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Conducting outbreak investigations

Recently the book Deadly outbreaks - How medical detectives save lives threatened by killer pandemics, exotic viruses, and drug- resistant parasites by Alexandra Levitt has been published. Being an epidemiologist myself, although less involved in acute outbreaks of diseases, I was happy to receive a copy of the book before actual publication in return for a review of the book.

However, being busy with consultancy work during the day, I kept postponing reading the book at night, as I assumed it would feel like working again. It turned out I was wrong. From the moment I started I could actually not stop reading it. It felt like reading a thriller by Karin Slaughter, although it are actually seven books in one, as each of the chapters covers a different 'crime scene'. In this case the criminals (or serial killers) are infectious diseases, an autoimmune condition or a drug overdoses, and the investigators epidemiologists (called "disease detectives" by the U.S. Centers for Disease Control and Prevention's Epidemic Intelligence Service) and their colleagues (in e.g. animal health, environmental health, neurology, toxicology, immunology, etc).

Each chapter describes the notification of unexpected/suspicious cases of a disease, the search to find the cause of the outbreak, the investigators involved, and the final result.

As the author is a health scientist herself, the (field) epidemiological theory is also discussed, in a way I think is also clear to non-epidemiologists. Different study designs are discussed (case control studies, retrospective studies based on e.g. medical records);  the process of research from a clear case definition (definite/laboratory confirmed, probable, possible cases) to active case-finding to  data collection from cases to analyzing the data (identifying risk factors by calculating a relative risk).

The book makes very clear that epidemiologists are different from e.g. a doctor in the sense that an epidemiologist typically looks at many cases at the same time, trying to figure out what all the cases have in common (to find out why some people get ill and others are not), while a doctor looks at one patient at the time. Second, it highlights that epidemiologist are often generalists which can investigate many diseases as the research methods are in principle the same. However, epidemiologists work in a team with other (content) experts as without their knowledge, interpretation of epidemiologic results can be difficult. And the stories also illustrate that it is sometimes is important to think creatively / out of the box and just have some luck in order to find the cause of an outbreak.

My only critic is that some of the stories are fairly old (they cover the period 1976-2007), and hence probably already partly know by the public (e.g. Legionnaire's disease). However, you can only write these stories when an investigation is totally finalized hence it will take some time before stories about more recent epidemics (e.g. West Nile Fever in Texas, Salmonellosis in North Carolina, drug-resistant TB in Los Angeles) will be written up and bundled.

So it is a book to relax with, but also to learn the methodology of outbreak investigations from. And hopefully it stimulates current students to choose field epidemiology as their area of work.

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Random sampling versus randomisation

I recently examined a MPH thesis in which the student stated that “the intervention and control were assigned using a random sampling technique.” I have noted in the past that students mix-up random sampling and randomization. I therefore explain both concepts together in this article.

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3 Responses leave one →
    ron laporte


    Nice newsletter. I read with great interest. My wife and I plan to take a Safari , perhaps in Kruger National Park. I saw you were there and liked it. I was just wondering about your thoughts

    thanks so much


    dr savita shardul

    I like d article..I am an epidemiologist functioning at state HQ in India.. I want to have a copy of the same. plz guide me how?


    Dear Dr Savita, You can e.g. order the book from Amazon http://www.amazon.com/Deadly-Outbreaks-Detectives-Threatened-Drug-Resistant/dp/1626360359 Kind regards, Annette


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