Rickettsia felis was initially detected as a rickettsia-like agent in an electron micrograph of a cat flea. It was described as the ELB agent, after the name of the facility where the picture was taken (EL Laboratory, Soquel, CA). Characterization of this organism was delayed by difficulties in finding efficient means of in vitro propagation, primarily due to the low temperature (28º C) required of cell lines for initial propagation. Following initial isolation there is an adaption that then allows propagation in the low temperature range (32º C) of mammalian cell lines.
Detection of antibody to this organism is based entirely on reactivity to the OmpB protein. Due to a lack of s-layer OmpA and severe truncation of the LPS antigen, antibody detection by micro-immunofluorescence (MIF) and ELISA strongly correlate (>99%) and are both sensitive and specific.
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