Mostly chicken embryos are used, following a method developed by Ernest William Goodpasture and his colleagues at Vanderbilt University in the early 1930s.

[15] Pathogenic Rickettsia species are transmitted by numerous types of arthropods, including chiggers, ticks, fleas, and lice, and are associated with both human and plant diseases.

[16] In March 2010, Swedish researchers reported a case of bacterial meningitis in a woman caused by Rickettsia helvetica previously thought to be harmless.

Pelagibacter Subgroups Ib, II, IIIa, IIIb, IV and V Proto-mitochondria Neorickettsia Wolbachia Anaplasma Ehrlichia Midichloria Orientia Rickettsia Plant diseases have been associated with these Rickettsia-like organisms (RLOs):[22] Infection occurs in nonhuman mammals; for example, species of Rickettsia have been found to afflict the South American guanaco, Lama guanacoe[24] potentially marsupials[25][26] and reptiles.

Unlike the latter, the genome of R. prowazekii, however, contains a complete set of genes encoding for the tricarboxylic acid cycle and the respiratory chain complex.

Still, the genomes of the Rickettsia, as well as the mitochondria, are frequently said to be "small, highly derived products of several types of reductive evolution".

[31] Human immune response to the scrub typhus pathogen, Orientia tsutsugamushi, appears to provide a beneficial effect against HIV infection progress, negatively influencing the virus replication process.

Surprisingly, the other infection reported to be likely to provide the same effect (decrease in viral load) is the virus-caused illness dengue fever.

Comparative analysis of genomic sequences have also identified five conserved signature indels in important proteins, which are uniquely found in members of the genus Rickettsia.