Infectious disease surveillance and monitoring for animal and human health: summary January 2025
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 |
|---|---|---|
| Marburg virus disease | Tanzania | New |
| Sudan virus disease | Uganda | New |
Marburg virus disease (MARD)– Tanzania
Event summary
On 10 January 2025, the World Health Organization (WHO) reported suspected cases of MARD in Biharamulo and Muleba districts, Kagera region, Tanzania. Initial reporting indicated there were 6 cases, of which 5 had died. These cases presented with viral haemorrhagic fever symptoms including headache, high fever, back pain, diarrhoea, tiredness and bleeding. By 11 January 2025, 9 suspected cases and 8 deaths had been reported. The Government of Tanzania officially confirmed an outbreak of MARD on 20 January 2025.
As of 31 January 2025, a total of 10 fatal cases (2 confirmed and 8 probable) have been reported. All of the cases are epidemiologically linked to the index case. The reported cases range in age from 1 to 75 years, with a median age of 30 years. Females account for 70% (n=7) of the cases. No new cases have been identified since 20 January 2025. A total of 281 contacts have been identified for isolation and follow up.
Epidemiological investigations established that the index (confirmed) case was a 27-year-old female from Biharamulo District, who died on 19 January 2025. Epidemiological links were identified between the index case and a cluster of 8 deaths that occurred between December 2024 and January 2025. The first death within this cluster was reported to have developed symptoms on 9 December 2024 and died on 16 December 2024. The earliest fatal case was not sampled for any retrospective testing.
This outbreak follows a recent MARD outbreak in neighbouring Rwanda which took place from September to December 2024 and resulted in 66 confirmed cases and 15 deaths (case fatality rate (CFR) of 23%).
Incident assessment
This is the second MARD outbreak in Tanzania’s Kagera region. The last reported MARD outbreak occurred between March and May 2023, and resulted in 9 cases (8 confirmed) and 6 deaths (CFR of 67%). The source of exposure in the previous outbreak has not yet been identified. Fruit bats, which are a zoonotic reservoir for Marburg virus are endemic to the area and could present an ongoing risk for future spillover events. In a recent MARD outbreak in Rwanda, the likely index case was a miner that had occupational exposure to fruit bats.
The WHO assessed this outbreak as high risk at the national and regional levels. At national level, the factors that determine this risk level include: the involvement of healthcare workers amongst the suspected cases (indicating nosocomial transmission), the high CFR, the delayed reporting of the suspected cases across 2 districts (suggesting wider geographic spread) and an unknown source of exposure. At the regional level, Kagera is a transit hub with routes that cross into Rwanda, Uganda, Burundi, and the Democratic Republic of the Congo.
In response to the outbreak, the UKHSA has activated its Returning Workers Scheme, aimed at monitoring the health of individuals who deploy to affected areas where they may be exposed to MARD as part of their work. UK-specific clinical management guidelines and additional information on MARD can be found here.
Sudan virus disease (SVD) - Uganda
Event summary
On 30 January 2025, Uganda’s Ministry of Health confirmed an outbreak of SVD in Kampala. Sudan virus (SUDV) is one of 4 ebolaviruses that cause Ebola disease. This is the 8th outbreak of Ebola disease in Uganda.
As of 30 January 2025, 1 confirmed fatal case has been reported. The case was a healthcare worker who sought treatment at multiple health facilities as well as a traditional healer. The case had a symptom onset date between 20 to 21 January 2025, which included high fever, chest pain and breathing difficulties. This progressed to bleeding from multiple body sites and multi-organ failure. The case died on 29 January 2025 at the Mulago National Referral Hospital.
45 contacts have been identified including 34 healthcare workers and 11 family members. The Ugandan Ministry of Health has activated public health measures and deployed incident response teams to respond to this outbreak.
Figure 1. Map of Uganda with sub-divisions annotated that have reported historical cases or outbreak of SVD (teal) or in the current outbreak (2025).
Incident assessment
Of the 8 Ebola disease outbreaks reported in Uganda, 5 were due to SVD (one in 2000, one in 2011, 2 outbreaks in 2012 and one in 2022). Historically, the CFR for SVD outbreaks has been between 41% and 70%. The last SVD outbreak in Uganda took place between September 2022 and January 2023 and resulted in 164 cases and 77 deaths (CFR of 47%). Uganda is well experienced with Ebola disease outbreaks and has been proactive in reporting and responding to this outbreak.
The WHO is supporting Uganda through operational, financial, and technical assistance as well as providing access to experimental candidate vaccine and therapeutics. On 31 January 2025, the WHO made available 2,160 candidate SVD vaccine doses and candidate treatments (a monoclonal antibody and an antiviral) for use in clinical trials. The WHO currently assesses this outbreak as a high risk for potential public health impacts as there are no licensed vaccines or therapeutics for SVD.
In response to the outbreak, the UKHSA has activated its Returning Workers Scheme, aimed at monitoring the health of individuals who deploy to affected areas where they may be exposed to SVD as part of their work. UK-specific clinical management guidelines and additional information on SVD can be found here.
Summary of other incidents
| Disease or infection | Location |
|---|---|
| Chapare haemorrhagic fever | Bolivia |
| Cholera | Multi-country |
| Wild poliovirus type 1 (WPV1) | Multi-country |
| Yellow fever | South America |
| Zika virus | India |
Chapare haemorrhagic fever
On 7 January 2025, the International Health Regulations National Focal Point for Bolivia notified the WHO of a fatal case of Chapare virus in the La Paz Department. The case was laboratory confirmed on 2 January 2025. The case experienced symptoms on 19 December 2024, which included fever, headache, muscle pain, joint pain, and bleeding gums. He sought medical attention on 24 December 2024, was transferred to a local health centre on 30 December 2024 and died on the same day. Epidemiological investigations revealed rodent infestation around the cases home and possible occupational exposure to rodent burrows: risk factors for zoonotic transmission.
No secondary cases were identified, with 2 close contacts testing negative for Chapare virus. This is the fifth documented outbreak of Chapare Haemorrhagic Fever in Bolivia and globally since the virus was first detected in 2003.
Cholera
During January 2025, notable cholera outbreaks were reported from Angola, Ghana, South Sudan, Sudan, Uganda, and Zimbabwe.
Angola declared a cholera outbreak in the municipality of Cacuaco, Luanda province, on 7 January 2025. As of 30 January 2025, a total of 1,216 cases and 48 deaths have been reported. WHO has assisted with the outbreak response through the provision of 948,500 doses of oral cholera vaccine alongside water, sanitation and hygiene (WASH) supplies, education materials and training for community health workers.
As of 10 January 2025, Ghana has reported 398 confirmed cases, including 40 deaths, since the start of the cholera outbreak in October 2024. 5 regions have reported cases: Greater Accra, East, Central, Ashanti, and Western Regions. A sub-national vaccination campaign has been completed in 18 sub-districts within 4 hotspots of the Western Region and has reached 596,205 people.
Between October 2024 and January 2025, South Sudan reported 52,000 cholera cases and 450 deaths since the outbreak was declared. Cases were reported to have declined in most counties other than Juba, Mayom, Twic East and Aweil West. It was reported that the South Sudan Ministry of Health has received 2 million doses of vaccine and are awaiting a further 4 million doses to cover the affected counties. Neighbouring Sudan has reported 2,963 cases and 91 deaths between 2 January 2025 and 29 January 2025, bringing its cumulative case count to 52,517 and 1,407 deaths.
On 7 January 2025, a cholera outbreak was reported from Agogo Subcounty, Lamwo District, Uganda, that likely resulted from a funeral ceremony where the index case was infected. Investigations found that limited access to WASH may have contributed to the spread of the outbreak. A total of 87 cases (1 death) were reported between 7 to 17 January 2025 across 6 parishes in Agogo Subcounty (Pobar, Laruc, Rudi, Ngacino, Lopulingi and Lorunya).
Zimbabwe last recorded a cholera outbreak between February 2023 and July 2024. During November 2024, a new cholera outbreak was declared in Kariba district, Mashonaland West province. As of 21 January 2025, cholera had spread to 4 other provinces (Chipinge, East Mashonaland, Masvingo and Mashonaland Central) with a cumulative case count of 332 cases (30 confirmed), including 4 deaths.
Wild poliovirus type 1 (WPV1)
During January 2025, the Global Polio Eradication Initiative (GPEI) reported the first WPV1 cases in Pakistan and Afghanistan for 2025. Pakistan reported 74 cases of WPV1 during 2024. Afghanistan reported 25 cases of WPV1 during 2024. The Global Polio Surveillance Action Plan (2025-2026) was published on 13 January 2025, to extend the polio eradication strategy to 2029. GPEI’s strategic goal remains to eradicate WPV1 and to interrupt transmission of circulating vaccine-derived poliovirus type 2.
Yellow fever
During the first 4 weeks of 2025 (30 December 2024 to 26 January 2025), 16 confirmed cases of yellow fever and 7 deaths were reported from 3 countries in South America: Brazil (7 cases, including 4 deaths), Colombia (8 cases, including 2 deaths) and Peru (1 death). Brazil and Peru’s cases were confirmed with the use of RT-PCR. All cases had an exposure history to wild or wooded areas which are permissive environments for the mosquito vector. All cases were not vaccinated against yellow fever.
In 2025, Brazil has reported cases from the state of Sao Paulo. Colombia’s cases have been reported from the department of Tolima, with cases reported from rural municipalities that are adjacent to the Bosque de Galilea Regional National Park. These municipalities are rated as high risk for yellow fever. Peru’s singular fatal case in 2025 was in an individual that resided in the department of Huánuco. This case was also co-infected with leptospirosis.
During 2024, 61 confirmed cases, including 30 deaths, were reported from 5 South American countries: Bolivia (8 cases, 4 deaths), Brazil (8 cases, 4 deaths), Colombia (23 cases, 13 deaths), Guyana (3 cases) and Peru (19 cases, 9 deaths).
Zika virus
On 29 January 2025, WHO reported an unusual exceedance of Zika virus cases across 3 states in India during 2024. A total of 151 cases were reported from Maharashtra (140 cases), Karnataka (10 cases) and Gujarat (one case). As of 31 December 2024, there have been no reports of microcephaly and or Guillain-Barre syndrome associated with this outbreak.
The Integrated Disease Surveillance Programme (IDSP) of Maharashtra state has reported that 125 cases were reported from Pune district, 11 from Ahmednagar district, and one case each from the Kolhapur, Sangli and Solapur districts and the Mumbai suburban area. This is the highest number of reported Zika cases in Maharashtra since records began in 2021 (previous years 2021; one case, 2022; 3 cases, 2023; 18 cases). Zika virus is of particular risk to pregnant woman as it can cause foetal defects, including microcephaly. The state authorities have issued public health advisories, activated active surveillance, and are monitoring pregnant woman that have tested positive for Zika virus infection.
Publications of interest
Avian influenza A(H5)
By the end of 2024, the US had reported 67 human cases of avian influenza A(H5), of which 40 cases were associated with the dairy cattle industry, 23 cases with the poultry industry or poultry culling operations, one case with non-agricultural animal exposure and 3 cases with unidentified exposure source. A US case study of the first 46 cases (from March to October 2024) reported that these cases largely experienced mild illness with most patients receiving prompt antiviral treatment. It was also identified that in individuals with an occupational exposure risk, the use of personal protective equipment was suboptimal. No human-to-human transmission was identified in these cases.
The first severe human case of avian influenza A(H5N1) was reported in Canada during November 2024. This was also the first case of human infection with a clade 2.3.4.4b, genotype D1.1 avian influenza A(H5N1) virus. The corresponding case study documented the clinical presentation and also identified molecular markers of human adaptation in the polymerase basic 2 (PB2) gene and the haemagglutinin (HA) gene of the isolated virus genome.
A number of molecular studies on avian influenza A(H5N1) adaptation of HA and PB2 were published in January 2025:
- HA receptor binding to bovine and mammalian cells using clade 2.3.4.4b viruses of avian and mammalian origin
- Bovine origin avian influenza A(H5N1) viruses have a strong preference for avian-like sialic acid receptors and a slight preference for human-like sialic acid receptors
- Clade 2.3.4.4b, genotype B3.13 viruses have PB2 adaptations that enhances viral replication by better utilising bovine host factors
Avian influenza A(H5N2)
In April 2024, Mexico reported a fatal case of untypable influenza A in an individual with underlying medical conditions. Using genetic sequencing, avian influenza A(H5N2) was identified which was a 99% nucleotide match with a 2024 avian-origin sequence from backyard poultry farms in Texcoco; a locality near the residence of this fatal human case. In March 2024, an outbreak of low pathogenicity avian influenza A(H5N2) was detected in poultry in Texcoco. The high genetic identity suggests a direct relationship between the virus identified in this human case and from the prior avian outbreak.
This is the first reported human case of infection with avian influenza A(H5N2). However, due to the underlying conditions of the patient, it is unclear how much the viral infection contributed to the severity of disease and ultimately the death of the case.
Avian influenza A(H9N2)
Vietnam reported its first fatal human case of avian influenza A(H9N2) in April 2024. The case was an individual who had underlying conditions and had no known exposure to sick or dead poultry. The individual had a backyard poultry flock which tested negative for avian influenza viruses 27 days post-symptom onset. A poultry market close to the case’s residence was also investigated with only one sample returning a positive test for avian influenza A(H5N1) and no reports of avian influenza outbreaks reported in the preceding 3 months.
A retrospective genomics based investigation reported that the likely source of exposure was through household poultry. The investigation highlighted that it was unknown how infection of avian influenza A(H9N2) had contributed to the progression of the disease the case experienced.
Mpox
A new observational cohort study of clade Ib mpox cases using a WHO standardised protocol published their findings in January 2025. The first 100 participants followed in this study were from South Kivu, the Democratic Republic of the Congo (DRC) and followed the route of transmission, disease severity and mpox lesion location. This study provides early evidence on how clade Ib mpox transmits and presents, which could inform public health messaging and strategies. A historical study (2010-2023) of national data from the DRC highlighted key gaps in surveillance confirmatory testing. It also described the shift in age pattern in confirmed mpox cases, which may be related to the waning population immunity from historic routine smallpox vaccination.
China published the whole genome analysis from their first case of clade Ib mpox imported from the African region. Phylogenetic analysis indicated that this case clustered amongst other clade Ib mpox sequences reported from multiple African and European countries. A short correspondence was also published in The Lancet, covering recent clinical trials of the antiviral, tecovirimat, against mpox clades I and II.
Oropouche fever
During 2024, Brazil reported a number of foetal deaths, miscarriages and congenital anomalies thought to be related to Oropouche virus (OROV) infection. A case study sought to determine whether historical cases of congenital malformations and a small sample of 2024 cases were infected by OROV. Three historical cases and 3 cases from 2024 were positive for OROV by serum sampling.
Crimean-Congo haemorrhagic fever (CCHF)
CCHF is an emerging vector-borne disease in Europe. Sporadic cases have been reported in the Balkans and Mediterranean regions, with transmission mediated by bites from infected ticks or with direct contact with infected blood or tissues of infected ticks, people, or livestock. A narrative review was conducted to examine travel-associated cases of CCHF globally and within the European region and provide evidence for a One Health approach to monitor CCHF prevalence and the public health response in Europe in anticipation of further geographical spread of CCHF.
During 2023 and 2024, North Macedonia reported its first CCHF cases since the 1970’s. An epidemiological investigation showed that there was some genetic evidence of undetected co-circulation and reassortment of CCHF viruses. This suggested that North Macedonia is an area where CCHF viruses from Turkey and Kosovo intersect and co-circulate.
West Nile virus (WNV)
In Western Europe, WNV lineage 1 has been the causative agent of sporadic cases or outbreaks in both humans and animals. WNV lineage 2 emerged in 2004 in Central Europe and has since spread to central and southern European countries. Lineage 2 isolates have caused outbreaks of neuroinvasive disease in humans and animals. A recent study sought to identify the prevalence and circulating lineage in eastern Croatia through the sampling of mosquito vectors. The genomic analysis revealed that WNV lineage 2 was present with evidence to suggest the viruses are of Hungarian origin linked migratory birds that transit the African European route.
Polio
Between September and December of 2024, circulating vaccine-derived poliovirus (cVDPV) was detected in several European countries (Finland, Germany, Poland, Spain and the UK) through wastewater surveillance. This triggered public health actions and has highlighted the value of continuous environmental surveillance, even in areas considered to be polio free. The nature of cVDPV means that these viruses can circulate over a long period of time and remain undetected to cause infections in individuals who are no longer immune due to waning immunity.
During 2024, in Guinea, cVDPV type 3 was detected as part of the acute flaccid paralysis surveillance system. cVDPV3 has previously been detected in cases and environmental samples in other regions of the world. Genomic analysis of the cases in Guinea showed that these were unrelated to previous sequences identified in Israel and Pakistan in 2023.
Novel pathogens and diseases
Orthonairovirus
A screening study of 252 febrile patients in China who had been bitten by a tick was conducted using metatranscriptomic sequencing of serum samples between May and July 2023. Serum samples from 2 patients had indications of an unknown virus which was sequenced and de novo assembled. Sequencing revealed it had less than 75.6% amino acid identify compared to known orthonairovirus members, indicating a new viral species. The isolated virus also had a cytopathic effect in cell culture assays and was visualized with electron microscopy. This virus was provisionally named as Xue-Cheng virus, after the city where it was first identified.
Spotted Fever Group Rickettsia (SFGR)
This study aimed to identify the prevalence of SFGRs in northwestern China. 425 DNA samples from ticks were collected from the Ningxia region and analysed. Of these, 210 samples were positive for SFGRs. Based on a phylogenetic tree generated from the sequences in this study, 2 possible new Rickettsia genotypes were identified. A candidate new species was identified given the genetic divergence from other SFG Rickettsia species, which was named Candidatus Rickettsia vulgarisii.
Henipavirus
During 2021, a mammalian study examined RNA samples from 4 northern short-tailed shrews which revealed a novel henipavirus, named Camp Hill virus. This study used RNA metagenomic sequencing to show that this virus belonged to the shrew henipavirus clade. Henipavirus is notable for Hendra virus and Nipah virus which have been linked to outbreaks in Australia and Southeast Asia with mortality rates of between 40 and 75%. This study indicated that the northern short-tailed shrew may be a potential zoonotic host for future spillover events. Of note, the sampled shrews also had a high prevalence of Camp Ripley virus (a hantavirus) which suggested co-infection in this animal reservoir.
Further reading
A Surrogate BSL2-compliant Infection Model Recapitulating Key Aspects of Human Marburg Virus Disease
Malaria vaccine introduction in Africa: progress and challenges
Related resources
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