Research and analysis

Global high consequence infectious disease events: summary February 2025

Updated 3 April 2025

Interpreting this report

The report provides updates on known, high consequence infectious disease (HCID) events around the world as monitored by UK Health Security Agency’s (UKHSA) epidemic intelligence activities.

The report is divided into 2 sections covering all the defined HCID pathogens. The first section contains contact and airborne HCIDs that have been specified for the HCID programme by NHS England. The second section contains additional HCIDs that are important for situational awareness.

Each section contains information on known pathogens and includes descriptions of recent events. If an undiagnosed disease event occurs that could be interpreted as a potential HCID, a third section will be added to the report.

Events found during routine scanning activities that occur in endemic areas will briefly be noted in the report. Active surveillance, other than daily epidemic intelligence activities, of events in endemic areas will not be conducted (for example, actively searching government websites or other sources for data on case numbers).

The target audience for this report is any healthcare professional who may be involved in HCID identification, treatment and management.

Risk rating

Included for each disease is a current risk rating based on the probability of introduction to the UK and potential impact on the UK public. Past UK experience and the global occurrence of travel-associated cases are also considered. Currently, all diseases are classified into one of 3 categories: Low, very low and exceptionally low to negligible.

Incidents of significance of primary HCIDs

Contact HCIDs

Crimean-Congo haemorrhagic fever (CCHF)

Geographical risk areas	Endemic in Africa, the Balkans, the Middle East and western and south-central Asia. Cases have also been reported in Russia and Georgia. Spain has previously reported locally acquired cases (first reported in 2016, with the latest case reported in 2024). Portugal reported its first human case in August 2024 with symptom onset in July 2024.
Sources and routes of infection	• bite from, or crushing of, an infected tick  • contact with the blood, tissues or body fluids of infected humans or animals
UK experience to date	Two cases have been reported in individuals who have travelled to the UK from Afghanistan in 2012 and Bulgaria in 2014.
Risk rating	Low – rarely reported in travellers.
Recent cases or outbreaks	No confirmed or suspected human cases were reported in February 2025.

Ebola disease (EBOD)

Geographical risk areas	Map of countries which have reported EBOD cases up to January 2023. Since then, an outbreak has been reported in Uganda (January 2025).
Sources and routes of infection	• contact with blood, tissues or body fluids of infected animals, or consumption of raw or undercooked infected animal tissue • contact with infected human blood or body fluids
UK experience to date	Four confirmed cases (one lab-acquired in the UK in 1976, 3 healthcare workers associated with West African epidemic 2014 to 2015).
Risk rating	Very low – other than during the West Africa outbreak, exported cases are extremely rare.
Recent cases or outbreaks	Since the declaration of the Sudan virus disease outbreak on 30 January 2025, a total of 9 confirmed cases, including one death, have been reported across 4 districts (Jinja, Kampala, Mbale, and Wakiso) in Uganda as of 20 February 2025. 8 cases have received care at treatment centres and have since been discharged, while 58 contacts remain under follow up in quarantine facilities.

Lassa fever

Geographical risk areas	Endemic in sub-Saharan West Africa.
Sources and routes of infection	• contact with excreta, or materials contaminated with excreta from an infected rodent  • inhalation of aerosols of excreta from an infected rodent  • contact with infected human blood or body fluids
UK experience to date	Three travel-related Lassa fever cases reported in 2022. Prior to this, 8 imported Lassa fever cases had been reported since 1980, all in travellers from West Africa.
Risk rating	Low – overall, Lassa fever is the most common imported viral haemorrhagic fever (VHF) but importations to the UK are still rare.
Recent cases or outbreaks	Between 1 January and 23 February 2025, Nigeria reported 506 confirmed, 5 probable and 1,981 suspected cases of Lassa fever. 95 deaths were reported amongst confirmed cases (case fatality rate (CFR) of 18.8%). This is the same CFR compared to the equivalent period in 2024. Confirmed cases have been reported from 12 out of 36 states. On 10 February 2025, the Sierra Leone Ministry of Health declared a Lassa fever outbreak in Koinadugu District, Northern Province, following the detection of a fatal case. As of 21 February 2025, a total of 39 Lassa fever cases (7 confirmed) and 5 deaths (CFR of 71% amongst confirmed cases), have been reported across 3 out of 16 counties.

Marburg virus disease (MARD)

Geographical risk areas	Sporadic outbreaks have previously been reported in Central and Eastern Africa. Outbreaks were reported for the first time in Guinea (in 2021), Ghana (in 2022), Equatorial Guinea and Tanzania (in 2023) and Rwanda (in 2024).
Sources and routes of infection	• exposure in mines or caves inhabited by Rousettus bat colonies • contact with infected human blood or body fluids
UK experience to date	No reported cases in the UK.
Risk rating	Very low – globally, 5 travel-related exported MARD cases have previously been reported in the literature.
Recent cases or outbreaks	As of 22 February 2025, Tanzania’s Ministry of Health have reported no new confirmed cases of MARD associated with the outbreak declared on 20 January 2025 in the Kagera Region. A total of 10 cases (2 confirmed, 8 probable) have been reported, all of which were fatal (CFR of 100%).

Airborne HCIDs

Avian influenza A(H7N9) virus

Geographical risk areas	All reported human infections have been acquired in China.
Sources and routes of infection	• close contact with infected birds or their environments  • close contact with infected humans (no sustained human-to-human transmission)
UK experience to date	No known cases in the UK.
Risk rating	Very low (UKHSA risk assessment).
Recent cases or outbreaks	No confirmed or suspected human cases were reported in February 2025.

Avian influenza A(H5N1) virus

Geographical risk areas	Human cases have been predominantly reported in Southeast Asia, but also in Egypt, Iraq, Pakistan, Turkey and Nigeria. However, since the panzootic of A(H5N1) emerged in 2021, human spillover cases (clade 2.3.4.4b) have been reported in Spain, the US, and the UK. The first human cases of avian influenza A(H5N1) (clade 2.3.4.4b) from South America were reported in early 2023, from Ecuador and Chile. Since October 2023, 11 human cases of clade 2.3.2.1c have been reported in Cambodia.
Sources and routes of infection	• Close contact with infected animals (notably birds) or their environments • Close contact with infected humans is a theoretical risk although there is currently no evidence of any human-to-human transmission having occurred).
UK experience to date	Since December 2021, 7 detections were reported in the UK, one in 2022, 4 in 2023, one in 2024, and one in 2025.
Risk rating	Very low (UKHSA risk assessment).
Recent cases or outbreaks	On 25 February 2025, Cambodia’s Ministry of Health reported a fatal human case of avian influenza A(H5N1) in a child who had been in close contact with infected backyard poultry. This is the second reported fatal case of avian influenza A(H5N1) in Cambodia for 2025. Since April 2024, and as of 26 February 2025, a total of 70 confirmed human cases of avian influenza A(H5), including one death, have been reported in the US. Of these, 67 cases reported exposure to avian influenza A(H5N1) infected poultry or dairy cattle. The source of exposure remains undetermined for 3 cases. During February 2025, Ohio, Wyoming, and Nevada states reported their first confirmed cases in humans. Both human cases detected in Nevada and Wyoming were sequenced as the D1.1 genotype, which was detected in dairy cattle for the first time in January 2025. For further information see the US Centres for Disease Control and Prevention H5 Bird Flu: Current Situation webpage.

Middle East respiratory syndrome (MERS-CoV)

Geographical risk areas	MERS has been concentrated in countries from the Arabian Peninsula, with the majority of cases having occurred in the Kingdom of Saudi Arabia. Other previously affected countries in the region include Yemen, Oman, United Arab Emirates, Qatar, Bahrain, Kuwait, Jordan, Lebanon and Iran. MERS is transmitted from camels and has been detected in camels from the Arabian Peninsula and also parts of North, West and Eastern Africa.
Sources and routes of infection	• Transmission through the air •Direct contact with contaminated environment • Direct contact with camels or consumption of raw camel milk • Working in or exposure to healthcare settings where outbreaks are occurring airborne particles
UK experience to date	Five cases in total – 3 imported cases (2012, 2013 and 2018), 2 secondary cases in close family members of the case in 2013, 3 deaths.
Risk rating	Very low (UKHSA risk assessment).
Recent cases or outbreaks	No confirmed or suspected human cases were reported in February 2025.

Mpox (Clade I only)

Geographical risk areas	Central and East African countries including Burundi, Cameroon, Central African Republic, Democratic Republic of the Congo, Gabon, Kenya, Republic of the Congo, Rwanda, and Uganda.
Sources and routes of infection	• close contact with an infected animal (in an endemic country) or an infected person • contact with clothing or linens (such as bedding or towels) used by an infected person • direct contact with mpox skin lesions or scabs • coughing or sneezing of an individual with an mpox rash • consumption of contaminated bushmeat
UK experience to date	Ten cases in total – 3 imported cases (2024), 5 imported cases (2025) and 2 secondary cases in household members of a case from 2024.
Risk rating	The importation risk of clade I mpox into the UK is considered medium. The risk of potential spread in the UK and risk of acquisition in the UK is considered low to medium. Travel-associated cases of clade I mpox have been reported from Belgium, Canada, Germany, India, Oman, Pakistan, Sweden, Thailand, United States. Secondary transmission of cases within household contacts has been reported in the UK, Germany and Belgium.
Recent cases or outbreaks	In endemic countries where clade I mpox is know to circulate access to subclade specific PCR or sequencing may be limited. Therefore, we report below all reported mpox cases from these countries, regardless of whether the samples have undergone specific subclade testing. A comprehensive list of mpox clade I affected countries is available from the UKHSA. Since 2024, and up to 23 February 2025, a total of 7 confirmed mpox cases have been reported in Angola. Clade Ib mpox has been reported in Angola. Since Burundi declared an mpox outbreak in July 2024, 10,911 mpox cases (3,568 confirmed) and one death have been reported as of 26 February 2025. Clade Ib mpox has been reported in Burundi. The Central African Republic (CAR) reported 100 confirmed mpox cases and 3 deaths between 1 January 2024 and 9 February 2025. Clade Ia mpox has been reported in the CAR. On 13 February 2025, the World Health Organization (WHO) reported a total of 7 confirmed cases of clade Ib mpox in China since the beginning of 2024. The latest case had recently travelled from the United Arab Emirates. Between 1 January 2024 and 23 February 2025, the DRC reported 78,690 mpox cases (16,255 confirmed), including 1,560 deaths (CFR of 2%). To compare, during 2023 the DRC reported 14,434 mpox cases including 728 deaths. Clades Ia and Ib mpox have been reported in the DRC. Kenya officially reported its first confirmed case of clade Ib mpox on 31 July 2024. As of 26 February 2025, 48 confirmed cases and one death have been reported. On 6 February 2025, the Republic of Ireland reported their first confirmed clade I mpox case in an individual who had travelled to the DRC. The clade subtype was not specified. Both clades Ia and Ib are known to circulate in the DRC. In the Republic of the Congo (RoC), between 1 January 2024 to 23 February 2025, 43 confirmed mpox cases and no deaths have been reported. During 2023, 95 mpox cases, including 5 deaths, were reported. Furthermore, on 27 February 2025, the Africa Centres for Disease Control and Prevention reported the RoC’s first confirmed case of clade Ib mpox in Brazzaville. Prior to this detection, only clade Ia mpox had been reported in the RoC. Rwanda declared an outbreak of clade Ib mpox on 26 July 2024. Since then, a total of 6,503 mpox cases (105 confirmed) and no deaths have been reported up to 23 February 2025. On 21 February 2025, South Africa’s National Institute for Communicable Diseases detected their first case of clade I mpox in South Africa. The case had travelled to Uganda where there has been ongoing community transmission of clade Ib mpox. Contact tracing identified 2 additional cases linked to the initial case. These cases have been sequenced as clade Ib mpox. On 7 February 2025, South Sudan’s Ministry of Health declared an mpox outbreak in Juba, Central Equatoria State, following the confirmation of clade I mpox case (unspecified subtype). As of 27 February 2025, a total of 6 confirmed cases have been reported in South Sudan. Uganda first identified 2 confirmed cases of clade Ib mpox on 15 July 2024. As of 21 February 2025, 3,391 confirmed cases and 23 deaths have been reported across 91 districts. Most cases have been reported amongst individuals aged between 18 to 29 years old. On 7 February 2025, the United Arab Emirates reported its first case of clade Ib mpox in an individual with travel history to Uganda. There has been ongoing community transmission of clade Ib mpox in Uganda. Since 30 October 2024, and as of 28 February 2025, a total of 10 confirmed clade Ib mpox cases have been reported in the UK, all of which have been detected in England. 8 cases have been associated with travel to countries experiencing community transmission of clade Ib mpox and 2 cases were secondary cases within a household. During February 2025, the United States reported 2 new clade Ib mpox cases in New Hampshire (one case) and New York (one case) states. This brings the total number of cases since November 2024 to 4. All cases have been travel associated in individuals returning from areas experiencing clade I mpox transmission. Zambia identified clade Ib mpox for the first time during November 2024. As of 14 February 2025, a total of 21 confirmed cases have been reported, with most reported in Lusaka (14 cases).

Nipah virus

Geographical risk areas	South East Asia, predominantly in Bangladesh and India. Cases have also been reported in Malaysia and Singapore.
Sources and routes of infection	• direct or indirect exposure to infected bats • consumption of contaminated raw date palm sap • close contact with infected pigs or humans
UK experience to date	No known cases in the UK.
Risk rating	Exceptionally low to negligible – no travel-related infections in the literature.
Recent cases or outbreaks	No confirmed or suspected human cases were reported in February 2025.

Pneumonic plague (Yersinia pestis)

Geographical risk areas	Predominantly sub-Saharan Africa but also Asia, North Africa, South America, Western USA. Endemic in Madagascar, Peru, and the DRC.
Sources and routes of infection	• flea bites  • close contact with infected animals  • close contact with human cases of pneumonic plague
UK experience to date	Last outbreak in the UK was in 1918.
Risk rating	Exceptionally low to negligible
Recent cases or outbreaks	No confirmed or suspected human cases were reported in February 2025.

Severe acute respiratory syndrome (SARS)

Geographical risk areas	Currently none. Two historical outbreaks originating from China in 2002 and 2004.
Sources and routes of infection	• airborne particles  • direct contact with contaminated environment
UK experience to date	Four imported SARS cases related to the 2002 outbreak.
Risk rating	Exceptionally low to negligible
Recent cases or outbreaks	No confirmed or suspected human cases reported globally since 2004.

Incidents of significance of additional HCIDs

Argentine haemorrhagic fever (Junin virus)

Geographical risk areas	Argentina (central). Endemic to the provinces of Buenos Aires, Córdoba, Santa Fe and La Pampa.
Sources and routes of infection	• direct contact with infected rodents  • inhalation of infectious rodent fluids and excreta  • person-to-person transmission has been documented
UK experience to date	No known cases in the UK.
Risk rating	Exceptionally low to negligible – one travel-related case was identified in Belgium in 2020.
Recent cases or outbreaks	On 26 February 2025, media reported one suspected and 2 confirmed cases of Argentine haemorrhagic fever in Buenos Aires, Argentina.

Bolivian haemorrhagic fever (Machupo virus)

Geographical risk areas	Bolivia – cases have been identified in the departments of Beni (Mamoré, Iténez and Yucuma provinces) and Cochabamba (Cercado province).
Sources and routes of infection	• direct contact with infected rodents  • inhalation of infectious rodent fluids and excreta  • person-to-person transmission has been documented
UK experience to date	No known cases in the UK.
Risk rating	Exceptionally low to negligible – travel-related cases have never been reported.
Recent cases or outbreaks	No confirmed or suspected human cases were reported in February 2025.

Lujo virus disease

Geographical risk areas	A single case acquired in Zambia led to a cluster in South Africa in 2008.
Sources and routes of infection	• presumed rodent contact (excreta, or materials contaminated with excreta of infected rodent)  • person to person via body fluids
UK experience to date	No known cases in the UK.
Risk rating	Exceptionally low to negligible – a single travel-related case has been reported. No cases have been reported anywhere since 2008.
Recent cases or outbreaks	No cases have been reported anywhere since 2008.

Severe fever with thrombocytopenia syndrome (SFTS)

Geographical risk areas	Mainly reported from China (south-eastern), Japan and Korea. Cases have also been reported in Taiwan, Thailand, Myanmar and Vietnam. Serological evidence of SFTS in Pakistan.
Sources and routes of infection	• presumed to be tick exposure  • person-to-person transmission described in household and hospital contacts, via contact with blood or bloodstained body fluids
UK experience to date	No known cases in the UK.
Risk rating	Exceptionally low to negligible – not known to have occurred in travellers.
Recent cases or outbreaks	No confirmed or suspected human cases were reported in February 2025.

Andes virus (Hantavirus)

Geographical risk areas	Chile and Southern Argentina.
Sources and routes of infection	• rodent contact (excreta, or materials contaminated with excreta from an infected rodent) • person-to-person transmission described in household and hospital contacts
UK experience to date	No known cases in the UK.
Risk rating	Very low – rare cases in travellers have been reported.
Recent cases or outbreaks	In 2025, up to 15 February 2025, Argentina’s Ministry of Health reported 8 confirmed hantavirus cases nationally. According to media, 2 fatal cases have also been reported in Buenos Aires and Santa Fe provinces. During 2024, a total of 64 confirmed hantavirus cases were reported nationally.   On 3 February 2025, the Nuble Region Health Authority, Chile, reported its first confirmed hantavirus case of 2025 in a forestry worker.

Avian influenza A(H5N6) virus

Geographical risk areas	Mostly China. New strain reported in Greece in March 2017, and subsequently found in Western Europe in birds.
Sources and routes of infection	Close contact with infected birds or their environments.
UK experience to date	No known cases in the UK.
Risk rating	Very low – not known to have occurred in travellers (UKHSA risk assessment).
Recent cases or outbreaks	No confirmed or suspected human cases were reported in February 2025.

Avian influenza A(H7N7) virus

Geographical risk areas	Sporadic occurrence in birds across mainland Europe and the UK. A human case was reported in Ireland in 1996, 89 cases were reported in the Netherlands in 2003, and 3 human cases were reported in Italy in 2013.
Sources and routes of infection	• close contact with infected birds or their environments  • close contact with infected humans (no sustained human-to-human transmission reported)
UK experience to date	No known cases in the UK.
Risk rating	Very low – human cases are rare, and severe disease even rarer.
Recent cases or outbreaks	No confirmed or suspected human cases were reported in February 2025.

Authors of this report

Emerging Infections and Zoonoses Team, UKHSA