Health
Growing Concerns Over Vole Fever Virus with Ebola-like Symptoms
There’s growing concern among scientists as a potentially lethal virus, capable of jumping from rodents to humans and causing Ebola-like bleeding, is spreading across northern Europe. The pathogen has been discovered within rodent populations in Sweden.
The term ‘vole fever’ is used to denote a rare illness known as nephropathia epidemica, caused by the Puumala virus carried by bank voles. Haemorrhagic fevers, which this virus can potentially cause in humans, are a group of often severe and life-threatening diseases caused by various viruses. They encompass yellow fever, Ebola, and Crimean-Congo hemorrhagic fever.
In an unexpected turn of events, a case of vole fever was diagnosed far south in Sweden’s Scania County in 2018, over 500 kilometers from where the disease had previously been detected. A second case surfaced in the same county in 2020. Intriguingly, in both instances, the patients hadn’t traveled and contracted the infection in their home area.
The patients exhibited symptoms typical of hemorrhagic fever with renal syndrome (HFRS), such as fever, general malaise, nosebleeds, and poor kidney function. While both patients managed to recover, these unusual cases prompted scientists from Uppsala University to investigate why this rare disease was materializing far from its typical habitat.
In an effort to unravel this mystery, the researchers conducted genetic testing on bank voles from Scania county, specifically those living near the patients’ homes. They were looking for any signs of hantavirus, a family of viruses commonly found in mice, rats, and voles. Certain hantaviruses can infect people, leading to diseases like HFRS and hantavirus pulmonary syndrome (HPS).
The Uppsala University scientists noted that both HFRS and HPS are notifiable under the Communicable Diseases Act due to their potential seriousness, possibly leading to death. Typically, in northern and central Europe, a variant of the virus, the Puumala hantavirus, causes a relatively mild form of HFRS. Yet, this hantavirus can also trigger severe HRFS which, in the worst cases, can be fatal.
In Sweden, between 100–450 cases of vole fever necessitate hospital care each year, primarily originating in the northern part of the country. However, when the researchers analyzed the bank voles from Scania county, they found that nine out of 74 carried hantavirus genes. Remarkably, the strain they were carrying wasn’t the same as the one prevalent in northern Sweden.
Instead, the virus infecting the southern voles bore close resemblance to Puumala viruses from Finland or Russian Karelia, hundreds of miles away. Somehow, this strain had emerged in southern Sweden’s bank vole population, most likely within the last decade or so, causing concern about potential threats to public health.
Elin Economou Lundeberg, a study author and infectious diseases doctor at Kristianstad Central Hospital, commented, “We were surprised that such a high proportion of the relatively few voles that we caught were actually carrying a hantavirus that makes people ill.”
Scientists are now eager to discover the origins of this strain and map its distribution in southern Sweden. Professor Åke Lundkvist of Uppsala University, a co-author of the study, asked, “If the virus has existed in the area for a long time and has simply not been discovered, why haven’t more people become ill?”
Europe has been on high alert concerning haemorrhagic fevers before, with outbreaks of Crimean-Congo haemorrhagic fever reported in places like Balkans, Turkey, Russia, and even popular holiday destinations like Spain. The rapid global spread of diseases emphasizes the importance of swift investigation when infectious diseases appear in new geographical regions.
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