The diseases that kill people most often can depend heavily on where they live. World Health Organization data shows a sharp divide between high- and low-income countries.
Chronic illnesses dominate mortality in wealthier nations, while infectious diseases, newborn complications and other preventable conditions remain major killers in poorer countries.
The global pattern of death has also changed considerably over the past two decades. In 2000, four of the world’s 10 leading causes of death were noncommunicable diseases. By 2019, seven of the top 10 were chronic conditions, reflecting the growing impact of heart disease, cancer, diabetes and other long-term illnesses as populations age and life expectancy increases.
Ischemic heart disease remained the world’s leading cause of death, followed by stroke and chronic obstructive pulmonary disease, or COPD. Lower respiratory infections, neonatal conditions, cancers of the trachea, bronchus and lung, Alzheimer’s disease and other dementias, diarrheal diseases, diabetes and kidney disease also ranked among the leading causes.
Heart disease leads worldwide
Heart disease has remained the world’s leading cause of death for two decades, but its toll has grown substantially.
Ischemic heart disease caused about 2 million deaths worldwide in 2000. By 2019, that figure had climbed to nearly 9 million, accounting for about 16% of all deaths globally.
The increase reflects the broader shift toward noncommunicable diseases as populations live longer and face a growing burden of chronic health conditions.
Chronic diseases dominate wealthier nations
In high-income countries, the leading causes of death are overwhelmingly noncommunicable diseases.
Ischemic heart disease ranks first, followed by Alzheimer’s disease and other dementias and stroke. Lung cancer, COPD, lower respiratory infections, colorectal cancer, kidney disease, hypertension and diabetes also feature prominently among the top causes.
Dementia stands out as one of the clearest differences between richer and poorer nations. Alzheimer’s disease and other dementias are among the leading causes of death in high-income countries but do not rank among the top 10 in low-income countries, where people are more likely to die at younger ages from infectious and preventable diseases.
Preventable conditions hit poorer countries harder
Low-income countries face a markedly different mortality pattern.
Neonatal conditions are the leading cause of death, followed by lower respiratory infections, ischemic heart disease, stroke and diarrheal diseases. Road traffic injuries also rank among the major causes.
The disparity is particularly evident among newborns. Neonatal conditions are not among the top 10 causes of death in high-income countries but remain the leading cause in low-income nations, highlighting the importance of access to quality maternal and newborn care.
Diarrheal diseases provide another stark example. They remain the fifth-leading cause of death in low-income countries but have largely disappeared from the leading causes in wealthier nations, where access to clean water, sanitation and medical treatment is generally greater.
Infectious diseases remain a major threat
Medical advances have reduced the global impact of several infectious diseases, but they continue to take a heavy toll in poorer countries.
Malaria, tuberculosis and HIV/AIDS ranked sixth, eighth and ninth, respectively, among the leading causes of death in low-income countries. None ranked among the top 10 in high-income countries.
Globally, HIV/AIDS fell from eighth among the leading causes of death in 2000 to 19th in 2019. Deaths linked to the virus in Africa also fell by more than half during that period. Tuberculosis likewise dropped out of the global top 10.
Diabetes deaths rise
While several infectious diseases have declined, diabetes has moved in the opposite direction.
Deaths from diabetes increased by about 70% worldwide between 2000 and 2019, with an increase of about 80% among men. The trend reflects the growing global burden of chronic disease and the health challenges associated with aging populations and changing lifestyles.
Road traffic deaths show another divide
Road injuries are another major cause of death in poorer countries.
Traffic crashes ranked as the seventh-leading cause of death in low-income nations. Deaths from road injuries increased by nearly 50% in Africa and the Eastern Mediterranean between 2000 and 2019.
The higher toll is linked to a range of factors, including road safety conditions, access to emergency medical care and the strength of transportation infrastructure.
Respiratory infections remain deadly
Lower respiratory infections, including pneumonia, remain among the deadliest communicable diseases worldwide.
They are one of the few infectious causes to rank among the leading causes of death in both high- and low-income countries. They ranked sixth in high-income countries and second in low-income nations, illustrating how differences in health care access can influence survival from the same disease.
People are living longer
The WHO data also points to significant gains in life expectancy.
Global average life expectancy reached about 73 years in 2019, roughly six years higher than at the beginning of the century. However, those additional years were not all spent in good health. About five of the six added years were lived in good health, according to the data.
Longer lives have also contributed to the growing prevalence of age-related diseases, including dementia and some cancers.
Cancer is more prominent in wealthier countries
Cancer is another major cause of death in high-income nations.
Cancers of the trachea, bronchus and lung and colorectal cancer rank among the leading causes of death in those countries. They do not appear among the top 10 causes in low-income nations, where people are more likely to die earlier from infectious diseases, neonatal conditions and other preventable illnesses.
COVID-19 changed the mortality landscape
The WHO figures used for the global rankings cover the period through 2019, before the COVID-19 pandemic dramatically altered patterns of illness and death.
The pandemic caused more than 1.5 million reported deaths during its early period and placed unprecedented pressure on health systems. It also highlighted the heightened risks faced by people with underlying conditions such as diabetes, heart disease and chronic respiratory illnesses.
Understanding why people die is critical to improving public health.
Accurate mortality records allow governments to identify the diseases responsible for the greatest number of deaths, assess the effectiveness of their health systems and determine where limited resources should be directed.
Yet many low-income countries still lack comprehensive systems for registering deaths and determining their causes. Without reliable data, governments can struggle to establish how many people are dying, what is killing them and which health problems require the most urgent attention.
The global differences in mortality reveal more than a list of diseases. They show how income, health care, sanitation, living conditions and life expectancy can influence both how long people live and the health conditions they face along the way.
