Clinical diagnosis of scrub typhus is often difficult because the symptoms are very similar to those of other febrile illness such as dengue, leptospirosis, malaria and other viral hemorrhagic fevers. Though better diagnostic tests are available for rickettsial diseases and scrub typhus elsewhere, the Weil-Felix test is still commonly used in India, mainly because microimmunofluorescence assays (M-IFA) were not available in India till recently and relevant staff had insufficient training. The present study was performed to investigate the performance of M-IFA, IgM ELISA, and Weil-Felix test on 546 non-repeated serum samples from subjects suspected of having scrub typhus. One hundred and forty-three of these 546 samples were positive by M-IFA; these cases were also confirmed clinically to have scrub typhus based on their dramatic responses to doxycycline therapy. IgM ELISA was positive in 122 of the 143 M-IFA positive cases and the Weil-Felix test in 96. Though the Weil-Felix test is a heterophile agglutination test, it was found in this study to have good specificity but far too little sensitivity to use as a routine diagnostic test. IgM ELISA can be a good substitute for M-IFA. Incorporation of multiple prototype antigens on M-IFA slides is likely one of the reasons for its superior performance. As newer and better diagnostic assays become available for scrub typhus diagnosis in developed countries, it will be imperative to also use such tests in other endemic countries to prevent over-or under-diagnosis of scrub typhus.

Orientia tsutsugamushi (Ots) is an obligate, intracellular, mite-transmitted human pathogen which causes scrub typhus. Understanding the diversity of Ots antigens is essential for designing specific diagnostic assays and efficient vaccines. The protective immunodominant type-specific 56 kDa antigen (TSA) of Ots varies locally and across its geographic distribution. TSA contains four hypervariable domains. We bioinformatically analyzed 345 partial sequences of TSA available from India, most of which contain only the three variable domains (VDI-III) and three spacer conserved domains (SVDI, SVDII/III, SVDIII). The total number (152) of antigenic types (amino acid variants) varied from 14–36 in the six domains of TSA that we studied. Notably, 55% (787/1435) of the predicted CD4 T-cell epitopes (TCEs) from all the six domains had high binding affinities (HBA) to at least one of the prevalent Indian human leukocyte antigen (HLA) alleles. A surprisingly high proportion (61%) of such TCEs were from spacer domains; indeed 100% of the CD4 TCEs in the SVDI were HBA. TSA sequences from India had more antigenic types (AT) than TSA from Korea. Overall, >90% of predicted CD4 TCEs from spacer domains were predicted to have HBA against one or more prevalent HLA types from Indian, Korean, Asia-Pacific region or global population data sets, while only <50% of CD4 TCEs in variable domains exhibited such HBA. The phylogenetically and immunologically important amino acids in the conserved spacer domains were identified. Our results suggest that the conserved spacer domains are predicted to be functionally more important than previously appreciated in immune responses to Ots infections. Changes occurring at the TCE level of TSA may contribute to the wide range of pathogenicity of Ots in humans and mouse models. CD4 T-cell functional experiments are needed to assess the immunological significance of these HBA spacer domains and their role in clearance of Ots from Indian patients.

Orientia tsutsugamushi (Ots) frequently causes severe scrub typhus infections in the Asia-Pacific region. Korean investigators have demonstrated that Ots encodes five different autotransporter domain (ATD) proteins (ScaA-ScaE). ScaA functions as an adhesin and confers protective immunity in a lethal mouse model of Ots infection. Specific antibodies are detected against ScaA and ScaC in Korean scrub typhus patients. However, there is limited data on the distribution of the Sca protein genes in diverse isolates of Ots. By BLAST analysis with the conserved beta barrel autotransporter domain (ATD) regions of the sca proteins, we discovered a sixth gene scaF among 3 of 10 new partial Ots genome sequences available at NCBI GenBank (Sido, Karp, AFSC7). We designed two to seven specific TaqMan assays to detect the ATD for each of the six sca genes. The TaqMan assays among those for each sca gene which gave the greatest sensitivity and linearity with DNA log dilutions were then used for screening DNAs from Ots isolates grown in L929 mouse cells for sca genes. The sca prevalence survey was performed for all six sca genes with 178 DNAs from isolates from 12 countries. The survey results were confirmed by conventional PCR with primers from conserved regions of the passenger domains (PD) and ATD of the sca proteins. The ATD was highly conserved between the DNAs of different genotypes compared to the sca PD but each TaqMan assay was sca specific. The percentage positivity for 56 kDa and scaA genes in the 178 DNAs using Ha primers was 59.6% and 62.4%, respectively. Our scaA conventional ATD PCR assay was positive in 98.3% but scaA was present in all 178 DNAs (100%) by ATD TaqMan. scaB, scaC, scaD, scaE and scaF were detected in 33.7%, 97.8%, 93.8%, 97.2% and 43.3% isolates by ATD TaqMan, respectively. The ATDs of Ots sca genes are thus sufficiently conserved between different genotypes for molecular assay design. Four sca genes are widely distributed among diverse Ots isolates from diverse geographical areas. scaB and scaF were detected in fewer Ots isolates and absent from some available genome sequences. Whether the utility of the ScaA, ScaC, ScaD, and ScaE antigenic passenger protein domains exceeds that of the mixed 56 kDa type surface antigens of Ots now used in combination diagnostic assays needs to be determined before they can be considered as suitable alternative serological antigens for diagnosis of scrub typhus.

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in motor power of all four limbs was seen, with simultaneous emergence of deep tendon reflexes. By the tenth day, ventilator support was weaned. At the time of discharge, free ambulation with the help of a walker was possible. Four weeks later at outpatient review, he had regained full motor power in all four limbs and had no remaining signs and symptoms of his recent neurotoxicity. Discussion Neurological manifestations may result from envenomation from the elapidae group snakes such as cobra and krait. Snake bite is an occupational hazard for farmers or labourers working in open fields or forests and for people sleeping in the open. A high index of suspicion is required in such cases, as in most instances a definite history of snake bite is absent and the bite marks are not visible. LIS is a rare neurological condition where complete paralysis of voluntary muscles occurs except those of the eye; cognition remains intact. Bauer described three types of locked in states: (1) total, with complete quadriplegia with anarthria; (2) classic, similar to total, but with preserved vertical eye movements and consciousness; and (3) incomplete, similar to classic, with some voluntary movements present along with eye movements. 2 Common causes of LIS are polyneuropathy, toxins, myasthenia gravis, encephalitis, stroke and trauma. 3 LIS from snake envenomation occurs as a result of neuromuscular transmission blockade at the peripheral level from post-synaptical binding at acetylcholine receptors in cobra bites or pre-synaptical binding, preventing acetylcholine release, in krait bites. 4 Only very few such cases have been reported in the literature. 5-7 LIS can readily be misdiagnosed as brain death; slow recovery may add to this misinterpretation. 8 The use of anti-venom therapy and ventilator almost always results in complete recovery with no residual neurological deficit in LIS.

Background: Scrub typhus is a common tropical infection presenting as acute febrile illness. Acute Respiratory Distress Syndrome (ARDS) is a serious complication of scrub typhus and is often associated with high mortality. This study was aimed to analyse risk factors of ARDS in Scrub typhus patients.Methods: This study was a prospective observational case control study conducted from June 2012 to June 2015 in Kasturba Hospital, Manipal, Karnataka, India. ARDS was diagnosed as per Berlin criteria.Results: During the study period, a total of 320 patients were diagnosed to have scrub typhus as per our criteria. All the patients were from state of Karnataka except for 1 patient, who was from state of Kerala. A total of 20 (6.25%) patients (cases) were diagnosed to have ARDS and 300 (93.75%) patients (controls) did not have ARDS. After multivariate analysis of the risk factors only two risk factors had significant association with development of ARDS: sepsis (OR 4.34,95% CI 0.51,36.76) and septic shock (OR 16.57 95% CI 1.64,166.76).Conclusions: ARDS is a common and serious complication of scrub typhus. It often occurs along with other complications. Presence of dyspnoea, sepsis, septic shock, hypoalbuminemia should alert clinicians about ARDS. ARDS due to scrub typhus is associated with high mortality. Early recognition and prompt therapy can reduce mortality.

Eschar in scrub typhus aids in early diagnosis and institution of appropriate therapy; however, the eschar positivity rates vary greatly in endemic regions. Multiple eschars in scrub typhus are a rare presentation. Our patient presented with fever and multiple eschars and was empirically started on doxycycline. Nested polymerase chain reaction from all the four eschars and from EDTA blood were positive for 56-kDa type-specific antigen which is specific for Orientia tsutsugamushi The patient recovered completely after 7 days of antibiotic treatment. He was from an area where scrub typhus was not observed previously. An eschar in an acute febrile patient from the "tsutsugamushi triangle" is a valuable sign in scrub typhus diagnosis. A search for multiple eschars in scrub typhus must be made by clinicians.

ObjectiveTo evaluate the field performance of a multiplex PCR (M-PCR) assay for detection of herpes simplex virus (HSV)-1 and HSV-2, Treponema pallidum (T. pallidum) and Haemophilus ducreyi (H. ducreyi) in genital ulcer disease (GUD) specimens.MethodsGUD M-PCR was performed on 186 remnant specimens, previously collected for HSV testing, by four public health laboratories (PHLs) and the Laboratory Reference and Research Branch (LRRB) at the Centers for Disease Control and Prevention. The results from the PHLs were compared with those of LRRB, which served as the reference testing method, and percentage agreement was calculated.ResultsHSV was detected in 31 of 52 (59.6%), 20 of 40 (50%), 43 of 44 (97.7%) and 19 of 50 (38.0%) specimens from PHL1, PHL2, PHL3 and PHL4, respectively. There were seven discrepant results for HSV, and the overall percent agreement between the PHLs and the LRRB was 94%–100%, with a kappa value of 0.922, which demonstrates high agreement. T. pallidum was identified in 7 of 51 (13.7%) specimens from PHL1 with 94.1% agreement and in 2 of 40 (5.0%) specimens from PHL2 with 100% agreement. The LRRB identified three additional T. pallidum-positive specimens from PHL1. The kappa value (0.849) for T. pallidum testing suggests good agreement. Consistent with the LRRB results, no T. pallidum was detected in specimens from PHL3 and PHL4, and H. ducreyi was not detected at any of the study sites.ConclusionsThe GUD M-PCR assay performed well in four independent PHLs and 12 suspected syphilis cases were identified in this study. The M-PCR assay could provide improved diagnostic options for GUD infections in state and local PHLs.