As an aggressive flu virus sweeps the country, "Bieber Fever" is bearing down on San Antonio.
The Biebs' visit to the Alamo City may have come at the worst time for Beliebers and non-Beliebers trying to stay healthy -- and sane.
Unlike the flu, there are no known vaccinations for Bieber Fever.
Symptoms vary from case to case, but may include high-pitched screaming, increased sweating, T-shirt making, dancing, cell phone photography, high fives, headaches and sometimes fainting.
So are you sure you have the flu? Because it could be Bieber Fever. God forbid it's both. Click here to check out our Bieber Fever slideshow to see if you may be experiencing similar symptoms.
Do you have Bieber fever? Send photos of your signs, shirts and other swag to firstname.lastname@example.org!