Cheap Bioweapon: Newsweek had this description of Iraqi bioterror techniques:

In the Baghdad prison known as The Palace of the End, in the first years of Saddam Hussein’s reign, his torturers sometimes used a crude but effective biological weapon. They'd take an inmate with tuberculosis, who was coughing blood, and force him to spit into the mouths of others. Not all prisoners caught the disease, but all were infected with the terror.

Even without the tuberculosis, it would be equally disgusting.