Study: 85 pathogens cause massive loss of life globally
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Key takeaways:
- Global estimates showed that 85 pathogens were responsible for more than 700 million disability-adjusted life-years in 2019.
- The three leading pathogens were tuberculosis, malaria and HIV/AIDS.
An estimate of the global burden of 85 infectious diseases suggests they were associated with more than 700 million disability-adjusted life-years in 2019 — "a substantial portion of the overall burden from all diseases," researchers said.
The researchers described disability-adjusted life-yeas as "the sum of the years of life lost due to premature mortality and years lived with disability due to the occurrence of disease."
Experts said the findings demonstrated the need for addition research and drug development. The 85 pathogens in the study included bacteria, viruses, fungi and parasites, and some disproportionately affect young children.
“Infectious diseases are a significant cause of morbidity and mortality worldwide, particularly in low- and middle-income countries (LMICs). However, despite their substantial impact on public and global health, there is often a lack of attention and resources allocated to combat them effectively,” Mohsen Naghavi, MD, MPH, PhD, a professor of health metric science at the Institute for Health Metrics and Evaluation at the University of Washington, told Healio.
“This was the reason why our main goal behind this study was to develop the most comprehensive understanding to date of the global burden caused by 85 pathogens, pathogen groups and infectious entities,” he said.
Naghavi said that while there have been previous studies attempting estimates of the burden of infectious diseases, “a substantial gap in understanding the complete impact of various pathogens was a lingering issue.”
“We believe that providing meticulous estimates of the burden associated with each pathogen is one of the most important steps toward evidence-based priority-setting and global health policy,” he said.
Naghavi and colleagues estimated disability-adjusted life-years (DALYs) associated with 85 pathogens in 2019, globally, regionally and for 204 countries and territories, by applying a novel approach that accounted for underlying, immediate and intermediate causes of death.
They also compared the burden among all pathogens using pathogen-specific ratios created using cause of death, hospital discharge and minimally invasive tissue sampling data to incorporate the burden of immediate and intermediate causes of death.
Overall, the study showed that globally, in 2019, an estimated 704 million (95% uncertainty intervals [UI], 610–820) DALYs were associated with 85 different pathogens. Naghavi said that the majority of these pathogens also lacked a vaccine and that the burden of associated pathogens without vaccines was notably higher among children aged younger than 5 years and individuals in resource-poor settings.
Specifically, the study estimates included 309 million (95% UI, 250–377; 43.9% of the burden) DALYs in children aged younger than 5 years. This accounted for 27.7% of the previously reported total DALYs from all causes in 2019, and 65.5% in those aged younger than 5 years.
After comparing super-regions, the researchers found “considerable differences” in the estimated pathogen associated burdens in relation to DALYs from all causes. The highest burden was observed in sub-Saharan Africa (314 million; 61.5% of total regional burden) and the lowest in the high-income super-region (31.8 million; 9.8%).
The three leading pathogens responsible for more than 50 million DALYs each in 2019 were tuberculosis (65.1 million), malaria (53.6 million) and HIV/AIDS (52.1 million), according to the study. The researchers noted that malaria was the leading pathogen for DALYs in children aged younger than 5 years (37.2 million).
“Our estimation approach utilized a comprehensive measure associated with disease burden, which, to our knowledge, is the most inclusive method used to date,” Naghavi said, adding that this is important from the clinical vantage point since this measure considers all scenarios in which a pathogen contributes to death or disability — even if the cause of death is not directly attributed to the pathogen itself.
“By doing so, we captured the full impact of pathogens on mortality and disability, providing a more accurate assessment of their burden.”
Based on the study findings, Naghavi suggested that funding should be allocated “more strategically” to address specific pathogens and infections. Specifically, he said that investments in highly efficacious vaccines and novel antimicrobials could have substantial long-term health and cost benefits, even for diseases that currently have a rather low burden.
“We believe research funding should be better aligned with the burden of pathogens we have shown,” he said. “And that is exactly the reason why we conducted this study — to highlight the critical priorities for public health, including vaccine and drug production, as well as allocation of funds for pathogen prevention and treatment at both national and global levels. Our emphasis is thus on enhancing efforts in both prevention and treatment.”
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IHME Pathogen Core Group. Lancet Infect Dis. 2024;doi:10.1016/S1473-3099(24)00158-0
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