Outbreaks under monitoring: background and methodology
Published 28 August 2025
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Background to the outbreaks under monitoring report
Following an Ebola virus disease (EBOD) incident in England in 2014, a new High consequence infectious diseases (HCID) programme was commissioned in 2015 with the aim of providing a national system of readiness, and defined processes and protocols for managing suspected and confirmed cases of HCIDs. The expectation was that lessons learnt from managing the previous EBOD incidents in the UK would be embedded in public health response and management of future known and unknown HCIDs.
Since December 2016, the Emerging Infections and Zoonoses (EIZ) team in the UK Health Security Agency (UKHSA, at that point called Public Health England) produced a monthly report providing updates on known HCID events around the world, with the aim of raising awareness among healthcare professionals involved in HCID identification, treatment and management.
In addition to the HCID report, the EIZ team produced an ‘Emerging infections monthly summary’ (EIMS). The summary provided an overview of incidents of public health significance which were under close monitoring, covering pathogens beyond the HCID list. The EIMS also included sections on novel pathogens and diseases and publications of interest.
The production of HCID and EIMS reports ceased in March 2025 and in August 2025 they were replaced with a new outbreaks under monitoring report. This aims to provide timelier and more succinct summaries of specific disease events in almost real-time for active incident monitoring. The report provides relevant information on HCIDs and selected emerging infections (see pre-defined inclusion criteria below) as detected through the EIZ team’s epidemic intelligence (EI) activities.
There will be the possibility of expanding the pathogen list as the report evolves over time. In addition to the inclusion criteria listed for each disease in the next section, the report may cover:
- unusual or unexpected events (undiagnosed morbidity and/or mortality)
- outbreaks of unknown origin
- outbreaks (of known diseases) with substantial cases or mortality
- events triggering high media attention
- first case of disease X in a new country
- discovery of novel pathogens, particularly those with zoonotic potential
The information for each disease event will include the location, reporting date, a short epidemiological summary and links to relevant UKHSA guidance and further information pages.
Epidemic intelligence activities for the ‘Outbreaks under monitoring’ report
Epidemic intelligence (EI) is a structured methodology for detecting, assessing and communicating new and emerging public health threats, with an early warning objective. EI processes are undertaken each weekday by specialised scientists in the EIZ team.
Signals are predominantly detected using the World Health Organization’s Epidemic Intelligence from Open Sources (EIOS) platform. The EIOS platform collates thousands of articles daily from a broad range of publicly available sources including media, government and ministry of health websites and news aggregators.
All relevant signals are recorded in a dedicated EI database, which includes details on the date and source of the signal, a description of the incident, its geographical location, and an EI confidence rating (which depends on the source of the information). Where possible, official sources of information are sought to verify signals. Subsequent reports with any new information are also recorded. See Epidemic intelligence activities for further information.
Signals logged in the database are discussed by the EIZ team for inclusion in the report as per inclusion criteria below.
Definitions of the reporting parameters
Disease or pathogen
This refers to the infectious disease in the inclusion criteria that is being reported.
Location
This refers to the country where the disease event was reported.
Reporting date
This refers to the date the signal was first reported in the public domain.
Summary
A short descriptive epidemiology summary of the disease event being reported.
Further information
This provides links to available background information and guidance from UKHSA, the World Health Organization or other government guidance (for example, the European Centre for Disease Prevention and Control, United States Centers for Disease Control and Prevention) where applicable. Links to UKHSA risk assessments will be provided where available.
Disease inclusion criteria for posting on the new ‘Outbreaks under monitoring’ report
This list is a guide and not exhaustive and will be subject to ongoing review.
| Disease or pathogen | Inclusion criteria |
|---|---|
| Andes virus infection | Report all confirmed Andes virus cases |
| Report single travel-associated cases (rare) in Europe | |
| Report human to human transmission particularly in health care settings | |
| Anthrax | Report outbreaks where a source is still unknown, particularly in European countries |
| Report any bio-terrorism incidents or potential incidents where there is justified or reasonable suspicion of a deliberate act | |
| Arboviruses (Dengue, Zika virus, yellow fever, Oropouche fever, Chikungunya, West Nile virus, Japanese encephalitis) | Report arboviral outbreaks in popular UK tourist destination where there may be a risk to UK nationals |
| Report changes in vector distribution in Europe | |
| Report arboviral outbreaks beginning out of season, or exceedance in cases | |
| Report first detections of arbovirus in a vector in countries particularly in Europe | |
| Report autochthonous cases in new areas | |
| Argentine haemorrhagic fever (Junin virus) | Report the first case of the season in endemic areas and updates to national data over the season thereafter |
| Report cases occurring outside of transmission season | |
| Include media reports of single cases in non-endemic areas | |
| Report single cases and clusters outside of endemic regions | |
| Avian influenza A(H7N9) and (H5N1) | Report the first human case of the season, and updates to national data over the season |
| Report detections in a new mammalian species for the first time only if there are associated human cases | |
| Report novel subtype | |
| Avian influenza A(H5N6) and (H7N7) | Report all human cases |
| Report detections in a new mammalian species for the first time only if there are associated human cases | |
| Report novel subtype | |
| Bolivian haemorrhagic fever (Machupo virus) | Report the first case of the season in endemic areas and updates to national data over the season thereafter |
| Report cases occurring outside of transmission season Include media reports of single cases in non-endemic areas | |
| Report single cases and clusters outside of endemic regions | |
| Botulism | Report outbreaks where there may be implications for UK nationals or international travellers (for example, Paris Rugby World Cup outbreak associated with a restaurant and resulted in cases reported from multiple countries) |
| Cholera | Report ongoing outbreaks with countries with British interest or popular UK tourist destinations |
| Report outbreaks in a new country or geographical region of a country for the first time | |
| Report on outbreaks with evidence of case export regionally or internationally (particularly to Europe) | |
| Coronaviruses (COVID-19 and other emerging coronaviruses) | Report new variants detected for the first time with implications for more transmissibility and disease severity |
| Report newly designated variants of concern | |
| Exclude variants under monitoring (VUMs) and variants under investigation (VUIs) | |
| Surge in cases particularly in Europe | |
| Crimean Congo haemorrhagic fever (CCHF) | Report the first case of the season, and updates to national data over the season |
| Report every CCHF human case from non-endemic countries | |
| Report changes in competent vector distribution (Hyalomma ticks) | |
| Report first detections of CCHFV in ticks, animals or humans in a country | |
| Diphtheria | Report notable outbreaks only – particularly in migrant populations in Europe |
| Ebola virus disease (EBOD) | Report all cases |
| Hepatitis A&E | Report notable outbreaks in Europe or where there may be exposure risk to UK nationals, report exceedances in cases in developed countries |
| Lassa fever | Report cases and clusters in non-endemic countries |
| Report when there is an exceedance in case numbers (for example, higher case numbers than the 5-year average) or a change in epidemiology or seasonality in endemic countries (country specific) | |
| Legionella infection | Report clusters of Legionnaires’ disease in Europe and other developed countries or tourist destinations where UK nationals are more likely to be affected (for example, hotel outbreak) |
| Lujo virus disease | Report all cases |
| Marburg virus disease (MARD) | Report all cases |
| Middle East respiratory syndrome (MERS) | Report all cases |
| Mpox (all clades) | Country reporting cases (all clades) for the first time |
| Country reporting exceedance in cases outbreak associated with a mass gathering event (for example, festivals) | |
| Change in epidemiological characteristics | |
| Surge in cases in a country which is a tourist destination for UK travellers | |
| Multidrug-resistant or extensively drug-resistant tuberculosis | Report exceedances in cases in countries with strong links to the UK or migrant populations that might travel to the UK |
| Nipah virus infection | Report all cases |
| Novel pathogens | Report newly detected (novel) pathogens or strains in animals or humans where there is substantial media traction or zoonotic potential |
| Pertussis | Report exceedance in cases or notable outbreaks in Europe |
| Pneumonic plague (Yesinia pestis) | Report all cases of pneumonic plague |
| Exclude reports of bubonic plague or where plague type is unspecified in endemic countries | |
| Report all cases of plague occurring in a new country for the first time | |
| Report outbreaks where plague type is unspecified with substantial cases or mortality, or triggering high media attention | |
| Polio | Report all human cases and environmental detections in new countries or where detections are rare, particularly in the European region |
| Rabies | Report all travel-associated cases in UK and Europe |
| Report animal and human detections in low-risk countries with interest to UK nationals. | |
| Severe acute respiratory syndrome (SARS) | Report all cases |
| Severe fever with thrombocytopaenia syndrome (SFTS) | Report the first case of the season, and updates to national data over the season |
| Report cases or peaks occurring outside of transmission season | |
| Report cases in countries reporting SFTS for the first time | |
| Sexually transmitted infections (STIs) | Report cases of extensively drug-resistant or multidrug-resistant Shigella or gonorrhoea |
| Report notable increases in other STIs, particularly if strong links to UK, for example USA or Europe | |
| Tick-borne diseases (for example, Lyme disease, tick-borne encephalitis, Powassan virus, babesiosis) | Reporting outbreaks and exceedance of previous numbers in countries in Europe |
| Zoonotic influenzas | Report all new sub-types and first cases in humans. |
| Countries reporting case numbers and deaths above usual seasonal levels | |
| Report all human swine influenza A(H1N1)v cases |