What is Epidemiology?

How likely you are going to change your health-related behavior, if your provider suggests so?

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How do you prefer to wear your clothes?

Monday, February 14, 2011

Big epidemiology event - SARS

Let me share my own experience with SARS (Severe Acute Repiratory Syndrome) when I was in China. It started in 2002 when I was a freshman in college.

SARS is a very big one time epidemiology event from 2002 to 2003. According to the fact sheet from CDC, it is a fatal respiratory disease caused by a coronavirus in human. Patient would have high fever at the beginning, then pneumonia mostly. It could spread by close person-to-person contact, such as hugging, kissing. [1] There are  8,098 SARS cases from 29 countries were reported to the World Health Organization (WHO) in total with 9.6% case-fatality rate. [2] It was a very scary epidemiology event.

As I remembered that was my first year in college, I was so excited about being a college student and finally be away from my parents. :) Suddenly, SARS started without any early signs.  At the very beginning, the media in China blocked this bad news, no one knows about it and no one knows how serious it is. Especially, when SARS began, it was around Chinese New Year. A lot of people were travelling to their homes or going shopping for their New Year party and every public area became very crowd, such as airport, train station, bus station, as well as all shopping malls and markets. But no one knows a fatal disease is spreading. I think this is the most pathetic thing. 

Until SARS became uncontrollable, the media start to report this disease. And Chinese government began to report to CDC and WHO. Because of the delay reporting, we all think this happens to fast and became extremely dangerous too quickly. Because this infectious disease is very severe and can be infect person-to-person based on CDC and WHO's announcement, everyone began to panic and was afraid to go out and talk in public. 
Meanwhile, there were a lot of legislations passed. For example, no any activities that require more than 10 people presenting at the same time. Every single people needs to measure their own body temperature every day and report to their community. Anyone whose temperature excess normal temperature must report to their local SARS control center and quarantine for at least seven days.  every college had to close and forbid any student go out or come in, including my college. 

So, at that time, I couldn't go home or any where... I have to stay at my college without any classes, everybody should stay at their own apartment and minimize the chance of getting infection. We had been lock at school for a whole semester. As a student should feel so good to have a semester without any classes, but none of my classmates are happy. I wish the media in China could report SARS earlier and the Chinese government should report it to CDC and WHO earlier. If we could control it at first place instead of letting it spread, it won't become so serious and it won't destroy so many lives...

This is the most serious epidemic event that I've been lived with. Below is the picture of a school in China showing a professional spraying disinfectant for every classroom.

1. Severe Acute Repiratory Syndrome (SARS) fact sheet, CDC. http://www.cdc.gov/ncidod/sars/factsheet.htm
2. Revised US Surverllance Case Definition for Severe Acute Repiratory Syndrome (SARS) and Update on SARS Cases -- United States and Worldwide, December 2003. MMWR, CDC. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5249a2.htm

The picture is cited from http://www.sdshiyan.sd.cn/shiyan/sch_news/2003/0421/news2.htm

Sunday, February 13, 2011

What is epidemiology?

As I said that this blog is going to share with you what I learned in epidemiology, so the first topic would be the very basic concept: what is epidemiology, exactly?

What is your answer to the survey question at the very beginning of my blog? The answer should be all of them. Did you get it right? I have to be honest with you. Before taking this course, I thought epidemiology included only the first two areas: study of distribution and determinants. Based on the text book, it also includes applications. [1 (page3)] 

Additionally, before learning this course, I thought epidemiology was a very light job, because I only thought of epidemiology when some outbreak of certain disease happened. After learning the basic concepts of epidemiology, I realize that there are three different types of prevention, which include primary prevention even before something happens, such as immunization. [1 (page6)] Therefore, epidemiology is actually an underestimated job, because if no outbreak happens, their efforts are easy to be ignored by population; while if outbreak happens, people always blame them...

Based on the epidemiology triangle (Figure 1) below from the textbook, any epidemiology events are caused by interaction of the host (mostly means "who" gets the disease), an infectious agent (mainly means "what" causes the disease), and the environment factor (normally means "where" the disease occurs). The vector is a media which transmit the disease. [1 (page19)] Let's use tuberculosis as an example, the host would be human, the agent would be bacteria that causes TB, and the environment would be unsanitary environment. The vector should be air, because it spread by air when TB patients cough or sneeze. [2]

Figure 1. Epidemiology triangle 

Also, I learned how to determine and investigate a outbreak. Firstly, if a disease exceeds its normal frequency of occurrence, we consider it as a epidemic disease. Secondly, we need to figure out how long its incubation period is by interviewing people and figure out the specific group. Thirdly, calculate the attach rate in order to get an idea of what determinants are. Lastly, come up some recommendations for controlling and preventing this disease. [1 (chapter2)]

But I am still confused about whether epidemiology is only dealing with infectious diseases. Does it also include other non-infectious diseases, such as diabetes?

1. Gordis L. Epidemiology. 4th ed. Elsevier. 2008. ISBN: 9781416040026
2. Konstantinos, A (2010). Testing for tuberculosis, Australian Prescriber. 33 (1): 12-18.

Welcome to my blog!

Welcome to my blog for epidemiology. As a new comer in this interesting area, I will post any topics after I learn them. If you are also a new comer, I wish we could learn it together. If you are an expert, please correct me if I made any mistake. :)