1. DoD Cholinesterase Reference Laboratory , Joint Base San Antonio-Fort Sam Houston, TX 78234, USA
2. Division of Epidemiology and Disease Surveillance, U.S. Army Public Health Command-Central , Joint Base San Antonio-Fort Sam Houston, TX 78234, USA
3. DoD Food Analysis and Diagnostic Laboratory , Joint Base San Antonio-Fort Sam Houston, TX 78234, USA
4. U.S. Army Public Health Command-Central , Joint Base San Antonio-Fort Sam Houston, TX 78234, USA