Bacillus anthracis (anthrax) and Bacillus cereus can infect all persons, since illness may result from eating contaminated foods. However, those with compromised immune systems as well as the very young and old may suffer the most serious side effects.

Inhalation of anthrax spores can affect persons who handle contaminated animal products as well as those who come in contact with mail or packages contaminated with spores by terrorists. People who work directly with animals, such as laboratory personnel or veterinarians, may be at a higher risk for anthrax.

B. cereus and B. anthracis may also pose a higher risk for those working in food preparation areas and slaughterhouses. Although intact tissues and meat from animals are sterile, they may become contaminated after slaughter.

Generally, the nausea, cramp-like abdominal pains, and watery diarrheal symptoms from B. cereus resolve by themselves, although some individuals may require medical intervention. Infections of anthrax (B. anthracis) cause severe symptoms that require medical attention.