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.
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)
Youth must be given awareness regarding HIV infection before they get engaged in sexual activities. Parent counseling and monitoring can play an important role in communicating the preventive measures to the youth. They must reinforce on health messages and let their children know how to protect from infectious diseases like HIV.
As according to the research, it was found that the minority and African youth MSM are unaware of their HIV infection and thus they put their partners' life in risk too. Regular checkup and tests should be taken of the young people. In most of the cases of sex abuse, people are unable to come back to their normal life but they get addict of drugs and alcohol which leads them towards sexual activities. They must be given proper psychological therapy so that they may come out of the dilemma.
CDC has employed multifaceted approach to address the large number of HIV infections existing in U.S. young people. It has conducted effective interventions that can be locally organized to make a high impact. These programs include Project AIM that aims to reduce HIV risk activities among youth; Empowerment program for the welfare of bisexual men and young gay; guiding programs encouraging regular HIV testing and building positive social connections.
CDC is also engaged in research so that to better understand particular community or population and develop interventions to bring positive changes in course of high rate of HIV infection among youth. These research programs include:
Division of Adolescent and School Health gathers data and present report on youth health risk activities. Moreover, it brings school-based health policies and practices in to account and also develop strategies for institutes to promote health among youth.
Youth Risk Behavioral Surveillance System is a system that observes six types of health risk behaviors that may lead to disability and death among teens and youth. These include sexual risk behaviors and drug use.
Division of HIV / AIDS Prevention aims to evaluate intervention programs like those for teen African-American girls in juvenile detention facilities, Hispanic parents and young African-American MSM. It also promotes preventive measures through media that is by gaming systems, mobile phones, social media, websites, comics and stories.
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.