Published: June 6, 2025
Disclaimer: This article is for informational purposes only and does not constitute medical advice. For any health concerns, consult a qualified healthcare professional.
What Is the Usutu Virus?
The Usutu virus (USUV) is a mosquito-borne flavivirus primarily affecting birds, particularly blackbirds and other songbirds. First detected in Africa in 1959, the virus has spread across Europe over the last two decades and was first confirmed in UK birds in 2020.
Scientific Classification:
- Family: Flaviviridae
- Related to: West Nile virus, Zika virus, Japanese encephalitis
According to the UK Health Security Agency (UKHSA), while human infections are rare, surveillance is increasing due to the virus’s growing presence in European and UK ecosystems.
🔗 UKHSA: Emerging Zoonotic Threats
How Does It Spread?
The Usutu virus is transmitted by mosquitoes, particularly Culex species, which feed on infected birds. The virus circulates in a bird–mosquito–bird cycle. Occasionally, humans and other mammals can become accidental hosts, but they do not spread the virus further.
Transmission Pathway:
- Infected bird is bitten by a mosquito.
- Mosquito becomes a carrier.
- Mosquito bites another bird or, in rare cases, a human.
- Human infection may occur but is usually asymptomatic or mild.
Climate change and warmer temperatures are expanding mosquito habitats across the UK, potentially increasing the risk of zoonotic spillover.
“With milder winters and wetter summers, we are seeing a northward shift in mosquito species capable of transmitting viruses like Usutu,” explains Dr. Alex Hill, a public health entomologist at the University of London.
(Source: Nature Ecology & Evolution)
Impact on Blackbirds and Other Birds in the UK
The Usutu virus is especially deadly to blackbirds, with many dying suddenly and showing signs of neurological issues, including:
- Lethargy
- Disorientation
- Uncoordinated movement
- Fluffed-up feathers
- Death within 24–48 hours
The British Trust for Ornithology (BTO) has reported clusters of blackbird deaths in southeast England, particularly during warmer months. Post-mortem examinations confirmed USUV in a number of cases.
🔗 BTO: Usutu Virus in British Birds
Can Humans Be Infected?
Yes, but human infection is extremely rare and usually mild or asymptomatic. Documented human cases in Europe (e.g., Italy, Germany) have shown:
- Mild fever
- Headache
- Rash
- Fatigue
In very rare cases, especially in immunocompromised individuals, the virus may cause neurological complications, such as encephalitis or meningitis.
According to the European Centre for Disease Prevention and Control (ECDC):
“As of 2024, only a small number of confirmed human cases have been recorded across the EU. Most infections are incidental and self-limiting.”
Is There a Risk to the General UK Public?
Current risk to the general UK population is low.
However, health authorities are maintaining active surveillance due to:
- Expanding mosquito habitats
- The virus’s potential to mutate
- Increasing reports of bird die-offs
The UKHSA and Animal and Plant Health Agency (APHA) are conducting mosquito and bird testing in high-risk zones.
“There is no current evidence of widespread human infection in the UK, but continued monitoring is essential,” states UKHSA’s Zoonotic Surveillance Division.
What Can You Do? (Precautions & Reporting)
✅ Prevent Mosquito Bites (Especially if living in warm, wet regions):
- Use insect repellents with DEET or icaridin.
- Install mosquito screens on windows.
- Remove standing water in gardens (birdbaths, plant saucers, buckets).
- Wear long sleeves and trousers in the evening.
✅ Report Unusual Bird Deaths:
- If you find multiple dead blackbirds or other songbirds in your area:
- Do not touch with bare hands
- Report sightings to:
Usutu Virus in Other Countries: A Quick Timeline
| Year | Country | Key Event |
|---|---|---|
| 1959 | South Africa | First recorded case |
| 2001 | Austria | First European outbreak |
| 2016 | Germany | Major blackbird die-off |
| 2020 | United Kingdom | First confirmed cases in birds |
| 2025 | United Kingdom | Active monitoring and research ongoing |
Conclusion: Stay Aware, Not Alarmed
The Usutu virus represents a low but emerging zoonotic threat in the UK. While blackbirds are most vulnerable, and human cases remain extremely rare, climate change and changing mosquito patterns mean that viruses like USUV are increasingly relevant for both public health and biodiversity.
By staying informed, reporting unusual bird deaths, and taking basic mosquito precautions, you help support national surveillance and protect both human and wildlife health.
Sources & References
- British Trust for Ornithology (BTO)
- European Centre for Disease Prevention and Control (ECDC)
- Garden Wildlife Health
- Nature Journal: Climate-Driven Vector Expansion
- Fera Science Ltd – Zoonotic Surveillance
About the Author
Sandeep is a health and science writer for Pulsewire, with a focus on emerging public health risks and environmental change. He compiles verified insights from global health authorities, scientific journals, and UK surveillance bodies to help readers stay informed and proactive.
