text: Severe infections Patients with severe infections may require hospitalization. The more severe symptoms occur later in response to thrombosis (blood clotting) caused by R. rickettsii targeting endothelial cells in vascular tissue. They may become hyponatremic, experience elevated liver enzymes, and other more pronounced symptoms.  It is not uncommon for severe cases to involve respiratory system, central nervous system, gastrointestinal system, or renal system complications. In the case of meningoencephalitis, R. rickettsii causes cellular damage to brain tissue, resulting in inflammation. Additionally, acute respiratory distress syndrome and Coagulopathy occur in cases that advance to severe stages of RMSF. This disease is worst for elderly patients, males, African Americans, alcoholics, and patients with G6PD deficiency.  The mortality rate for RMSF is 3 to 5 percent in treated cases, but 13 to 25 in untreated cases. Deaths usually are caused by heart and kidney failure.
  Treatment
  RMSF symptoms can vary from moderate to severe cases, and a delay in treatment is often associated with a higher case-fatality rate. The most common and effective treatment for Rocky mountain spotted fever is the anti-microbial agent doxycycline. This antibiotic acts as a bacteriostatic drug by inhibiting protein synthesis via blockage of the 30S ribosomal subunit.
  Other treatments with chloramphenicol, fluoroquinolones, and macrolides have been explored. However, treatment with only chloramphenicol compared to other treatments (tetracycline-class drugs only, both chloramphenicol and tetracycline-class drugs, and neither drug) was associated with a case-fatality rate three times higher. Chloramphenicol, like doxycycline, also functions as a bacteriostatic drug, but it binds to the 50S ribosomal subunit in order to prevent protein synthesis. Macrolides target the 50S subunit as well; however, they block the exit site for peptides, while chloramphenicol blocks the aminoacyl-tRNA attachment site for transfer RNA.