Clinical Evaluation of Rapid Diagnostic Test Kit for Scrub Typhus with Improved Performance

Diagnosis of scrub typhus is challenging due to its more than twenty serotypes and the similar clinical symptoms with other acute febrile illnesses including leptospirosis, murine typhus and hemorrhagic fever with renal syndrome. Accuracy and rapidity of a diagnostic test to Orientia tsutsugamushi is an important step to diagnose this disease. To discriminate scrub typhus from other diseases, the improved ImmuneMed Scrub Typhus Rapid Diagnostic Test (RDT) was evaluated in Korea and Sri Lanka. The sensitivity at the base of each IgM and IgG indirect immunofluorescent assay (IFA) in Korean patients was 98.6% and 97.1%, and the specificity was 98.2% and 97.7% respectively. The sensitivity and specificity for retrospective diagnosis at the base of IFA in Sri Lanka was 92.1% and 96.1%. ImmuneMed RDT was not reactive to any serum from seventeen diseases including hemorrhagic fever with renal syndrome (n = 48), leptospirosis (n = 23), and murine typhus (n = 48). ImmuneMed RDT shows superior sensitivity (98.6% and 97.1%) compared with SD Bioline RDT (84.4% at IgM and 83.3% at IgG) in Korea. The retrospective diagnosis of ImmuneMed RDT exhibits 94.0% identity with enzyme-linked Immunosorbent assay (ELISA) using South India patient serum samples. These results suggest that this RDT can replace other diagnostic tests and is applicable for global diagnosis of scrub typhus. This rapid and accurate diagnosis will be beneficial for diagnosing and managing scrub typhus.

Identification of Outer Membrane Vesicles Derived from Orientia tsutsugamushi

Orientia tsutsugamushi, a causative pathogen of Scrub typhus, is a gram-negative intracellular bacterium. Outer membrane vesicles (OMVs) are produced from the membrane of bacteria and play many roles related to the survival of the pathogen. However, there have been no reports confirming whether O. tsutsugamushi indeed produce OMVs. O. tsutsugamushi boryong was cultured in ECV-304 cells for the purification of OMVs. Western blot analysis and immunoenrichment using anti-O. tsutsugamushi monoclonal antibody and electron microscopy were employed for identification and characterization of OMVs. We confirm the presence of OMVs derived from O. tsutsugamushi, and also found that those OMVs contain a major surface antigen of 56-kDa protein and variant immunogenic antigens.

Epidemic of Scrub Typhus in Haroti Region of Rajasthan.

Scrub typhus is a rare form of disease caused by gram negative bacterium Orientia tsutsugamushi, of family Rickettsiaceae, transmitted by bite of infected trombiculid mite larva (chigger). The present prospective study is undertaken with the aim of the clinical manifestations, course, complications and outcome of scrub typhus in Haroti region of Rajasthan state during the recent epidemic. Method: This prospective study was conducted in indoor patients of MBS hospital and various private nursing homes in Kota city from August 2012 to November 2012. Twenty cases with positive Scrub typhus card test in the age group of 20 years to 60 years, comprising of 14 males and 06 females were included in the study group in clinically suspected cases with fever, rashes, cough with or without eschar and regional lymphadenopathy. Cases were studied in detail and followed up for improvement and any permanent damage or death. Results: Out of 20 patients, 16 patients improved and discharged from hospital in stable condition without any disability. 02 patients (10%) died because of late presentation and multiorgan involvement especially respiratory failure or meningoencephalitis. Conclusion: Haroti witnessed recent epidemic of Scrub typhus. Renal, respiratory and neurological complications were main cause of mortality and morbidity.

Diagnosis of scrub typhus: introduction of the immunochromatographic test in Korea

No abstract available.

Rhabdomyolysis in scrub typhus: an unusual presentation

Scrub typhus is the most common zoonosis of public health importance in rural areas of Asia, Northern Australia and Pacific Islands. The clinical spectrum of the disease varies from acute febrile illness to multi-organ involvement with systemic complications. Delay in diagnosis and treatment often lead to increased morbidity and mortality. Rhabdomyolysis is a rare complication seen in an infectious disease. We report a 50-year-old farmer with scrub typhus presented with rhabdomyolysis and acute renal failure who succumbed to the disease in hospital

Improvement of the Diagnostic Sensitivity of Scrub Typhus Using a Mixture of Recombinant Antigens Derived from Orientia tsutsugamushi Serotypes

Diagnosis of scrub typhus is difficult because its symptoms are very similar to other acute febrile illnesses, such as leptospirosis, murine typhus, and other viral hemorrhagic fevers. To differentiate scrub typhus from other acute febrile diseases, a rapid and reliable serological diagnosis is important. We have developed a chimeric recombinant antigen cr56 and two other recombinant antigens, r21 and kr56, from various serotypes of Orientia tsutsugamushi. They were tested for the detection of antibodies against O. tsutsugamushi in the patient's serum samples using enzyme-linked immunosorbent assay (ELISA) and dot-blot analyses. As of conventional immunofluorescence assay (IFA), when the mixture of these three recombinant antigens was used, both sensitivity and specificity of the recombinant antigens were increased up to 98% in IgM and IgG at ELISA and dot blotting. Additionally, both sensitivity and specificity by detection of IgM and IgG antibodies at rapid diagnostic test (RDT), using the mixture of three antigens and gold conjugated antibodies, were 99%. Our results suggest the use of mixture of these recombinant antigen proteins in ELISA or RDT is suitable as a diagnostic test for scrub typhus.

Scrub typhus in children at a tertiary hospital in southern India: Clinical profile and complications

To study the clinical profile of and complications in children with scrub typhus. Prospective observational study. Tertiary care hospital. Children up to 12 years of age who had a fever for more than five days without an identifiable infection were included. All children who were suspected of having rickettsial infections were defined as having scrub typhus if they had a positive Weil-Felix test result [OX-K 1:80 or more] and one or more of the following clinical features [after exclusion of other diagnoses]: rash, edema, hepatosplenomegaly, lymphadenopathy, an eschar, and a tick bite or tick exposure. Thirty-five children were diagnosed with scrub typhus between February 2010 and February 2011. The age of the patients ranged from 1.5 to 12 years. Edema, crackles/rhonchi, hepatomegaly and hypotension were encountered in 60%, 23%, 91% and 34% of patients, respectively. An eschar was observed in 11% of the cases. Complications included myocarditis with cardiogenic shock in 34% of the cases and acute kidney injury in 20% of the cases. Anicteric hepatitis and thrombocytopenia were observed in 31% and 61% of cases, respectively. One patient died. High incidences of myocarditis and acute kidney injury were observed, which indicates that the children were treated at a late stage of the disease. Clinicians should be cognizant that myocarditis and acute kidney injury are serious manifestations of pediatric scrub typhus. 2011 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved

Phylogenetic Analysis of the 56-kDa Type-Specific Protein Genes of Orientia tsutsugamushi in Central Korea

There are several antigenic variants of Orientia tsutsugamushi. The 56-kDa type-specific antigen (TSA) is responsible for the antigenic variation. Nucleotide sequences of the 56-kDa TSA obtained from 44 eschar samples of Korean scrub typhus patients and from 40 representative strains retrieved from the GenBank database were analyzed phylogenetically. Clinical patient data were assessed based on the genotyping results. Of the 44 nucleotide sequences, 32 (72.7%) clustered with the Boryong genotype, which is the major genotype in Korea. Eleven nucleotide sequences (25%) clustered with the Kawasaki genotype, not identified in Korea until 2010. One nucleotide sequence was consistent with the Karp genotype. The clinical course of the patients infected with each genotype showed no differences. Diagnostic performance of the immunofluorescence assay (IFA) using the 56-kDa TSA from Gilliam, Karp and Boryong as test antigens were not different for the Boryong and Kawasaki genotypes. Although Boryong is still the predominant genotype, the results suggest that Kawasaki genotype is quite prevalent in Chungbuk province of Korea.

Phylogenetic Analysis of the 56-kDa Type-Specific Protein Genes of Orientia tsutsugamushi in Central Korea

There are several antigenic variants of Orientia tsutsugamushi. The 56-kDa type-specific antigen (TSA) is responsible for the antigenic variation. Nucleotide sequences of the 56-kDa TSA obtained from 44 eschar samples of Korean scrub typhus patients and from 40 representative strains retrieved from the GenBank database were analyzed phylogenetically. Clinical patient data were assessed based on the genotyping results. Of the 44 nucleotide sequences, 32 (72.7%) clustered with the Boryong genotype, which is the major genotype in Korea. Eleven nucleotide sequences (25%) clustered with the Kawasaki genotype, not identified in Korea until 2010. One nucleotide sequence was consistent with the Karp genotype. The clinical course of the patients infected with each genotype showed no differences. Diagnostic performance of the immunofluorescence assay (IFA) using the 56-kDa TSA from Gilliam, Karp and Boryong as test antigens were not different for the Boryong and Kawasaki genotypes. Although Boryong is still the predominant genotype, the results suggest that Kawasaki genotype is quite prevalent in Chungbuk province of Korea.

Nested polymerase chain reaction on blood clots for gene encoding 56 kDa antigen and serology for the diagnosis of scrub typhus.

Purpose : Scrub typhus is a zoonotic illness endemic in the Asia-Pacific region. Early diagnosis and appropriate management contribute significantly to preventing adverse outcomes including mortality. Serology is widely used for diagnosing scrub typhus. Recent reports suggest that polymerase chain reaction (PCR) could be a rapid and reliable alternative. This study assessed the utility of these tests for scrub typhus diagnosis. Materials and Methods : Nested PCR to detect the 56 kDa antigen gene of O. tsutsugamushi was performed on blood clots from 87 individuals with clinically suspected scrub typhus. Weil-Felix test and scrub typhus IgM ELISA were performed on serum samples from the same patients. As a gold standard reference test was not available, latent class analysis (LCA) was used to assess the performance of the three tests. Results : The LCA analysis showed the sensitivity of Weil-Felix test, IgM ELISA and PCR to be 59%, 100% and 58% respectively. The specificity of ELISA was only 73%, whereas those of the Weil-Felix test and PCR were 94% and 100% respectively. Conclusion : Nested PCR using blood clots while specific, lacked sensitivity as compared to IgM ELISA. In resource-poor settings Weil-Felix test still remains valuable despite its moderate sensitivity.

Two Cases of Scrub Typhus Presenting with Guillain-Barre Syndrome with Respiratory Failure

No abstract available.

Scrub typhus associated with systemic lupus erythematosus: a case report

The etiology of systemic lupus erythematosus [SLE] is largely unknown and there is a probable contribution of genetic, hormonal, immunological and environmental factors for its manifestation. The widespread immunological destruction of many organs in SLE and the associated decreased immunity increase the risk of infections. Steroids and other immunosuppressant are important in the treatment of SLE, but they further increase the risk of infections, and sometimes with rare organisms. We present a case of an adolescent girl with prolonged fever, joint pains and without skin rashes. The initial diagnosis was SLE. She was treated with steroids with improvement in her general condition and relief of joint pains. However the fever persisted and subsequent investigations revealed an associated scrub typhus. The fever subsided after treatment with oral tetracycline. There were no complications of scrub typhus. Since scrub typhus infection is not common in the Arabian Peninsula the disease was not initially thought of. In the investigation of prolonged fever in SLE, viral, bacterial, protozoal as well as rickettsial diseases should be borne in mind

Pediatric scrub typhus in Indian Himalayas.

To retrospectively confirm the suspected rickettsial disease (Scrub typhus) using a gold standard diagnostic test i.e. microimmunofluorescence in pediatric patients with acute febrile illness of unknown etiology. Two serological tests, Weil-Felix and Microimmunofluorescence were used to confirm infection. All five children had fever, vomiting and generalized lymphadenopathy, but none had eschar or rash. One was cured with doxycycline, remaining four patients treated with azithromycin and one died despite treatment. Scrub typhus is a cause of fever of unknown origin in Himalayan region of India and azithromycin is an effective alternative to doxycycline in treating this disease.

Serological evidence for wide distribution of spotted fevers & typhus fever in Tamil Nadu.

BACKGROUND & OBJECTIVE: Although the re-emergence of spotted fevers and typhus was documented from southern India a few years ago, there was a paucity of community based data. Therefore a collaborative study was carried out in several districts of Tamil Nadu to understand the distribution of these infections. METHODS: Blood (3 ml) was collected from patients presenting to primary health centres (PHCs) with fever >10 days duration in 15 districts of Tamil Nadu during January 2004 to December 2005. Patients negative for malaria, were tested by Weil-Felix test. Clinical data were collected from patients visiting two hospitals. RESULTS: A total 306 samples were tested in 2004 and 115 (37.5%) had titres of >or=80 with OX K antigen, suggesting a diagnosis of scrub typhus. During 2005, 964 patients were tested and 89 (9.2%) were positive for scrub typhus. An additional 44 (4.6%) were positive for other rickettsial illnesses. In both years majority of scrub typhus occurred in individuals above 14 yr of age. Cases increased from August until the earlier part of next year. INTERPRETATION & CONCLUSION: This community based study from south India involving several districts in Tamil Nadu, showed that scrub typhus and rickettsial illnesses were widely distributed in the State. Measures to increase awareness and also to diagnose and treat this infection in the affected areas are essential.

Follow-up analysis on the epidemic strains of Orientia tsutsugamushi in the first outbreak of scrub typhus in Henan Province, China.

To obtain knowledge of the genetic characteristics and types of the epidemic strains of Orientia tsutsugamushi in the first outbreak of scrub typhus in Henan Province, genus and type-specific primers were employed to amplify a fragment of the gene of 56 kDa protein. Serotyping demonstrated that, of the 19 patients [15 patients in recovery phase (10-40 days) and 4 of patients in acute phase (1-7 days)], 4 were infected with Gilliam type, 8 with Kato type, 6 with Karp type, and 1 with an unknown type. Successful genotyping was obtained for only 3 patients, indicating that 2 were infected with Karp type and 1 with Taiwan Kato type. Thus the outbreak of scrub typhus in Henan Province was caused by at least two epidemic strains.