title: Molecular detection ofOrientia tsutsugamushifrom suspected scrub typhus cases.
abstract: BACKGROUND
  Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi. The disease is under-diagnosed in India, because of low index of suspicion and also due to its nonspecific presentation, and lack of confirmatory diagnostic tests.
  
  
  OBJECTIVE
  This study was undertaken to diagnose scrub typhus in patients with undifferentiated fevers by serology and molecular methods.
  
  
  METHODS
  A total of 68 blood samples were collected from patients clinically suspected to have scrub typhus. After transportation to the laboratory, the serum was separated from the blood and subjected to rapid card test. The ethylenediaminetetraacetic acid blood samples were subjected to DNA extraction using QIAamp DNA Mini Kit followed by nested polymerase chain reaction (nPCR).
  
  
  RESULTS
  24/68 (35.29%) cases showed the presence of antibody against scrub typhus by serology. 6/68 (8.8%) patients showed the presence of outer membrane protein antigen gene 56 kDa by nPCR. 5/24 serology positive cases showed the presence of 56 kDa outer membrane protein antigen gene by nPCR. A large number of cases positive by serology were negative by PCR which may indicate a low sensitivity of this test either due to low copy numbers or due to excess host DNA.
  
  
  CONCLUSIONS
  Delay in treatment may increase disease severity and leads to higher mortality. Thus, molecular methods of diagnosis may aid in the early diagnosis of infection and enable prompt treatment. This is the first report on the diagnosis of scrub typhus in the suburbs of Chennai using molecular methods and reemphasizes the need for increased awareness of rickettsial infections in rural areas.
authors.affiliation: Department of Microbiology, Dr. A. L. Mudaliar PG Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai, Tamil Nadu, India.
authors.forename: Seethalakshmi
authors.initials: S
authors.lastname: Srinivasan
authors.affiliation: Department of Microbiology, Dr. A. L. Mudaliar PG Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai, Tamil Nadu, India.
authors.forename: Thangam
authors.initials: T
authors.lastname: Menon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D005260:Female; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D012285:Orientia tsutsugamushi / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012612:Scrub Typhus / Q000175:diagnosis* / Q000382:microbiology*; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods; D055815:Young Adult