title: Serological Evidence of Scrub Typhus among Cases of PUO in the Kashmir Valley- A Hospital Based Study.
abstract: BACKGROUND
  Rickettsial infections are being increasingly recognized as a cause of acute febrile illnesses and should be considered a distinct possibility in patients presenting with suggestive clinical features. Their diagnosis remains a challenge in a country like ours where tests like immunofluorescence assay cannot be routinely done. Results of serological tests, when correlated with patients clinical profile can aid in the timely diagnosis of scrub typhus.
  
  
  OBJECTIVE
  To find out the extent to which scrub typhus contributes to Pyrexia of Unknown Origin (PUO) in patients admitted to or attending the OPD of our hospital using simple tests like Weil-Felix Agglutination Test (WFT) and Enzyme Linked Immunosorbent Assay (ELISA).
  
  
  METHODS
  A cross-sectional study was carried out in the Department of Microbiology, Government Medical College and Hospital, Srinagar, over a period of eight months (1(st) March to 31(st) October 2015). Serum samples from patients suffering from Pyrexia of Unknown Origin (PUO) were processed for the detection of Scrub typhus. A total of 162 samples were included in the study. These were subjected to WFT using OX-K strain. The serum samples were diluted 1/20 to 1/640 and a titre of ≥ 1:160 was considered as positive. The samples were also tested for IgM and IgG antibodies for scrub typhus by ELISA and tube agglutination test was done to detect typhoid fever and brucellosis.
  
  
  RESULTS
  Of the 162 serum samples tested 22.8% tested positive scrub typhus by WFT. IgM ELISA and IgG was positive in 8 (4.9%) and 15 (9.3%) samples respectively. Sensitivity, specificity, positive and negative predictive values of WFT; taking IgM ELISA as a reference standard were 75%, 79.9%, 16.2% and 98.4% respectively.
  
  
  CONCLUSIONS
  Scrub typhus is prevalent in our state and the results of WFT supplemented by those of ELISA can aid in its diagnosis. However the results of these tests should always be regarded in light of the clinical condition of the patient.
authors.affiliation: Professor and Head, Department of Microbiology, Govt Medical College and Hospital , Srinagar, India .
authors.forename: Anjum
authors.initials: A
authors.lastname: Farhana
authors.affiliation: Consultant, Department of Microbiology, Govt Medical College and Hospital , Srinagar, India .
authors.forename: Nargis
authors.initials: N
authors.lastname: Bali
authors.affiliation: Senior Resident, Department of Microbiology, Govt Medical College and Hospital , Srinagar, India .
authors.forename: Farhath
authors.initials: F
authors.lastname: Kanth
authors.affiliation: Senior Resident, Department of Microbiology, Govt Medical College and Hospital , Srinagar, India .
authors.forename: Rumana
authors.initials: R
authors.lastname: Farooq
authors.affiliation: Consultant, Department of PSM, Govt Medical College and Hospital , Srinagar, India .
authors.forename: Inam Ul
authors.initials: IU
authors.lastname: Haq
authors.affiliation: Professor and Head, Department of Medicine, Govt Medical College and Hospital , Srinagar, India .
authors.forename: Parvaiz
authors.initials: P
authors.lastname: Shah
keywords: IgM ELISA; Indirect immunofluorescence test; Orentia tsutsugamushi; Rickettsia; Weil Felix Test