Rickettsia prowazekii

Rickettsia prowazekii is a gram-negative, obligate intracellular parasite that is the causative agent of the disease Epidemic typhus. This bacterium is named after Howard Taylor Ricketts and Stanislaus von Prowazek, who both died from typhus after investigating its causes.

Taxonomy

Rickettsia prowazekii belongs to the genus Rickettsia, which is a part of the phylum Proteobacteria, class Alphaproteobacteria, order Rickettsiales, and family Rickettsiaceae. The genus Rickettsia is divided into four groups: spotted fever, typhus, ancestral, and transitional. Rickettsia prowazekii is a member of the typhus group.

Morphology

Rickettsia prowazekii is a small, rod-shaped bacterium, typically measuring 0.3 to 0.5 μm in width and 1.0 to 2.0 μm in length. It is non-motile and does not form spores. The bacterium is gram-negative, meaning it does not retain the violet crystal violet stain used in the Gram staining method of bacterial differentiation.

Life Cycle

Rickettsia prowazekii is an obligate intracellular parasite, meaning it can only survive and reproduce within the cells of a host organism. The bacterium is typically transmitted to humans through the bite of an infected body louse (Pediculus humanus corporis). Once inside the host, the bacteria invade endothelial cells, where they replicate and eventually cause cell death.

Pathogenesis and Clinical Features

Infection with Rickettsia prowazekii causes Epidemic typhus, a severe febrile illness characterized by high fever, headache, chills, and rash. If left untreated, the disease can be fatal.

Diagnosis and Treatment

Diagnosis of Rickettsia prowazekii infection is typically based on clinical symptoms and confirmed by serological testing. The preferred treatment is the antibiotic doxycycline.

Epidemiology

Epidemic typhus is most commonly found in areas with poor sanitation and crowded living conditions, where body lice can thrive. Outbreaks have historically occurred in times of war and famine.

Prevention and Control

Prevention of Rickettsia prowazekii infection primarily involves control of body lice. This can be achieved through improved sanitation and personal hygiene practices.

See Also

• Rickettsia rickettsii
• Rickettsia typhi
• Orientia tsutsugamushi