Rickettsial Zoonosis with Particular Reference to Scrub Typhus: A Review Paper

Abstract

Rickettsiae comprise a group of microorganisms that phylogenetically occupy a position between bacteria and viruses. They are obligate intracellular gram-negative coccobacillary forms that multiply within eukaryotic cells. A general characteristic of rickettsiae is that mammals and arthropods are natural hosts. Scrub typhus is zoonotic rickettsiosis transmitted to humans through the bite of thrombiculid mites. Orientia tsutsugamushi is the causative agent for scrub typhus and humans are accidental hosts and become infected when they are bitten by chiggers infected with the agent. The agent multiply at the inoculation site with the formation of a papule that ulcerates and becomes necrotic, evolving into an eschar, with regional lymphadenopathy that progress to generalized lymphadenopathy within a few days. Scrub typhus may be diagnosed in the laboratory by isolation of the organism; serology and molecular diagnosis (PCR). Tetracycline and Chloramphenicol are proven therapy for the rickettsial diseases. The disease can be prevented by the use of personal protective measures including repellents, people entering an exposed area should wear closed in footwear such as boots with socks, and long trousers.

Keywords: Rickettsiae, Scrub typhus