Horizon Priority Pathogens
Horizon Priority Pathogens is a carefully curated watchlist published by Beyond the Horizon Project, designed to identify and prioritise infectious disease threats of significant concern to public health within the United Kingdom. This list is regularly reviewed and updated based on expert analysis, ongoing epidemiological surveillance, and comprehensive risk assessments. Pathogens included on the watchlist have been selected due to their current or potential threat, considering factors such as transmissibility, severity, zoonotic potential, and likelihood of emergence or re-emergence. The primary aim of the Horizon Priority Pathogens watchlist is to highlight diseases that warrant increased vigilance, proactive preparedness, and targeted policy interventions, enabling earlier detection and response to potential health security risks.
Tuberculosis (TB) and Multi-Drug Resistant Tuberculosis (MDRTB)
England continues to see a sustained increase in tuberculosis (TB), with 1,172 cases reported in Q1 2025—maintaining the elevated levels recorded in 2024 (UKHSA, 2025). The 2024 total reached 5,480 cases, marking a 13% year-on-year rise from 2023. Notification rates have risen to 9.5 per 100,000 population, approaching the World Health Organization’s low-incidence threshold. The majority of cases (81.5%) occurred in people born outside the UK. Multi-drug resistant TB (MDR-TB), although less common, poses a significant treatment challenge, with ongoing concerns about delayed diagnosis and treatment adherence in vulnerable populations. London and the West Midlands remain the most affected regions.
Type: Bacterial Infectious Disease
Region: England-wide; notably London and West Midlands
Date: Continued increase noted in Q1 2025
Risk Level: High
Status: Persistent and rising
Mpox (Monkeypox) – Clade Ib Importation
Multiple Mpox cases linked to Monkeypox virus Clade Ib reported in the UK, latest case in London February 2025 linked to travel from Uganda (UKHSA, 2025). Clade Ib presents increased severity and higher fatality compared to previous strains (ECDC, 2025). Transmission remains limited to close contacts, with no broader community spread.
Type: Zoonotic Viral Disease
Region: UK (London); linked to travel from Uganda
Date: First detected in October 2024
Risk Level: Moderate
Status: Active (Under Surveillance)
Marburg Virus Disease (Imported Risk)
Tanzania outbreak of Marburg virus declared January 2025 in Kagera region, 10 cases and 9 deaths reported (90% fatality rate) (WHO, 2025). UK risk low but high impact if imported due to virus lethality and potential rapid spread in healthcare settings (ECDC, 2025).
Type: Viral Haemorrhagic Fever (Filovirus)
Region: No UK cases; Active outbreak in Tanzania (Kagera region)
Date: Outbreak declared January 2025
Risk Level: Low (high consequence if imported)
Status: Watch (International Outbreak Monitoring)
Measles Resurgence
The UK is experiencing a significant resurgence of measles due to reduced MMR vaccination coverage exacerbated by vaccine hesitancy and disruption during COVID-19. Scotland reported its worst measles outbreak in 25 years, with clusters concentrated in Glasgow (Public Health Scotland, 2025). England recorded over 150 confirmed cases between January and March 2025, primarily concentrated in London (UKHSA, 2025). Measles is highly contagious, posing severe risks including pneumonia and encephalitis.
Type: Viral Infectious Disease
Region: UK-wide; notably Scotland (Glasgow) and England (London)
Date: First resurgence noted in November 2024
Risk Level: High
Status: Active and escalating
Avian Influenza A(H5N1)
Highly pathogenic avian influenza A(H5N1) widespread among UK poultry and wildlife. Human infection confirmed in West Midlands January 2025, linked to infected poultry (The Guardian, 2025). March 2025 detection in sheep in Yorkshire raises concerns about mammalian adaptation and increased zoonotic risks (CIDRAP, 2025). Potential for genetic reassortment poses pandemic threat.
Type: Zoonotic Viral Disease
Region: UK (poultry farms, wildlife); human case in West Midlands
Date: January 2025 (first human case identified)
Risk Level: Moderate
Status: Active (Animal outbreaks); Human cases monitored closely