Social epidemiology is the study of the causes and distribution of diseases. Social epidemiology can reveal how social problems are connected to the health of different populations. These epidemiological studies show that the health problems of high-income nations differ greatly from those of low-income nations. Some diseases, like cancer, are universal. But others, like obesity, heart disease, respiratory disease, and diabetes, are much more common in high-income countries, and are a direct result of a sedentary lifestyle combined with a poor diet. High-income nations also have a higher incidence of depression (Bromet et al., 2011). In contrast, low-income nations suffer significantly from malaria and tuberculosis.

How does health differ around the world? Some theorists differentiate between three types of countries: core nations, semi-peripheral nations, and peripheral nations (see Chapter 10. Global Society). Sociologists describe core nations as highly developed or industrialized; semi-peripheral nations are often developing or newly industrialized; and peripheral nations are relatively undeveloped. While the most pervasive issue in the Canadian care system is timely access to health care and access to family doctors, semi-peripheral and peripheral nations face a host of additional concerns. Reviewing the status of global health offers insight into the various ways that politics and wealth shape access to health care, and it shows which populations are most affected by health disparities.

One clear trend that emerged in the social epidemiological literature is the shift in the type of diseases and health issues that affect populations as societies modernize. The epidemiologic transition or “health transition” refers to the long-term change in a population’s dominant health problems or profile, from acute infectious diseases to chronic, degenerative diseases, as societies modernize and develop (Omram, 1971; Young, 1988). Infectious diseases, like measles, influenza, chronic diarrhea, tuberculosis, and plague, refer to diseases caused by micro-organisms such as bacteria or viruses, and are often communicable, leading to epidemic outbreaks. These are diseases common to sedentary societies exposed to water-borne pathogens, human waste, the diseases of domesticated animals, nutritional deficits, and periodic famine. Chronic diseases, like cancer, heart disease, diabetes, hypertension, and obesity, are non-communicable and characterized by the slow onset of symptoms. They are more characteristic of the causes of death in societies that have higher standards of living, better access to a regular supply of nutritious food, public sanitation measures, and immunization programs to control infectious diseases. They have often been referred to therefore as “diseases of modernization” or “Western diseases” because they are symptomatic of effects of modernization on longevity and lifestyle.

Health in High-Income Societies

Obesity can be used as an example to illustrate the issue of chronic diseases in high-income societies. Obesity is on the rise in high-income nations and has been linked to many diseases, including cardiovascular problems, musculoskeletal problems, diabetes, and respiratory issues. According to the Organisation for Economic Co-operation and Development (2013), obesity rates are rising in all countries, with the greatest gains being made in the highest-income countries. The United States has the highest obesity rate for adults, while Canada rated fifth. Wallace Huffman and his fellow researchers (2006) contend that several factors are contributing to the rise in obesity in developed countries:

1. Improvements in technology and reduced family size have led to a reduction of work to be done in household production.
2. Unhealthy market goods, including processed foods, sweetened drinks, and sweet and salty snacks are replacing home-produced goods.
3. Leisure activities are growing more sedentary; for example, computer games, web surfing, and television viewing.
4. More workers are shifting from active work (agriculture and manufacturing) to service industries.
5. Increased access to passive transportation has led to more driving and less walking.

Obesity and weight issues have significant societal costs, including lower life expectancies and higher shared health care costs.

While ischemic heart disease caused by narrowed heart arteries is the single most prevalent cause of death in higher-income countries, cancers of all types combine to be a higher overall cause of death. Cancer accounts for twice as many deaths as cardiovascular disease in higher-income countries (Mahase 2019).

High-income countries also have higher rates of depression than less affluent nations. A recent study (Bromet et al., 2011) shows that the average lifetime prevalence of major depressive episodes in the 10 highest-income countries in the study was 14.6%; this compared to 11.1%t in the eight low- and middle-income countries. The researchers speculate that the higher rate of depression may be linked to the greater income inequality that exists in the highest-income nations. “The poorest respondents in France, Germany, New Zealand and the USA had an approximately twofold increased odds of MDE compared with those in the highest income group” (Bromet et al., 2011).

Health in Low-Income Societies

In peripheral nations with low per capita income, it is not the cost of health care that is the most pressing concern; rather, low-income countries must manage such problems as infectious disease, high infant mortality rates, scarce medical personnel, and inadequate water and sewer systems. Such issues, which high-income countries rarely even think about, are central to the lives of most people in low-income nations. Due to such health concerns, low-income nations have higher rates of infant mortality and lower average life spans.

One of the biggest contributors to medical issues in low-income countries is a lack of access to clean water and basic sanitation resources. According to a 2011 UNICEF report, almost half of the developing world’s population lacks improved sanitation facilities. The World Health Organization (WHO) tracks health-related data for 193 countries. In their 2021 World Health Statistics report, they document the following statistics:

1. Globally in 2019, the rate of mortality for children under five was 38 per 1,000 live births, which is a dramatic change from previous decades. In 1990, the rate was 93 deaths per 1,000 births. In low-income countries, however, that rate is much higher. The child mortality rate in low-income nations was 11 times higher than that of high-income countries—76 deaths per 1,000 births compared to 7 deaths per 1,000 births. To consider it regionally, the highest under-five mortality rate remains in the WHO African Region (74 per 1000 live births), around 9 times higher than that in the WHO European Region (8 per 1000 live births) (World Health Organization, 2021).
2. The most frequent causes of death in children under five years old are pneumonia, diarrhea, congenital anomalies, preterm birth complications, birth asphyxia/trauma, and malaria, all of which can be prevented or treated with affordable interventions including immunization, adequate nutrition, safe water and food, and quality care by a trained health provider when needed (World Health Organization, 2021).
3. The availability of doctors and nurses in low-income countries is one-tenth that of nations with a high income. Challenges in access to medical education and access to patients exacerbate this issue for would-be medical professionals in low-income countries (World Health Organization, 2011).

Media Attributions

• Figure 19.6 Mozambique 02100 by Steve Evans, via Flickr, is used under a CC BY-NC 2.0 licence.