Occurring in or affecting wild animals [from the Latin silvaticus: of the woods; wild; savage]

Sylvan means forest-dwelling or occurring in wildlife.

First known use: 1661

Black gum at peak autumn, Centre County, Thickhead Mountain Wild Area of Rothrock State Forest. [Nicholas A. Tonelli @ flickr]

Sylvatic diseases are those occurring in, affecting, or transmitted by wild animals. [Ed: Here is a post-mortem image of a Cotton rat infected with Echinococcus multilocularis — ew!]

Sylvatic plague refers specifically to the form of plague in rural wildlife (in contrast to plague in urban wildlife). It is the same infectious bacterial disease, caused by the Yersinia pestis bacterium. In the wild, it primarily affects rodents such as prairie dogs. It is the cause of bubonic plague in humans.

The Black-Tailed Prairie Dog: looking almost exactly unlike a dog. [Wikimedia Commons]

Sylvatic cycle refers to the wild portion of the natural transmission cycle of a pathogen. Pathogens that contain a sylvatic cycle include trichinella, dengue viruses, and Yersinia pestis.

For instance, the domestic life cycle for T. spiralis (the cause of trichinosis) involves humans, pigs, and rodents. Pigs eat the infectious cysts in raw meat — often pork or rats [I don’t eat dog either]. If humans eat raw or undercooked infected pork, the trichinella larvae settle at the small intestine, molting four times in rapid succession into adulthood.

Trichinella spiralis in bear meat [Wikimedia Commons]

There they re-emerge to find a mate and sexually reproduce, the gravida female releasing her eggs into the intestinal villi and the male sloughs off into the lumen [woe is he]. The larvae spread via the blood stream to any organ, but preferentially look for and invade skeletal muscle cells. There, they take the muscle cells hostage.

Dengue virus and Chikungunya virus, too, have a sylvatic cycle.


Where, today, is the sylvan voice to cry:

Make straight the way for the Lord?

Ed: I don’t eat dog, swine, rodent, … or bear.

References, in order of their appearance:
  1. Sylvatic – Merriam-Webster Dictionary online
  2. Sylvatic diseases – Wikipedia
  3. Yersinia pestis – Wikipedia
  4. Sylvatic cycle – Wikipedia
  5. Trichinosis – Wikipedia
  6. TWiP 4: Trichinella life cycle podcast, January 31, 2010 – Microbe World
  7. Dengue virus – Wikipedia
  8. Trichinella –
  9. John 1:23 – The Holy Bible [KJV] (see also Isaiah 40:3)

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