Essentials of Anatomy and Physiology

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Table 22–3 DISEASES CAUSED BY BACTERIA (Continued)

Bacterial Species Discussion/Disease(s) Caused

Brucellaspecies

gram () bacillus

Haemophilus influenzae

gram () bacillus

Haemophilus aegyptius

gram () bacillus

Bordetella pertussis

gram () bacillus

Vibrio cholerae

gram () bacillus

(comma shaped)

Vibrio parahaemolyticus

gram () bacillus

(comma shaped)

Vibrio vulnificus

gram () bacillus

(comma shaped)

Campylobacter jejuni

gram () helical bacillus

Helicobacter pylori

gram () helical bacillus

Legionella pneumophila

gram () bacillus

Mycobacterium tuberculosis

acid-fast bacillus

Brucellosis (undulant fever): extreme weakness and fatigue, anorexia, a fever that rises

and falls. Reservoirs are cattle, sheep, goats, and pigs; people acquire infection by

contact with contaminated animal products. In the U.S., this is an occupational dis-

ease: meat processing workers, vets, farmers. Vaccines are available for animals.

Meningitis in children, especially those less than 2 years of age. Older people may have

mild upper respiratory infections or a potentially fatal epiglottitis. The vaccine (Hib)

contains the capsules of the bacteria and is recommended for infants beginning at

age 2 months. This was the most common cause of meningitis in the U.S., approxi-

mately 20,000 cases per year. The vaccine has provided a 90% reduction.

Conjunctivitis: painful inflammation of the conjunctiva; spread by direct contact or

fomites; may occur in epidemics among groups of children. No vaccine.

Whooping cough (pertussis): paroxysms of violent coughing that may last for several

weeks. Adults may have less severe coughing and go undiagnosed. Pneumonia is a

complication that may be fatal, especially for children less than 1 year of age. People

are the only host. Concern about the safety of the original vaccine has prompted the

development of newer vaccines, but in the U.S. the number of cases has increased

sharply, in part because of parental complacency.

Cholera: profuse watery diarrhea; infection ranges from mild to fatal. Spread of infection

is usually by way of water contaminated with human feces. Rare in the U.S.; epi-

demic in Asia, Africa, and South America. A new oral vaccine seems very effective.

Enteritis: diarrhea and nausea. Acquired by ingestion of raw or lightly cooked seafood;

usually self-limiting.

Gangrene and septicemia: acquired from ocean water that contaminates a wound or by

the ingestion of raw shellfish. Illness is often severe and protracted, and it may be

fatal, especially for people who are immunosuppressed or who have liver disease. No

vaccine.

Enteritis: diarrhea that is often self-limiting but may be severe in the elderly or very

young. Reservoirs are animals such as poultry; people acquire infection from contam-

inated meat. In the U.S., estimates are 2 million cases per year. No vaccine.

Gastric ulcers: most are caused by H.pylori, which has also been implicated in cancer of

the stomach.

Legionellosis, which occurs in two forms: Legionnaire’s disease is a pneumonia that may

be fatal; Pontiac fever is a mild upper respiratory infection that is usually self-limiting.

The bacteria are found in natural water, including soil, and may contaminate air con-

ditioning systems or water supplies. Person-to-person transmission does not seem to

occur. Has become an important cause of nosocomial pneumonia. No vaccine.

Tuberculosis (TB): formation of tubercles containing bacteria and white blood cells, usu-

ally in the lung. Lung tissue is destroyed (caseation necrosis) and is removed by

macrophages, leaving large cavities. The bacteria are spread by respiratory droplets

from people with active cases. Many people acquire a primary infection that

becomes dormant and is without symptoms, yet may be triggered later into an

active secondary infection. The BCG vaccine is not used in the U.S., but is in other

parts of the world. In the U.S., TB cases are frequent among homeless people, those

with AIDS, and in closed populations such as prisons. Worldwide, the WHO estimates

that there are 7–8 million new infections each year and 3 million deaths; 30% of the

world’s people are infected with active or latent TB. Strains of the bacteria resistant

to the standard TB medications are becoming much more common and pose a diffi-

cult treatment problem. New vaccines are being tested.