Research and analysis

Global high consequence infectious disease events: summary January to June 2023

Updated 25 April 2024

Interpreting this report

The report provides updates on known, high consequence infectious disease (HCID) events around the world as monitored by the 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.

Risk rating

Included for each disease is a current risk rating based on the probability of introduction to the UK and potential impact. 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/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 Asia. In Europe, cases have been reported in Russia and Georgia. Spain has previously reported locally acquired cases (first reported in 2016, with the latest case reported in 2022).
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
Likelihood assessment	Low – rarely reported in travellers.
Recent cases or outbreaks	Between January and 17 June 2023, a total of 359 suspected CCHF cases, including 11 deaths were reported from 27 provinces in Afghanistan. Afghanistan reported 103 confirmed CCHF cases, including 15 deaths during 2022. On 26 May 2023, media reported 8 cases of CCHF from Georgia. Cases were detected in the regions of Samtskhe-Javakheti and Shida Kartli. In 2022, 47 confirmed cases were recorded in Georgia, including 3 deaths. On 7 June 2023, media reported that 19 cases of CCHF, including one death, had been identified in Iran since the beginning of the year. On 24 June 2023, media reported that more than 250 cases of CCHF, including over 35 deaths had been recorded throughout all governorates of Iraq since January 2023. The highest number of cases were recorded in Dhi Qar Governorate (67 cases, including 10 deaths). On 28 May 2023, the World Health Organization (WHO) reported a single fatal case of CCHF in Namibia. Namibia has recorded 6 CCHF outbreaks since 2016, with a total of 3 deaths. On 9 June 2023, Pakistan’s National Institute of Health reported that 27 confirmed cases of CCHF, including 5 deaths have been reported in Balochistan Province in 2023. In Russia, media reports that 9 suspected and one confirmed case of CCHF have been reported in the Rostov region and that 8 confirmed cases have been reported from the North Caucasus region in 2023 (6 from Stavropol Territory and 2 from Kalmykia). On 21 May WHO reported 2 cases of CCHF in Senegal to date in 2023 (Dakar and Louga regions). One death was reported.

Ebola virus disease (EVD)

Geographical risk areas	Map of countries which have reported EVD cases.
Sources and routes of infection	• contact with blood, tissues or body fluids of infected animals, or consumption of infected animal tissue (such as bushmeat) • contact with infected human blood or body fluids
UK experience to date	Four confirmed cases (1 lab-acquired in the UK in 1976, 3 healthcare workers associated with West African epidemic 2014 to 2015).
Likelihood assessment	Very low – other than during the West Africa outbreak, exported cases are extremely rare.
Recent cases or outbreaks	On 20 September 2022, an outbreak of EVD caused by Sudan ebolavirus was declared in Uganda. The last case was confirmed on 27 November. A total of 142 confirmed (55 deaths) and 22 probable cases (22 deaths) were reported. The outbreak was declared over on 11 January 2023.

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 cases reported in 2022. Prior to this, 13 imported cases had been reported since 1971, all in travellers from West Africa.
Likelihood assessment	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 Ghana, an outbreak of Lassa fever was declared in the Greater Accra Region on 24 February 2023. The last case was confirmed on 1 March 2023. A total of 27 confirmed cases, including one death were reported. Ghana declared the outbreak over on 2 May 2023. In March 2023, one confirmed fatal case of Lassa fever was reported from Nzérékoré Health District in Guinea. Between 6 January 2022 and 11 June 2023, Liberia has reported a total of 79 confirmed Lassa fever cases, including 23 deaths (case fatality rate of 29%). Between January and 11 June 2023, Nigeria has reported 958 confirmed, 8 probable and 5,903 suspected Lassa fever cases. Among confirmed cases, 164 deaths were reported (case fatality rate of 17%). This is an increase in confirmed cases in comparison to the equivalent 2022 period (802 cases). Media reported in February 2023 that 2 fatal cases of Lassa fever had been reported from Bo District in the Southern Province of Sierra Leone.

Marburg virus disease

Geographical risk areas	Sporadic outbreaks have previously been reported in Central and Eastern Africa. A human case was reported in August 2021 in Guinea; this was the first case to be identified in West Africa. Cases were reported in Ghana for the first time in July 2022. Outbreaks were reported for the first time in Equatorial Guinea in February 2023 and in Tanzania in March 2023.
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.
Likelihood assessment	Very low – globally, 5 travel-related exported cases have previously been reported in the literature.
Recent cases or outbreaks	The first ever outbreak of MVD was declared by health authorities in Equatorial Guinea on 13 February 2023. A total of 4 provinces (Centro Sur, Kié-Ntem, Litoral and Wele-Nzas) were affected. The outbreak, which had a total of 17 confirmed (including 12 deaths) and 23 probable cases (all fatal), was declared over on 8 June 2023. On 21 March 2023, health authorities in Tanzania declared the countries first ever outbreak of MVD. The outbreak affected the north-western region of Kagera. It had a total of 9 cases (8 confirmed and one probable), including 6 deaths, and was declared over on 2 June 2023. There is no evidence suggesting that the concurrent outbreaks in Equatorial Guinea and Tanzania were linked.

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.
Likelihood assessment	Very low (UKHSA risk assessment).
Recent cases or outbreaks	No reports of confirmed or suspected human cases were identified between January and June 2023.

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 US in 2022, 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.
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	As of June 2023, 3 asymptomatic detections were reported in the UK, one in 2022 and 2 in 2023.
Likelihood assessment	Very low (UKHSA risk assessment).
Recent cases or outbreaks	On 23 February 2023, WHO was informed of a fatal paediatric case of avian influenza A(H5N1) clade 2.3.2.1c in Cambodia. A second asymptomatic case, the father of the first case, was reported on 24 February 2023. Both cases had exposure to sick and dead backyard poultry. WHO states that there is no evidence of human-to-human transmission associated with this event given the information available. These are the first human cases of A(H5N1) reported in Cambodia since 2014. On 8 March 2023, a human case of avian influenza A(H5N1) was reported from Jiangsu Province, China. The case reported having exposure to live domestic poultry before symptom onset. Since 2005, 55 human cases of avian influenza A(H5N1) have been reported from mainland China. On 9 January 2023, one human case of avian influenza A(H5) was reported from Ecuador, in which the case developed symptoms in late December 2022. Subtype A(H5N1) was subsequently confirmed. This was the first human case of avian influenza A(H5N1) to be reported from South America. A second human case of avian influenza A(H5N1) was reported in South America, from Chile, on 29 March 2023. On 16 May 2023, UKHSA reported the detection of influenza A(H5N1) in 2 poultry workers in England, during an asymptomatic testing programme for people in contact with infected birds. One human detection may represent contamination of the respiratory tract, while the second is more uncertain and could be consistent with infection. UKHSA has not detected evidence of human-to-human transmission. One case has been reported previously in the UK, in 2022. In addition to these 7 cases of avian influenza A(H5N1) reported between January and June 2023, in October 2022, Vietnam reported one human infection of avian influenza A(H5) in a 5-year-old girl for the first time since 2014. The girl developed severe symptoms. While the subtype was not initially detected, subtype A(H5N1) was later confirmed.

Middle East respiratory syndrome (MERS)

Geographical risk areas	The Arabian Peninsula – Yemen, Qatar, Oman, Bahrain, Kuwait, Saudi Arabia and United Arab Emirates.
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 cases in total – 3 imported cases (2012, 2013 and 2018), 2 secondary cases in close family members of the case in 2013, 3 deaths.
Likelihood assessment	Very low (UKHSA risk assessment).
Recent cases or outbreaks	A case of MERS-CoV was confirmed in Oman in January 2023 (the date of symptom onset was 28 December 2022), with no secondary cases reported. Including this new case, Oman has reported 26 cases of MERS-CoV, including 7 deaths (case fatality rate of 27%), since 2013.

Mpox (Clade I only)

Geographical risk areas	Central Africa including Central African Republic, Cameroon, the Democratic Republic of the Congo, Gabon and Congo.
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	In June 2022, the Advisory Committee on Dangerous Pathogens (ACDP) recommended that the strain of monkeypox virus (MPXV) largely responsible for the global outbreak (Clade IIb, B.1 lineage) should no longer be classified as an HCID. In January 2023, the ACDP recommended that all Clade II MPXV should no longer be classified as an HCID. No cases of Clade I mpox have been reported in the UK. Between 2018 and 2021, 7 cases of mpox were identified in the UK which would no longer be classified as HCID mpox, but were treated as HCID cases at the time: 4 of the cases were imported from Nigeria, 2 cases were household contacts and one case was a healthcare worker involved in the care of an imported case.
Likelihood assessment	Very low – no known importations of Clade I mpox into the UK.
Recent cases or outbreaks	Sequencing data is rarely available for mpox cases reported from endemic African countries where Clade I MPXV is known to circulate. Of these countries, confirmed mpox cases have been reported from: Cameroon, with 41 confirmed cases, including 3 deaths reported between 4 March 2022 and 23 June 2023. The Central African Republic, with 30 confirmed cases, including one death reported between 14 January 2022 and 16 June 2023. The Democratic Republic of the Congo, with 675 confirmed cases, including 3 deaths reported between 20 May 2022 and 16 June 2023. The Republic of the Congo, with 5 confirmed cases reported between 22 April 2022 and 16 June 2023. No associated deaths were reported.

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.
Likelihood assessment	Exceptionally low/negligible – no travel-related infections in the literature.
Recent cases or outbreaks	Between 1 January and 4 March 2023, a total of 14 Nipah virus cases, including 10 deaths, were reported in Bangladesh. These cases were associated with the consumption of date juice, with the exception of one secondary case in an infant. Case numbers reported in Bangladesh in 2023 are higher compared to cases reported in the previous 5 years (3 in 2022, 2 in 2021, 7 in 2020, 8 in 2019 and 4 in 2018).

Pneumonic plague (Yersinia pestis)

Geographical risk areas	Predominantly sub-Saharan Africa but also Asia, North Africa, South America, Western US. Endemic in Madagascar, Peru, and 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.
Likelihood assessment	Exceptionally low/negligible – no travel-related infections in the literature.
Recent cases or outbreaks	No reports of confirmed or suspected human cases of pneumonic plague have been identified between January and June 2023.

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 cases related to the 2002 outbreak.
Likelihood assessment	Exceptionally low/negligible – no cases have been reported since 2004.
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.
Likelihood assessment	Exceptionally low – one travel-related case was identified in Belgium in 2020.
Recent cases or outbreaks	No reports of confirmed or suspected human cases have been identified between January and June 2023.

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.
Likelihood assessment	Exceptionally low/negligible – travel-related cases have never been reported.
Recent cases or outbreaks	No reports of confirmed or suspected human cases have been identified between January and June 2023.

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.
Likelihood assessment	Exceptionally low/negligible – a single travel-related case has been reported. No cases have been reported anywhere since 2008.
Recent cases or outbreaks	No confirmed or suspected human cases reported 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.
Likelihood assessment	Exceptionally low/negligible – not known to have occurred in travellers.
Recent cases or outbreaks	On 21 March 2023, media reported a fatal case of SFTS from Kumamoto Prefecture, Japan. In 2023, as of 24 June, a total of 31 cases of SFTF have been reported in South Korea. Media have reported at least 2 fatal cases, including one from South Jeolla Province in April 2023, and a second from North Chungcheong Province in July 2023.

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.
Likelihood assessment	Very low – rare cases in travellers have been reported.
Recent cases or outbreaks	No reports of hantavirus infection caused by Andes virus have been identified between January and June 2023. However, hantavirus cases in which the type of hantavirus is not specified have been identified from the Andes virus risk areas of Argentina (one fatal case reported from Sante Fe and one fatal case reported from Río Negro in March, one case reported from Buenos Aires in April) and Chile (32 cases, including 6 deaths reported in 2023, as of 28 May).

Avian influenza A(H5N6) virus

Geographical risk areas	Mostly China. New strain 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.
Likelihood assessment	Very low – not known to have occurred in travellers (UKHSA risk assessment).
Recent cases or outbreaks	In China, 3 new human cases of avian influenza A(H5N6) were reported between January and June 2023. The first case was reported on 6 January 2023 from Hunan Province, in an individual who developed symptoms in November 2022. The second case was reported on 1 March 2023, from Guangdong Province, in an individual who had contact with live domestic poultry before symptom onset in December 2022. On 5 June 2023, a third case was reported from Nanchong, Sichuan province, in an individual who had exposure to live domestic poultry before symptom onset on 19 May 2023. From 2014 to June 2023, 84 human cases of avian influenza A(H5N6) have been reported by Mainland China health authorities.

Avian influenza A(H7N7) virus

Geographical risk areas	Sporadic occurrence in birds across 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.
Likelihood assessment	Very low – human cases are rare, and severe disease even rarer.
Recent cases or outbreaks	No reports of confirmed or suspected human cases were identified between January and June 2023.

Authors of this report

Emerging Infections and Zoonoses Team