europe – 18 of the people infected had just travelled back from Cuba and one of them from Brazil.
The ECDC says the risk of Europeans travelling to or residing in epidemic areas in South and Central America catching oropouche is “moderate” – but that the likelihood of being exposed to it in Europe is “extremely low”.
Dr Philip Veal, travel health consultant at UKHSA, explains why: “The midge that carries oropouche virus is not currently established in Europe.
“It is typically found in the Americas. There is no evidence that the virus can spread from person to person.”
What are the symptoms?
These are the symptoms oropouche outlined by the Centre for Controlled Diseases:
In rare cases, some people may develop more severe disease, including meningitis or encephalitis, according to Health Travel Pro.
Symptoms can start several days or even a week after being bitten, and typically last three to seven days.
While there are no specific treatments or vaccines available for it, most people recover without long-term effects.
“Treatment primarily focuses on managing symptoms and providing supportive care,” says Ms Goncalves
Patients are typically advised to rest, stay hydrated, and take over-the-counter pain relievers such as paracetamol to reduce fever and alleviate pain, she says.
“In more severe cases, hospitalisation may be necessary to provide supportive care, especially if complications arise, although severe cases are relatively rare.”
How can you avoid getting infected?
Dr Veal says those travelling to infected areas need to use typical methods of preventing insect bites.
He suggests using insect repellent, covering exposed skin and sleeping under a treated bed net.
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The ECDC recommends using insecticide-treated fine mesh mosquito bed nets when resting, as midges are small, and it has been reported they can slip through some nets.
Dr Veal also says travellers should plan ahead and visit the Travel Health Pro website to look up the latest health information and advice, particularly if they are pregnant.
