Cases of the Oropouche virus, informally known as sloth fever or sloth virus, have been found in Europe following an outbreak in South America.
More than 10,000 cases have been reported this year, 19 of them in Europe, and the first two deaths from the disease have been confirmed in Brazil. So what do we know about the virus, how did it get to Europe, and what are the risks?
Oropouche virus is a zoonotic disease that is transmitted to humans primarily through the bite of infected midges, although some mosquitoes can also carry and spread the virus.
The species was first discovered in 1955 in the Oropouche River in Trinidad and Tobago, from which it takes its name.
Since then, the disease has become endemic in Latin America and the Caribbean, with sporadic outbreaks in countries such as Brazil and Peru. According to The Lancet Infectious Diseases, about 500,000 cases have been recorded since the disease was discovered.
Oropouche is colloquially known as sloth virus or sloth fever because the disease is thought to have its reservoir in pale-throated sloths, non-human primates and rodents, which means that these animals are the natural hosts and carriers of the virus.
The virus has also been found in areas home to sloths, which carry a variety of parasites and pathogens, said Carolina Goncalves, head pharmacist at Farmica.
“However, the name is misleading as the disease is spread through insect bites and not through direct contact with sloths,” she added.
Image: A South American midge may spread the virus. Photo: iStock
First virus death sparks concern
According to the Pan American Health Organization, the virus has recently become more widespread, with outbreaks this year in Brazil, Bolivia, Colombia, Peru and more recently in Cuba, where more than 10,000 cases have been reported after the virus had never been seen before.
The Brazilian Ministry of Health reported that two young Brazilian women with no other known illnesses have died during this outbreak, the first known deaths from oropauche and highlighting concerns about transmission of the disease from mother to child during pregnancy.
The ministry reported six cases of possible infection at birth and said investigations were ongoing into infection during pregnancy, possible congenital abnormalities and stillbirths linked to the virus.
“There is still a lot we don't know about the Oropauche virus, but one of the main concerns arising from the current outbreak in South America is the potential adverse effects on the unborn baby,” said Dr Eny Paixao, associate professor at the London School of Hygiene and Tropical Medicine.
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“Very limited studies have found antibodies to the virus in babies born with microcephaly and suggest there may be an association between infection and miscarriage and fetal death in Brazil, but more research is needed to investigate a potential causal relationship,” Dr Paixao said.
Experts say there's still a lot we don't know about Olopouche in general, and more research is needed in general.
How did the Olopouch infestation get so bad?
Dr Paixao said several factors could be behind the recent outbreak, including “increased surveillance, changes in climate and environment, and potential changes in the virus”.
“Changes in temperature and precipitation could affect transmission. For example, rising temperatures could speed up the development of midges, which, along with mosquitoes, are the main vectors for the virus in South America,” she says.
The causes of the recent increase in cases require further investigation, Dr. Paixao continued, adding that “until there are advances in vaccine development, mosquito and midge control, or natural immunity in the population of Brazil (and other affected countries) increases, the challenges posed by this neglected tropical disease will continue.”
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First case in Europe – could there be a spread here too?
According to the European Centre for Disease Prevention and Control (ECDC), 19 cases of herpes labialis were reported for the first time in Europe in June and July, of which 12 were reported in Spain, five in Italy and two in Germany.
However, these cases were imported into Europe, with 18 of the infected people having recently returned from Cuba and one from Brazil.
The ECDC says the risk of catching Oropouche disease for Europeans travelling to or living in endemic areas of South or Central America is “medium”, but the chances of contracting the disease in Europe are “extremely low”.
Dr Philip Veal, travel health consultant at UKHSA, explains why: “The midge that transmits Oropouche virus is not currently established in Europe.
“The virus is found primarily in the Americas. There is no evidence that the virus can be transmitted from person to person.”
What are the symptoms?
These are the symptoms of cold sores as outlined by the Centers for Disease Control:
Fever, severe headache, chills, muscle pain, joint pain, nausea/vomiting, chills, sensitivity to light
In rare cases, some people may develop more serious illnesses such as meningitis or encephalitis, according to Health Travel Pro.
Symptoms may begin several days or even a week after the bite and usually last for 3 to 7 days.
There is no specific treatment or vaccine, but most people recover without long-term effects.
“Treatment is primarily focused on symptom management and supportive care,” Gonsalves said.
Patients are typically advised to rest, drink fluids and take over-the-counter painkillers such as paracetamol to reduce fever and ease pain, she said.
“Severe cases are relatively rare, but hospitalization may be required for supportive care, especially if complications arise.”
How can I avoid infection?
Dr Veal said people travelling to infected areas should use standard methods to prevent insect bites.
He recommends using insect repellent, covering exposed skin and sleeping under treated mosquito nets.
The midges are small and have been reported to be able to slip through some mosquito nets, so ECDC recommends using fine-mesh insecticide-treated mosquito nets during breaks.
Veal also said travellers, especially pregnant women, should plan ahead and visit the Travel Health Pro website for the latest health information and advice.
