Syphilis Definition Syphilis, which is a chronic infectious disease caused by the bacterium Treponema pallidum subspecies pallidum , is usually acquired by sexual contact with another infected individual. Syphilis is remarkable among infectious diseases for its large variety of clinical…
Definition Chlamydiae are obligate intracellular bacteria that cause a variety of human and animal diseases and much morbidity. Within the Chlamydia genus are now 11 validated species: C. trachomatis, C. pneumoniae, C. psittaci , C. abortus , C. avium ,…
Mycoplasma pneumoniae Definition Mycoplasma organisms of the class Mollicutes are ubiquitous as pathogens and colonizing agents in the plant, animal, and insect kingdoms. They represent the smallest known free-living forms, but because they have fastidious growth requirements, they are difficult…
Definition Granuloma inguinale, also known as donovanosis, is a chronic and progressive bacterial ulcerative disease that predominantly affects the skin and mucous membranes of the genital, inguinal, perirectal, and anal regions, often associated with sexual transmission. The Pathogen Donovanosis is…
Definition Bartonella are vector-borne bacteria responsible for a wide spectrum of human acute and chronic diseases. More than 40 different bacterial species from this genus have been isolated from animals and humans. The human infections linked to these different bacteria…
Definition Legionellosis refers to two clinical syndromes caused by Legionella bacteria: pneumonia and Pontiac fever. Legionella pneumonia (legionnaires disease) can be episodic or occur in outbreaks, and it can be acquired in the community or in health care settings. Pontiac…
Definition Whooping cough, also known as pertussis, is a toxin-mediated, highly contagious respiratory illness that affects all age groups and is characterized by distinctive, violent, paroxysmal coughing episodes, which end in the classic inspiratory whoop that gives the disease its…
The genus Yersinia currently contains 26 officially recognized species, of which three are known to be important human pathogens, Yersinia pestis, Y. enterocolitica, and Y. pseudotuberculosis . The remaining species are generally considered nonpathogenic and are most frequently isolated from…
Definition Tularemia is an infectious zoonosis caused by Francisella tularensis , which is an aerobic, pleomorphic, gram-negative bacillus. Many animal species harbor this organism, most prominently rabbits, squirrels, and muskrats. Humans acquire the infection by various means, including direct contact…
Definition Brucellosis, previously known as Malta fever, Mediterranean fever, or undulant fever, is a zoonotic disease caused by bacteria of the genus Brucella . Human infection, which has protean manifestations, is acquired via direct contact, ingestion, or inhalation. Most disease…