Epidemiology: definition, methods, and population health applications

Epidemiology

Definition and Description of Epidemiology

The word epidemiology was derived from the Greek words where "epi" means upon, "demos" means people, and "logos" means study.

Epidemiology can be defined in detail as the study of 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. (Last, 2001)

Here, in the definition the distribution refers to analysis of persons, classes of people, places that are being affected by the specific disease and determinants refers to factors that influence population health; these factors may be chemical, physical, biological, social, economic, cultural, behavioral or genetic. Health-related states refers to causes of death, diseases and behaviors such as use of tobacco, use of health services and reactions to preventive treatments. Specified population refers to those groups who indicate identifiable characteristics and application to prevention and control is aim of public health to protect, promote and restore health.

Epidemiological study focuses on a certain population that can be defined in terms of geographical or other criteria. The population may be selected from specific country or area at a specific time. Once population is selected, it can be further divided into subgroups based on age, gender, ethnicity or so on. Epidemiologists usually study on issues related to disability, illness, and death; they are more concerned about improving health and positive health states.

Public Health refers to combined actions in course of improving population health. One of the tools used for this purpose is epidemiology. In past, epidemiology studies focused more on cause of communicable diseases and that leads to work in identification of preventive methods. (Bonita, Beaglehole, & Kjellstorm, 2006)

Steps and Methods of Epidemiology

Epidemiology employs different sound scientific methods for the inquiry of the problem. It is a data-driven process following an unbiased and systematic approach for the collection, interpretation and analysis of data.

As for basic methods, epidemiology studies make careful observations and compare them via valid comparison groups. The observations like number of persons suffering from a particular disease in a particular area and time or the frequency of exposure with disease among people are different from that what is expected. There are other scientific methods also been used in epidemiology including informatics and biostatistics with economic, behavioral, social and biologic sciences? (U.S. Department of Health and Human Services)

Epidemiology is also often called as the science of public health. It is a quantitative discipline that is based on current knowledge of statistics, probability and sound research methods. Moreover, it is also method of causal reasoning that develops and tests hypothesis defined in scientific fields like physics, behavioral sciences, biology and ergonomics.

An epidemiological study is comprised of the following steps:

Initial observation and data collection of the population to assess the high frequency of a particular disease or outbreak during a specific time period.

Develop a case by defining the percentage of population at risk because of the certain disease.

Collect and analyze data and describe disease under study by means of epidemic curve, spot map and tabulation to show the frequency rate of risk factors.

Develop hypothesis

Conduct analytical studies by measuring risks and refining hypothesis.

Test hypothesis and summarize findings

Suggest and define interventions or preventive programs.

(Health Knowledge, 2012)

Routine and Research Data Related to AIDS in USA

Acquired Immunodeficiency Syndrome or AIDS was first identified in USA in 1981 as unique disease entity. As according to statistics there were about 10 million people who suffered from human immunodeficiency virus or HIV by 1990. 17,000 people died in USA in 2009 due to AIDS. Since now, 1.7 million people in U.S. are found to be suffering from HIV, out of which 619,000 have already been died and 1.2 million people who are suffering has the higher percentage of adolescents and adults. AIDS is been considered as the most destructive infectious disease epidemics in USA since all the 50 states reported HIV diagnoses.

As according to estimates of Centre of Disease Control and Prevention or CDC, more than one million people in USA has HIV infection and one of every five HIV patients is not aware of the HIV infection he/she suffering from. Every year, about 50,000 Americans gets infected from HIV. The disease is most common among bisexual, gay and MSM people.

The higher percentage of youth in USA is getting infected of HIV. This percentage mainly includes young African America, minority races and ethnicities and Latino. There are several prevention programs running in the states who educate the public regarding the initiation and safer sex.

As according to the statistics of December 2011, young persons accounted 39% of new HIV infections in USA. Youth between the ages 15-29 showed 21% of U.S. population. Year 2009 statistics of youth ageing13-29 showed 69% of new HIV infections in U.S.. The statistics shows that U.S. youth is at high risk of HIV infection.

In 2009, 8,924 young people were diagnosed with AIDS over 40 states representing 20% of the people diagnosed with the disease. Of this percentage, 75% of the young people had age 20-24 that is 6,237 persons. Black youth ageing 13-24 showed 65% of HIV diagnoses. The highest percentage of HIV diagnoses was shown by the youth ageing 20-29.

The reason of high percentage of HIV infection among youth is unprotected sex, early age at sexual initiation and older sex partners. As according to CDC statistics of 2009, many teenagers start having sexual intercourse in their early age. About 46% of high school students have already done sexual intercourse; 5.9% of the children had sex before the age of 13. During the 3 months survey, 34.2% students reported sexual intercourse out of which 38.9% never used condom. Young people doing sexual intercourse with older partners are also at high risk of being infected with HIV. Young people in U.S. are also highly involved in usage of drugs, alcohol, and tobacco. According to CBC 2009 statistics, it was found 24.2% of the high school students are habitual of daily taking four to five alcoholic drinks in a row and 20.8% students take alcohol at least one time in a day. Alcoholic drinks are primary reason of being involved in sexual activities whether taken occasionally or regularly. Youngsters taking alcoholic drinks are more likely to get involved in unprotected sexual intercourse activities. Most of the drug addicted teens exchange sex for their need of drugs or alcohol and thus becomes the victim of AIDS. (CDC, 2011)

Epidemiological Triangle

Epidemiological triangle model is been developed by scientists to study health problems. It helps to understand about the infectious diseases like HIV / AIDS and how they spread among the population. This scientific model can be applied over number of situations.

There are three corners or vertices of triangle that are called as Agent, Host and Environment. Agent refers to the microbe causing disease; it is also called as the "What" of Triangle. Host refers to organism that harbors disease or the victim of the disease; called as "Who." Environment is the favorable external factors that help in transmitting disease infection; called as "Where" of the triangle. In the center of triangle, there is measure of time; the time describes period of illness and the life span after being infected with the disease.

Applying epidemiological triangle in case of AIDS in U.S., HIV infection act as the agent; teens have the highest percentage who are suffering from AIDS so teens are the host in a triangle. HIV infection is transmitted through bisexual, gay, men having sex with men or MSM, early age sexual intercourse and infected blood transfusion or used injections. New born baby may also suffer from AIDS if his/her mother suffers from the disease. These environmental factors help the infection to transmit in to other person's body. (AIDS, 2012)

Type of Epidemiology

In case of HIV / AIDS epidemiological study, descriptive epidemiology is applied. Since, researches have already made enough research on environmental factors and people suffering from AIDS so in this case, there is a need to prepare interventions and control measures. Moreover, in this study, the difference in statistics of African-American teens has been explained and number of occurrences or HIV cases are explained as is done in case of descriptive epidemiology.

In the recent HIV cure research, it was stated that though there is no cure yet been discovered for the disease but there are preventive measures to keep one safe. There are other cure approaches been developed to increase the life period of AIDS patient. Better cure is been discovered for dealing with viral latency, stem cells transplants and VISCONTI cohort. Further researches are also been carried on African-American teens and HIV Transmission Risks. (Highleyman, 2012)

The Government of Obama is also putting maximum efforts to create AIDS- free Generation. For this purpose, U.S. contribute highly for the Global Fund to Fight AIDS and other infectious diseases. In 2011, 40 million people were been tested for HIV and provided counseling. It is because of these efforts that the increasing rate of AIDS is now been controlled to some extent. (The White House, 2012)