Research and analysis

Global high consequence infectious disease events: summary August 2024

Updated 3 April 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 31 August 2024, the World Health Organization (WHO) reported 941 CCHF cases (237 confirmed), including 78 deaths (case fatality rate (CFR) of 8.3%), from Afghanistan. Confirmed cases were reported from 12 provinces. In 2023, Afghanistan reported 1,243 CCHF cases (383 confirmed), including 114 deaths (CFR of 9.2%). In August 2024, media reported two fatal cases of CCHF in Nineveh, Iraq. The first case, a 50-year-old female, became symptomatic on 20 July 2024 and died on 1 August 2024. The second case, a 32-year-old female, became symptomatic on 17 August 2024. Nineveh has reported 17 confirmed CCHF cases and 4 deaths so far in 2024. In Pakistan, on 15 August 2024, media reported one confirmed case of CCHF in a 32-year-old male in Karachi who was a butcher. This is the first case reported in the city in 2024. On 17 August 2024, media reported one fatal case of CCHF in a 42-year-old male in Quetta, Balochistan. On 28 August 2024, media reported one confirmed and one suspected case of CCHF in Quetta. The confirmed case was in a 14-year-old male. Balochistan is the province of Pakistan most affected by CCHF due to unregulated cross-border animal transportation. On 19 August 2024, media reported one case of CCHF in Volgograd, Russia in 2024. Volgograd is in an area endemic for CCHF. On 12 August 2024, the Africa Centres for Disease Control and Prevention (Africa CDC) reported that as of 9 August 2024 there have been 5 confirmed CCHF cases from Senegal. Cases were reported from Dakar (one case), Kaolack (2 cases), Matam (one case) and Yeumbeul (one case). In Spain, one suspected CCHF case was reported by the health service of Andalusia in a 46-year-old male resident of Seville, who became symptomatic on 31 July 2024. On 23 August 2024, one confirmed CCHF case in Plasencia was reported by the health service of Extremadura. The 65-year-old male resided in Madrid and it is not known where he was bitten by the infected tick. On 14 August 2024, Portugal’s Director General for Health reported the countries first locally acquired case of CCHF. The confirmed CCHF case, an 80-year-old male from Bragança developed symptoms on 11 July 2024. The case reportedly carried out agricultural activities during the incubation period. On 24 August 2024, media reported that the case had died.

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 August 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 various countries in 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 Guinea, 27 cases and 2 deaths have been reported between 1 January and 23 August 2024. Between 1 January and 31 August 2024, Liberia has reported 59 Lassa fever cases including 8 deaths. This outbreak began in January 2022. Between 1 January and 1 September 2024, Nigeria reported 993 confirmed and 8,051 suspected Lassa fever cases. 169 deaths were reported amongst confirmed cases (CFR of 17.0%). This is a slightly lower CFR compared to the same period in 2023 (17.1%). 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 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.
Risk rating	Very low – globally, 5 travel-related exported MVD cases have previously been reported in the literature.
Recent cases or outbreaks	No confirmed or suspected human cases were reported in August 2024.

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 August 2024.

Avian influenza A(H5N1) virus

Geographical risk areas	Human cases have been predominantly reported in Southeast 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	Since December 2021, 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	In August 2024, 3 human cases of avian influenza A(H5N1) were reported in Cambodia, taking the total number cases reported in 2024 to 10. The first case is a 4-year-old male from Romeas Hek district, Svay Rieng province. The case became symptomatic on 30 July 2024 following contact with dead chickens on 18 July 2024. The second case is a 16-year-old female from Chantrea district, Svay Rieng province, who had contact with backyard poultry 4 days before symptom onset. The case was confirmed on 3 August 2024 by the National Institute of Public Health and the Institute Pasteur. The third case was a 15-year-old female from Kanhcheach district, Svay Rieng province, who died on 20 August 2024. 5 days prior to symptom onset, the case had direct contact with dead poultry. The United States Centers for Disease Control and Prevention (US CDC) reported on 2 August 2024 that since April 2024, 13 human cases of avian influenza A(H5N1) have been reported. 4 cases have been associated with exposure to infected dairy cattle and 9 cases have been associated with infected poultry. The latest genetic sequencing from 3 human cases associated with a poultry farm in Colorado confirmed the viruses were from clade 2.3.4.4b, closely related to recent poultry and dairy cow outbreaks. The US CDC states that the current health risk to the general public remains low.

Middle East respiratory syndrome (MERS-CoV)

Geographical risk areas	The 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	No confirmed or suspected human cases were reported in August 2024.

Mpox (clade I only)

Geographical risk areas	Central Africa including, Burundi, Cameroon, Central African Republic, the Democratic Republic of the Congo (DRC), 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	Very low – no known importations of Clade I mpox into the UK.
Recent cases or outbreaks	Sequencing data is often not available for mpox cases reported from endemic African countries where Clade I mpox virus is known to circulate. Therefore, we report below all reported mpox cases from these countries, regardless of whether the samples have been sequenced or clade-tested. On 14 August 2024, the WHO declared a Public Health Emergency of International Concern due to an upsurge in mpox cases reported from the African Region. Burundi declared an mpox outbreak on 25 July 2024. Since then, and as of 28 August 2024, 241 confirmed and 820 suspected mpox cases (no deaths) have been reported from 29 health districts. The Central African Republic reported 45 confirmed and 247 suspected cases of mpox, including 1 death, between 1 January and 18 August 2024. Africa CDC reported on 16 August 2024 that clade I mpox had been isolated from confirmed cases. Between 1 January and 26 August 2024, the Democratic Republic of the Congo (DRC) reported 18,839 mpox cases of which 4,874 were confirmed, and 621 deaths (CFR 3.3%). During 2023, the DRC reported its highest annual number of mpox cases (14,434 cases, including 728 deaths). On 22 August 2024, Gabon reported a confirmed mpox case. The case was hospitalised on 21 August 2024 and had a recent travel history to Uganda. 6 suspected cases were detected through surveillance. Clade type information is not currently available. Kenya officially reported its first confirmed case of clade Ib mpox on 31 July 2024 on the Kenya-Tanzania border, in a case travelling from Uganda to Rwanda via Kenya. On 23 August 2024, a second mpox case in Kenya was confirmed, and one suspected case is being investigated. In the Republic of the Congo, between 9 January and 11 August 2024, 124 mpox cases (19 confirmed) and no deaths were reported from 4 out of 12 provinces. During 2023, 95 mpox cases, including 5 deaths were reported. On 25 July 2024, Rwanda reported its first 2 cases of clade Ib mpox. As of 16 August 2024, 4 mpox cases had been confirmed in Rwanda. All of the cases had recent travel history outside of the country. Uganda confirmed cases of clade Ib mpox on 15 July 2024. As of 23 August 2024, 4 confirmed cases and no deaths have been reported. 41 contacts are being followed up. Outside of the African Region, travel-associated clade I mpox cases have been reported in Sweden (on 15 August 2024) and Thailand (on 22 August 2024). Both cases had travel histories to African countries experiencing clade I mpox outbreaks. No secondary transmission associated with these cases has been 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.
Risk rating	Exceptionally low to negligible – no travel-related infections in the literature.
Recent cases or outbreaks	On 21 July 2024, a fatal case of Nipah virus infection was reported from the Malappuram District, Kerala State, India. By 22 August 2024, 472 contacts of the fatal case had completed follow-up and Kerala State’s Directorate of Health Services declared the outbreak over.

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 August 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	On 20 August 2024, media reported one case of Argentine haemorrhagic fever in a young male in Santa Fe, Argentina. The case was hospitalised for treatment in a serious condition. Media reported that since the beginning of 2024, 33 confirmed and 709 suspected cases of Argentine haemorrhagic fever (including 6 deaths) have been registered in Argentina.

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 August 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 1 January and 28 August 2024, Japan’s National Institute of Infectious Diseases reported 91 SFTS cases. During August 2024, week 32 (beginning 4 August) to week 35 (25 August), 2 SFTS cases were reported. Between 1 January and 31 August 2024, the Korean Disease Control and Prevention Agency reported 83 SFTS cases.

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 23 July 2024, media reported a fatal case of hantavirus in a 16-year-old female in Guachipas, Argentina. On 3 August 2024, media reported that a viral sample from the case had very low sequence identity with previous cases from Argentina, suggesting that the fatality was caused by a new genotype of hantavirus. On 18 August 2024, media reported one case of hantavirus in a 29-year-old female in Bariloche, Argentina. This is the fourth case of hantavirus registered in Río Negro in 2024. 3 deaths have been reported in the region in 2024. The article did not specify the type of hantavirus.

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 (UKHSA risk assessment).
Recent cases or outbreaks	No confirmed or suspected human cases were reported in August 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 August 2024.

Authors of this report

Emerging Infections and Zoonoses Team, UKHSA