Research and analysis

Global high consequence infectious disease events: summary September 2024

Updated 16 January 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	Between 1 January and 14 September 2024, the World Health Organization (WHO) reported 999 CCHF cases (237 confirmed), including 84 deaths (case fatality rate (CFR) of 8.4%), from Afghanistan. Confirmed cases were reported from 8 provinces. The most affected provinces include Kabul (160 cases), Balkh (23 cases) and Kunduz (20 cases). In 2023, Afghanistan reported 1,243 CCHF cases (383 confirmed), including 114 deaths (CFR of 9.2%). According to media on 23 September 2024, 178 CCHF cases and 26 deaths have been reported in the Dhi Qar Province, Iraq, during 2024. A further 3 cases were reported in Duhok governorate during September 2024. On 14 September 2024, media reported that during 2024, the total number of CCHF cases and deaths recorded in Balochistan, Pakistan, had reached 30 cases and 8 deaths.

Ebola virus disease (EVD)

Geographical risk areas	Map of countries which have reported EVD cases up to January 2023. No outbreaks of EVD have since been reported.
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	No confirmed or suspected human cases were reported in September 2024.

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	In September 2024, 2 confirmed cases of Lassa fever were reported from Bong County, Liberia. Between 1 January and 17 September 2024, 61 Lassa fever cases (30 confirmed; 31 suspected), including 8 deaths, have been reported nationally. This outbreak began in January 2022. Between 1 January and 28 September 2024 (week 39), Nigeria reported 9,429 Lassa fever cases (1,018 confirmed; 8,411 suspected). 172 deaths were reported amongst confirmed cases (CFR of 16.9 %). This is an equivalent CFR compared to the same period in 2023 (16.8%). Confirmed cases have been reported from 28 out of 36 states.

Marburg virus disease (MVD)

Geographical risk areas	Sporadic outbreaks have previously been reported in Central and Eastern Africa. A human case of MVD was reported in August 2021 in Guinea; this was the first case to be identified in West Africa. MVD cases were reported in Ghana for the first time in July 2022. MVD outbreaks were reported for the first time in Equatorial Guinea in February 2023 in Tanzania in March 2023 and in Rwanda in September 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 MVD cases have previously been reported in the literature.
Recent cases or outbreaks	On 27 September 2024, Rwanda’s Ministry of Health reported an outbreak of MVD for the first time. As of 30 September 2024, 27 confirmed MVD cases and 9 deaths (CFR of 33.3%) were reported. Most cases have been amongst healthcare workers associated with healthcare facilities in the capital, Kigali. 300 contacts are being contact traced by health officials. The WHO assesses the risk of further cases occurring in this outbreak as very high at the national level, high at the regional level, and low at the global level. Investigations are ongoing to determine the full extent of the outbreak and the risk assessment will be updated as more information becomes available.

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 September 2024.

Avian influenza A(H5N1) virus

Geographical risk areas	Human cases have been predominantly reported in South East Asia, but also in Egypt, Iraq, Pakistan, Turkey and Nigeria. Human cases (clade 2.3.4.4b) were reported in Spain and the USA in 2022 and 2024, and in the UK in 2022 and 2023. The first human cases of avian influenza A(H5N1) (clade 2.3.4.4b) were reported from South America in 2023, from Ecuador and Chile. Since October 2023, several 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 (no sustained human-to-human transmission)
UK experience to date	As of September 2023, 5 detections were reported in the UK, one in 2022 and 4 in 2023.
Risk rating	Very low (UKHSA risk assessment).
Recent cases or outbreaks	During September 2024, a confirmed human case of avian influenza A(H5N1) was reported in Missouri, United States (US).   On 27 September 2024, the US Centres for Disease Control and Prevention (CDC) reported that on 27 September 2024, the US Centres for Disease Control and Prevention (CDC) reported that no contacts of the case, including 6 healthcare workers who developed mild symptoms following exposure, have tested positive for avian influenza A(H5N1). This is the 14th human case of avian influenza A(H5N1) reported in the United States during 2024 and the first case with no known exposure to sick or infected animals. Of the 14 human cases of avian influenza A(H5) infections reported: 4 cases were associated with exposure to infected cattle, 9 cases were associate with exposure to infected poultry and 1 case with no known exposure. 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	Arabian Peninsula – Bahrain, Jordan, Iraq, Kingdom of Saudi Arabia, Kuwait, Oman, Qatar, United Arab Emirates, Yemen. Evidence has also been reported in Iran and Kenya.
Sources and routes of infection	• airborne particles • direct contact with contaminated environment  • direct contact with camels or consumption of raw camel milk
UK experience to date	Five MERS-CoV 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	On 29 September 2024, the WHO reported one confirmed case of MERS-CoV in the Kingdom of Saudi Arabia (KSA). The male case had a symptom onset date on 28 August 2024, was hospitalised on 31 August 2024 and discharged himself from the KSA medical system on 1 September 2024. He subsequently travelled to Pakistan on 2 September 2024, prior to laboratory test results confirming MERS-CoV infection on 4 September 2024. Authorities in Pakistan located and isolated the patient who was finally discharged following a negative test result for MERS-CoV on 13 September 2024. There were no secondary cases linked to this case. Since the beginning of 2024, 5 cases of MERS-CoV and 4 associated deaths have been reported in KSA. The WHO’s overall risk assessment remains as moderate at both the global and regional levels.

Mpox (clade I only)

Geographical risk areas	Central African countries including Burundi, Cameroon, Central African Republic, Democratic Republic of the Congo, Gabon, Republic of the Congo, 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	No cases of Clade I mpox have been reported in the UK.
Risk rating	Low to Medium – no known importations of clade I mpox into the UK. Travel-associated cases of clade I mpox have been reported from India, Sweden and Thailand (one case each) with no onwards transmission.
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. Between 1 January and 27 September 2024, the Democratic Republic of the Congo (DRC) reported 27,487 mpox cases (5,812 confirmed), including 859 deaths (CFR of 3.1%), from all 26 provinces. During 2023, the DRC reported its highest annual number of mpox cases (14,434 cases, including 728 deaths). Since Burundi declared an mpox outbreak on 25 July 2024, 2,087 mpox cases (696 confirmed) and no deaths have been reported from 36 out of 49 health districts as of 27 September 2024. Rwanda declared an outbreak of clade Ib mpox on 26 July 2024. During September 2024, 2 new confirmed cases were reported by Rwandan health authorities, bringing the cumulative total to 6 confirmed cases and 0 deaths. Amongst the confirmed cases, 5 had a history of international travel before symptom onset and 1 was a contact of a confirmed case. Uganda first identified 2 confirmed cases of clade Ib mpox on 15 July 2024. As of 25 September 2024, 84 cases (25 confirmed) and no deaths have been reported. Kenya officially reported its first confirmed case of clade Ib mpox on 31 July 2024. Up to 29 September 2024, 13 cases (8 confirmed) have been reported. In the Republic of the Congo, as of 27 September 2024, 204 mpox cases (21 confirmed) and no deaths were reported from 5 out of 12 provinces. During 2023, 95 mpox cases, including 5 deaths, were reported. Between 1 January and 27 September 2024; Gabon reported 17 cases of mpox (2 confirmed), however, the clade type was not specified. The Central African Republic reported 324 cases of mpox (57 confirmed) and 1 death. Clade Ia mpox was detected in confirmed cases. On 13 September 2024, India recorded a case of clade Ib mpox in a traveller that had returned from the United Arab Emirates. This is the third case of clade Ib mpox reported outside the African Region.

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	During September 2024, a fatal case of Nipah virus disease (NVD) was reported in Malappuram District, Kerala, India. This is the second fatal case (unconnected to the first case for 2024 reported in July 2024) of NVD in Kerala reported during 2024. 267 contacts were identified, tested and isolated for follow-up. No secondary transmission was reported from this case.

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 September 2024.

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	In 2024, up to 8 September 2024, the Buenos Aires Province Ministry of Health, Argentina, reported 20 confirmed cases of Argentine haemorrhagic fever.

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 September 2024.

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	Between January and September 2024, the Korea Disease Control and Prevention Agency reported 97 SFTS cases. This is a lower number of cases reported compared to the equivalent 2023 period (125 cases). Between January and September 2024, Japan’s National Institute of Infectious Diseases reported 97 SFTS cases. During September 2024, 6 SFTS cases were reported.

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	On 25 September 2024, media reported 1 case of hantavirus in Concepcion, Biobío Region, Chile. The article did not specify the type of hantavirus. During 2024, 4 cases of hantavirus have been reported in the Biobío region, which is similar to the equivalent period in 2023.

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 September 2024.

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 September 2024.

Authors of this report

Emerging Infections and Zoonoses Team, UKHSA