Rickettsia and Rickettsial Diseases

Rickettsia prowazekii and R. rickettsii are HHS and USDA select agents (http://biosafety.utk.edu/pdfs/salist.pdf), and R. prowazekii is a category B bioterrorism agent as determined by the Centers for Disease Control and Prevention (CDC) (http://www.bt.cdc.gov/agent/agentlist-category.asp). The criteria for CDC category B bioterrorism agents are that the organisms are moderately easy to disseminate, cause diseases with moderate morbidity and low mortality and require specific enhancements of diagnostic capacity and enhanced disease surveillance. However, the case fatality ratios of both R. prowazekii and R. rickettsii may exceed the CDC bioterrorism agent category B level. Epidemic typhus caused by R. prowazekii and Rocky Mountain spotted fever (RMSF) caused by R. rickettsii can reach up to 60% fatalities without antibiotic treatment and 4% even with antibiotic treatment (Raoult et al., 2004). Rickettsia had been explored for biowarfare use. The former Soviet Union developed R. prowazekii as a biologic weapon in the 1930s (Alibek K and Handelman S, 2009). During World War II, the Japanese performed human experiments with rickettsial agents for purposes of biologic weapon development during their occupation of China (Harris S, 1992).