Scrub Typhus Vaccine: Past, Present and Future

isolates inAsia are of karp or Gilliam serotypes (1,2).The diseaseaccounts for 23% of all febrile episodes in endemic regionswith 35% mortality if left untreated (3). Due to the possibilityof frequent relapses and emergence of antibiotic resistantstrains (4) the development of scrub typhus vaccines isbeing actively pursued as they can offer the long termprevention from the morbidity, mortality and also obviatethe difficulties posed by vector control and preventivechemoprophylaxis.Researchers have faced extremedifficulty in the development of scrub typhus vaccine dueto its antigenic diversity- a vaccine developed for one areamay not be protective for another area and this complexitycontinues to hamper the ongoing efforts for the productionof a viable vaccine. Initial vaccines with killed Orientatsutsugamushi strains were disappointing as the animalstudies were not equally successful in human trials. In viewof the absence of natural attenuated