Uses of Epidemiology

Epidemiology describes disease occurrence. Identifies the causes of disease, finds factors that increase a person’s risk of disease, describes the extent of disease in a population and also describes the natural history of a disease. Epidemiology describes the characteristics of a disease. Evaluates preventive measures. Guides policy decisions, can be used to describe both healthy and unhealthy populations.  Can be used to describe the population demographically

Track trends

Uses surveys to measure status of the population. Establishes risk factors. Determines the health of a community

Specialties in Epidemiology

There are many specialties in epidemiology similar to what is found in medicine. For examples, chronic disease, behavioral, environmental, forensic, genetic, infectious disease, injury, perinatal, reproductive health, social, and violence epidemiology.

Epidemiology and Research

Important roles of epidemiology

               Monitors the health status of a population. Searches for risk factors.  After a hypothesis is developed;it  provides descriptive analysis of problem and

conduct a study to test hypotheses          

Scientific Method

A rigorous set of rules designed to describe the health status of a population. It helps explain etiology. Serves as a basis for developing  prevention and control programs

The steps used to conduct epidemiologic research

Determine the primary agent. Understand causation. Determine characteristics of agent. Determine mode of transmission. Determine contributing factor. Assess geographic patterns. Define natural history

Determine control measures. Determine prevention measures

Planning health services

Determine hypothesis (or tentative explanation)

              Hypothesis

Purpose

To develop a statement based on sound biological theories that can be tested.

               Null hypothesis

Stated as if the investigator believes there will be no relationship between the study factors and the outcome

               Epidemics

This refers to a disease or condition that affects a greater than expected number of individuals at the same time.  Number of events far less important than the change from normal occurrence in the past. Normal occurrence of disease in a population is known as endemic level.

Epidemic threshold : The upper end of normal range of disease occurrence for a specific population, time frame, and location.

Pandemic:  A geographically widespread epidemic. For example, plague of Athens in 430-427 and 425 BC. Spanish Flu 1918-1919

HIV is currently a pandemic. Infection rates as high as 25% in southern and eastern Africa. AIDS could kill 31 million people in India and 18 million in China by 2025. AIDS death toll in Africa may reach 90-100 million by 2025

Historical Milestone in Epidemiology.

In many cases, diseases were controlled using research methods before identifying the responsible agent.  Smallpox vaccine was developed 160 years before virus was identified (Edward Jenner). Association between dirty water and cholera was found 44 years before bacteria was identified  (John Snow). Child bed fever was associated with physician’s unclean hands 32 years before causal agent discovered ( Ignaz Semmelweis)

James Lind successfully treated scurvy with limes, lemons, and oranges 175 years before ascorbic acid was discovered. Joseph Goldberger proved pellagra was of nutritional origin 10 years before vitamin B3 was discovered

Ethics in Epidemiology

There are several important reasons to study ethics and use ethical principles. Epidemiology involves individuals. Subjects often derive no direct benefit and personally identifiable information may be collected ( SSN, DOB and Full name) Studies are  often funded from public sources

 Human Subject Research:

Defined as any research activity involving people. Includes original research where information are collected from subjects by questionnaires or by a research of existing records. Secondary data analysis of census or health data published by federal agencies does not fall under the human subjects’ research umbrella.

History

Code of ethics was developed because of scientific abuses. Nazi human experimentation in concentration camps. Experiments resulted in death, disfigurement or permanent disability. They serve as examples of medical torture, lacked informed consent.

                    The Nuremberg Code

Scientific abuses led to development of Nuremberg Code.  Key elements of the Nuremberg Code are

Voluntary consent, expected to provide yield fruitful results. Based on animal studies and natural history, avoid all unnecessary physical and mental suffering. No “a priori ‘reason to believe harm will occur. Degree of risk never outweighs benefit. Provider proper facilities, preparation and equipment. Conduct research by scientifically qualified persons. Subjects can always “quit “. Scientist must always be willing and able to end study.

The Belmont Report

Identifies three fundamental ethical principles for all human subject research. Respect for persons. Beneficence and justice. Principles remain the basis for HHS human subject protection regulations.