At the time this episode aired, anthrax counted as an exotic disease. Although military scientists had weaponized it by this point, this was not common knowledge despite Nixon's order to destroy all stocks (carried out in the early 1970s). Production of weapons-grade anthrax was limited to rich, powerful governments; the disease didn't really become a household word until a series of attacks carried out through the mail in the early 21st century brought it to public attention.