EPIDEMIOLOGY

ADVANCED PUBLIC HEALTH

WEEK 1-COMPLIATION

INTRODUCTION TO EPIDEMIOLOGY

Exercise 1.1

Define epidemiology

Answer:

Epidemiology is defined as “the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the prevention and control of health problems”

Term	Explanation
Study	Includes: surveillance, observation, hypothesis testing, analytic research and experiments.
Distribution	Refers to analysis of: times, persons, places and classes of people affected
Determinants	Include factors that influence health: biological, chemical, physical, social, cultural, economic, genetic and behavioral
Health-related states and events	Refer to: diseases, causes of death, behaviors such as use of tobacco, positive health states, reactions to preventive regimes and provision and use of health services.
Specified populations	Include those with identifiable characteristics, such as occupational groups.
Application to prevention and control	The aims of public health—to promote, protect, and restore health.

Exercise 1.2

Discuss the historical background of epidemiology to it recent development in the modern age.

Answer:

Epidemiology originates from Hippocrates’ observation more than 2000 years ago that environmental factors influence the occurrence of disease. However, it was not until the nineteenth century that the distribution of disease in specific human population groups was measured to any large extent.

Epidemiologic thinking has been traced from Hippocrates (circa 400 B.C.) through Graunt (1662), Farr, Snow (both mid-1800’s), and others.

Hippocrates (circa 400 B.C.) attempted to explain disease occurrence from a rational instead of a supernatural viewpoint. In his essay entitled “On Airs, Waters, and Places,” Hippocrates suggested that environmental and host factors such as behaviors might influence the development of disease.

John Graunt, a London haberdasher who published his landmark analysis of mortality data in 1662. He was the first to quantify patterns of birth, death, and disease occurrence, noting male-female disparities, high infant mortality, urban-rural differences, and seasonal variations

In the mid-1800’s, William Farr began to systematically collect and analyze Britain’s mortality statistics. Farr, considered the “father of modern vital statistics and surveillance”, developed many of the basic practices used today in vital statistics and disease classification. He extended the epidemiologic analysis of morbidity and mortality data, looking at the effects of marital status, occupation, and altitude. He also developed many epidemiologic concepts and techniques still in use today.

In 1854, John Snow was conducted a series of investigations in London that later earned him the title “the father of field epidemiology.” Twenty years before the development of the microscope, Snow conducted studies of cholera outbreaks both to discover the cause of disease and to prevent its recurrence.

Epidemiology in its modern form is a relatively new discipline and uses quantitative methods to study diseases in human populations to inform prevention and control efforts.

For example, Richard Doll and Andrew Hill studied the relationship between tobacco use and lung cancer, beginning in the 1950s.Their work was preceded by experimental studies on the carcinogenicity of tobacco tars and by clinical observations linking tobacco use and other possible factors to lung cancer. By using long-term cohort studies, they were able to establish the association between smoking and lung cancer

Exercise 1.3

What is the scope/focus of epidemiology?

Answer:

A focus/ scope of an epidemiological study is the population defined in specific geographical area or other terms; for example, a specific group of hospital patients or factory workers could be the unit of study.

Exercise 1.4

Outline the role of epidemiology in public health

Answer:

Public health refer to the collective action taken to improve population health. Hence, with the aim of improving population health, epidemiology serves as a major tool in such action.

Therefore, Epidemiology is a tool that is essential for carrying out four fundamental functions or roles pertaining to the improvement of population health: public health surveillance, disease investigation, analytic studies, and program evaluation

·         Identification of the cause of disease (analytic studies)

o   Epidemiology and information from epidemiologic methods are largely used to identify the causes of most disease, mode of transmission with the aim of developing appropriate control and preventive methods/measures for such disease. Hence, when the cause of a disease is known it becomes easier to develop preventive policies to prevent its occurrence.

o   Diabetes, for example, has both genetic and environmental components

o   It is also used to determine the effectiveness of preventive intervention on a population through health promotion.

 

 

 

·         Determine the natural history of diseases (disease investigation)

o   Information from epidemiology methods are used to determine the course and outcome of disease in a particular population, individuals or groups.

o   This gives a clear picture of the disease process and curative measures to implement prevent the spread of the disease, improve changes of recovery and prevent death.

 

·         To assess the health status of populations (public health surveillance)

o   Epidemiology is often used to assess and describe the health status of population groups

o   Knowledge of the disease burden in populations (health status of population) is essential for health authorities, who seek to use limited resources to the best possible effect by identifying priority health programmes for prevention and care.

·         Evaluation of intervention (program evaluation)

o   Epidemiology and information from epidemiologic methods are used to evaluate the effectiveness and efficiency of health services/ Programme/ intervention.

o   This means determining things such as the appropriate length of stay in hospital for specific conditions, the value of treating high blood pressure, the efficiency of sanitation measures to control diarrheal diseases and the impact of reducing lead additives in petrol

 

Exercise 1.5

In the early 1980’s, epidemiologists recognized that AIDS occurred most frequently in men who had sex with men and in intravenous drug users.

Describe how this information might be used for each of the following:

·         Population or community health assessment

·         Individual decisions

·         Search for causes

Answer:

·         Population or community health assessment.

To effectively assess the health of population or community, the public health officer must determine whether health care services are available, accessible, affordable and efficient.

In the course of this, the public health officer finds answers to questions such as: what are the actual and potential health problem in the community? Who is at risk? Which health problems are increasing or have the potential to increase? Which health problems are declining or have the potential to decline? How does this relate to the level and distribution of service available.

Hence, the information provided in the early 1980’s, clearly indicates that AIDS occurred most frequently in men who had sex with men and in intravenous drug users.

Therefore, the actual health problem present is AIDS. The people at risk are men and intravenous drug users. The health problem that is increasing and have the potential to increase is AIDS.

This clearly indicated that level and distribution of health services and program available is inadequate and ineffective to curb the existing health problem.

·         Individual decisions

Over the years, Epidemiology and information generated from epidemiologic methods and research have consciously or unconsciously influenced the health behavior and choices of people in every aspects of their lives every day.

The information provided in the early 1980’s, clearly indicates that AIDS occurred most frequently in men who had sex with men and in intravenous drug users.

This epidemiologic information will largely influence the choices of most men pertaining to selection of sexual partners. It shall make men resort to female sexual partners and do so with sexual protection to avoid contracting AIDS.

This information will also influence the route of drug administration by most drug users. It may also cause them to be meticulous with any drug administration via the intravenous route.

This and many more epidemiologic information are relevant to the choices that people make pertaining to the health and these choices affects their lives over time.

·         Search for causes

Information obtained from epidemiologic methods and research are geared towards the search for causes and factors that influence the risk of disease occurrence.

The information provided in the early 1980’s, clearly indicates that AIDS occurred most frequently in men who had sex with men and in intravenous drug users.

This demonstrates that the cause of AIDS is associated with sexual and drug related health behaviors. Hence, factors that influence the occurrence of this disease is when men have sex with men and when drug users administer drugs via the intravenous route.

The identification of causes of a disease can result in the identification of preventive method/measures for the disease

Exercise 1.6

Outline few achievements in epidemiology

Answer:

Epidemiology and information from epidemiologic methods have contributed enormously to the elimination or eradication of the following diseases:

·         Smallpox

o   eradication of smallpox

o   non subclinical carriers

o   No human host

·         Methyl mercury poisoning (Minamata disease)

o   Poisonous mercury substances from minamata factory were introduced into water bodies.

o   awareness were raised

o   interventions were provided

·         Rheumatic fever and rheumatic heart disease

o   Epidemiology find out that poor housing accounts largely for rheumatic fever.

o   People turned to build proper houses.

·         Iodine deficiency diseases

o   cause of Goiter

o   Intervention such as production of iodated salt to solve iodine deficiency.

·         Tobacco use, asbestos and lung cancer

·         Hip fractures

o   Development of modifiable measure to reduce rip fracture in the aged.

·         HIV/AIDS

o   Identity the risk factors that predispose one to getting HIV.

o   Provided intervention for the prevention, treatment and control.

·         Severe acute respiratory syndrome (SARS).