The continuing challenge of infectious diseases
Authors: Karen H Keddy, Tesfaye Gobena
Journal: The Lancet Infectious Diseases (2024)

In 2019, 2540 million (95% uncertainty interval [UI] 2290–2810) disability-adjusted life years (DALYs) were attributed to non-communicable and communicable diseases and injuries globally.1Vos T Lim SS Abbafati C et al.Global burden of 369 diseases and injuries in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019.Lancet. 2020; 396: 1204-1222Summary Full Text Full Text PDF PubMed Scopus (7510) Google Scholar In The Lancet Infectious Diseases, the IHME Pathogen Core Group have now estimated a burden of 704 million (610–820) DALYs to be associated with 85 pathogens (encompassing causative agents, pathogen groups, infectious diseases, and aggregate categories),2IHME Pathogen Core GroupGlobal burden associated with 85 pathogens in 2019: a systematic analysis for the Global Burden of Disease Study 2019.Lancet Infect Dis. 2024; (published online April 16.)https://doi.org/10.1016/S1473-3099(24)00158-0Google Scholar or more than a quarter (27·7%) of all DALYs attributable to disease and injury, in 2019. Although the primary disease burdens in high-income and upper-middle-income countries included cardiovascular diseases and cancer,1Vos T Lim SS Abbafati C et al.Global burden of 369 diseases and injuries in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019.Lancet. 2020; 396: 1204-1222Summary Full Text Full Text PDF PubMed Scopus (7510) Google Scholar low-income and lower-middle-income countries were disproportionately affected by infectious diseases.2IHME Pathogen Core GroupGlobal burden associated with 85 pathogens in 2019: a systematic analysis for the Global Burden of Disease Study 2019.Lancet Infect Dis. 2024; (published online April 16.)https://doi.org/10.1016/S1473-3099(24)00158-0Google Scholar According to super-region, the greatest fraction of pathogen-associated DALYs among the all-cause DALY burden was estimated in sub-Saharan Africa, irrespective of age, and the region's proportions were greater than the global DALY proportions for infectious diseases (regional contribution of pathogen-associated DALYs to all-cause DALYs in children aged <5 years was 79·3% in sub-Saharan Africa versus 65·5% globally, and in individuals ≥5 years, 45·2% in sub-Saharan Africa versus 19·1% globally; compared with 16·5% in children <5 years and 9·7% in individuals ≥5 years in the high-income super-region).2IHME Pathogen Core GroupGlobal burden associated with 85 pathogens in 2019: a systematic analysis for the Global Burden of Disease Study 2019.Lancet Infect Dis. 2024; (published online April 16.)https://doi.org/10.1016/S1473-3099(24)00158-0Google Scholar As could be expected, tuberculosis, malaria, and HIV or AIDS were the leading pathogens in terms of associated DALY burden,2IHME Pathogen Core GroupGlobal burden associated with 85 pathogens in 2019: a systematic analysis for the Global Burden of Disease Study 2019.Lancet Infect Dis. 2024; (published online April 16.)https://doi.org/10.1016/S1473-3099(24)00158-0Google Scholar despite the considerable efforts made to combat these diseases. The overall DALY burden attributed to malaria was estimated at 65·7 million (95% UI 37·1–105·3) in 1990,3Shi D Wei L Liang H Yan D Zhang J Wang Z Trends of the global, regional and national incidence, mortality, and disability-adjusted life years of malaria, 1990–2019: an analysis of the Global Burden of Disease Study 2019.Risk Manag Healthc Policy. 2023; 16: 1187-1201Crossref PubMed Scopus (1) Google Scholar compared with an associated DALY burden of 53·6 million (27·0–91·3) in 2019.2IHME Pathogen Core GroupGlobal burden associated with 85 pathogens in 2019: a systematic analysis for the Global Burden of Disease Study 2019.Lancet Infect Dis. 2024; (published online April 16.)https://doi.org/10.1016/S1473-3099(24)00158-0Google Scholar Nevertheless, variation in incidence and death was previously reported across regions.3Shi D Wei L Liang H Yan D Zhang J Wang Z Trends of the global, regional and national incidence, mortality, and disability-adjusted life years of malaria, 1990–2019: an analysis of the Global Burden of Disease Study 2019.Risk Manag Healthc Policy. 2023; 16: 1187-1201Crossref PubMed Scopus (1) Google Scholar The largest number of incident cases was estimated in western sub-Saharan Africa (115·2 million [95% UI 89·0–152·7]) in 2019, followed by eastern sub-Saharan Africa (56·4 million [42·4–73·2]). The highest number of deaths was estimated in western sub-Saharan Africa, at 0·4 million (95% UI 0·2–0·7) deaths, followed by eastern sub-Saharan Africa (0·1 million [0·05–0·2]). Despite an overall decrease in global DALYs attributable to malaria over the 30-year period from 1990 to 2019, malaria DALYs increased in western sub-Saharan Africa (1990: 22·8 million [95% UI 11·5–39·3); 2019: 27·4 million [13·5–48·1]).3Shi D Wei L Liang H Yan D Zhang J Wang Z Trends of the global, regional and national incidence, mortality, and disability-adjusted life years of malaria, 1990–2019: an analysis of the Global Burden of Disease Study 2019.Risk Manag Healthc Policy. 2023; 16: 1187-1201Crossref PubMed Scopus (1) Google Scholar In 2019, the global age-standardised DALY burden for tuberculosis in HIV-negative individuals was estimated at 59·0 million (95% UI 53·7–64·6).4Xue Y Zhou J Wang P et al.Burden of tuberculosis and its association with socio-economic development status in 204 countries and territories, 1990–2019.Front Med (Lausanne). 2022; 9905245Google Scholar This burden comprised 53·4 million (46·7–59·7) DALYs for drug-susceptible tuberculosis, 5·2 million (2·3–9·8) DALYs for multidrug-resistant tuberculosis, and 0·4 million (0·2–0·7) DALYs for extremely drug-resistant tuberculosis.4Xue Y Zhou J Wang P et al.Burden of tuberculosis and its association with socio-economic development status in 204 countries and territories, 1990–2019.Front Med (Lausanne). 2022; 9905245Google Scholar In 2019, an estimated 52·1 million (95% UI 46·6–60·9) DALYs were associated with HIV or AIDS.2IHME Pathogen Core GroupGlobal burden associated with 85 pathogens in 2019: a systematic analysis for the Global Burden of Disease Study 2019.Lancet Infect Dis. 2024; (published online April 16.)https://doi.org/10.1016/S1473-3099(24)00158-0Google Scholar The global age-standardised DALY rate for HIV or AIDS increased by 221·9 (95% UI 204·4–239·5) DALYs per 100 000 cases compared with 1990.5Tian X Chen J Wang X et al.Global, regional, and national HIV/AIDS disease burden levels and trends in 1990–2019: a systematic analysis for the Global Burden of Disease 2019 study.Front Public Health. 2023; 111068664Google Scholar Also in 2019, higher age-standardised incidence rates were observed in low sociodemographic index (SDI) countries compared with high SDI countries.5Tian X Chen J Wang X et al.Global, regional, and national HIV/AIDS disease burden levels and trends in 1990–2019: a systematic analysis for the Global Burden of Disease 2019 study.Front Public Health. 2023; 111068664Google Scholar The combined burdens of HIV and tuberculosis remain concerning, and variation has been reported in the trends of drug-susceptible and drug-resistant tuberculosis in HIV-positive individuals.4Xue Y Zhou J Wang P et al.Burden of tuberculosis and its association with socio-economic development status in 204 countries and territories, 1990–2019.Front Med (Lausanne). 2022; 9905245Google Scholar In 2019, the global age-standardised DALY burden in HIV-positive individuals with tuberculosis was estimated at 13·7 million (95% UI 10·1–17·6) for drug-susceptible tuberculosis, 1·3 million (0·6–2·5) for drug-resistant tuberculosis, and 0·05 million (0·02–0·09) for extremely drug-resistant tuberculosis, representing an annualised age-standardised rate of change of –33·8%, –30·1% (1990–2019), and 3·3% (2010–19), respectively.4Xue Y Zhou J Wang P et al.Burden of tuberculosis and its association with socio-economic development status in 204 countries and territories, 1990–2019.Front Med (Lausanne). 2022; 9905245Google Scholar Although the global DALYs associated with tuberculosis in HIV-negative individuals decreased by 62·8% (95% CI 58·0–66·6) during 1990–2019, the incidence of extremely drug-resistant tuberculosis in HIV-positive patients has increased differentially across countries over 2010–19, and disproportionately so in countries in sub-Saharan Africa.4Xue Y Zhou J Wang P et al.Burden of tuberculosis and its association with socio-economic development status in 204 countries and territories, 1990–2019.Front Med (Lausanne). 2022; 9905245Google Scholar Notably, the analysis by the IHME Group is focused on 2019,2IHME Pathogen Core GroupGlobal burden associated with 85 pathogens in 2019: a systematic analysis for the Global Burden of Disease Study 2019.Lancet Infect Dis. 2024; (published online April 16.)https://doi.org/10.1016/S1473-3099(24)00158-0Google Scholar which preceded the COVID-19 pandemic. Recent estimates have indicated that the global age-standardised all-cause mortality rates decreased between 1950 and 2019 by 62·8% (95% UI 60·5–65·1), but increased during the early COVID-19 pandemic period between 2020 and 2021 by 5·1% (0·9–9·6).6GBD 2021 Demographics CollaboratorsGlobal age-sex-specific mortality, life expectancy, and population estimates in 204 countries and territories and 811 subnational locations, 1950–2021, and the impact of the COVID-19 pandemic: a comprehensive demographic analysis for the Global Burden of Disease Study 2021.Lancet. 2024; (published online March 11.)https://doi.org/10.1016/S0140-6736(24)00476-8Google Scholar In addition, during the pandemic there were substantial failures in low-income and lower-middle-income countries in the control of the big three (malaria, HIV, and tuberculosis), including failures in national vaccination programmes, due to national lockdowns, overburdened health systems with COVID-19 cases, and reallocation of public health funding to cope with the pandemic. The early mortality rate estimates for the first 2 years of the pandemic might yet increase, as mortality data for vaccine-preventable childhood infections of malaria, HIV, and tuberculosis become available.6GBD 2021 Demographics CollaboratorsGlobal age-sex-specific mortality, life expectancy, and population estimates in 204 countries and territories and 811 subnational locations, 1950–2021, and the impact of the COVID-19 pandemic: a comprehensive demographic analysis for the Global Burden of Disease Study 2021.Lancet. 2024; (published online March 11.)https://doi.org/10.1016/S0140-6736(24)00476-8Google Scholar Despite clear evidence that infectious disease burdens can be reduced with appropriate interventions, with global burden estimates for most infectious diseases decreasing considerably between 1990 and 2019,1Vos T Lim SS Abbafati C et al.Global burden of 369 diseases and injuries in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019.Lancet. 2020; 396: 1204-1222Summary Full Text Full Text PDF PubMed Scopus (7510) Google Scholar emerging challenges such as antimicrobial resistance,7Murray CJL Ikuta KS Sharara F et al.Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis.Lancet. 2022; 399: 629-655Summary Full Text Full Text PDF PubMed Scopus (4520) Google Scholar vaccine hesitancy, and increasing in-country inequality, as measured by the Gini index8Adeleye BN Income inequality, human capital and institutional quality in sub-Saharan Africa.Soc Indic Res. 2024; 171: 133-157Crossref Scopus (1) Google Scholar, 9Ochi A Inequality and the impact of growth on poverty in sub-Saharan Africa: a GMM estimator in a dynamic panel threshold model.Reg Sci Policy Pract. 2023; 15: 1373-1395Crossref Scopus (2) Google Scholar (with most countries in sub-Saharan Africa having an index >35·3 [low income] or >45·1 [middle income]8Adeleye BN Income inequality, human capital and institutional quality in sub-Saharan Africa.Soc Indic Res. 2024; 171: 133-157Crossref Scopus (1) Google Scholar) might mean that these gains are not sustained. There is an urgent need to identify why well established interventions, such as the acceptability of vaccination, water, sanitation, and hygiene, and antimicrobial stewardship, are failing, whether interventions are implemented as intended, what dynamics within a country influence implementation, and how context might affect the outcomes.10Ridde V Pérez D Robert E Using implementation science theories and frameworks in global health.BMJ Glob Health. 2020; 5e002269Crossref Scopus (61) Google Scholar Defining infection disease burdens is not an end in itself; we now need to understand how to sustainably reduce these burdens. We declare no competing interests. Global burden associated with 85 pathogens in 2019: a systematic analysis for the Global Burden of Disease Study 2019Our detailed breakdown of DALYs associated with a comprehensive list of pathogens on a global, regional, and country level has revealed the magnitude of the problem and helps to indicate where research funding mismatch might exist. Given the disproportionate impact of infection on low-income and middle-income countries, an essential next step is for countries and relevant stakeholders to address these gaps by making targeted investments. Full-Text PDF Open Access