Rickettsia parkeri

Rickettsia_parkeri_Rickettsiosis_Argentina_Eschar_Papulovesicular_Rash_Histopathology_-_Romer_et_al_2011.jpg

Rickettsia parkeri is a species of bacterium in the genus Rickettsia. It is a member of the spotted fever group (SFG) of rickettsiae, which are known to cause spotted fever illnesses in humans. This bacterium was first identified in 1939 in the United States and has since been recognized as a human pathogen.

Taxonomy and Classification

Rickettsia parkeri belongs to the family Rickettsiaceae, order Rickettsiales, class Alphaproteobacteria, and phylum Proteobacteria. It is closely related to other members of the spotted fever group, such as Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever.

Morphology and Genetics

Rickettsia parkeri is a small, obligate intracellular bacterium. It has a gram-negative cell wall structure and is typically rod-shaped. The genome of Rickettsia parkeri has been sequenced, revealing genes that are involved in its pathogenicity and intracellular survival.

Epidemiology

Rickettsia parkeri is primarily transmitted to humans through the bite of infected ticks. The primary vector in the United States is the Gulf Coast tick (Amblyomma maculatum). Cases of Rickettsia parkeri rickettsiosis have been reported in various regions, including the southeastern and south-central United States, as well as parts of South America.

Clinical Manifestations

Infection with Rickettsia parkeri, known as Rickettsia parkeri rickettsiosis, typically presents with mild to moderate symptoms. Common clinical features include fever, headache, rash, and an eschar at the site of the tick bite. The illness is generally less severe than Rocky Mountain spotted fever.

Diagnosis

Diagnosis of Rickettsia parkeri infection is based on clinical presentation, history of tick exposure, and laboratory testing. Polymerase chain reaction (PCR) and serological tests are commonly used to detect the presence of Rickettsia parkeri DNA or antibodies in patient samples.

Treatment

The treatment of choice for Rickettsia parkeri rickettsiosis is doxycycline, an antibiotic that is effective against rickettsial infections. Early treatment is important to prevent complications and ensure a favorable outcome.

Prevention

Preventive measures include avoiding tick-infested areas, using tick repellents, wearing protective clothing, and performing regular tick checks after potential exposure. Prompt removal of attached ticks can also reduce the risk of infection.

See Also

• Rickettsia
• Spotted fever group
• Rocky Mountain spotted fever
• Tick-borne diseases