My recent trip to Thailand renewed my interest in and respect for the field of epidemiology. Both the friends we visited are epidemiologists, with fascinating stories to tell about their work.

Julia recently worked for the Centers for Disease Control's Epidemic Intelligence Service. When anthrax cases began appearing in late 2001, she worked long hours in Washington, D.C., helping to manage the crisis. She was part of a team of investigators who analyzed each anthrax case, compiled data, and helped organize a rapid response when a new suspected case was reported.

That's just one of the interesting investigations she has done during her career.

Her husband, Dimitri, works for an organization devoted to controlling the spread of HIV/AIDS in Asia. Though based in Bangkok, he travels to Papua, New Guinea, Cambodia and other countries in the Asia-Pacific region, helping identify how HIV spreads in each country in order to develop effective prevention programs.

Epidemiology is often thought of as the study of epidemics, but it is also the study of health trends as they affect public health. To fully understand the patterns of disease and health issues, epidemiologists investigate every aspect of a problem in order to find solutions and ultimately prevent or at least control their spread.

Without epidemiologists, individual health care providers would not be nearly as effective, because we would lack a deep understanding of the patterns of disease and other health issues.

When a new disease emerges (such as SARS, Ebola or mad cow disease), or a significant health trend is recognized (such as the obesity epidemic or child abuse), epidemiologists may be dispatched to investigate.

Epidemiologists gather information to determine how widespread a problem is.

They may find just 22 cases of anthrax or millions of cases of malaria worldwide. Epidemiologists collect and analyze data, so we have statistics that tell us how many cases of a disease have occurred, where and when they happened, and the outcomes.

Then, they determine the cause of the problem. For an infectious disease, the cause may be a virus, bacteria, fungus, parasite or prion. For a health issue such as Sudden Infant Death Syndrome (SIDS), epidemiologists found that parental smoking and putting babies to sleep on their stomachs are risk factors.

Epidemiologists also examine how a disease is spread. For example, West Nile Virus spreads via mosquito bites, many types of diarrheal diseases can spread through contact with improperly chlorinated water in swimming or wading pools, tuberculosis spreads when an infected person coughs and hepatitis B is spread through sexual or blood-to-blood contact.

Understanding what types of people are affected by a health problem is the next step. Black inner-city children have high rates of asthma when they live in cockroach-infected buildings. Sleep apnea affects twice as many middle- aged men as women. Travelers to tropical areas are at risk for dengue fever.

Once the scope of the problem, the causes, how it is spread and who is at risk is fully understood, epidemiologists help public health agencies and health care providers focus efforts on the prevention and treatment of the problem.

The Epidemic Intelligence Service is in large part responsible for the worldwide eradication of smallpox in the 1970s. I hope the eradication of polio will be next.

Epidemiologists are detectives. Not only do they collect all the pieces of a puzzle, but they also put them together so it makes sense. They use statistics to chart trends, so that proactive steps can be taken to minimize future health risks. The ultimate goal of epidemiology is to protect everyone's health.

Kathryn B. Brown is a family nurse practitioner with a master's degree in nursing from OHSU. Is there a health topic you would like to read about? Send ideas to You can find more local health news and information in the Health section at


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