Research and analysis

Global high consequence infectious disease events: summary March 2025

Updated 15 May 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	During March 2025, the first cases of CCHF were reported from Iraq. One case was reported in the Dhi Qar governorate on 2 March 2025, and one case was reported in Nineveh province on 28 March 2025. Uganda has reported 6 cases of CCHF (2 confirmed, 1 probable, and 3 suspected) since the beginning of 2025. Cases have been reported from the Kyegegwa and Mubende districts.

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 (SVD) outbreak on 30 January 2025 in Uganda, 14 cases (12 confirmed and 2 probable) including 4 deaths have been reported. This equates to a case fatality rate (CFR) of 28.6%. Cases have been reported from 7 districts: Jinja, Kabarole, Kampala, Kyegegwa, Mbale, Ntoroko and Wakiso. The last confirmed case was reported on 6 March 2025, and was discharged from hospital on 15 March 2025. The Ugandan Ministry of Health initiated a 42-day countdown to declaring the end of the outbreak on 19 March 2025. A total of 340 contacts have been traced in this outbreak. As of 27 March 2025, no active contacts are in follow-up.

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 30 March 2025, Nigeria reported 659 confirmed, 7 probable and 3,779 suspected cases of Lassa fever. 122 deaths were reported amongst confirmed cases (CFR of 18.5%). This is a lower CFR compared to the equivalent period in 2024 (18.7%). Confirmed cases have been reported from 18 out of 36 states. On 7 March 2025, the UKHSA reported that it was following-up a number of contacts after a symptomatic Lassa fever case travelled to England from Nigeria. The case was diagnosed with Lassa fever upon their return to Nigeria, where they died. No secondary cases were identified in the UK.

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	On 13 March 2025, Tanzania’s Ministry of Health declared the end of its MARD outbreak, following 42 days since the last confirmed case died on 28 January 2025. The outbreak was first declared on 20 January 2025, in Biharamulo District, Kagera region. A total of 10 cases (2 confirmed, 8 probable) were reported, all of which were fatal.

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 March 2025.

Avian influenza A(H5N1) virus

Category	Details
Geographical risk areas	Human cases have been predominantly reported in Southeast Asia, but also in Egypt, Iraq, Pakistan, Turkey and Nigeria. Since the panzootic of avian influenza A(H5N1) emerged in 2021, human spillover cases (clade 2.3.4.4b) have been reported in Canada, Chile, Ecuador, Spain, the US, and the UK. Since October 2023, clade 2.3.2.1c viruses have been responsible for sporadic cases of human infections 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 23 March 2025, Cambodia’s Ministry of Health reported a fatal human case of avian influenza A(H5N1) in a child whose family had a link to poultry farming and had reported recent chicken deaths with signs of illness. This is the third reported fatal case of avian influenza A(H5N1) in Cambodia in 2025. During March 2025, media reported a fatal human case of avian influenza A(H5N1) in a child in Palnadu district, Andhra Pradesh, India. The child had consumed a piece of raw chicken and died on 16 March 2025. Swab samples were tested at the All India Institute of Medical Sciences and at the National Institute of Virology (Pune), which confirmed the diagnosis. No other cases were identified.

Middle East respiratory syndrome (MERS-CoV)

Geographical risk areas	MERS-CoV 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-CoV 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	During March 2025, a human case of MERS-CoV was reported in Saudi Arabia. No further details were provided. Between 6 September 2024 and 28 February 2025, 4 confirmed MERS-CoV cases, including 2 deaths, were reported in Saudi Arabia.

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	On 28 March 2025, Bangladesh’s Institute of Epidemiology, Disease Control and Research reported that as of 10 March 2025, 3 fatal cases of Nipah virus infection were recorded since the beginning of 2025. The cases were from Pabna, Bhola and Chuadanga districts.

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 March 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	Between 1 January and 30 March 2025, 51 cases (6 confirmed) of Argentine haemorrhagic fever, including one confirmed death, were reported in Buenos Aires, Argentina. The Ministry of Health reports that the number of confirmed cases so far have been higher than the equivalent period in 2024.

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 March 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	During March 2025, Japan reported 2 cases of SFTS. These are Japan’s first cases in 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 30 March 2025, Buenos Aires regional Ministry of Health reported 9 confirmed cases of hantavirus. Nationally, up to 29 March 2025, Argentina’s Ministry of Health reported 20 confirmed cases of hantavirus. 4 deaths due to hantavirus were reported in Barioloche, Chaco and Rio Negro provinces. The death reported in Barioloche was investigated further, with genomic sequencing confirming Andes virus infection. During March 2025, media reported the first cases of hantavirus in Los Rios, Chile. A total of 4 cases, including one death, have been reported across Los Rios, Nuble, and Santo Domingo regions, so far in 2025.

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 March 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 March 2025.

Authors of this report

Emerging Infections and Zoonoses Team, UKHSA