Infectious disease surveillance and monitoring for animal and human health: summary December 2024
Updated 24 April 2025
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Interpreting this report
The UK Health Security Agency’s (UKHSA) Emerging Infections and Zoonoses (EIZ) team uses an integrated horizon scanning approach, which combines information on both human and animal health, to identify and assess outbreaks and incidents of new and emerging infectious diseases globally. For further information about the EIZ team’s horizon scanning process, please see our Epidemic intelligence activities.
This summary provides an overview of incidents (new and updated) of public health significance, which are under close monitoring. The incidents are divided into 2 sections: Notable incidents of public health significance and Other incidents of interest. For each notable incident of public health significance, an incident assessment is provided, based on the EIZ team’s interpretation of the available information.
The report also includes a section that focuses on Novel pathogens and diseases and a final Publications of interest section, which contains new publications relevant to emerging infections.
Epidemiological updates for diseases classified as a high consequence infectious disease (HCID) are published in UKHSA’s HCID monthly summary, unless they are considered a notable incident of public health significance, in which case a more detailed summary will be provided in this report.
For more information, or to sign up to the distribution list to receive an email alert when new reports are published, please contact epiintel@ukhsa.gov.uk
Notable incidents of public health significance
Summary of incidents
| Disease or infection | Location | New or update since the last report |
|---|---|---|
| Avian influenza A(H5N1) | United States | Update |
| Marburg virus disease (declared over) | Rwanda | Update |
Avian influenza A(H5N1) – United States
Event summary
On 27 December 2024, the United States Centers for Disease Control and Prevention (US CDC) reported 66 confirmed and 7 probable human cases of avian influenza A(H5) between 1 January and 27 December 2024. Most of the confirmed cases were associated with the agricultural industry (63 cases).
On 18 December 2024, the US CDC reported the first severe case of avian influenza A(H5N1) in Louisiana State. The case was initially reported as a presumptive case by the Louisiana Department of Health on 13 December 2024 and later confirmed by the US CDC on 18 December 2024. The case had exposure to sick and dead birds in backyard flocks. No transmission from the case to other individuals was reported.
On 26 December 2024, the US CDC published genomic sequencing results of virus isolated from the case’s samples. The overall hemagglutinin (HA) sequences were related to other D1.1 genotype viruses recently detected in wild birds and poultry in the United States.
Deep sequencing of the HA gene segment detected a low frequency of changes in notable amino acid residues A134A/V, N182N/K and E186E/D. These changes may increase virus binding to alpha2-6 receptors which are found in the upper respiratory tract of humans. However, the frequency of these changes were low and were not identified in virus isolated from poultry on the property of the patient indicating these changes emerged during infection of the patient. Major mammalian adaptations such as mutations in PB2 E627K were not present. Similar to other D1.1 genotype viruses found in birds, the PB2 M631L mutation was not present (The PB2 M631L mutation is associated with virus adaptation to mammalian hosts and has been detected in more than 99% of sequences from infected dairy cattle).
Incident assessment
This case is the first severe human case of avian influenza A(H5N1) reported in the United States. Globally, between 1 January 2003 to 12 December 2024, 954 cases of human infection with avian influenza A(H5N1) virus and 464 deaths (case fatality rate (CFR) of 48.6%) were reported from 24 countries. Whenever avian influenza viruses are circulating in animals, there is a potential risk of sporadic human cases following exposure to infected animals or their contaminated environments. Human cases of avian influenza A(H5) are rare and there is limited evidence of human-to-human transmission of these viruses.
Since 2021, 5 human cases of avian influenza A(H5N1) clade 2.3.4.4b have been reported in the UK. These cases were associated with poultry exposures and were either asymptomatic or had mild symptoms. The D1.1 genotype is not circulating in the UK. For further information on avian influenza viruses, see the UKHSA’s avian influenza webpage.
Marburg virus disease - Rwanda
Event summary
On 20 December 2024, Rwanda’s Ministry of Health (MoH) declared an end to the Marburg virus disease (MARD) outbreak following 42 days (2 consecutive incubation periods of the virus) since the last confirmed case was discharged on 7 November 2024. The outbreak began on 27 September 2024, and resulted in 66 confirmed cases including 15 deaths (CFR of 23%). During the outbreak, 78% of the confirmed cases were healthcare workers from 2 hospitals in Kigali. Epidemiological investigations and genomic sequencing revealed the source of the outbreak to be of zoonotic origin linked to a cave inhabited by fruit bats.
Most confirmed cases were males (68%), and adults (46%) within the 30 to 39 age range. The majority of confirmed cases (61 cases) were reported in the first 3 weeks of the outbreak. The last confirmed case and death were recorded on 30 October and 14 November 2024, respectively.
Rwanda’s MoH continues to work with the World Health Organization (WHO) and other partners to ensure continued monitoring to ensure rapid detection of any flare-ups or new spillover events.
Incident assessment
This was the first ever outbreak of MARD in Rwanda, and third largest MARD outbreak reported to date. The WHO assessed the risk of the outbreak as low at national, regional and global levels. A high proportion of cases were among healthcare workers, highlighting nosocomial transmission. Through a coordinated response by the Rwanda’s MoH with support from the WHO and partners, the outbreak was contained. However, although the outbreak has been declared over, a risk of re-emergence cannot be completely ruled out as Marburg virus can persist in bodily fluids of recovered cases and there are animal reservoirs present within Rwanda. No cases of MARD have ever been reported in the UK. If a case were to be imported into the UK from an endemic area, there are a range of robust clinical, infection prevention and control measures available which would be adapted for use as necessary to reduce the risk of transmission.
Summary of other incidents
| Disease or infection | Location |
|---|---|
| Anthrax | Uganda |
| Chikungunya | Réunion |
| Cholera | Multi-country |
| Dengue | Panama |
| Vaccine derived polio virus | Multi-country |
| Zika virus | Americas region |
Anthrax
In Uganda, media reported 2 fatal human anthrax cases in Kazo District on 12 December 2024. Both cases were butchers and reported symptoms indicative of anthrax 5 days after eating contaminated meat. Investigations are ongoing to trace the source of the contaminated meat. On 19 December 2024, media reported 2 fatal human anthrax cases in Sembabule District, as well as several individuals reportedly receiving treatment Samples from affected cattle were sent for testing to determine an exposure. It is unclear if the cases from these districts are related to the same source.
Chikungunya
In Réunion, the first autochthonous case of chikungunya since 2014 was reported on 23 August 2024. Between 23 August 2024 and 17 December 2024, 53 cases of chikungunya were reported. Most cases were reported in Sheunon ravine district (27 cases). In response to the outbreak, the Regional Health Agency activated the level 2B of their emergency response framework, further strengthening public health actions and partnerships with municipalities and inter-municipalities.
Cholera
In South Sudan, as of 22 December 2024, 9,102 suspected cholera cases and 146 deaths were reported from 28 counties across 7 states. Rubkona County reported the most cases (4,972 suspected cases), followed by Juba County (1,547 suspected cases). The most affected age groups include 0 to 4-year-olds (32.5% of cases) followed by 5 to14 year olds (22.8% of cases). In 2023, more than 7,000 cholera cases and 200 related deaths were reported in South Sudan.
In Ghana, a cholera outbreak began on 4 October 2024 after an individual presenting with cholera-like symptoms sought medical care. From 4 October to 23 December 2024, Ghana reported 4,155 suspected cases of cholera and 35 deaths. Cases were reported in Greater Accra region, Central, Eastern, Western and Ashanti region. The Western region reported the most cholera associated deaths (17 fatalities). An oral cholera vaccination campaign took place in cholera hotspots between 30 November and 19 December 2024 resulting in the vaccination of 662,906 out of 792,482 eligible people targeted.
In Malawi, 215 confirmed cholera cases and 13 deaths were reported between 8 September and 30 December 2024 by the Ministry of Health. Since the outbreak began, 10 districts have reported cases.
In Myanmar, 8,000 cholera cases were reported from Yangon and Rakhine regions from June 2024 to 19 December 2024.
On 22 December 2024, Thailand’s Ministry of Public Health (MoH) reported a cholera outbreak in Tak province which is close to Myanmar. Between 1 January and 24 December 2024, 8 cholera cases (4 Vibrio cholerae El Tor Ogawa cases, 3 Vibrio cholerae O139 cases and Vibrio cholerae El Tor Inaba case) were reported in Thailand. Thailand MoH reported that medical supplies have been dispatched to Tak province. On 24 December 2024, media reported the temporary closure of Tak Province border point.
In Yemen, the WHO reported 249,900 suspected cholera cases and 861 associated deaths between 1 January and 1 December 2024. Yemen accounts for 35% of the global cholera case burden, and 18% of global reported mortality.
Dengue
In Panama, 32,077 dengue cases and 52 associated deaths were reported between 1 January and 28 December 2024. The Metropolitan region reported the highest number of cases (8,553 cases) followed by San Miguelito (4,286 cases), Panama West (3,353 cases) and Colón (3,277 cases). The WHO reported that 20,924 dengue cases were recorded in 2023, and 11,924 cases were reported
Vaccine derived polio virus
On 9 December 2024, Finnish public health authorities reported the detection of vaccine-derived poliovirus type 2 (VDPV2) in wastewater samples in Tampere.
On 10 December 2024, the UKHSA reported the detection of VDPV2 in Leeds, London and West Sussex. UKHSA states that the isolates were linked to VDPV2 that has been widely circulating in the African region and are unrelated to previous detections of VDPV2 in the UK.
Zika virus
Between 1 January and 31 December 2024, 43,589 Zika virus cases (including 1,999 confirmed cases) were reported in the Region of the Americas. Brazil reported the highest number of cases (42,333 cases) followed by Argentina (564 cases).
Publications of interest
Crimean-Congo haemorrhagic fever (CCHF)
CCHF is a severe tick-borne viral haemorrhagic fever caused by CCHF virus in the Bunyaviridae family. CCHF is endemic in countries in Africa, the Balkans, the Middle East, and western and south-central Asia. In this study, the authors report the first confirmed autochthonous CCHF case in Portugal since 1985. The case was an 80-year-old male resident of Braganca, who was bitten by a tick prior to onset of symptoms and his death.
Ebola virus disease (EBOD)
On 4 December 2024, Gavi (the Vaccine Alliance) announced that Sierra Leone has become the first country to launch a national Ebolavirus vaccination campaign aimed at vaccinating 20,000 frontline workers across 16 districts with a single vaccine dose. The frontline workers will include healthcare professionals and first responders such as ambulance drivers, traditional healers, religious leaders, security forces and those that are at high risk of being exposed to Ebolavirus. Vaccine doses will be provided from the Gavi global vaccine stockpile.
Between May 2014 and November 2025, Sierra Leone was severely affected by an outbreak of EBOD, resulting in 8,704 cases including 3,589 deaths. 221 deaths were among health workers, accounting for 6.85% of Sierra Leone’s healthcare workforce at that time.
Novel pathogens and diseases
Mammarenaviruses
Mammarenaviruses are significant zoonotic pathogens that are predominantly found in rodents. Based on antigenic properties, geographic relatedness and genome sequences, these viruses are split into 2 groups –New World and Old World viruses. The authors in this study report the detection of a novel Mammarenaviruses strain in 6 of 183 necropsy samples collected from European hedgehogs in Italy
Further reading
Influenza A(H5N1) Virus Clade 2.3.2.1a in Traveler Returning to Australia from India, 2024
A single mutation in bovine influenza H5N1 hemagglutinin switches specificity to human receptors
Mpox: technical elements of preparedness and response for clade I - Technical Briefing #10
Gatherings in the context of the 2024 mpox outbreak: public health guidance
1. High consequence infectious diseases monthly summaries
2. National flu and COVID-19 surveillance reports
3. Avian influenza (influenza A H5N1): technical briefings
4. Avian influenza (bird flu) in Europe, Russia and the UK reports
5. Bird flu (avian influenza): latest situation in England updates
6. Human Animal Infections and Risk Surveillance (HAIRS) group risk assessments and statements
7. Animal and Plant Health Agency (APHA) monitoring of disease in livestock and poultry monthly reports
Authors of this report
UKHSA’s Emerging Infections and Zoonoses team epiintel@ukhsa.gov.uk