Watch list of diseases and public health signals, Hajj-Umrah, 2025–2026

The Hajj and Umrah mass gathering in Makkah attracts pilgrims from over 190 countries, more than half of whom are elderly and from resource-limited regions. Air travel, highly mixed demographics, preexisting chronic conditions, animal importation and sacrifice, and regional climate and environmental challenges challenge on-site clinical care and global disease epidemiology necessitate frequent review of public health events. We synthesized current outbreak reports from global and national stakeholders to identify infectious non-infectious public health events and signals and their implications for to Hajj and Umrah -2025/2026. Infectious disease signals include zoonotic and vector-borne diseases such as Chandipura virus and Naegleria fowleri in India, Nipah virus in South Asia, Rift Valley fever in Africa, and New World screwworm in Latin America. Influenza (H5N1, H9N2), Meningococcal disease, mpox, polio, and Ebola remain risks. Hajj-Umrah clinicians may encounter patients with diseases caused by West Nile, Dengue, Chikungunya, measles viruses. Clinicians may detect antimicrobial resistance and mass gatherings may amplify antimicrobial resistance, with multidrug-resistant respiratory pathogens frequently detected among pilgrims. Risks of above infections include expansion of transmission, and introduction to host country populations. Non-infectious threats—heat-related illness, crowd trauma, cardiometabolic decompensation, and mental fatigue—remain persistent hazards. This summary excludes many other endemic diseases that are public challenges in many countries. Some signals are self-limiting and do not pose a threat to Umrah and Hajj or global health security, but awareness of them can improve clinical acumen. Some conditions deserve global attention given the potential for continued transmission. Targeted vaccination, surveillance, and syndromic vigilance remain key preventive pillars. Genomic and environmental surveillance innovations can transform these events into platforms for early detection and prevention of emerging public health threats.