The genera Anaplasma, Ehrlichia, Cowdria, Neorickettsia and Wolbachia encompass a group of obligate intracellular bacteria that reside in vacuoles of eukaryotic cells and were previously placed in taxa based upon morphological, ecological, epidemiological and clinical characteristics. Recent genetic analyses of 16S rRNA genes, groESL and surface protein genes have indicated that the existing ta...

In order to investigate new hosts for Anaplasmataceae agents in Brazil, we collected blood samples from 21 wild birds. Using molecular techniques, we detected the presence of Anaplasma phagocytophilum, Ehrlichia chaffeensis, and an Ehrlichia species closely related to Ehrlichia canis in carnivorous avian blood samples. In addition, an Ehrlichia species closely related to an Ehrlichia species fo...

Ehrlichiosis is a tick-borne disease that affects both humans and animals. The few existing reports on ehrlichiosis in Brazilian cats have been based on observation of morulae in leukocytes and, more recently, on molecular detection of Ehrlichia sp. In this study, we assessed occurrences of Ehrlichia sp. in the blood of 200 domestic cats in São Luís, Maranhão. Of the 200 animals tested, 11 (5.5...

The organisms of the Order Rickettsiales, in the families Rickettsiaceae and Anaplasmataceae, were reclassified in 2001 following phylogenetic analyses of the 16S rRNA and groESL gene sequences (Dumler and colleagues, 2001). Some Ehrlichia spp. were transferred to the Neorickettsia genus (including E. risticii) and some Ehrlichia spp., including E. phagocytophila (also called E. equi and human ...

The aim of the study was to determine the frequency and associated factors of Ehrlichia canis infection in dogs. Blood samples from 150 dogs infested with ticks in 10 veterinary clinics in the city of Huanuco in Peru were collected. The dogs were randomly selected without regard to breed, age or sex. Ehrlichia canis antibodies were detected by chromatographic immunoassay.51.3% of dogs were infe...

The ticks Amblyomma americanum and Ixodes scapularis, strongly implicated vectors of Ehrlichia chaffeensis and the human granulocytic ehrlichiosis (HGE) agent, respectively, commonly are found on white-tailed deer (Odocoileus virginianus). As deer can be infected with E. chaffeensis, the HGE agent, and another Ehrlichia-like organism, a deer population parasitized by both tick species in coasta...

We report here the complete genome sequencing of Ehrlichia mineirensis, an Ehrlichia organism that was isolated from the hemolymph of Rhipicephalus microplus-engorged females. E. mineirensis is the best characterized Ehrlichia isolate from a novel cattle-related clade closely related to the monocytotropic pathogen E. canis.

Ehrlichiae are gram-negative obligate intracellular bacteria that cause potentially fatal human monocytic ehrlichiosis. We previously showed that natural killer (NK) cells play a critical role in host defense against Ehrlichia during primary infection. However, the contribution of NK cells to the memory response against Ehrlichia remains elusive. Primary infection of C57BL/6 mice with Ehrlichia...

Although cellular immunity is essential for host defense during intracellular bacterial infections, humoral immunity can also play a significant role in host defense during infection by some intracellular bacteria, including the ehrlichiae. Antibodies can protect susceptible SCID mice from fatal Ehrlichia chaffeensis infection, an observation that has been hypothesized to involve the opsonizati...

We investigated if the monocytic Ehrlichia are totally dependent on their host cells for energy, or, as Rickettsia, are capable of some ATP synthesis in vitro. The Miyayama strain of Ehrlichia sennetsu and the Maryland and Illinois strains of Ehrlichia risticii were cultivated in a mouse macrophage cell line, separated from host cell constituents by procedures that included Renografin or Percol...