Sunday, August 9, 2015

Germ Warriors by Clint Willis ****

Germ Warriors edited by Clint Willis is an anthology of stories about epidemiology and diagnosis. If it was a TV series, it might be named: CDC: The deadly cases.

For example, the chapter on food-borne pathogens explored the ubiquitous nature (30-50% incidence in some cases) of e coli and salmonella with emphasis on the dual challenges of today's large-scale and international food market.

First, with food items, both fresh and packaged, being sourced internationally, it is impossible for the USDA to monitor quality. However, this is a bit of a red herring, as the USDA doesn't even have resources to monitor domestic food production.

The second point is that  the scale of operations magnifies problems and makes tracking difficult.
A single patty may mingle meat of a hundred different animals from four different countries. ... a single contaminated carcass ... can pollute eight tons of finished ground beef.
The chapter on the challenge of diagnosing rare diseases was one of the best. The example was a case of necrotizing fasciitis that "kills up to 70 percent of the people that get it."

This chapter introduces the Zebra problem:
an old saying taught in medical school: if you hear hoofbeats in Texas, think horses not zebras [Actually the phrase was coined by Dr. Theodore Woodward, professor at the University of Maryland School of Medicine, with no reference to Texas.]
For every case of necrotizing fasciitis, there are 3,000 cases of cellulitis with very similar symptoms.

In addition to necrotizing fasciitis, e coli and salmonella, the book covers ebola, plague, malaria, AIDS, Lassa virus, and mad cow disease. The anthology contains a diverse collection of (sometimes scary) stories of brave and dedicated medical scientists working to identify, prevent, and treat a wide collection of (fortunately) rare diseases.

Don't read it if you have unidentified symptoms or tendencies towards hypochondria.

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