Everything we know about ‘sloth fever’ as it spreads to Europe

A rare virus known as ‘sloth fever’ has been detected in three European countries, with a doctor warning it could ‘become unstoppable’.

Oropouche virus disease, as it is officially known, has been dubbed ‘sloth fever’ because the tree-dwelling animals that live in South America are thought to be an animal host for it.

Dubbed a ‘mysterious threat’ in the prestigious Lancet journal, little is known about it as it is still an emerging disease.

The first known deaths from the virus were reported in Brazil last month, both of women in their twenties.

Mainly spread by midges, there is no known vaccine or cure for the disease, and typical prevention methods such as using nets to sleep under may not be effective as the midges are so small.

Of cases in Europe, so far twelve cases have been reported in Spain, five in Italy, and two in Germany.

They were among those with recent history of travel to areas where the virus is already established, and there has not yet been any case of human-to-human transmission detected.

However, the unusually rapid spread of the virus in South America and Cuba is ringing alarm bells, with tourists warned to beware.

What symptoms does ‘sloth fever’ cause?

As the moniker suggests, one of the main symptoms is fever. It’s often mistaken for the better-known Dengue fever, which is generally spread by mosquitoes in tropical areas, but also reported in parts of Europe.

Symptoms include headache, fever, muscle aches, stiff joints, nausea, vomiting, chills, or sensitivity to light.

Most people recover with no lasting effects, but there are fears the virus could be dangerous to unborn babies, potentially causing stillbirth, miscarriage or deformities in the fetus.

Symptoms typically start four to eight days after being bitten and last three to six days. There is no specific medicine available to cure it, and patients can only be given supportive treatment.

Severe cases may result in neuroinvasive disease such as meningitis, according to the US-based Centers for Disease Control and Prevention (CDC).

On July 17, an alert was given by the UN about possible negative health effects to unborn babies if the mother contracts the disease while pregnant. Potential cases of pregnant mother-to-child transmission in Brazil are being looked into.

Among the cases under investigation are four newborns with microcephaly (a smaller than normal head) found to have antibodies against Oropouche virus in serum samples, though they tested negative for other viruses such as Zika known to effect fetuses.

Another case under investigation is of a woman who suffered a still birth at 30 weeks gestation in June this year, having contracted the Oropouche virus.

Should we be worried about ‘sloth fever’?

Yes and no.

In a second Lancet article published in January, researchers said: ‘Over the past 70 years, a notable increase in the incidence and geographical spread of reported Oropouche virus infections has been observed, highlighting a growing public health concern.’

Dr Paul Hunter, a professor of medicine at the University of East Anglia, told the Telegraph that he would advise ‘against non-essential travel to infected areas for pregnant women’.

He added that he is ‘almost certain’ that in Europe there are more infections than have yet been detected and reported.

Dr Danny Altmann, a Professor of Immunology at Imperial College London, told the paper there is a ‘real need for vigilance’ as the virus was ‘taking off this summer in the Americas’ meaning tourists should be aware.

He added that southern Europe and North America could one day be much more at risk from diseases such as Sloth Fever and Zika because global warming is allowing the midges and mosquitoes which spread them to expand the areas they can thrive.

This article was originally published on August 13, 2024.

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