We tested the antibiotic susceptibilities of eight strains of Anaplasma phagocytophilum (the agent of human granulocytic ehrlichiosis) collected in various geographic areas of the United States, including Minnesota, Wisconsin, California, and New York. The results are homogeneous and show that doxycycline, rifampin, and levofloxacin are the most active antibiotics against these strains in vitro.

Anaplasma phagocytophilum, the causative agent of human granulocytic anaplasmosis, is an obligate intracellular bacterium most commonly acquired from tick bites. High seroprevalence rates in endemic regions suggest that transfusion transmission of A phagocytophilum would be a common event; however, only 2 cases have previously been reported. The exact cause of this discrepancy is not known. Who...

In order to understand the genetic diversity of A. marginale, several efforts have been made around the world. This rickettsia affects a significant number of ruminants, causing bovine anaplasmosis, so the interest in its virulence and how it is transmitted have drawn interest not only from a molecular point of view but also, recently, some genomics research have been performed to elucidate gen...

BACKGROUND Anaplasma phagocytophilum (formerly Ehrlichia phagocytophila) is an obligate intracellular bacterium causing the disease tick-borne fever (TBF) in domestic ruminants. An effective vaccine against the infection has been demanded for livestock by sheep farmers and veterinary practitioners for years. FINDINGS In the present study, we immunized lambs with an inactivated suspension of 1...

Microbes transmitted to mammals by arthropods contend with many factors that could impede survival. To survive, host fitness with infection must outweigh costs. In this issue of the JCI, Neelakanta et al. demonstrate that ticks infected with Anaplasma phagocytophilum show enhanced fitness against freezing injury owing to induced expression of tick "antifreeze glycoprotein." This allows A. phago...

Real-time PCR analysis of a groESL heat shock operon segment showed the presence of two genetic lineages of Anaplasma phagocytophilum in Ixodes ricinus ticks as well as one variant in wild red and roe deer, the latter supposedly representing the natural reservoir of one variant of A. phagocytophilum.

Major surface protein 2 (MSP2) and MSP3 of the persistent bovine ehrlichial pathogen Anaplasma marginale are immunodominant proteins that undergo antigenic variation. The recently completed sequence of MSP3 revealed blocks of amino acids in the N and C termini that are conserved with MSP2. This study tested the hypothesis that CD4+ T cells specific for MSP2 recognize naturally processed epitope...

Patient Age, y/sex Occupation Hospital Days with fever after possible tick bite Symptom onset Fever Rash Additional symptom/sign Underlying disorder Laboratory findings (reference values)† Treatment 1 87/F Farmer A 5 d after working on farm 2010 May 39.7C Yes Malaise Hypertension, hyperlipidemia WBC, 8.7 × 10 cells/L (3.5–9.2 × 10 cells/L); Plt, 196 × 10 cells/L (155–365 × 10 cells/L); AST, 145...

Ticks may transmit pathogens to ruminants worldwide, creating diseases such as anaplasmosis, babesiosis, ehrlichiosis and theileriosis. In Europe, the most important tick vector is Ixodes ricinus and the most widespread tick-borne infection in animals is Anaplasma phagocytophilum. This infection causes tick-borne fever (TBF) in ruminants, a disease which may not only cause suboptimal growth, bu...

Strain superinfection affects the dynamics of epidemiological spread of pathogens through a host population. Superinfection has recently been shown to occur for two genetically distinct strains of the tick-borne pathogen Anaplasma marginale that encode distinctly different surface protein variants. Superinfected animals could serve as a reservoir for onward transmission of both strains if the t...