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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.ÌýPast 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 primaryÌýHCIDs

°ä´Ç²Ô³Ù²¹³¦³ÙÌýHCIDs

Crimean-Congo haemorrhagic fever (CCHF)

ÌýGeographical 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 (, with the ). Portugal reported its first human case in with symptom onset in July 2024.
ÌýSources and routes of infection	• bite from, or crushing of, an infected tickÌý • contact with the blood, tissues or body fluids of infected humans or animals
ÌýUKÌýexperience to dateÌýÌý	Two cases have been reported in individuals who have travelled to the UK from and .
ÌýRisk rating Ìý	Low – rarely reported in travellers.
ÌýRecent cases or outbreaksÌý	During December 2024, 21 new cases of CCHF and one associated death was reported in Afghanistan. Between 1 January and 28 December 2024, Afghanistan reported equating to a case fatality rate (CFR) of 7.8%.

Ebola disease (EBOD)

ÌýGeographical risk areasÌý	ÌýMap of Ebola disease in Africa
ÌýSources and routes of infectionÌýÌý	• 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 fluidsÌý
ÌýUKÌýexperience to dateÌý	Four confirmed cases (one lab-acquired in the UK in 1976, 3 healthcare workers associated with West African epidemic 2014 to 2015).Ìý
ÌýRisk ratingÌýÌý	Very low – other than during the West Africa outbreak, exported cases are extremely rare.Ìý
ÌýRecent cases or outbreaksÌý	No confirmed or suspected human cases were reported in December 2024.

Lassa fever

ÌýGeographical risk areasÌý	Endemic in sub-Saharan West Africa.
ÌýSources and routes of infectionÌý	• contact with excreta, or materials contaminated with excreta from an infected rodentÌý • inhalation of aerosols of excreta from an infected rodentÌý • contact with infected human blood or body fluids
ÌýUKÌýexperience to dateÌý	. Prior to this, 8 imported Lassa fever cases had been reported since 1980, all in travellers from West Africa.
ÌýRisk ratingÌý	Low – overall, Lassa fever is the most common imported viral haemorrhagic fever (VHF) but importations to the UK are still rare.Ìý
ÌýRecent cases or outbreaks	Between 1 January and 29 December 2024, Nigeria reported (1,309 confirmed; 10,098 suspected; 23 probable). 214 deaths were reported amongst confirmed cases (case fatality rate (CFR) of 16.3%). This is a lower CFR compared to the same period in 2023 (17.9%). Confirmed cases have been reported from 28 out of 36 states. 955 cases (192 confirmed cases) were reported during December 2024.

Marburg virus disease (MARD)

ÌýGeographical risk areas	Sporadic outbreaks have previously been reported in Central and Eastern Africa. Outbreaks were reported for the first time in (in 2021), (in 2022), and (in 2023) and (in 2024). Ìý
ÌýSources and routes of infection	• exposure in mines or caves inhabited by Rousettus bat colonies • contact with infected human blood or body fluids
ÌýUKÌýexperience to date	ÌýNo reported cases in the UK.
ÌýRisk rating	Very low – globally, 5 travel-related exported MARD cases have previously been reported in the literature.
ÌýRecent cases or outbreaks	On , the Ministry of Health of Rwanda declared an end to the MARD outbreak which started on . The WHO summary for this outbreak can be found .

AirborneÌýHCIDs

Avian influenza A(H7N9) virus

ÌýGeographical risk areas	All reported human infections have been .	Ìý
ÌýSources and routes of infection	• close contact with infected birds or their environmentsÌý • close contact with infected humans (no sustained human-to-human transmission)	Ìý
ÌýUKÌýexperience to date	No known cases in the UK.	Ìý
ÌýRisk rating	ÌýVery low (UKHSAÌýrisk assessment).	Ìý
ÌýRecent cases or outbreaks	No confirmed or suspected human cases were reported in December 2024.	Ìý

Avian influenza A(H5N1) virus

ÌýGeographical risk areas	Human cases have been predominantly reported in Southeast Asia, but also in Egypt, Iraq, Pakistan, Turkey and Nigeria. Since 2022, human cases of clade 2.3.4.4b have been reported in , the , and the UK, and . Since October 2023, 11 human cases of clade 2.3.2.1c have been reported in .
ÌýSources 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).
ÌýUKÌýexperience to date	Since December 2021, 7 detections were reported in the UK, , 4 in 2023 and one in 2024.
ÌýRisk rating	ÌýVery low (UKHSAÌýrisk assessment).
ÌýRecent cases or outbreaks	Between 1 January and 31 December 2024, a total of have been reported in the US. 7 probable cases were also reported during 2024. Probable cases were cases that were unable to be confirmed at US CDC laboratories. During December 2024, were reported in the US in the states of California (8 cases), (one), (one). During 2024, 10 US states reported cases: California, Colorado, Iowa, Louisiana, Michigan, Missouri, Oregon, Texas, Washington and Wisconsin. The probable cases were reported from Arizona, California, Delaware and Washington. Of the , 40 cases were associated with the dairy cattle industry, 23 cases with the poultry industry or poultry culling operations, 1 case with non-agricultural animal exposure and 2 cases with unidentified exposure source/s. Notably, on 18 December 2024, the US CDC confirmed the infection in a human. The individual had backyard exposure to sick and dead birds. A for this case was published which showed some changes to virus receptor binding motifs. This virus belonged to clade 2.3.4.4b, genotype D1.1 which is different to genotype B3.13 currently associated with dairy cattle infections. For further information see the webpage.

Middle East respiratory syndrome (MERS-CoV)

ÌýGeographical 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 . MERS is transmitted from camels and has been detected in camels from the Arabian Peninsula and also parts of North, West and Eastern Africa.
ÌýSources 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 particlesÌý
ÌýUKÌýexperience to date	– 3 imported cases (2012, 2013 and 2018), 2 secondary cases in close family members of the case in 2013, 3 deaths.
ÌýRisk rating	ÌýVery low (UKHSAÌýrisk assessment).Ìý
ÌýRecent cases or outbreaks	No confirmed or suspected human cases were reported in December 2024.

Mpox (Clade I only)

ÌýGeographical risk areas	Central and East African countries including Ìý
ÌýSources 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
ÌýUKÌýexperience to date	Five cases in total – 3 imported cases (2024) and 2 secondary cases in household members of a case from 2024.
ÌýRisk rating	ÌýThe importation risk of clade I mpox into the UK is considered . 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 , , , , , , , , . Secondary transmission of cases within household contacts has been reported in the UK, and .
ÌýRecent 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. Burundi declared an mpox outbreak on . As of 22 December 2024, and have been reported from 45 out of 49 health districts. The Central African Republic reported and 3 deaths (CFR of 3.1%) between 1 January and 8 December 2024. Clade Ia mpox was detected in confirmed cases. Between 1 January and 15 December 2024, the Democratic Republic of the Congo (DRC) reported , including 1,308 deaths (CFR of 2.2%), from all 26 provinces. Of which,Ìý 7,475 cases (1,653 confirmed) and 80 cases were reported during December 2024. During 2023, the DRC reported its (14,434 cases, including 728 deaths). Kenya officially reported its first confirmed case of clade Ib mpox on . During December 2024, it reported 8 new cases of mpox, and as of 30 December 2024 recorded aÌý cumulative total of (CFR of 3.2%) across 12 counties. The mpox death was reported in an individual with . Uganda first identified 2 confirmed cases of clade Ib mpox on . During December 2024, it reported 525 new cases (519 confirmed), and as of 29 December 2024 recorded a cumulative total of (CFR of 0.5 %) across 60 districts. Rwanda declared an outbreak of clade Ib mpox on . During December 2024, it reported 1,260 new cases (30 confirmed), and as of 29 December 2024 recorded a cumulative total of . Zambia reported its first clade Ib mpox case during . During December 2024, were reported within the same household, with the clade type not reported, bringing the total case count to 3 cases. During December 2024, 4 countries outside of the African Region reported travel-associated cases of clade I mpox. Of these, 3 countries reported their first-ever detections (, and ) and one country reported its second travel-associated case (). The cases reported from Pakistan and Oman had a travel history to the United Arab Emirates (UAE). The UAE has not reported any cases of clade Ib mpox during 2024. Ìý

Nipah virus

ÌýGeographical risk areas	South East Asia, predominantly in . Cases have also been reported in Malaysia and Singapore.
ÌýSources 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
ÌýUKÌýexperience to date	ÌýNo known cases in the UK.
ÌýRisk rating	Exceptionally low to negligible – no travel-related infections in the literature.Ìý
ÌýRecent cases or outbreaks	No confirmed or suspected human cases were reported in December 2024.

Pneumonic plague (Yersinia pestis)

ÌýGeographical risk areas	Predominantly . Endemic in Madagascar, Peru, andÌýthe DRC.
ÌýSources and routes of infection	• flea bitesÌý • close contact with infected animalsÌý • close contact with human cases of pneumonic plague
ÌýUKÌýexperience to date	Last outbreak in the UK was in 1918.
ÌýRisk rating	Exceptionally low to negligible
ÌýRecent cases or outbreaks	No confirmed or suspected human cases were reported in December 2024.

Severe acute respiratory syndrome (SARS)

ÌýGeographical risk areas	Currently none. Two historical outbreaks originating from China in 2002 and 2004.
ÌýSources and routes of infection	• airborne particlesÌý • direct contact with contaminated environment
ÌýUKÌýexperience to date	related to the 2002 outbreak.Ìý
ÌýRisk rating	Exceptionally low to negligible
ÌýRecent cases or outbreaks	No confirmed or suspected human cases reported globally since 2004.

Incidents of significance of additionalÌýHCIDs

Argentine haemorrhagic fever (Junin virus)

ÌýGeographical risk areas	(central). Endemic to the provinces of Buenos Aires, Córdoba, Santa Fe and La Pampa.
ÌýSources and routes of infection	• direct contact with infected rodentsÌý • inhalation of infectious rodent fluids and excretaÌý • person-to-person transmission has been documented
ÌýUKÌýexperience to date	ÌýNo known cases in the UK.
ÌýRisk rating	Exceptionally low to negligible – was identified in Belgium in 2020.
ÌýRecent cases or outbreaks	Between 1 January 2024 and 29 December 2024, (AHF) were reported in Argentina. During 2024, the most affected district was San Nicolas which had 19 confirmed AHF cases. The number of confirmed cases is higher compared to 2023 (7 confirmed cases) and similar to 2022 (27 confirmed cases).

Bolivian haemorrhagic fever (Machupo virus)

ÌýGeographical risk areas	Bolivia – (Mamoré, Iténez and Yucuma provinces) and Cochabamba (Cercado province).
ÌýSources and routes of infection	• direct contact with infected rodentsÌý • inhalation of infectious rodent fluids and excretaÌý • person-to-person transmission has been documented
ÌýUKÌýexperience to date	ÌýNo known cases in the UK.
ÌýRisk rating	Exceptionally low to negligible – travel-related cases have never been reported.
ÌýRecent cases or outbreaks	No confirmed or suspected human cases were reported in December 2024.

Lujo virus disease

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

Severe fever with thrombocytopenia syndrome (SFTS)

ÌýGeographical risk areas	Mainly reported from China (south-eastern), Japan and Korea. Cases have also been reported in , , and . Serological evidence of SFTS in .Ìý
ÌýSources and routes of infection	• presumed to be tick exposureÌý • person-to-person transmission described in household and hospital contacts, via contact with blood or bloodstained body fluids
ÌýUKÌýexperience to date	No known cases in the UK.
ÌýRisk rating	Exceptionally low to negligible – not known to have occurred in travellers.
ÌýRecent cases or outbreaks	Between January and 26 December 2024, the Korea Disease Control and Prevention Agency reported . 1 case during December 2024. This is a lower number of reported cases compared to the 5 year average (2019 – 2023) (205 cases). Between January and 29 December 2024, Japan’s National Institute of Infectious Diseases reported . During December 2024, 3 SFTS cases were reported.

Andes virus (Hantavirus)

ÌýGeographical risk areas	ÌýChile and Southern Argentina.Ìý
ÌýSources 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
ÌýUKÌýexperience to date	ÌýNo known cases in the UK.
ÌýRisk rating	ÌýVery low – rare cases in travellers have been reported.Ìý
ÌýRecent cases or outbreaks	On 13 December 2024, the Department of Health in Ñuble region of Chile, reported a with cardiopulmonary syndrome. The exact type was not reported. This brings the total case count in 2024 to 5 cases. During 2023, 7 cases of hantavirus infection and 1 death were reported Ñuble region, Chile. During December 2024, the Buenos Aires Provincial Department of Health reported (the type was not reported). The cumulative total at the end of December 2024 is .

Avian influenza A(H5N6) virus

ÌýGeographical risk areas	Mostly China. New strain reported in , and subsequently found in Western Europe in birds.Ìý
ÌýSources and routes of infection	Close contact with infected birds or their environments.Ìý
ÌýUKÌýexperience to date	ÌýNo known cases in the UK.Ìý
ÌýRisk rating	Very low – not known to have occurred in travellers (UKHSAÌýrisk assessment).
ÌýRecent cases or outbreaks	No confirmed or suspected human cases were reported in December 2024.

Avian influenza A(H7N7) virus

ÌýGeographical risk areas	Sporadic occurrence in birds across mainland Europe and the UK. in 1996, in 2003, and in 2013.
ÌýSources and routes of infection	• close contact with infected birds or their environmentsÌý • close contact with infected humans (no sustained human-to-human transmission reported)Ìý
ÌýUKÌýexperience to date	ÌýNo known cases in the UK.
ÌýRisk rating	ÌýVery low – human cases are rare, and severe disease even rarer.
ÌýRecent cases or outbreaks	No confirmed or suspected human cases were reported in December 2024.

Authors of this report

Emerging Infections and Zoonoses Team, UKHSA