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RESULTS AND DISCUSSION

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Presentation on theme: "RESULTS AND DISCUSSION"— Presentation transcript:

1 RESULTS AND DISCUSSION
Poster Board Number: D-718 Control number 1950 All India Institute of Medical Sciences, New Delhi Phone , - Scrub typhus in North India : A prospective analysis of clinical epidemiology and evaluation of laboratory methods for diagnosis Nitin Gupta*1,R Chaudhry1, AB Dey2, SK Kabra3, R Lodha3, BR Mirdha1, BK Das1, V Sreenivas4 1Department of Microbiology, 2Department of Geriatric Medicine, 3Department of Paediatrics, 4Department of Biostatistics, All India Institute of Medical Sciences, New Delhi Evaluation of methods for diagnosis of Scrub typhus IgM ELISA: A set of 40 sera samples collected from healthy volunteers from New Delhi were used to establish region specific cutoff for IgM ELISA. The cut off was calculated as mean OD(0.332) + 3SD (0.169) The cut off calculated was 0.839 Of the 25 IFA positive sera, 23 were positive while 2 of the 137 IFA negative sera were positive. The sensitivity & specificity were 92% & 98.5% respectively Rapid Flow Assay (IgM): Of the 25 IFA positive sera, 29 were positive while none of the 137 IFA negative sera was positive The sensitivity & specificity were calculated as 76% & 100% respectively Nested PCR: Of the 25 IFA positive samples, 10 were positive while none of the 137 IFA negative samples were positive The sensitivity & specificity were calculated as 40% & 100% respectively. The sensitivity of PCR was low as most samples were sent long after the febrile illness started. By this time most patients would have already received antibiotic therapy2 or they would no longer be in the stage of bacteremia INTRODUCTION Scrub Typhus-A rickettsial disease caused by the bite of larval stage of trombiculid mite Most reports in India are from the Southern peninsula, and Sub-himalayan region Classical case description includes Fever, lymphadenopathy, rash and eschar Serology is the mainstay in diagnosis and immunofluoroscence assay(IFA) is considered as the gold standard, however IFA has its limitations There is a need for evaluation of other methods for detection AIMS AND OBJECTIVES Evaluation of the clinical epidemiology and laboratory parameters of patients diagnosed with scrub typhus Evaluation of immunodiagnostic and molecular methods with respect to IFA for detection in patients of Scrub typhus in New Delhi MATERIALS AND METHODS A total of 162 patients of all age groups attending AIIMS clinics with clinically suspected Scrub typhus over a period of 18 months (October 2013 to March 2015) were taken Complete history and examination along with relevant laboratory investigations were performed Serum samples obtained from the patient were subjected to IFA for IgM Serum samples were also subjected to IgM ELISA & Rapid Flow Assay (for IgM) for Scrub typhus A nested PCR assay was performed on whole blood samples to detect a 483 bp segment of 56 k Da gene using conditions described by Furuya et al.1 Positive samples were subjected to IgM ELISA for Leptospira to look for co-infection Parameters IgM ELISA RFA IFA Turn around time 2hrs 5 min 1.5 hrs Minimum no. of samples for one test 5 1 8 Instruments required Incubator spectrophotometer none Incubator, fluorescence microscope Technical expertise required Not required Cost per sample Rs 450 Rs 240 Rs 625 RESULTS AND DISCUSSION A total of 15.43% (25 out of 162) of suspected patients were positive for IgM antibodies by immunofluoroscence assay There was a definite seasonal clustering with 80% of the Scrub typhus cases reporting in the months of October to December The younger age group (11-30 years) was more frequently affected (14/25, 56%). Male: Female ratio was 1.27:1 Diagnostic test Sensitivity Specificity PPV NPV IgM ELISA 92% 98.5% RFA 76% 100% 95.8% Nested PCR 40% 90.13% Co-infection with Leptospirosis Scrub typhus and Leptospirosis co-infection has been reported worldwide and also from India in recent past All the 25 IFA positive samples were subjected to IgM ELISA for Leptospirosis 9 samples were positive for IgM antibodies against Leptospira also The 7 samples that were positive for both were further analysed to confirm whether they were actual cases of co- infection Only 1 patient was confirmed as a case of co-infetion with PCR assays positive for both scrub typhus and leptospirosis Clinical and laboratory profile of patients with scrub typhus SUMMARY AND CONCLUSIONS Clinical features Numbers Percentage Fever 25/25 100% Rash 7/25 28 % Lymphadenopathy 3/25 12 % Eschar Hepatomegaly 12/25 48 % Splenomegaly 5/25 20 % Pulmonary 17/25 68 % CNS 4/25 16 % CVS 6/25 24 % Laboratory findings Numbers Percentage Leucocytosis 11/25 44% Thrombocytopenia 10/25 40% Transaminitis 13/25 52% Scrub typhus is an under reported infectious disease from this part of the country The typical manifestations like rash, lymphadenopathy and eschar are rare Patients with fever, pulmonary manifestations and/ or deranged LFT presenting in the months of August to December should be evaluated for Scrub typhus Even though molecular techniques like PCR are highly specific, their low sensitivity makes them an unsuitable alternative for immunodiagnostic tests. Their use as an adjunct to immunodiagnosis is desirable wherever possible REFERENCES 1. Furuya Y, Yoshida Y, Katayama T et al. Specific amplification of Rickettsia tsutsugamushi DNA from clinical specimens by polymerase chain reaction. J Clin Microbiol.1993; 29: 2. Kim DM, Byun JN. Effects of antibiotic treatment on the results of nested PCRs for scrub typhus. J Clin Microbio Oct; 46(10). The prevalence of classical mainfestations like lymphadenopathy and eschar were found to be low while pulmonary manifestations and hepatomegaly were fairly common


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