In 1922, Hone first described human infections “closely resembling typhus fever.” Since 1926, when Maxcy successfully identified murine typhus as a distinct clinical and epidemiologic entity, and 1931, when Dyer isolated a new typhus group named Rickettsia from rats and…
Rickettsia prowazekii is the only rickettsial species that can cause devastating, naturally occurring epidemics capable of killing a substantial proportion of human populations infested with body lice. Epidemics are associated with conditions that prevent bathing and washing of clothes in…
Q fever remains an intriguing disease despite being studied for more than 80 years. Molecular diagnostics and genomic analysis are adding to our understanding of the disease. The large outbreak in the Netherlands, other outbreaks, and longitudinal studies from France…
Rickettsialpox is a worldwide mite-borne rickettsiosis presenting as a febrile and vesicular eruption. It is caused by Rickettsia akari, associated with mice, and transmitted by its ectoparasite, the mite Liponyssoides sanguineus. Etiology Rickettsia akari is classified among spotted fever group…
The spotted fevers comprise a large group of tick-, mite-, and flea-borne zoonotic infections that are caused by closely related rickettsiae. These include Rocky Mountain spotted fever (RMSF), boutonneuse fever, African tick bite fever, North Asian tick typhus, lymphangitis-associated rickettsiosis,…
Bacteriology Originally, all small gram-negative bacteria, associated (or not) with arthropods and strictly or facultatively intracellular, were considered Rickettsiaceae. The advent of 16S ribosomal RNA gene sequencing and phylogeny has deeply challenged this classification. The controversy has centered on how…
Taxonomy and Microbiology The clinically important genital mycoplasmas— Mycoplasma hominis, Mycoplasma genitalium, Ureaplasma urealyticum, and Ureaplasma parvum —belong to the Mollicutes class and Mycoplasmataceae family of bacteria. Mycoplasma spp. and Ureaplasma spp. are the only two genera in this family.…
Reviewed for currency January, 2020 The concept of atypical pneumonia antedated the start of the antibiotic era. At least as early as World War I it was recognized that “…in the larger number of cases observed in the [military] camps…
Chlamydiae are obligate intracellular bacterial pathogens whose entry into mucosal epithelial cells is necessary for intracellular survival and subsequent growth. Chlamydiae cause a variety of diseases in animal species at virtually all phylogenic levels, from amphibians and reptiles to birds…
Reviewed for currency January 14, 2021 Psittacosis is a systemic infection that frequently causes pneumonia. Its relationship to bird exposure has been known for more than 100 years. In 1879, Ritter studied an outbreak in Switzerland and called it pneumotyphus.…