Ehrlichia

Abstract

Ehr.lich' i.a . M.L. fem. n. Ehrlichia named after Paul Ehrlich, a German bacteriologist. Proteobacteria / Alphaproteobacteria / Rickettsiales / Anaplasmataceae / Ehrlichia Coccoid to ellipsoidal cells . Found in cytoplasmic vacuoles in endothelial or hemopoietic mammalian host cells , including macrophages, monocytes, neutrophils, and cells of the bone marrow, liver, spleen, or lymph nodes. Often occur in clusters (morulae). Pleomorphic; occur as reticulate cells and “ dense core forms ” with condensed cytoplasm (Popov et al., 1998). Gram negative. Nonmotile. Some species grow in cultured tick cells or in cultured mammalian monocytes, macrophages, or endothelial cells. Cause disease in ruminants , canids , rodents , and humans . Ticks are the primary vectors and hosts . Belong to the Alphaproteobacteria by 16S rDNA gene sequence analysis; the organisms exhibit ≥97.6% 16S rRNA gene sequence identity with one another. Where studied, these bacteria possess surface protein antigen genes that are tandemly arranged in the chromosome and have a high degree of sequence similarity (Ohashi et al., 1998a, b; Reddy et al., 1998; McBride et al., 2000; Yu et al., 2000a). The mol % G + C of the DNA is : 30–56. Type species : Ehrlichia canis (Donatien and Lestoquard 1935) Moshkovski 1945, 18 ( Rickettsia canis Donatien and Lestoquard 1935, 419) emend. Dumler, Barbet, Bekker, Dasch, Palmer, Ray, Rikihisa and Rurangirwa 2001, 2159.

Etiologies of Zoonotic Tropical Febrile Illnesses That Are Not Part of the Notifiable Diseases in Colombia

“…Ehrlichia genus is composed of obligate intracellular Gram-negative pleomorphic tick-borne bacteria, which infect a wide range of host cells, including endothelial and hemopoietic cells (e.g., macrophages and neutrophils), in which they form clusters known as morulae [ 149 ]. To date, Ehrlichia chaffeensis , Ehrlichia ewingii , and Ehrlichia muris subsp.…”

“…Nevertheless, novel species are continuously being detected from several animal hosts. It is likely that some of these may have a zoonotic potential [ 149 , 150 , 151 ]. On the other hand, several authors have suggested that Ehrlichia canis , a pathogen of dogs, may also be linked to human disease [ 152 ]; however, to date, this is still controversial, and more studies are needed to clarify it.…”