Global and regional burden of 34 key pathogens in the elderly population in 2021: A systematic analysis of the global burden of disease study 2021

Background Infectious diseases caused by bacterial and viral pathogens remain major contributors to global mortality and disease burden, especially for older adults. Despite progress in disease control, the pathogen-specific burden across multiple disease categories, especially among the elderly population, has not been comprehensively quantified. This study estimates the global and regional burden of 34 key pathogens in 2021, with a specific focus on mortality and disability-adjusted life years (DALYs) in older adults. Method This study utilized data from the Global Burden of Disease (GBD) 2021 study to estimate mortality and DALYs attributable to 34 key bacterial and viral pathogens across 204 countries and territories. Pathogen-specific contributions were determined using the GBD comparative risk assessment framework and cause-of-death ensemble modeling. Age-standardized death and DALYs rate were calculated, and variations were examined across Socio-demographic Index (SDI) categories and geographic regions. Uncertainty intervals (UIs) were generated through Monte Carlo simulations. Findings In 2021, Staphylococcus aureus was the leading pathogen, responsible for 325,165 deaths (95 % UI: 281,827–356,269) and 4766,188 DALYs (95 % UI 4218,780–5202,881), with age-standardized rate of 32.40 death (95 % UI 27.94–35.53) and 459.37 DALYs (95 % UI 404.90–501.85) per 100,000 population. Pathogens such as Respiratory syncytial virus , Enteropathogenic E. coli , and Aeromonas caused the least global burden. Regionally, Staphylococcus aureus was the primary cause of mortality and DALYs in 15 of 21 GBD regions, with the highest mortality in Eastern Sub-Saharan Africa and the highest DALYs rate in Southern Sub-Saharan Africa. Streptococcus pneumoniae and Staphylococcus aureus were the leading contributors to infectious disease burden in elder populations, with their impact increasing with age. A strong inverse correlation was observed between SDI and age-standardized rate of death and DALYs, with lower SDI regions, such as Sub-Saharan Africa, bearing the highest burden. Interpretation This study highlights the disproportionate impact of infectious pathogens on older adults, particularly in low-SDI regions, and underscores the need for targeted interventions, resource allocation, and healthcare improvements to address this growing public health challenge. These findings provide critical insights to inform global strategies for reducing pathogen-related mortality and disability among the elderly population.