- Ehrlichia
- A genus of small, often pleomorphic, coccoid to ellipsoidal, nonmotile, Gram-negative bacteria (order Rickettsiales) that occur either singly or in compact inclusions in circulating mammalian leukocytes; species are the etiologic agents of ehrlichiosis and are transmitted by ticks. The type species is E. canis. [P. Ehrlich]- E. canis the bacterial species causing the tick-borne disease canine ehrlichiosis in dogs (transmitted by the tick Rhipicephalus sanguineus); it is the type species of the genus E.. Occasionally causes tick-borne infection in humans.- E. chaffeensis a recently described bacterial species associated with human ehrlichiosis; infects human monocytes and is carried by the tick vector, Amblyomma americanum, the Lone Star tick.- E. equi a bacterial species that causes human granulocytic ehrlichiosis; occurs in the Midatlantic, southern New England, and southern Midwest and is spread by ticks (Ixodes).- E. phagocytophila a bacterial species that causes human granulocytic ehrlichiosis; also causes tick-borne fever in cattle; occurs in the Midatlantic, southern New England, and southern Midwest and is spread by ticks (Ixodes).
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Ehr·lich·ia er-'lik-ē-ə n a genus of gram-negative nonmotile rickettsial bacteria that are intracellular parasites infecting the cytoplasm esp. of circulating white blood cells (as monocytes and granulocytes), that are transmitted chiefly by tick bites, and that are pathogens of animals and humansEhr·lich 'er-.lik Paul (1854-1915)German chemist and bacteriologist. Ehrlich is celebrated for his pioneering research in hematology, immunology, and chemotherapy. He held a series of research positions at several institutions, including Berlin's Charité Hospital, Robert Koch's Institute for Infectious Diseases, and Frankfurt's Royal Institute for Experimental Therapy. His contributions included the invention of a new staining technique for the tuberculosis bacillus discovered by Robert Koch. The technique proved to be vitally important for the microscopic diagnosis of tuberculosis. Ehrlich is also credited with the important discovery that oxygen consumption varies with different types of tissue and that these variations constitute a measure of the intensity of vital cell processes. Perhaps his greatest achievement was his investigation into the mechanisms of bacterial infection and immunity. He developed a method for measuring the effectiveness of sera that was adopted worldwide for the standardization of diphtheria serum. His recognition of the limitations of serum therapy led to his search for synthesized substances that can kill parasites or inhibit their growth without damaging the organism. His researches marked the birth of chemotherapy. His study of the spirochete (Treponema pallidum) that causes syphilis led to his discovery of salvarsan, the first effective treatment for syphilis. With Élie Metchnikoff, he was awarded the 1908 Nobel Prize for Physiology or Medicine.* * *
Ehr·lich·ia (ār-likґe-ə) [Paul Ehrlich] a genus of tick-borne bacteria of the family Anaplasmataceae, consisting of gram-negative, nonmotile coccoid to ellipsoidal cells; organisms are parasitic in mammalian endothelial and hematopoietic cells, occurring in cytoplasmic vacuoles and often forming inclusion bodies (morulae), and produce disease in dogs, cattle, sheep, and humans. The type species is E. caґnis.
Medical dictionary. 2011.
