What are people dying of in the world?

About 56 million people die every year. Many of these deaths will occur far away; others will occur among us. Many of them we may never know about... This is a small guide to the main causes of death.

According to data collected by Our World in Data, about 56 million people die in the world every year. The leading cause of death is cardiovascular disease; nearly 18 million lives are lost to it, about a third of the total. And if they are grouped into a single category, cancers are responsible for almost 10 million deaths. Overall, 73% die from non-contagious diseases.

Deaths due to infectious diseases now account for 19%. This group includes mainly respiratory (2.56 million) and digestive (2.38 million) diseases, including diarrhea (1.6 million). A quarter of a century ago, the percentage of deaths due to infectious diseases was 33%, and, in general, it is higher in poor countries.

The drop from 33 percent to 19 percent is linked to progress. The poorer a country is, the higher the percentage of deaths due to infectious diseases. The opposite is true for non-infectious diseases. The other large category of deaths is that of injuries, but these hardly vary over time and represent 8% (it was 9% 25 years earlier).

Almost 4% of children die before their fifth birthday. In other words, nearly six million die each year. The main direct cause of death for these children is respiratory infections (about 800,000). One out of every three people who die from them is under the age of five. 650,000 babies under the age of one month die from neonatal conditions or complications. And diarrhea is also a major cause of infant death; although the number has fallen sharply, about half a million children die from it.

Together, these conditions are responsible for a large loss of life. So are road traffic accidents (1.2 million deaths, many of them among adolescents and young people), and acquired immunodeficiency syndrome (AIDS), which kills nearly 1 million people (84 percent under 50). Of the 800,000 who take their own lives each year, 460,000 are under 50.

At the opposite extreme are the various forms of dementia, which are responsible for 2.5 million deaths annually. That figure has risen sharply and will continue to rise as life expectancy increases because of the decline, especially in deaths due to infectious diseases. It is precisely for that reason that it does not result in the loss of many years of life.

Three causes of death do not have the quantitative relevance of the previous ones but receive a lot of media attention; they are homicides, terrorist attacks, and natural disasters. Some 400,000 people die each year from homicide, and 26,000 from terrorist acts. Natural disasters cause 9,600 deaths.

Hunger, tobacco, and obesity

When we talk about causes of death we refer to the proximate or immediate causes, to the diseases that cause them. As we know, some factors increase or decrease the probability of contracting diseases that can be fatal.

According to the FAO, around six million children under the age of five die every year from hunger. The total number of lives lost to hunger is certainly close to nine million, but it is the under-fives who are most vulnerable to its effects. A small proportion of these deaths are due to starvation. Most are caused by a persistent lack of food and essential nutrients, which leaves children weak, underweight, and vulnerable.

On the other hand, every year eight million people die from tobacco, and obesity is responsible for almost five million deaths; in both cases, half are under 70 years old. Alcohol kills 2.8 million people (two million of whom are under 70). Finally, there are environmental factors: air pollution causes the death of 3.4 million, and household pollution causes 1.6 million.

The Covid-19 arrives

In 2020, a new term has been introduced into this macabre accounting: the covid-19 pandemic. As of May 18, there have been more than 315,000 confirmed deaths worldwide from this cause, although the actual figure is surely much higher. As an example, in Spain, the deaths recorded in the civil registers were, between March 17 and May 5, of the order of 56% more than in the same period in other years.

It can be assumed that this excess of deaths is due to the effects of the disease so actual deaths from this cause represent about 30% more than those officially reported for the same period. Assuming that, overall, the actual number of deaths in the rest of the world is underestimated to a similar extent, there would be 400,000 deaths per covid-19 to date.

We still do not know what percentage of infected people die from SARS-CoV-2. If it were 0.1% and all human beings could be infected, the total number of deaths could, hypothetically, reach 7m.

If it were 0.1% and all humans could be infected, the total number of deaths could hypothetically be as high as 7 million. According to the data in the ENE-COVID report on seroprevalence, published on 13 May, and other studies, this percentage is probably higher than 0.5%, so deaths around the world could easily exceed six figures. It would thus become a significant factor in mortality.

The above figures do not include all the people who will die from indirect causes, which we could call the side effects of the virus. Fortunately, global food trade has been able to be sustained for the time being, but as Maximo Torero, FAO's chief economist, has warned, the measures taken by most countries to curb the effects of covid-19 could also have devastating consequences, due to serious disruptions in the world's food supply.

Thousands of lives will be lost due to other causes. It has been estimated that between 253 500 and 1 157 000 children under five and 12 200 to 56 700 mothers in developing countries will die over the next six months due to deteriorating health systems and food availability. Thousands of lives will be lost due to the economic downturn caused by restrictions on activity and mobility. And many people are also more than likely to die from avoiding going to the hospital for fear, perhaps, of contracting the disease.

Many of these deaths will occur far away; others will occur among us. Many of them may never be recorded.

By Juan Ignacio Pérez Iglesias, Professor of Physiology, University of the Basque Country / Euskal Herriko Unibertsitatea. This article was originally published in The Conversation.