HAIRS risk assessment: Usutu virus

Question 1

About the Human Animal Infections and Risk Surveillance group

Accepted Answer

This document was prepared by the UK Health Security Agency (UKHSA) on behalf of the joint Human Animal Infections and Risk Surveillance (HAIRS) group.

HAIRS is a multi-agency cross-government horizon scanning and risk assessment group, which acts as a forum to identify and discuss infections with potential for interspecies transfer (particularly zoonotic infections). Its work cuts across several organisations, including:

UKHSA
Department for Environment, Food and Rural Affairs (Defra)
Department for Health and Social Care (DHSC)
Animal and Plant Health Agency (APHA)
Food Standards Agency (FSA)
Food Standards Scotland (FSS)
Public Health Wales (PHW)
Public Health Scotland (PHS)
Department of Agriculture, Environment and Rural Affairs for Northern Ireland (DAERA)
Welsh Government
Scottish Government
Public Health Agency of Northern Ireland
Department of Agriculture, Food and the Marine, Republic of Ireland
Health Service Executive, Republic of Ireland
Infrastructure, Housing and Environment, Government of Jersey
Isle of Man Government
States Veterinary Officer, Bailiwick of Guernsey

Information on the risk assessment processes used by the HAIRS group can be found on GOV.UK.

Version control

Date of this assessment: September 2025

Version: 5.0

Reason for the assessment: Updated to reflect the latest Usutu virus epidemiology in Europe, ongoing mosquito surveillance in the UK and detections of Usutu virus in wild and captive birds in the UK since 2020.

Completed by: HAIRS members

Non-HAIRS group experts consulted:

Dr. Arran Folly, Animal and Plant Health Agency Vector-borne disease group
The joint NHS Blood and Transplant (NHSBT) - UKHSA Epidemiology Unit
Prof. Andrew Cunningham, the Zoological Society of London
Dr. Becki Lawson, the Zoological Society of London

Date of previous risk assessment(s): 31 October 2012 (V1.0); 15 December 2016 (V2.0); 30 September 2020 (V3.0); December 2023 (V4.0).

Information on the risk assessment processes used by the HAIRS group can be found online.

Question 2

Summary of risk assessment for Usutu virus in the UK population

Accepted Answer

Overview

In Europe, Usutu virus (USUV), a mosquito-borne flavivirus, was first recognised in Austria in wild birds in 2001, and subsequently its range expanded across the European Region. In August 2020, the first USUV infected wild birds in the UK were identified.

Since then, a small number of wild and captive birds tested positive between 2021 and 2024, inclusive, predominantly in the southern and eastern counties of England. Subsequently, extensive mosquito surveillance and molecular screening has found evidence of USUV across large parts of south and south-eastern counties of England. As of September 2025, no human cases of USUV have been reported in the UK.

Assessment of the risk of infection in the UK:

Probability

The probability of human infection with USUV in the UK population is considered low.

Impact

The impact of USUV on human health in the UK would be considered Very low to Low for the general UK population, but Low to Moderate for higher risk groups including immunosuppressed individuals.

Level of confidence in assessment of risk

Satisfactory.

Evidence gaps

The circulation of USUV in bird hosts and mosquito vectors is not well understood globally.

There is a scarcity of seroprevalence data to assess the real prevalence of USUV infection in humans globally, particularly in relation to background exposure to West Nile virus (WNV), as laboratory testing may not always discriminate between the two flavivirus infections.

A better understanding of USUV circulation across the UK in mosquito vectors, potential reservoir bird hosts and humans. This requires a review of monitoring strategies through the implementation of the One Health approach.

Actions and recommendations

For animal health and veterinary professionals

Continue risk-based surveillance for USUV infections in birds and mosquitoes in the UK beyond the current period of funding.

For public health professionals

Continue to monitor the situation in European countries for increasing reports of human USUV cases or changes in pathogenicity of human infections.

Continue to look for evidence of USUV in blood donations and other substances of human origin (SOHO) in travellers returning from higher risk areas.

Consider conducting a risk-based serosurveillance study for USUV in humans in the UK, including within blood donations and SOHO.

Raise awareness of USUV amongst clinicians in known risk areas with USUV circulation, particularly in southern and eastern counties of England.

For both public and animal health professionals

Raise public awareness on mosquito bite prevention measures, particularly in known risk areas.

Question 3

Step 1. Assessment of the probability of infection in the UK human population

Accepted Answer

This section of the assessment examines the likelihood of an infectious threat causing infection in the UK human population. Where a new agent is identified there may be insufficient information to carry out a risk assessment and this should be clearly documented. Please read in conjunction with the Probability algorithm found in Annexe A.

Is this a recognised human disease?

Outcome

Yes.

Quality of evidence

Good.

Usutu virus (USUV) is a mosquito borne flavivirus first detected in South Africa in 1959 (1). USUV belongs to the Japanese encephalitis virus serocomplex and is phylogenetically similar to other human and animal pathogens such as West Nile virus (WNV) (2, 3).

USUV is maintained through an enzootic cycle involving birds (predominantly Passeriformes (mostly passerines such as blackbirds) and Strigiformes (owls)) as amplifying reservoir hosts and ornithophilic mosquito species as vectors (mainly Culex (Cx) species) (1). Mammals, including humans, are incidental dead-end hosts. This is because viraemia in an infected mammal does not reach high enough levels to ensure transmission via mosquito bites and continuation of the transmission cycle. USUV ribonucleic acid (RNA) has been identified in dogs, wild boar, ruminants including sheep and roe deer, as well as in captive exotic species (4).

USUV is an emerging infection in humans but the number of globally confirmed clinical infections to date is very low. The first recorded human cases were in the Central African Republic in 1981 and in Burkina Faso in 2004. Since then, most human infections have been reported in mainland Europe, with an observed increase in reporting frequency during recent years. This may be due to raised awareness of the disease, changes in testing or screening (for example, of blood donors) or due to increased human exposure as USUV becomes established and is identified in susceptible bird, mosquito and human populations across a wider geographical range in Europe.

In humans, USUV has an estimated incubation period of between 3 to 12 days following the bite of an infected mosquito. Due to limited clinical data available for USUV infection, this estimation is extrapolated from WNV infection as a reference (5).

Seroprevalence studies in Italy indicate that the prevalence of antibodies against USUV in humans is higher than anti-WNV antibodies in areas where both viruses co-circulate, supporting the hypothesis that most human USUV infections are mild or asymptomatic (6). Although the full spectrum of clinical presentation of USUV infections in humans has yet to be fully described, it ranges from mostly asymptomatic or mild symptoms (characterised by fever, myalgia, headache, asthenia and rash (7)) to a rare severe neuroinvasive presentation most often observed in immunocompromised individuals or patients with comorbidity (for examples see (8) and (9 to 12)).

In Europe, most human infections have been reported from Italy, where there is active circulation of USUV and an extensive USUV and WNV surveillance program in place. In 2024, 6 human cases of febrile illness caused by USUV were detected in Italy, similar to 2023 when 7 human cases were reported, of which 5 were identified in blood donors (13, 14). Carletti and others summarised published reports describing a total of 49 human infections with USUV identified in central Italy as of 2018 (15). Of these, which were diagnosed using molecular, serological or virus isolation techniques, 25 were identified in healthy blood donors as part of surveillance (16, 17).

Of the 104 USUV infection cases reported in the European Region between 2012 to 2021, most cases had been reported in Italy (56 cases), Austria (26 cases) and the Netherlands (11 cases), while 11 cases presented with neuroinvasive symptoms across Croatia, Czech Republic, France, Italy, and Hungary. Evidence of acute human infections have also been reported in Switzerland, and more recently 6 autochthonous cases were reported in Nouvelle-Aquitaine Region of France during 2023 (18, 19). Cadar and Simonin described how USUV antibody prevalence ranged from 0.02% to 3% among healthy blood donors in seroprevalence studies carried out in Austria, Germany, Italy, France, Hungary, the Netherlands, Romania and Serbia between 2009 and 2020 (4, 20).

Additionally, higher seropositivity rates (6 to 7%) were observed in more exposed populations such as healthy forestry workers and bird ringers (21, 22). There is evidence in some countries to suggest that seropositivity rates have slowly increased over time (23). To date, 3 USUV associated fatalities have been reported globally, all in immunosuppressed individuals, form Croatia, Italy, and Hungary (one death each) (24 to 26).

Is the disease endemic in humans within the UK?

Outcome

No.

Quality of evidence

Good.

As of September 2025, no human infections of USUV have been reported in the UK.

Humans are dead-end hosts for USUV as viraemia in an infected human does not reach high enough levels to ensure transmission through mosquito bites and continuation of the transmission cycle. Instances of human infection are usually a result of USUV transmission through the bite of an infected mosquito, which has fed on an infected bird.

Evidence suggests a large proportion of human infections are asymptomatic. Most infections in mainland Europe have been diagnosed in asymptomatic blood donors identified on blood screening using a PCR test for WNV, with subsequent specific USUV testing. In the UK, a similar approach has been used by NHS Blood and Transplant (NHSBT) in England and the Scottish National Blood Transfusion Service (SNBTS) to screen returning travellers since 2012 and 2013, respectively. The Welsh Blood Service commenced WNV testing in 2024. UK blood services test samples from donors who have reported a travel history between May and November in the last 28 days to areas where WNV is circulating. USUV is known to co-circulate with WNV, and the molecular test for WNV (currently Roche Cobas 6800/8800 Nucleic Acid Test to identify WNV lineage 1 and 2) may also cross-react with USUV RNA, therefore a positive result would trigger further testing. Between 2012 and 31 December 2024, approximately 520,000 samples from returning travellers were tested by NHSBT, with 4 reactive tests (in 2014, 2016, 2022 and 2024), but no confirmed USUV cases were identified (joint NHSBT-UKHSA Epidemiology Unit data).

Regarding clinical case-finding, cases of undiagnosed encephalitis referred to UKHSA’s Rare and Imported Pathogens Laboratory for investigation have undergone serological testing for WNV even in the absence of a travel history. Depending on the dates of illness and sample collection, samples which have detectable WNV antibodies have undergone subsequent WNV PCR testing, and, if negative, were then tested for USUV with a developmental PCR. Again, no USUV cases have been identified to date. Due to the serological cross reactivity between WNV and USUV, this approach is likely to identify acute USUV cases referred for testing. Although no human cases have been identified, mild cases may not present to healthcare services, and only those with prolonged encephalitis symptoms are likely to be identified by this approach.

Is the disease endemic in animals within the UK?

Outcome

Yes, but limited to South East England where surveillance is established.

Quality of evidence

Satisfactory.

Birds

The Animal and Plant Health Agency’s (APHA) surveillance for USUV in wild birds in Great Britain from 2005 to 2019 did not result in any detections of USUV (27).

In late August 2020, USUV RNA was detected in samples from a small number of wild birds (5 blackbirds and one house sparrow) submitted to APHA’s wildlife disease surveillance programme from a site in Greater London (the index site) (28). This was regarded as the first detection of USUV in wild birds in the UK.

Detections in blackbirds occurred annually at the same site between 2020 and 2023 (29). Genomic characterisation and molecular clock analysis of the isolates detected in Greater London, between 2020 to 2023 inclusive, from birds indicate that the virus is USUV Africa 3.2 lineage. These UK detections are most closely related to each other compared to publicly available mainland European isolates, suggesting that the virus is persisting year-on-year in the UK.

During 2023, USUV was detected in a dead blackbird found in Cambridgeshire representing the first USUV detection in the UK outside of the Greater London area (30).

Additional detections were observed in 2 blackbirds from the index site, 2 great grey owls which were relocated from ZSL Whipsnade Zoo to ZSL London Zoo, and 3 dead blackbirds from wildlife rehabilitation centres in southern England. Both blackbirds and great grey owls are highly susceptible to fatal USUV disease. Phylogenetic analysis of these isolates, including a positive sample taken from a blackbird in East Sussex, provide evidence that the UK may be experiencing repeated introductions of USUV due to differences in their sequences to existing UK detections.

In 2024, active bird surveillance was undertaken in southern England on a subset of relevant passerine host species. USUV RNA was detected in the feather pulp from a juvenile whitethroat, blackcap feathers, in addition to a chiffchaff feather from Cambridgeshire representing a geographical expansion. USUV RNA was also detected in a cloacal swab from a blackcap in Dorset, and seroconversion was detected in 7 blackbirds from Surrey, Hampshire and Kent.

Mosquitoes

A joint Public Health England – APHA study in 2013 in North Kent tested over 1,000 Cx modestus mosquitoes for USUV and all were negative for USUV (31). Following the first detection of USUV in wild birds in 2020, mosquito surveillance in Greater London identified USUV RNA in 4 Cx. pipiens s.l. pools (32).

Mosquito monitoring had previously been conducted at the same site in 2015, during which time USUV was not detected. Sampling for mosquitoes, including host-seeking females, overwintering females, and developing larvae has been conducted at ZSL London zoo since the 2020 USUV outbreak. Apart from detections in Cx. pipiens s.l. pools mentioned above, USUV RNA was detected in one larval pool in 2023, suggesting that vertical transmission of USUV is occurring at the index site as a mechanism for viral persistence (33).

In 2023, wider mosquito surveillance and USUV screening of mosquito pools detected the presence of USUV in 92 positive mosquito pools from 15 species of mosquito, in a variety of locations from Dorset to Kent and as far north as Cambridgeshire, including parts of Essex and Greater London.

Although a range of species of mosquito were to be found infected, not all are considered primary enzootic vectors with most detections in Cx. pipiens and Anopheles claviger. Mosquito surveillance has detected USUV RNA from 3 Cx. modestus pools (Thames estuary and Essex), which are potential bridge vectors highlighting a potential risk for spillover to humans. Furthermore, mosquito surveillance in 2024 continued to detect the presence of USUV RNA in 27 pools from across 10 species of mosquitoes collected from Southeast England during the mosquito active season.

Recent evidence indicates USUV is endemic in wild birds and mosquitoes in south-east England, with ongoing surveillance a priority to establish the extent of the current geographic USUV range (34).

Since the initial introduction of USUV in the UK in 2020, USUV detections have continued to be observed annually with at least 4 separate introductions in the South East Region of England. Throughout the years genomic sequencing has also revealed several USUV in birds (wild and collection) and mosquitoes across South East England to be genetically similar suggesting that USUV has persisted in the UK regardless of new introductions of the virus.

Ongoing declines in the highly susceptible blackbird population have continued to be observed in Greater London since 2020 indicating that the virus may still be circulating and having a significant impact within this host species. This is corroborated by repeated USUV detections in blackbirds in Greater London since 2020. The detection of USUV in overwintering mosquitoes provides further evidence of the integration of USUV into the natural enzootic cycle within the UK’s natural temperate conditions. As surveillance is established within the South East Region, these detections provide evidence of USUV’s endemicity within the region. There is ongoing work to expand surveillance outside of the South East Region to understand the extent of the geographical expansion and endemicity of USUV in the UK.

Will there be human exposure?

Outcome

Yes.

Quality of evidence

Satisfactory.

While human exposure is possible, it is unlikely to be extensive. USUV is maintained in a similar mosquito-bird-mosquito cycle as WNV (35). Mosquito vectors of USUV can be found in the UK and whilst human exposure is possible, the most common vector which exists in the UK (Cx pipiens s.l.) exhibits a bird-biting biotype and rarely, if ever, bites humans.

Nuisance biting in the UK is a regional phenomenon, due to a variety of species including Culiseta annulata, although the role of this mosquito and other human-biting species in USUV transmission is not clear (36). Cx modestus are capable of being infected with USUV, behaving as a potential bridge vector, and are established in wetlands in Essex and Kent either side of the Thames estuary as far north as costal Suffolk (37).

It has also been detected in parts of Cambridgeshire Fens and along the south coast in Sussex and Hampshire. Although the invasive species Aedes albopictus and Ae. japonicus are not currently established in the UK, literature suggests that both species could be competent vectors of USUV (38, 39).

Are humans highly susceptible?

Outcome

No.

Quality of evidence

Satisfactory.

Angeloni and others described that from 2012 to 2021, most human cases of USUV infection in the European Region were asymptomatic (85 cases) or had only mild symptoms (febrile fever, 8 cases) and rarely neurological involvement (12 cases) (40).

Apparent moderate to severe clinical disease is rare in human USUV infections. The recent increasing numbers of reports of asymptomatic human USUV infections as well as cases of mild to severe neuroinvasive USUV in humans in Europe may be due to changes in awareness, testing of blood donors and improved surveillance, but may also be an effect of increased human exposure to this zoonotic pathogen.

Outcome of probability assessment

The probability of human infection with USUV in the UK population is considered low.

Question 4

Step 2: Assessment of the impact on human health

Satisfactory.

Whilst the majority of reported human cases are asymptomatic or present with mild symptoms, severe disease has been reported. Cadar and Simonin reported that over 100 cases of acute human infection with USUV have been described in Europe, including approximately 30 patients with neurological symptoms. Most cases in which neurological disorders have been observed had comorbidities of varying severity, but neurological involvement has also occasionally been observed in healthy individuals (4). The number of cases reported to date is insufficient to determine specific risk factors, and the full clinical presentation of USUV infection needs to be better defined.

On review of the source literature, there appear to be 22 cases of USUV neurological involvement reported in Europe (see Table 1). These cases ranged in age from 25 to 84 years of age and included males and females:

3 cases had no known immunosuppression or co-morbidities
6 cases were immunosuppressed (malignancy or transplant)
6 cases had co-morbidities such as cardiovascular disease or diabetes

Three fatalities, one each from Croatia, Italy and Hungary, were observed in immunosuppressed individuals (24 to 26). These are the only fatalities associated with USUV reported in the literature to date.

Table 1. A description of European human USUV cases in which neurological involvement has been reported between 2008 and 2024 (from 22 cases)

Year	Country	Gender / Age	Presentation	Co-morbidities and immunosuppression	Reference
2008	Italy	Male, 40	Meningo-encephalitis	Chronic liver disease	(11)
2008	Italy	Male, 73	Meningo-encephalitis	Chronic obstructive pulmonary disease, diabetes	(11)
2008	Italy	Female, 67	Acute encephalitis	Aortic and mitral valve insufficiency	(11)
2009	Italy	Female, 54	Acute encephalitis	Hypertension	(11)
2009	Italy	Female, 60s	Meningo-encephalitis	Immunosuppressed - B cell lymphoma and chemotherapy	(12)
2009	Italy	Female, 40s	Neurological disease with severe impairment of the cerebral functions - required intensive rehab	Immunocompromised patient following a liver transplant	(10)
2013	Croatia	Female, 29	Meningo-encephalitis - slow recovery	No known immunosuppression or co-morbidities	(43)
2013	Croatia	Unknown, 56	Meningo-encephalitis - prompt recovery	Arterial hypertension, hyperlipidaemia, and diabetes mellitus	(43)
2013	Croatia	Unknown, 61	Meningo-encephalitis Prompt recovery	Arterial hypertension, hyperlipidaemia, and diabetes mellitus	(43)
2016	France	Male, 39	Facial paralysis Recovered in a few weeks	No known immunosuppression or co-morbidities	(8)
2018	Italy	Male, 60s	Mild form of encephalitis Treated with acyclovir, recovered and d/c day 10	Hypertension, diabetes mellitus and an underlying malignancy	(6)
2018	Croatia	Unknown, 25	‘Neuroinvasive disease’	Not reported	(26)
2018	Croatia	Unknown, 84	‘Neuroinvasive disease’	Not reported	(26)
2018	Croatia	Unknown, 60	Meningo-encephalitis - fatal	Chronic lymphocytic leukaemia	(26)
2018	Hungary	Male, 40s	Meningitis – recovered without neurological sequelae	No known immunosuppression or co-morbidities	(44)
2022	Italy	Male, 80	Fatal meningoencephalitis infection few days after symptoms onset	Hypertension, past infiltrating prostate adenocarcinoma, psoriasis	(24)
2024	Croatia	Unknown	‘Neuroinvasive disease’	Not reported	(45)
2024	Croatia	Unknown	‘Neuroinvasive disease’	Not reported	(45)
2024	Croatia	Unknown	‘Neuroinvasive disease’	Not reported	(45)
2024	Croatia	Unknown	‘Neuroinvasive disease’	Not reported	(45)
2024	Croatia	Unknown	‘Neuroinvasive disease’	Not reported	(45)
2024	Hungary	Female, 61	Febrile, encephalopathy, neurological deterioration – fatal	Leukaemia, immunocompromised	(25)

Is it highly infectious to humans?

Outcome

No.

Quality of evidence

Satisfactory.

See above evidence.

Are effective interventions available?

Outcome

Yes and no: mosquito bite prevention advice and mosquito population management options are available, however, there are no licenced vaccines or specific antiviral therapies for humans.

Quality of evidence

Satisfactory.

The risk of contracting USUV could be reduced by preventing exposure to mosquitoes: use of repellent, long sleeves, avoiding being outside at dusk and dawn when mosquito vectors are most active.

There are options for the management of mosquitoes if particular species cause nuisance biting and pose a vector risk to humans. For example, mosquito populations can be controlled by either targeting their breeding sites or, more rarely, killing adult mosquitoes, however these interventions will be considered based on local and national risk assessments.

A handbook is available for wetlands managers on assessing suitability of wetlands for mosquitoes (46). Advice on the management of aquatic habitats around the home and in urban areas is available (47). However, this may not eliminate all biting or exposure risk.

There is no human vaccine available and no specific antiviral therapy. Most human infections appear asymptomatic or mild and self-limiting, and treatment for more serious presentations is supportive.

Would a significant number of people be affected?

Outcome

No.

Quality of evidence

Satisfactory.

It appears that USUV infection occurs only in a minority of those who are exposed to and bitten by infected mosquitoes. Although there is limited information on the incidence of mosquito biting in the UK, sustained nuisance human biting is currently considered to be a localised event (36).

Outcome of impact assessment

The impact of Usutu virus on human health in the UK is assessed as:

Very Low to Low for the general UK population

Low to Moderate for higher-risk groups (for example, immunocompromised individuals or those with comorbidities).

Question 5

Annexe A. Assessment of the probability of infection in the UK population algorithm

Accepted Answer

Question 6

Annexe B. Accessible text version of assessment of the probability of infection in the UK population algorithm

Accepted Answer

Outcomes are specified with (tick) beside the appropriate answer. Where the evidence may be insufficient to give a definitive answer to a question, the alternative is also considered with the most likely outcome shown with (2 ticks) or the alternative outcomes with a (tick).

Question 1: Is this a recognised human disease?

Yes

Go to question 3. (tick)

No

Go to question 2.

Question 2: Is this a zoonosis or is there a zoonotic potential?

Yes

Go to question 4.

No

The probability of infection in the UK population is considered very low.

Question 3: Is this disease endemic in humans within the UK?

Yes [note 1]

Go to question 5.

No

Go to question 4. (tick)

Note 1: This pathway considers reverse-zoonosis of a pathogen already in circulation in the human population.

Question 4: Is this disease endemic in animals in the UK?

Yes [note 2]

Go to question 8. (tick)

No

No

The probability of infection in the UK population is considered low. (tick)

Note 3: Includes susceptibility to animal-derived variants

Question 10: Is the disease highly infectious in humans?

Yes

The probability of infection in the UK population is considered high.

No

The probability of infection in the UK population is considered moderate.

Question 7

Annexe C. Assessment of the impact on human health algorithm

Accepted Answer

Question 8

Go to question 10.

No

No

The impact of infection in the UK population is considered very high.

Question 9

References

Accepted Answer

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About the Human Animal Infections and Risk Surveillance group

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Summary of risk assessment for Usutu virus in the UK population

Overview

Assessment of the risk of infection in the UK:

Probability

Impact

Level of confidence in assessment of risk

Evidence gaps

Actions and recommendations

For animal health and veterinary professionals

For public health professionals

For both public and animal health professionals

Step 1. Assessment of the probability of infection in the UK human population

Is this a recognised human disease?

Outcome

Quality of evidence

Is the disease endemic in humans within the UK?

Outcome

Quality of evidence

Is the disease endemic in animals within the UK?

Outcome

Quality of evidence

Birds

Mosquitoes

Will there be human exposure?

Outcome

Quality of evidence

Are humans highly susceptible?

Outcome

Quality of evidence

Outcome of probability assessment

Step 2: Assessment of the impact on human health

Is there human-to-human spread of this pathogen?

Outcome

Quality of evidence

Is there zoonotic or vector-borne spread of this pathogen?

Outcome

Quality of evidence

For zoonoses or vector-borne disease, is the animal host or vector present in the UK?

Outcome

Quality of evidence

Is the UK human population susceptible?

Outcome

Quality of evidence

Does it cause severe disease in humans?

Outcome

Quality of evidence

Table 1. A description of European human USUV cases in which neurological involvement has been reported between 2008 and 2024 (from 22 cases)

Is it highly infectious to humans?

Outcome

Quality of evidence

Are effective interventions available?

Outcome

Quality of evidence

Would a significant number of people be affected?

Outcome

Quality of evidence

Outcome of impact assessment

Annexe A. Assessment of the probability of infection in the UK population algorithm

Annexe B. Accessible text version of assessment of the probability of infection in the UK population algorithm

Question 1: Is this a recognised human disease?

Yes

No

Question 2: Is this a zoonosis or is there a zoonotic potential?

Yes

No

Question 3: Is this disease endemic in humans within the UK?

Yes [note 1]

No

Question 4: Is this disease endemic in animals in the UK?

Yes [note 2]

No

Question 5: Are there routes of introduction into animals in the UK?

Yes

No

Question 6: Are effective measures in place to mitigate against these?

Yes

No