I vectorized this with Inkscape from a public domain line drawing I found on Wikipedia by a user named "Rama". I also have posted this SVG file to the Wikimedia Commons:
http://commons.wikimedia.org/wiki/Image:Caduceus.svg
Original drawing:
http://commons.wikimedia.org/wiki/Image:Caduceus_large.jpg
Teacher silhouette black and white with desk and blackboard - Silhouette en noir et blanc d'une enseignante avec pupitre et tableau noir - Lehrerin Silhouette schwarz und wei
This image was donated by Pearson Scott Foresman, an educational publisher, to Wikimedia Commons, and is thereby in the Public Domain. --- See http://commons.wikimedia.org/wiki/Category:Pearson_Scott_Foresman_publisher
This image was donated by Pearson Scott Foresman, an educational publisher, to Wikimedia Commons, and is thereby in the Public Domain.
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See http://commons.wikimedia.org/wiki/Category:Pearson_Scott_Foresman_publisher