Overview
For the first time, Usutu virus (USUV) has been detected in Scotland – found in dead blackbirds on the Isle of Arran in summer 2025, confirmed by APHA. The mosquito-borne virus mainly affects wild birds and has circulated in England for six years. The risk to humans remains very low.
A New Virus Detected in Scotland
In summer 2025, local residents on the Isle of Arran noticed something unusual. Blackbirds were showing strange neurological signs – shaking, unable to fly – and many were found dead. Samples were sent for testing. On 1 April 2026, public announcements confirmed that the cause was Usutu virus (USUV) . This is the first time Usutu virus has been found in Scotland. The virus is carried by mosquitoes and mainly infects wild birds. It has been present in south-east England for six years, but now it has reached Scotland.
What is Usutu Virus?
Usutu virus belongs to the genus Flavivirus . It is a mosquito-borne virus. It was first identified in Africa in 1959 (in South Africa, from a mosquito). Since then, it has spread to several European countries. The virus primarily infects wild birds, especially blackbirds. In some parts of Europe, Usutu virus has caused serious declines in blackbird populations. The virus can also infect humans, but this is rare. Most human infections cause no symptoms or mild illness. Severe disease is very uncommon.
How Was Usutu Virus Detected in Scotland?
The discovery happened through the national passive wild avian surveillance programme run by the Animal and Plant Health Agency (APHA). Local residents on the Isle of Arran reported sick and dead blackbirds. Working with SRUC Veterinary Services and the Mosquito Scotland research programme at the University of Glasgow, APHA’s Vector-Borne Disease Group examined the samples. They used a laboratory method called reverse transcription-PCR (RT-PCR) . This test can detect the genetic material (RNA) of the virus. The test confirmed Usutu virus RNA in two blackbirds.
Genetic Lineage: Africa 3.2
Scientists also performed phylogenetic analysis – a method to compare the genetic code of the virus with other known strains. The Scottish samples belonged to the Usutu virus Africa 3.2 lineage . This is the same lineage that has already been found in other parts of the United Kingdom. This finding suggests that the virus has spread from existing UK detections (likely from south-east England) rather than being a new introduction from overseas.
Impact on Bird Populations
Usutu virus is a real threat to wild birds. In Europe, it has caused massive declines in blackbird populations. For example, in the Netherlands, blackbird numbers dropped sharply after Usutu virus arrived. The virus does not affect all bird species equally. Blackbirds are particularly susceptible. The detection in Scotland is worrying for conservationists. However, the virus has already been circulating in England for six years. It may only be a matter of time before it becomes established in Scotland as well.
Public Health Risk: Very Low
The public health risk from Usutu virus is very low . No human cases have ever been reported in the United Kingdom. In Europe, only a few human cases have been recorded, and most were mild. The virus is not easily transmitted to humans; it requires a mosquito bite from an infected mosquito. Even then, most people do not get sick. Severe illness is extremely rare. The authorities have reassured the public that there is no reason for alarm.
How Surveillance Works in the UK
The UK has a robust system for monitoring bird diseases. The APHA (Animal and Plant Health Agency) runs a national passive wild avian surveillance programme. This means that members of the public, veterinarians, and wildlife organisations report sick or dead birds. Samples are collected and tested for a range of pathogens, including Usutu virus and West Nile virus. The programme also includes mosquito monitoring. The Mosquito Scotland research programme at the University of Glasgow specifically tracks mosquito species and the viruses they may carry.
The detection on the Isle of Arran shows that the surveillance system is working. Without it, the virus might have gone unnoticed.
A Human Touch: The Resident Who Noticed
Isle of Arran resident Margaret McDonald walks her dog every morning. In August 2025, she noticed a blackbird stumbling on the path. “It couldn’t fly. Its head was twisted. I had never seen anything like it,” she said. She reported it to a local wildlife centre. That report started the chain of testing. “I am relieved that we now know what caused it. I hope the scientists can stop it from spreading further,” she added.
Dr. Nicola Seechurn, a virologist at the University of Glasgow, said, “This detection is important. It tells us that Usutu virus has moved north. We will continue to monitor mosquitoes and birds to understand the spread.”
What Does This Mean for Scotland?
The arrival of Usutu virus in Scotland is not unexpected. Climate change is allowing mosquito populations to expand northwards. Warmer summers mean more mosquitoes and a longer season for virus transmission. While the risk to humans is low, bird lovers may see fewer blackbirds in their gardens. The Scottish government has urged people to continue reporting sick or dead birds. This helps scientists track the virus.
Conclusion
The first detection of Usutu virus in Scotland on the Isle of Arran is a significant event for wildlife disease monitoring. The virus, transmitted by mosquitoes, has caused blackbird deaths in other parts of Europe. Public health risk remains very low. The discovery highlights the importance of passive surveillance and collaboration between agencies. As the climate warms, we may see more such viruses spreading to new areas. Vigilance is key.
Exam-Focused Points
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Virus name: Usutu virus (USUV)
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Type: Mosquito-borne flavivirus (genus Flavivirus)
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Main host: Wild birds, especially blackbirds
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First detection in Scotland: Summer 2025 on Isle of Arran; announced 1 April 2026
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Detection method: Reverse transcription-PCR (RT-PCR) on dead blackbirds
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Genetic lineage: Africa 3.2 (same as existing UK strains)
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Surveillance programme: APHA national passive wild avian surveillance
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Collaborating organisations: APHA, SRUC Veterinary Services, Mosquito Scotland (University of Glasgow)
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Public health risk: Very low; no human cases in UK
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Previous circulation: Six years in south-east England
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Symptoms in birds: Neurological signs, death
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Global context: First identified in Africa (1959); now in several European countries
Frequently Asked Questions (FAQ)
Q1: Can humans catch Usutu virus?
A: Yes, but it is very rare. Human infections have been recorded in parts of Europe, but most cause no symptoms or only mild illness. No human cases have been reported in the United Kingdom.
Q2: How is Usutu virus spread?
A: It is spread by mosquitoes. The mosquitoes pick up the virus from infected birds and can then pass it to other birds. Humans can be infected if bitten by an infected mosquito, but this is uncommon.
Q3: Should I be worried about my garden birds?
A: The virus mainly affects blackbirds. If you see a blackbird showing unusual behaviour (twitching, unable to fly) or find a dead blackbird, you can report it to the Animal and Plant Health Agency (APHA). However, the virus has been in England for six years, so it is not new to the UK.
Q4: What is reverse transcription-PCR (RT-PCR)?
A: It is a laboratory technique used to detect the genetic material (RNA) of a virus. It is very sensitive and can confirm the presence of Usutu virus in bird samples.
Q5: Is there a vaccine or treatment for Usutu virus?
A: There is no vaccine for humans. Treatment is supportive (managing symptoms). For birds, there is no treatment. Prevention focuses on controlling mosquito populations.