Helicobacter pylori

Gastritis, peptic ulcer, possibly stomach cancer

Ingestion of contaminated food or water, esp. unpasteurized milk; contact with infected pets

Increased recognition

Legionella pneumophila

Legionnaires' disease: malaise, myalgia, fever, headache, respiratory illness

Air-cooling systems, water supplies

Recognition in an epidemic situation

Listeria monocytogenes

Listeriosis: meningoencephalitis and/or septicemia

Ingestion of contaminated foods; contact with soil contaminated with infected animal feces; inhalation of organism

Probably increased awareness, recognition, and reporting

Mycobacterium tuberculosis

Tuberculosis: cough, weight loss, lung lesions; infection can spread to other organ systems

Exposure to sputum droplets (exhaled through a cough or sneeze) of a person with active disease

Immunosuppression

Staphylococcus aureus

Abscesses, pneumonia, endocarditis, toxic shock

Contact with the organism in a purulent lesion or on the hands

Recognition in an epidemic situation; possibly mutation

Streptococcus pyogenes (Group A)

Scarlet fever, rheumatic fever, toxic shock

Direct contact with infected persons or carriers; sometimes ingestion of contaminated foods

Change in virulence of the bacteria; possibly mutation

Vibrio cholerae

Cholera: severe diarrhea, rapid dehydration

Ingestion of water contaminated with the feces of infected persons; ingestion of food exposed to contaminated water

Poor sanitation/hygiene; possibly introduced via bilge-water from cargo ships

Vibrio vulnificus

Cellulitis; fatal bacteremia; diarrheal illness (occasionally)

Contact of superficial wounds with seawater or with contaminated (raw or undercooked) seafood; ingestion (occasionally)

Increased recognition