Research and analysis

Global high consequence infectious disease events: summary December 2021

Updated 28 March 2024

Interpreting this report

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

It is divided into 2 sections covering all the defined HCID pathogens. The first 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 include 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.

Likelihood assessment

Included for each disease is a ‘likelihood assessment’ – the likelihood of a case occurring in the UK – based on past UK experience and the global occurrence of travel-associated cases. There are currently 3 categories:

• Low
• Very low
• Exceptionally low

When considering clinical history, it is important to remember that cases can and do occur outside of the usual distribution area. It is not possible to assess accurately the risk of cases presenting to healthcare providers in England but taken together it is inevitable that occasional imported cases will be seen.

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.

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. First locally acquired case in Spain 2016 (HAIRS risk assessment).
Sources and routes of infection	• bite from or crushing of an infected tick • contact with blood or tissues from infected livestock • contact with infected patients, their blood or body fluids
UK experience to date	Two confirmed cases (ex-Afghanistan 2012, ex-Bulgaria 2014).
Likelihood assessment	Low – rarely reported in travellers (23 cases in world literature).
Recent cases or outbreaks	In December, an outbreak of CCHF was reported in Iraq. Between April and November 2021, there were 45 suspected cases, of which 15 were confirmed. CCHF is endemic in Iraq with recurrent outbreaks since it was first reported in 1978.

Ebola virus disease

Geographical risk areas	Sporadic outbreaks in Western, Central and Eastern Africa
Sources and routes of infection	• contact with 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	No confirmed or suspected cases were reported in December 2021. On 16 December, the Ebola virus disease outbreak in Béni health zone, North Kivu Province, Democratic Republic of Congo (DRC) was declared over, 42 days after the second negative test from the last confirmed case. During the outbreak, which was initially declared on 8 October, a total of 8 confirmed (6 deaths) and 3 probable (all fatal) cases were reported.

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	Fourteen cases since 1971, all ex-West Africa.
Likelihood assessment	Low – overall, Lassa fever is the most common imported viral haemorrhagic fever (VHF) but is still rare (a total of 35 imported cases reported globally since 1969).
Recent cases or outbreaks	In Nigeria, there have been 4,482 suspected and 482 confirmed cases of Lassa fever in 2021, as of 26 December. A total of 99 deaths have been reported amongst confirmed cases, resulting in a case fatality rate of 20.5%. This is lower than the number of cases reported during the same period in 2020 (6,668 suspected, 1,175 confirmed cases and 242 deaths; case fatality rate of 20.6%).

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.
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 known cases in the UK.
Likelihood assessment	Very low – globally, 5 travel-related cases have previously been reported in the literature.
Recent cases or outbreaks	No confirmed or suspected cases were reported in December 2021.

Airborne HCIDs

Avian influenza A(H7N9) virus

Geographical risk areas	All 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 confirmed or suspected human cases were reported in December 2021.

Avian influenza A(H5N1) virus

Geographical risk areas	Human cases predominantly in South East Asia, but also Egypt, Iraq, Pakistan, Turkey and Nigeria. Highly pathogenic H5N1 in birds is much more widespread, including in the UK.
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 confirmed or suspected human cases were reported in December 2021.

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
UK experience to date	Five cases in total – 3 imported cases (2012, 2013 and 2018), 2 secondary cases in close family members of the second case, 3 deaths.
Likelihood assessment	Very low (UKHSA risk assessment).
Recent cases or outbreaks	Saudi Arabia have reported 4 cases of MERS in December 2021. Of these cases, 2 occurred in December while 2 were retrospectively reported from October and November 2021. In 2021, there were 19 cases of MERS identified globally. Of these cases, 17 were reported by Saudi Arabia and 2 by the United Arab Emirates (in January 2021 and November 2021).

Monkeypox virus

Geographical risk areas	West and Central Africa.
Sources and routes of infection	• contact with clothing or linens (such as bedding or towels) used by an infected person • direct contact with monkeypox skin lesions or scabs • coughing or sneezing of an individual with a monkeypox rash
UK experience to date	To date, there have been 7 cases of monkeypox reported in the UK. In May 2021, a case of monkeypox was identified with prior travel from Delta State, Nigeria. Two family members were subsequently identified as having monkeypox. Prior to these 3 cases, there have been only 4 cases of monkeypox reported in the UK, including 3 cases previously imported from Nigeria (2 in September 2018 and 1 in December 2019). One other case, in 2018, was a healthcare worker who acquired infection following contact with contaminated bed linen.
Likelihood assessment	Very low – reported outside Africa for the first time in 2018. Since 2018, 8 importations of human cases of monkeypox have been reported in non-endemic countries in travellers to Israel (one case), Singapore (one case), the US (2 cases) and the UK (4 cases).
Recent cases or outbreaks	In DRC, 2,898 cases including 81 deaths were reported between 1 January and 12 December 2021. This compares to 6,257 suspected cases and 229 deaths reported in 2020. On 9 December, an outbreak was declared in the Tunda health district, Maniema Province, following disease confirmation at the National Institute of Biomedical Research. As of 12 December, 196 cases and 24 deaths have been reported in association with this outbreak. Between 1 January and 31 December 2021, Nigeria reported 64 suspected and 34 confirmed cases of monkeypox. No deaths were recorded.

Nipah virus

Geographical risk areas	South East Asia. Recent outbreaks in Bangladesh and India.
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 – no travel-related infections in the literature.
Recent cases or outbreaks	No confirmed or suspected human cases were reported in December 2021.

Pneumonic plague (Yersinia pestis)

Geographical risk areas	Predominantly sub-Saharan Africa but also Asia, North Africa, South America, Western US.
Sources and routes of infection	• flea bites • close contact with infected animals • contact with human cases of pneumonic plague
UK experience to date	Last outbreak in the UK was in 1918.
Likelihood assessment	Exceptionally low – no travel-related infections in the literature.
Recent cases or outbreaks	In Ituri province, DRC, 130 suspected plague cases and 14 deaths have been reported in 2021, as of 12 December. In 2020, 461 suspected cases and 31 deaths were reported in the province.

Severe acute respiratory syndrome (SARS)

Geographical risk areas	Currently none. Two 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 2002 outbreak.
Likelihood assessment	Exceptionally low – not reported since 2004.
Recent cases or outbreaks	No confirmed or suspected human cases reported since 2004.

Incidents of significance of additional HCIDs

Argentine haemorrhagic fever (Junin virus)

Geographical risk areas	Argentina (central). Limited to the provinces of Buenos Aires, Cordoba, Santa Fe, Entre Rios 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 confirmed or suspected human cases were reported in December 2021.

Bolivian haemorrhagic fever (Machupo virus)

Geographical risk areas	Bolivia – limited to the Department of Beni, municipalities of the provinces Iténez (Magdalena, Baures and Huacaraje) and Mamoré (Puerto Siles, San Joaquín and San Ramón).
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 – travel-related cases have never been reported.
Recent cases or outbreaks	No confirmed or suspected human cases were reported in December 2021.

Lujo virus disease

Geographical risk areas	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 – 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. First ever cases reported in Vietnam and Taiwan in 2019. 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 – not known to have occurred in travellers.
Recent cases or outbreaks	No confirmed or suspected human cases of SFTS were reported in December 2021.

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	As of December, no confirmed or suspected cases of Andes virus have been reported in 2021. In Chile, media reported 3 cases of hantavirus (including 1 death) in the Maule region during December 2021. The strain of hantavirus was not specified. In Argentina, media reported a fatal case of hantavirus infection in La Plata, Buenos Aires province, in December 2021. The strain of hantavirus was not specified.

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 December 2021, 6 human cases of avian influenza A(H5N6) were reported in mainland China. This brings the total number of cases reported so far in 2021 to 31. From 2014 to the end of December 2021, a total of 57 human cases have been reported in mainland China.

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 of conjunctivitis associated with H7N7 were reported in in Italy 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)
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 confirmed or suspected human cases were reported in December 2021.