Rickettsial Infections

Rickettsia are some of the smallest bacteria, which are about as big as large viruses. They are obligate parasites that are grown in live media. 
== Transmission ==
Transmitted by an arthropod vector such as fleas, ticks, and mites. 
== Infection ==
1-2 week incubation period followed by fever, chills and a rash. May lead to circulatory system collapse, which can result in death. Some strains have a high mortality rate
== Diagnosis ==
Antigen-antibody reactions (serology), which tests for antigens. Often too complicated to culture.
== Treatment ==
Tetracycline (doxacycline) is useful for all Rickettsial infections
== Diseases ==
=== Louse-borne ===
Causes epidemic typhus, and has a 50% mortality rate. Common in the homeless and prisons. It is transmitted through lice. 
=== Flea-borne ===
Causes endemic typhus, associated with water and ships. Carried by the fleas on rats. Causes a mild fever, no deaths.
=== Tick-borne (rocky mountain spotted fever) ===
Rash on wrists and ankles, and then begins to spread. 20% mortality rate untreated, and 5-10% mortality rate treated. It is more common in the spring and summer because ticks wake up and search for blood
=== Mite-borne ===
Scrub typhus, associated with chiggers that live on grass when larval, and mice when mature. Causes a 50% mortality rate, and is more common in Asia and Australia.
== Rickettsial-like infections ==
=== Q-fever ===
Caused by Coxiella burnetii from unpasturized milk. They can form endospores but few cause symptoms. They can be treated with tetracycline.
=== Cat scratch ===
Caused by Bartonella henselae, following a cat scratch or bite, and can go systemic in AIDS patients. DOC: Azithromycin