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Narita M, Monma N, Chiba K, Suzuki R, Fujita S, Hoshino C, Nakamura K, Sekikawa Y, Ikeda H, Inoue M, Shimbo T, Yamamoto S, Ando S, Takada N, Fujita H. Masqueraders Around Disaster: Clinical Features of Scrub Typhus in Fukushima, Japan. Open Forum Infect Dis 2024; 11:ofae215. [PMID: 38756759 PMCID: PMC11096087 DOI: 10.1093/ofid/ofae215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 04/16/2024] [Indexed: 05/18/2024] Open
Abstract
Background Scrub typhus (ST) is endemic in Fukushima, with the largest number of cases reported in Japan from 2009 to 2010. Although ST is highly treatable, its atypical clinical presentation impedes diagnosis, causing delays in treatment. Methods We review the clinical features of ST in adults from 2008 to 2017 at Ohta Nishinouchi General Hospital in Fukushima, Japan. Results Fifty-five cases (serotype Karp 24, Irie/Kawasaki 21, Hirano/Kuroki 10) of ST were confirmed via serology based on elevated immunoglobulin (Ig)M and IgG and polymerase chain reaction positivity of eschar samples. The mean age was 69 years, and 64% were female. The case fatality rate was 1.8% (1/55). Approximately 70% of cases (38/55) were not diagnosed as ST upon the initial clinic visit. Inappropriate use of antibiotics was identified in 22% of cases (12/55). In terms of atypical clinical features, 1 or more of the manifestations, fever, rash, and eschar, was absent in 31% of cases (17/55). Approximately 11% of cases presented without eschar (6/55; Karp 1, Irie/Kawasaki 1, Hirano/Kuroki 4). Moreover, severe complications were observed with shock and disseminated intravascular coagulation in 7% of cases (4/55), Thus, while 53% of cases presented with the typical triad (29/55), unusual complications and atypical features occurred in 40% (22/55). Conclusions Diagnosis of ST becomes clinically challenging in the absence of typical features. In Fukushima, an endemic area of ST, an atypical presentation involving multisystem disease is common.
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Affiliation(s)
- Masashi Narita
- Division of Infectious Diseases, Department of Internal Medicine, Okinawa Prefectural Nambu Medical Center & Children's Medical Center, Haebaru, Japan
- Division of Infectious Diseases, Department of Internal Medicine, Okinawa Prefectural Chubu Hospital, Uruma, Japan
- Department of Medicine, Ohta Nishinouch General Hospital, Koriyama, Japan
| | - Naota Monma
- Department of Infection Control, Fukushima Medical University, Fukushima, Japan
| | - Kazuki Chiba
- Fukushima Prefectural Institute of Public Health, Fukushima, Japan
| | - Rie Suzuki
- Fukushima Prefectural Institute of Public Health, Fukushima, Japan
| | - Shohei Fujita
- Fukushima Prefectural Institute of Public Health, Fukushima, Japan
| | | | - Kiwamu Nakamura
- Department of Infection Control, Fukushima Medical University, Fukushima, Japan
| | - Yoshiyuki Sekikawa
- Division of Infectious Diseases, Department of Internal Medicine, Japanese Red Cross Musashino Hospital, Musashino, Japan
| | | | - Minoru Inoue
- Department of Medicine, Ohta Nishinouch General Hospital, Koriyama, Japan
| | - Takuro Shimbo
- Department of Medicine, Ohta Nishinouch General Hospital, Koriyama, Japan
| | - Seigo Yamamoto
- Miyazaki Prefectural Institute for Public Health and Environment, Miyazaki, Japan (former affiliation)
| | - Shuji Ando
- National Institute of Infectious Diseases, Tokyo, Japan
| | - Nobuhiro Takada
- Department of Pathological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Hiromi Fujita
- Institute of Rickettsioses, Kita-Fukushima Medical Center, Fukushima, Japan
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Ritu GP, Arif W, Sihag KK, Chakravarthi A, Anthony TN, Srinivasan L, Balakrishnan V, Kumar A, Ayanar E, Devaraju P. Comparative Evaluation of Different Tissues and Molecular Techniques for the Zoonotic Surveillance of Scrub Typhus. Vector Borne Zoonotic Dis 2024; 24:299-307. [PMID: 38181193 DOI: 10.1089/vbz.2023.0069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2024] Open
Abstract
Background and Objectives: Scrub typhus (ST) is detected in one-fourth of patients with acute febrile illnesses, confirming its nationwide re-emergence. The disease, if not diagnosed, can lead to multiple organ dysfunction and mortality. Being a vector-borne zoonotic disease, the molecular survey for pathogens in animal hosts is essential to predict the risk of its transmission to humans. Hence, this study aimed at identifying the effective animal tissue and molecular technique for zoonotic surveillance of ST infection in small animal hosts. Methods: Rodents/shrews were trapped from seventeen randomly selected villages in Puducherry between July and September, 2022. The presence of Orientia tsutsugamushi in ectoparasites and tissues including blood, lung, liver, spleen, kidney, heart, brain, and intestine retrieved from the animals was screened by nested PCR targeting 56 kDa, real-time PCR (qPCR) targeting 47 kDa and traD, and conventional PCR targeting groEL. The Weil-Felix test was carried out to detect antibodies against O. tsutsugamushi in rodent/shrew serum samples. Diagnostic accuracy measures of the molecular tests were calculated for each of the tissues by latent class modeling. Results: O. tsutsugamushi detected in the rodents/shrews were identified to be Karp-like and Kawasaki-like strains. Upon statistical analysis, qPCR targeting 47 kDa exhibited the highest accuracy measures in most of the tissues analyzed, with perfect sensitivity and specificity of 100% and 97% for intestine and lung samples for the epidemiological surveillance, respectively. Interpretation and Conclusion: The study recommends qPCR targeting 47 kDa gene and analysis of intestine and lung along with blood for the zoonotic surveillance of ST infection.
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Affiliation(s)
- Georgina Parren Ritu
- MSc. Public Health Entomology Student, ICMR-Vector Control Research Centre, Indira Nagar, Puducherry
| | - Waseema Arif
- Unit of One Health, ICMR-Vector Control Research Centre, Indira Nagar, Puducherry
| | - Krishan Kumar Sihag
- Unit of One Health, ICMR-Vector Control Research Centre, Indira Nagar, Puducherry
| | | | | | - Lakshmy Srinivasan
- Unit of One Health, ICMR-Vector Control Research Centre, Indira Nagar, Puducherry
| | | | - Ashwani Kumar
- ICMR-Vector Control Research Centre, Indira Nagar, Puducherry
| | - Elango Ayanar
- Unit of Vector Biology and Control, ICMR-Vector Control Research Centre, Indira Nagar, Puducherry
| | - Panneer Devaraju
- Unit of One Health, ICMR-Vector Control Research Centre, Indira Nagar, Puducherry
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Govindarajan R, Sankar SG, Kumar MS, Rajamannar V, Krishnamoorthi R, Anand AAP, Kumar A, Samuel PP. Molecular detection of Orientia tsutsugamushi in ectoparasites & their small mammal hosts captured from scrub typhus endemic areas in Madurai district, India. Indian J Med Res 2024; 159:180-192. [PMID: 38494626 PMCID: PMC11050748 DOI: 10.4103/ijmr.ijmr_3530_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Indexed: 03/19/2024] Open
Abstract
BACKGROUND OBJECTIVES Scrub typhus, caused by Orientia tsutsugamushi present in small mammals harbouring the ectoparasites. A study was undertaken to detect the pathogen present in small mammals and its ectoparasites in the scrub typhus-reported areas. METHODS The small mammals (rodents/shrews) and its ectoparasites were screened for O. tsutsugamushi using nested PCR amplification of the groEL gene. Small mammals were collected by trapping and screened for ectoparasites (mites, ticks and fleas) by combing method. RESULTS All the chigger mites collected were tested negative for O. tsutsugamushi . Interestingly, adult non-trombiculid mites ( Oribatida sp., Dermanyssus gallinae ), fleas ( Xenopsylla astia, X. cheopis, Ctenophalides felis and Ctenophalides sp.) and ticks ( Rhipicephalus sanguineus , R. haemaphysaloides ) screened were found to be positive for O. tsutsugamushi , which the authors believe is the first report on these species globally. Bandicota bengalensis with O. tsutsugamushi infection is reported for the first time in India. The O. tsutsugamushi groEL sequences from the positive samples were similar to the reference strains, Karp and Ikeda and phylogenetically clustered in clade IV with less evolutionary divergence. The blood samples of Rattus rattus , Suncus murinus and B. bengalensis collected from this area were tested positive for O. tsutsugamushi ; interestingly, the sequence similarity was much pronounced with their ectoparasites indicating the transmission of the pathogen to host or vice versa . INTERPRETATION CONCLUSIONS The outcome of the present investigations widened our scope on the pathogens present in ectoparasites and rodents/shrews from this area. This will help to formulate the required vector control methods to combat zoonotic diseases.
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Affiliation(s)
- R. Govindarajan
- Division of Vector Borne Zoonotic Diseases, ICMR-Vector Control Research Centre Field Station, Madurai, Tamil Nadu, India
| | - S. Gowri Sankar
- Division of Vector Borne Zoonotic Diseases, ICMR-Vector Control Research Centre Field Station, Madurai, Tamil Nadu, India
| | - M. Senthil Kumar
- Division of Vector Borne Zoonotic Diseases, ICMR-Vector Control Research Centre Field Station, Madurai, Tamil Nadu, India
| | - V. Rajamannar
- Division of Vector Borne Zoonotic Diseases, ICMR-Vector Control Research Centre Field Station, Madurai, Tamil Nadu, India
| | | | | | - Ashwani Kumar
- ICMR-Vector Control Research Centre, Puducherry, India
| | - P. Philip Samuel
- Division of Vector Borne Zoonotic Diseases, ICMR-Vector Control Research Centre Field Station, Madurai, Tamil Nadu, India
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Bhardwaj P, Nanaware NS, Behera SP, Kulkarni S, Deval H, Kumar R, Dwivedi GR, Kant R, Singh R. CRISPR/Cas12a-Based Detection Platform for Early and Rapid Diagnosis of Scrub Typhus. BIOSENSORS 2023; 13:1021. [PMID: 38131781 PMCID: PMC10742217 DOI: 10.3390/bios13121021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 09/29/2023] [Accepted: 10/06/2023] [Indexed: 12/23/2023]
Abstract
Orientia tsutsugamushi is responsible for causing scrub typhus (ST) and is the leading cause of acute encephalitis syndrome (AES) in AES patients. A rapid and sensitive method to detect scrub typhus on-site is essential for the timely deployment of control measures. In the current study, we developed a rapid, sensitive, and instrument-free lateral flow assay (LFA) detection method based on CRISPR/Cas12a technology for diagnosing ST (named LoCIST). The method is completed in three steps: first, harnessing the ability of recombinase polymerase for isothermal amplification of the target gene; second, CRISPR/Cas12a-based recognition of the target; and third, end-point detection by LFA. The detection limit of LoCIST was found to be one gene copy of ST genomic DNA per reaction, and the process was complete within an hour. In 81 clinical samples, the assay showed no cross-reactivity with other rickettsial DNA and was 100% consistent with PCR detection of ST. LoCIST demonstrated 97.6% sensitivity and 100% specificity. Overall, the LoCIST offers a novel alternative for the portable, simple, sensitive, and specific detection of ST, and it may help prevent and control AES outbreaks due to ST. In conclusion, LoCIST does not require specialized equipment and poses a potential for future applications as a point-of-care diagnostic.
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Affiliation(s)
- Pooja Bhardwaj
- ICMR-Regional Medical Research Centre Gorakhpur, BRD Medical College Campus, Gorakhpur 273013, India; (P.B.); (S.P.B.); (H.D.); (G.R.D.); (R.K.)
| | | | - Sthita Pragnya Behera
- ICMR-Regional Medical Research Centre Gorakhpur, BRD Medical College Campus, Gorakhpur 273013, India; (P.B.); (S.P.B.); (H.D.); (G.R.D.); (R.K.)
| | - Smita Kulkarni
- ICMR-National AIDS Research Institute, Bhosari, Pune 411026, India; (N.S.N.); (S.K.)
| | - Hirawati Deval
- ICMR-Regional Medical Research Centre Gorakhpur, BRD Medical College Campus, Gorakhpur 273013, India; (P.B.); (S.P.B.); (H.D.); (G.R.D.); (R.K.)
| | - Rajesh Kumar
- RGSC, Department of Genetics and Plant Breeding, Banaras Hindu University, Varanasi 221005, India;
| | - Gaurav Raj Dwivedi
- ICMR-Regional Medical Research Centre Gorakhpur, BRD Medical College Campus, Gorakhpur 273013, India; (P.B.); (S.P.B.); (H.D.); (G.R.D.); (R.K.)
| | - Rajni Kant
- ICMR-Regional Medical Research Centre Gorakhpur, BRD Medical College Campus, Gorakhpur 273013, India; (P.B.); (S.P.B.); (H.D.); (G.R.D.); (R.K.)
| | - Rajeev Singh
- ICMR-Regional Medical Research Centre Gorakhpur, BRD Medical College Campus, Gorakhpur 273013, India; (P.B.); (S.P.B.); (H.D.); (G.R.D.); (R.K.)
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Saraswati K, Elliott I, Day NPJ, Baird JK, Blacksell SD, Ristiyanto, Moyes CL. Geographical distribution of scrub typhus and risk of Orientia tsutsugamushi infection in Indonesia: Evidence mapping. PLoS Negl Trop Dis 2023; 17:e0011412. [PMID: 37747922 PMCID: PMC10553813 DOI: 10.1371/journal.pntd.0011412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 10/05/2023] [Accepted: 09/07/2023] [Indexed: 09/27/2023] Open
Abstract
BACKGROUND Scrub typhus is a potentially fatal acute febrile illness caused by bacteria in the genus Orientia. Though cases have been documented, a comprehensive body of evidence has not previously been compiled to give an overview of scrub typhus in Indonesia. This study aimed to address this key knowledge gap by mapping and ranking geographic areas based on existing data on the presence or absence of the pathogen in humans, vectors, and host animals. METHODOLOGY/PRINCIPAL FINDINGS We performed searches on local and international electronic databases, websites, libraries, and collections including Embase, Medline, and Scopus to gather relevant evidence (including grey literature). After extracting data on the presence and absence of the pathogen and its vectors, we ranked the evidence based on the certainty for the presence of human infection risk. The country was divided into subnational units, and each were assigned a score based on the evidence available for that unit. We presented this in an evidence map. Orientia tsutsugamushi presence has been identified on all the main islands (Sumatra, Java, Borneo, Celebes, Papua). About two thirds of the data points were collected before 1946. South Sumatra and Biak had the strongest evidence for sustaining infectious vectors. There was only one laboratory confirmed case in a human identified but 2,780 probable cases were documented. The most common vector was Leptotrombidium deliense. CONCLUSIONS/SIGNIFICANCE Our review highlights the concerning lack of data on scrub typhus in Indonesia, the fourth most populous country in the world. The presence of seropositive samples, infected vectors and rodents confirm O. tsutsugamushi is widespread in Indonesia and likely to be causing significant morbidity and mortality. There is an urgent need to increase surveillance to better understand the burden of the disease across the archipelago and to inform national empirical fever treatment guidelines.
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Affiliation(s)
- Kartika Saraswati
- Oxford University Clinical Research Unit Indonesia, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Ivo Elliott
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Nicholas P. J. Day
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - J. Kevin Baird
- Oxford University Clinical Research Unit Indonesia, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Stuart D. Blacksell
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Ristiyanto
- Research Center for Public Health and Nutrition, Research Organization for Health, National Research and Innovation Agency, Salatiga, Indonesia
| | - Catherine L. Moyes
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
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Patil S, Patil A, Chaudhari S, Shinde S, Kolte S, Khan W, Kurkure N. Edifications on Indirect IgM ELISA and Immunofluorescence assay (IFA) of scrub typhus in humans and erudition of Orientia tsutsugamushi in the vector of cohabiting rodents. J Vector Borne Dis 2023; 60:244-251. [PMID: 37843234 DOI: 10.4103/0972-9062.355964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Scrub typhus is a vector-borne disease caused by Orientia tsutsugamushi, propagated into humans by the bite of infected mite belonging to genus Leptotrombodium. The present study was conducted in the Nagpur region of central India aiming towards a survey of cohabiting rodents and their potential vectors for the presence of Orientia tsutsugamushi by PCR method. The study also emphasizes serological diagnosis of the disease by employing indirect IgM ELISA and IFA amongst the human cases of pyrexia of unknown origin. Indirect IgM ELISA recorded 39.69% (31/92) seropositive patients, further processing of ELISA positive samples for IFA revealed 67.74 % (21/31) positivity for Boryong, Gilliam, Karp, and Kato serotypes. A total of 50 rodents were trapped from the cohabit areas of the patients. Three different types of rodents were identified; among which, Rattus bandicoot was highest. From these rodents, 164 vectors viz mites, lice, and fleas were collected. The highest chiggar index was recorded for Ornithonyssus biscotti mites (3.4). This study prompts a detailed analysis of different species of rodents and vectors in the said endemic region.
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Affiliation(s)
- Shubham Patil
- Department of Veterinary Public Health, Nagpur Veterinary College, Nagpur, India
| | - Archana Patil
- Department of Veterinary Public Health, Nagpur Veterinary College, Nagpur, India
| | - Sandip Chaudhari
- Department of Veterinary Public Health, Nagpur Veterinary College, Nagpur, India
| | - Shilpshri Shinde
- Department of Veterinary Public Health, Nagpur Veterinary College, Nagpur, India
| | - Sunil Kolte
- Department of Veterinary Parasitology, Nagpur Veterinary College, Nagpur, India
| | - Waqar Khan
- Department of Veterinary Public Health, Nagpur Veterinary College, Nagpur, India
| | - Nitin Kurkure
- Maharashtra Animal and Fishery Sciences University, Nagpur, India
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Seetha D, Nori SRC, Nair RR. Molecular-based study of scrub typhus in Kerala, South India from 2014 to 2021: a laboratory-based study. COMPARATIVE CLINICAL PATHOLOGY 2023; 32:347-356. [PMID: 36741550 PMCID: PMC9889949 DOI: 10.1007/s00580-023-03443-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 01/23/2023] [Indexed: 02/04/2023]
Abstract
Scrub typhus (ST) is a neglected acute, febrile, infectious disease caused by the intracellular parasite Orientia tsutsugamushi, a gram-negative coccobacillus of the family Rickettsiaceae. Early and precise diagnosis is crucial to reduce the risk of developing disease complications. However, IgM antibody enzyme-linked immunosorbent assay (IgM ELISA) and indirect immunofluorescence assay (IFA) remain essential for diagnosis. However, it could be more helpful for early diagnosis due to the need for uniformity of approach in the diagnostic accuracy studies to determine appropriate ELISA cut-offs for various geographic locations. Hence, we aim to study the O. tsutsugamushi type-specific 56 kilodalton (kDa) protein gene using nested PCR (nPCR) and DNA sequence analysis as a molecular marker for early diagnosis. Out of 10,439 suspected cases, 1147/10,439 (11%) patients were positive for IgM ELISA. A total of 1044/10,439 (10%) samples were randomly tested after nPCR and compared with IgM ELISA results and DNA sequence analysis. Using nested PCR and IgM ELISA methods, 13% (134/1044) and 12% (125/1044) of the samples were positive, respectively. The serology method could not replicate the substantial number of positive cases demonstrated by nPCR; therefore, significant mutual exclusivity of the two techniques requires further investigation. Furthermore, our phylogenetic analysis revealed a clustering of isolates with Karp-related strains, providing insight into the transmission dynamics. Therefore, molecular diagnostic methods may aid in the early diagnosis of infection and enable prompt treatment of ST in endemic regions. Our results show that IgM ELISA can provide complete diagnostic advantages in conjunction with nPCR and can be an essential tool for accurate diagnosis. In addition, the DNA sequencing analysis of the samples showed that Karp-related strains were the main strains. Furthermore, research with samples from various regions in combination with the entire genome sequencing of O. tsutsugamushi is required to understand the infection mechanism better and develop robust early detection methods. Supplementary Information The online version contains supplementary material available at 10.1007/s00580-023-03443-8.
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Affiliation(s)
- Dayakar Seetha
- Houston, USA
- Laboratory Medicine and Molecular Diagnostics, Rajiv Gandhi Centre for Biotechnology (RGCB), Thiruvananthapuram, 695585 India
| | - Sai Ravi Chandra Nori
- Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork Ireland
- School of Microbiology, University College Cork, Cork, Ireland
| | - Radhakrishnan R. Nair
- Laboratory Medicine and Molecular Diagnostics, Rajiv Gandhi Centre for Biotechnology (RGCB), Thiruvananthapuram, 695585 India
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Comparison of the Serion IgM ELISA and Microscopic Agglutination Test for diagnosis of Leptospira spp. infections in sera from different geographical origins and estimation of Leptospira seroprevalence in the Wiwa indigenous population from Colombia. PLoS Negl Trop Dis 2022; 16:e0009876. [PMID: 35666764 PMCID: PMC9223614 DOI: 10.1371/journal.pntd.0009876] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 06/23/2022] [Accepted: 04/22/2022] [Indexed: 11/23/2022] Open
Abstract
Leptospirosis is among the most important zoonotic diseases in (sub-)tropical countries. The research objective was to evaluate the accuracy of the Serion IgM ELISA EST125M against the Microscopic Agglutination Test (MAT = imperfect reference test); to assess its ability to diagnose acute leptospirosis infections and to detect previous exposure to leptospires in an endemic setting. In addition, to estimate the overall Leptospira spp. seroprevalence in the Wiwa indigenous population in North-East Colombia. We analysed serum samples from confirmed leptospirosis patients from the Netherlands (N = 14), blood donor sera from Switzerland (N = 20), and sera from a cross-sectional study in Colombia (N = 321). All leptospirosis ELISA-positive, and a random of negative samples from Colombia were tested by the MAT for confirmation. The ELISA performed with a sensitivity of 100% (95% CI 77% - 100%) and a specificity of 100% (95% CI 83% - 100%) based on MAT confirmed Leptospira spp. positive and negative samples. In the cross-sectional study in Colombia, the ELISA performed with a sensitivity of 100% (95% CI 2–100%) and a specificity of 21% (95% CI 15–28%). Assuming a 5% Leptospira spp. seroprevalence in this population, the positive predictive value was 6% and the negative predictive value 100%. The Leptospira spp. seroprevalence in the Wiwas tested by the ELISA was 39%; however, by MAT only 0.3%. The ELISA is suitable to diagnose leptospirosis in acutely ill patients in Europe several days after onset of disease. For cross-sectional studies it is not recommended due to its low specificity. Despite the evidence of a high leptospirosis prevalence in other study areas and populations in Colombia, the Wiwa do not seem to be highly exposed to Leptospira spp.. Nevertheless, leptospirosis should be considered and tested in patients presenting with febrile illness. Leptospirosis is among the most important zoonotic diseases in (sub-)tropical countries. The correct diagnosis of leptospirosis is very important to take a medical or public health decision. Therefore, we tested a serological test (ELISA) for its ability to correctly diagnose a negative sample as truly negative and a positive sample as truly positive. We tested the ELISA with European acute leptospirosis confirmed positive and negative samples and compared results with another serological test (microscopic agglutination test), which is the recognized reference test. Further, the ELISA was assessed for its ability to detect previous exposure to leptospires in serum samples from the indigenous Wiwa population from Colombia, where leptospirosis is expected to be endemic. The ELISA performed very well with sera from patients with acute leptospirosis, however had difficulties to diagnose negative samples as truly negative in the Colombian field samples; hence unexposed persons were falsely diagnosed to be positive. Therefore, we recommend using the ELISA to detect acute leptospirosis several days after onset of illness in a non-endemic environment, but are not convinced of its usefulness to screen a population for previous Leptospira spp. exposure.
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Systematic Surveillance of Rickettsial Diseases in 27 Hospitals from 26 Provinces throughout Vietnam. Trop Med Infect Dis 2022; 7:tropicalmed7060088. [PMID: 35736967 PMCID: PMC9231031 DOI: 10.3390/tropicalmed7060088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 05/28/2022] [Accepted: 05/29/2022] [Indexed: 11/27/2022] Open
Abstract
In Vietnam, the public health burden of rickettsial infections continues to be underestimated due to knowledge gaps in the epidemiology of these diseases. We conducted a systematic study among 27 hospitals from 26 provinces in eight ecological regions throughout Vietnam to investigate the prevalence, distribution, and clinical characteristics of rickettsial diseases. We recruited 1834 patients in the study from April 2018 to October 2019. The findings showed that rickettsial diseases were common among undifferentiated febrile patients, with 564 (30.8%) patients positive by qPCR for scrub typhus, murine typhus or spotted fever. Scrub typhus (484, 85.8%) was the most common rickettsial disease, followed by murine typhus (67, 11.9%) and spotted fever (10, 1.8%). Rickettsial diseases were widely distributed in all regions of Vietnam and presented with nonspecific clinical manifestations.
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Enne VI, Aydin A, Baldan R, Owen DR, Richardson H, Ricciardi F, Russell C, Nomamiukor-Ikeji BO, Swart AM, High J, Colles A, Barber J, Gant V, Livermore DM, O'Grady J. Multicentre evaluation of two multiplex PCR platforms for the rapid microbiological investigation of nosocomial pneumonia in UK ICUs: the INHALE WP1 study. Thorax 2022; 77:1220-1228. [PMID: 35027473 DOI: 10.1136/thoraxjnl-2021-216990] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 11/29/2021] [Indexed: 01/12/2023]
Abstract
BACKGROUND Culture-based microbiological investigation of hospital-acquired or ventilator-associated pneumonia (HAP or VAP) is insensitive, with aetiological agents often unidentified. This can lead to excess antimicrobial treatment of patients with susceptible pathogens, while those with resistant bacteria are treated inadequately for prolonged periods. Using PCR to seek pathogens and their resistance genes directly from clinical samples may improve therapy and stewardship. METHODS Surplus routine lower respiratory tract samples were collected from intensive care unit patients about to receive new or changed antibiotics for hospital-onset lower respiratory tract infections at 15 UK hospitals. Testing was performed using the BioFire FilmArray Pneumonia Panel (bioMérieux) and Unyvero Pneumonia Panel (Curetis). Concordance analysis compared machine and routine microbiology results, while Bayesian latent class (BLC) analysis estimated the sensitivity and specificity of each test, incorporating information from both PCR panels and routine microbiology. FINDINGS In 652 eligible samples; PCR identified pathogens in considerably more samples compared with routine microbiology: 60.4% and 74.2% for Unyvero and FilmArray respectively vs 44.2% by routine microbiology. PCR tests also detected more pathogens per sample than routine microbiology. For common HAP/VAP pathogens, FilmArray had sensitivity of 91.7%-100.0% and specificity of 87.5%-99.5%; Unyvero had sensitivity of 50.0%-100.0%%, and specificity of 89.4%-99.0%. BLC analysis indicated that, compared with PCR, routine microbiology had low sensitivity, ranging from 27.0% to 69.4%. INTERPRETATION Conventional and BLC analysis demonstrated that both platforms performed similarly and were considerably more sensitive than routine microbiology, detecting potential pathogens in patient samples reported as culture negative. The increased sensitivity of detection realised by PCR offers potential for improved antimicrobial prescribing.
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Affiliation(s)
- Virve I Enne
- Division of Infection and Immunity, University College London, London, UK
| | - Alp Aydin
- Division of Infection and Immunity, University College London, London, UK
| | - Rossella Baldan
- Centre for Clinical Infection and Diagnostic Research, King's College London, London, UK.,Norwich Medical School, University of East Anglia, Norwich, UK
| | - Dewi R Owen
- Division of Infection and Immunity, University College London, London, UK
| | | | - Federico Ricciardi
- Department of Statistical Science, University College London, London, UK
| | | | | | - Ann-Marie Swart
- Norwich Clinical Trials Unit, University of East Anglia, Norwich, UK
| | - Juliet High
- Norwich Clinical Trials Unit, University of East Anglia, Norwich, UK
| | - Antony Colles
- Norwich Clinical Trials Unit, University of East Anglia, Norwich, UK
| | - Julie Barber
- Department of Statistical Science, University College London, London, UK
| | - Vanya Gant
- Department of Clinical Microbiology, University College London Hospitals NHS Foundation Trust, London, UK.,NIHR Biomedical research Centre, University College London Hospitals, London, UK
| | | | - Justin O'Grady
- Norwich Medical School, University of East Anglia, Norwich, UK.,Quadram Institute Bioscience, Norwich, UK
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11
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Liao CC, Tsai CH, Lo HR, Lin PR, Lin CC, Chao YC. Development of a Scrub Typhus Diagnostic Platform Incorporating Cell-Surface Display Technology. Front Immunol 2021; 12:761136. [PMID: 34707621 PMCID: PMC8542878 DOI: 10.3389/fimmu.2021.761136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 09/23/2021] [Indexed: 11/13/2022] Open
Abstract
Scrub typhus (ST), also known as tsutsugamushi disease and caused by rickettsia Orientia tsutsugamushi, is an underestimated fatal epidemic in the Asia-Pacific region, resulting in a million human infections each year. ST is easily misdiagnosed as clinical diagnosis is based on non-specific skin eschar and flu-like symptoms. Thus, the lack of accurate, convenient, and low-cost detection methods for ST poses a global health threat. To address this problem, we adopted baculovirus surface-display technology to express three variants of TSA56, the major membrane antigen of O. tsutsugamushi, as well as the passenger domain of ScaC (ScaC-PD), on insect Sf21 cell surfaces rather than biosafety level 3 bacteria in an enzyme-linked immunosorbent assay (ELISA). Recombinant TSA56 and ScaC-PD were all properly expressed and displayed on Sf21 cells. Our cell-based ELISA comprising the four antigen-displaying cell types interacted with monoclonal antibodies as well as serum samples from ST-positive field-caught rats. This cell-based ELISA presented high accuracy (96.3%), sensitivity (98.6%), and specificity (84.6%) when tested against the ST-positive rat sera. Results of a pilot study using human sera were also highly consistent with the results of immunofluorescence analyses. By adopting this approach, we circumvented complex purification and refolding processes required to generate recombinant O. tsutsugamushi antigens and reduced the need for expensive equipment and extensively trained operators. Thus, our system has the potential to become a widely used serological platform for diagnosing ST.
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Affiliation(s)
- Chih-Chi Liao
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Chih-Hsuan Tsai
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Huei-Ru Lo
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Pey-Ru Lin
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
| | - Chang-Chi Lin
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
| | - Yu-Chan Chao
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.,Department of Entomology, National Chung Hsing University, Taichung, Taiwan.,Department of Entomology, College of Bioresources and Agriculture, National Taiwan University, Taipei, Taiwan.,Department of Plant Pathology and Microbiology, College of Bioresources and Agriculture, National Taiwan University, Taipei, Taiwan
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12
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Saraswati K, Maguire BJ, McLean ARD, Singh-Phulgenda S, Ngu RC, Newton PN, Day NPJ, Guérin PJ. Systematic review of the scrub typhus treatment landscape: Assessing the feasibility of an individual participant-level data (IPD) platform. PLoS Negl Trop Dis 2021; 15:e0009858. [PMID: 34648517 PMCID: PMC8547739 DOI: 10.1371/journal.pntd.0009858] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 10/26/2021] [Accepted: 09/28/2021] [Indexed: 01/18/2023] Open
Abstract
Background Scrub typhus is an acute febrile illness caused by intracellular bacteria from the genus Orientia. It is estimated that one billion people are at risk, with one million cases annually mainly affecting rural areas in Asia-Oceania. Relative to its burden, scrub typhus is understudied, and treatment recommendations vary with poor evidence base. These knowledge gaps could be addressed by establishing an individual participant-level data (IPD) platform, which would enable pooled, more detailed and statistically powered analyses to be conducted. This study aims to assess the characteristics of scrub typhus treatment studies and explore the feasibility and potential value of developing a scrub typhus IPD platform to address unanswered research questions. Methodology/principal findings We conducted a systematic literature review looking for prospective scrub typhus clinical treatment studies published from 1998 to 2020. Six electronic databases (Ovid Embase, Ovid Medline, Ovid Global Health, Cochrane Library, Scopus, Global Index Medicus), ClinicalTrials.gov, and WHO ICTRP were searched. We extracted data on study design, treatment tested, patient characteristics, diagnostic methods, geographical location, outcome measures, and statistical methodology. Among 3,100 articles screened, 127 were included in the analysis. 12,079 participants from 12 countries were enrolled in the identified studies. ELISA, PCR, and eschar presence were the most commonly used diagnostic methods. Doxycycline, azithromycin, and chloramphenicol were the most commonly administered antibiotics. Mortality, complications, adverse events, and clinical response were assessed in most studies. There was substantial heterogeneity in the diagnostic methods used, treatment administered (including dosing and duration), and outcome assessed across studies. There were few interventional studies and limited data collected on specific groups such as children and pregnant women. Conclusions/significance There were a limited number of interventional trials, highlighting that scrub typhus remains a neglected disease. The heterogeneous nature of the available data reflects the absence of consensus in treatment and research methodologies and poses a significant barrier to aggregating information across available published data without access to the underlying IPD. There is likely to be a substantial amount of data available to address knowledge gaps. Therefore, there is value for an IPD platform that will facilitate pooling and harmonisation of currently scattered data and enable in-depth investigation of priority research questions that can, ultimately, inform clinical practice and improve health outcomes for scrub typhus patients. Scrub typhus is a febrile illness most commonly found in rural tropical areas. It is caused by a Gram-negative bacteria belonging to the family Rickettsiaceae and transmitted by mites when they feed on vertebrates. There is an estimate of one million cases annually, with an estimated one billion people at risk, mostly in Asia-Oceania. But relative to the scale of the problem, scrub typhus is largely understudied. Evidence-based treatment recommendations by policymakers vary or are non-existent. We searched databases and registries for prospective scrub typhus clinical treatment studies published from 1998 to 2020 and reviewed them. Data from clinical trials and particularly for specific groups, such as pregnant women and children, were minimal. The methods used to measure treatment efficacy were heterogeneous, making it difficult to directly compare or conduct a meta-analysis based on aggregated data. One way to improve the current level of evidence would be by pooling and analysing individual participant-level data (IPD), i.e. the raw data from individual participants in completed studies. This review demonstrated that there is scope for developing a database for individual participant data to enable more detailed analyses. IPD meta-analyses could be a way to address knowledge gaps such as optimum dosing for children and pregnant women.
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Affiliation(s)
- Kartika Saraswati
- Eijkman-Oxford Clinical Research Unit, Eijkman Institute for Molecular Biology, Jakarta, Indonesia
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Infectious Diseases Data Observatory (IDDO), Oxford, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- * E-mail: (KS); (PJG)
| | - Brittany J. Maguire
- Infectious Diseases Data Observatory (IDDO), Oxford, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Alistair R. D. McLean
- Infectious Diseases Data Observatory (IDDO), Oxford, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Sauman Singh-Phulgenda
- Infectious Diseases Data Observatory (IDDO), Oxford, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Roland C. Ngu
- Infectious Diseases Data Observatory (IDDO), Oxford, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Paul N. Newton
- Infectious Diseases Data Observatory (IDDO), Oxford, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Lao-Oxford-Mahosot-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People’s Democratic Republic
| | - Nicholas P. J. Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Philippe J. Guérin
- Infectious Diseases Data Observatory (IDDO), Oxford, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- * E-mail: (KS); (PJG)
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13
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Lu CT, Wang LS, Hsueh PR. Scrub typhus and antibiotic-resistant Orientia tsutsugamushi. Expert Rev Anti Infect Ther 2021; 19:1519-1527. [PMID: 34109905 DOI: 10.1080/14787210.2021.1941869] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Introduction: Scrub typhus is one of the most underdiagnosed and under-reported febrile illnesses requiring hospitalization, mainly occurring in Southeast and East Asia and the Pacific Islands, in an area referred to as the 'Tsutsugamushi Triangle.' Scrub typhus is a zoonotic rickettsial disease that is transmitted to humans by trombiculid mites.Areas covered: A MEDLINE/PubMed search of the available literature was performed to describe the role of antibiotic-resistant scrub typhus in therapy failure.Expert opinion: Scrub typhus is characterized by an eschar that may appear 2-3 days before sudden-onset fever with chills, headache, backache, myalgia, profuse sweating, vomiting, and enlarged lymph nodes. A macular or maculopapular skin rash can develop within 3-8 days after the onset of fever. Various antibiotics, such as chloramphenicol, tetracycline, doxycycline, macrolides, quinolones, and rifampicin, have been used to treat scrub typhus. Resistance to tetracycline has been proposed to underlie delayed clinical improvement since 1996, but recent reports have questioned the existence of doxycycline resistance. Nevertheless, the existence and importance of antibiotic-resistant scrub typhus remain uncertain and require further study.
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Affiliation(s)
- Chin-Te Lu
- Department of Infectious Diseases, Lo-Hsu Medical Foundation, Lotung Poh-Ai Hospital, Yilan, Taiwan
| | - Lih-Shinn Wang
- Division of Infectious Diseases, Department of Internal Medicine, Buddhist Tzu Chi General Hospital and Tzu Chi University, Hualien, Taiwan
| | - Po-Ren Hsueh
- Department of Laboratory Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan.,Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
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14
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Dreyfus A, Ruf MT, Mayer-Scholl A, Zitzl T, Loosli N, Bier NS, Hiereth S, Ulrich S, Poppert S, Straubinger RK, Stenos J, Tshokey T. Exposure to Leptospira spp. and Associated Risk Factors in the Human, Cattle and Dog Populations in Bhutan. Pathogens 2021; 10:pathogens10030308. [PMID: 33800914 PMCID: PMC8000015 DOI: 10.3390/pathogens10030308] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/22/2021] [Accepted: 02/23/2021] [Indexed: 12/30/2022] Open
Abstract
Leptospirosis is a neglected worldwide zoonotic bacterial disease with a high prevalence in subtropical and tropical countries. The prevalence of Leptospira spp. in humans, cattle and dogs is unknown in Bhutan. Therefore, we sought to find out whether humans, cattle or dogs had been infected in the past with leptospires by measuring antibodies in the serum. We therefore collected blood from 864 humans ≥13 years of age, 130 bovines and 84 dogs from different rural and urban areas in Bhutan and tested the serum for antibodies specific for leptospires with a screening of enzyme-linked immunosorbent assays (ELISA) and a confirmatory microscopic agglutination test (MAT). In humans, 17.6% were seropositive by ELISA and 1.6% by MAT. The seropositivity was stronger in bovines (36.9%) and dogs (47.6%). "Having had a fever recently" (OR 5.2, p = 0.004), "working for the military" (OR 26.6, p = 0.028) and "being unemployed" (OR 12.9, p = 0.041) (reference category = housemaker) were statistically significantly associated with seropositivity when controlled for the effects of other risk factors. However, due to the small number of positive test results, the findings on risk factors should be interpreted with caution. Based on the serogroups found in the three species, dogs could be a source of infection for humans, or dogs and humans are exposed to the same environmental risk factors Clinical leptospirosis in humans and domestic animals should be investigated by testing blood and urine for the presence of leptospires by molecular methods (qPCR).
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Affiliation(s)
- Anou Dreyfus
- Department of Medicine, Swiss Tropical and Public Health Institute, 4055 Basel, Switzerland; (M.-T.R.); (N.L.); (S.P.)
- Medical Faculty, University of Basel, 4055 Basel, Switzerland
- Epidemiology and Clinical Research Unit, Institut Pasteur Madagascar, Antananarivo 101, Madagascar
- Correspondence:
| | - Marie-Thérèse Ruf
- Department of Medicine, Swiss Tropical and Public Health Institute, 4055 Basel, Switzerland; (M.-T.R.); (N.L.); (S.P.)
- Medical Faculty, University of Basel, 4055 Basel, Switzerland
| | - Anne Mayer-Scholl
- Department of Biological Safety, German Federal Institute for Risk Assessment, 10589 Berlin, Germany; (A.M.-S.); (N.S.B.)
| | - Theresa Zitzl
- Institute of Hygiene and Infectious Diseases of Animals, Justus Liebig University, 35392 Giessen, Germany;
- Chair for Bacteriology and Mycology, Institute for Infectious Diseases and Zoonoses, Faculty of Veterinary Medicine, Ludwig-Maximilians University Munich, 80539 Munich, Germany; (S.H.); (S.U.); or (R.K.S.)
| | - Nadine Loosli
- Department of Medicine, Swiss Tropical and Public Health Institute, 4055 Basel, Switzerland; (M.-T.R.); (N.L.); (S.P.)
- Medical Faculty, University of Basel, 4055 Basel, Switzerland
| | - Nadja Seyhan Bier
- Department of Biological Safety, German Federal Institute for Risk Assessment, 10589 Berlin, Germany; (A.M.-S.); (N.S.B.)
| | - Stephanie Hiereth
- Chair for Bacteriology and Mycology, Institute for Infectious Diseases and Zoonoses, Faculty of Veterinary Medicine, Ludwig-Maximilians University Munich, 80539 Munich, Germany; (S.H.); (S.U.); or (R.K.S.)
| | - Sebastian Ulrich
- Chair for Bacteriology and Mycology, Institute for Infectious Diseases and Zoonoses, Faculty of Veterinary Medicine, Ludwig-Maximilians University Munich, 80539 Munich, Germany; (S.H.); (S.U.); or (R.K.S.)
| | - Sven Poppert
- Department of Medicine, Swiss Tropical and Public Health Institute, 4055 Basel, Switzerland; (M.-T.R.); (N.L.); (S.P.)
- Medical Faculty, University of Basel, 4055 Basel, Switzerland
| | - Reinhard K. Straubinger
- Chair for Bacteriology and Mycology, Institute for Infectious Diseases and Zoonoses, Faculty of Veterinary Medicine, Ludwig-Maximilians University Munich, 80539 Munich, Germany; (S.H.); (S.U.); or (R.K.S.)
| | - John Stenos
- Australian Rickettsial Reference Laboratory, University Hospital Geelong, Geelong, VIC 3220, Australia;
| | - Tshokey Tshokey
- Department of Pathology and Laboratory Medicine, Jigme Dorji Wangchuck National Referral Hospital, Thimphu 11001, Bhutan;
- Faculty of Postgraduate Medicine, Khesar Gyalpo University of Medical Sciences of Bhutan, Thimphu 11001, Bhutan
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15
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Bafna P, Deepanjali S, Mandal J, Balamurugan N, Swaminathan RP, Kadhiravan T. Reevaluating the true diagnostic accuracy of dipstick tests to diagnose urinary tract infection using Bayesian latent class analysis. PLoS One 2021; 15:e0244870. [PMID: 33382863 PMCID: PMC7774958 DOI: 10.1371/journal.pone.0244870] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 12/17/2020] [Indexed: 01/14/2023] Open
Abstract
OBJECTIVE Previous studies on diagnostic accuracy of dipstick testing for leukocyte esterase (LE) and nitrite to diagnose urinary tract infection (UTI) had used urine culture, which is an imperfect gold standard. Estimates of diagnostic accuracy obtained using the classical gold standard framework might not reflect the true diagnostic accuracy of dipstick tests. METHODS We used the dataset from a prospective, observational study conducted in the emergency department of a teaching hospital in southern India. Patients with a clinical suspicion of UTI underwent dipstick testing for LE and nitrite, urine microscopy, and urine culture. Based on the results of urine microscopy and culture, UTI was classified into definite, probable, and possible. Patients with microscopic pyuria and a positive urine culture were adjudicated as definite UTI. Unequivocal imaging evidence of emphysematous pyelonephritis or perinephric collections was also considered definite UTI. We estimated the diagnostic accuracy of LE and nitrite tests using the classical analysis (assuming definite UTI as gold standard) and two different Bayesian latent class models (LCMs; 3-tests in 1-population and 2-tests in 2-populations models). RESULTS We studied 149 patients. Overall, 64 (43%) patients had definite, 76 (51%) had probable, and 2 (1.3%) had possible UTI; 7 (4.6%) had alternate diagnoses. In classical analysis, LE was more sensitive than nitrite (87.5% versus 70.5%), while nitrite was more specific (24% versus 58%). The 3-tests in 1-population Bayesian LCM indicated a substantially better sensitivity and specificity for LE (98.1% and 47.6%) and nitrite (88.2% and 97.7%). True sensitivity and specificity of urine culture as estimated by the model was 48.7% and 73.0%. Estimates of the 2-tests in 2-populations model were in agreement with the 3-tests in 1-population model. CONCLUSIONS Bayesian LCMs indicate a clinically important improvement in the true diagnostic accuracy of urine dipstick testing for LE and nitrite. Given this, a negative dipstick LE would rule-out UTI, while a positive dipstick nitrite would rule-in UTI in our study setting. True diagnostic accuracy of urine dipstick testing for UTI in various practice settings needs reevaluation using Bayesian LCMs.
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Affiliation(s)
- Prashant Bafna
- Department of Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India
| | - Surendran Deepanjali
- Department of Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India
- * E-mail:
| | - Jharna Mandal
- Department of Microbiology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India
| | - Nathan Balamurugan
- Department of Emergency Medicine & Trauma, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India
| | - Rathinam P. Swaminathan
- Department of Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India
| | - Tamilarasu Kadhiravan
- Department of Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India
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16
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Elders PND, Swe MMM, Phyo AP, McLean ARD, Lin HN, Soe K, Htay WYA, Tanganuchitcharnchai A, Hla TK, Tun NN, Nwe TT, Moe MM, Thein WM, Zaw NN, Kyaw WM, Linn H, Htwe YY, Smithuis FM, Blacksell SD, Ashley EA. Serological evidence indicates widespread distribution of rickettsioses in Myanmar. Int J Infect Dis 2020; 103:494-501. [PMID: 33310022 PMCID: PMC7862081 DOI: 10.1016/j.ijid.2020.12.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 11/26/2022] Open
Abstract
Diagnosis of rickettsial infections is difficult in low-resource settings; this leads to delays in receiving appropriate treatment. Before this study, the distribution of rickettsioses in Myanmar was not known. This serosurvey shows that rickettsioses are widespread in Myanmar. Particularly high prevalence of scrub typhus was found in central and northern regions.
Background Little research has been published on the prevalence of rickettsial infections in Myanmar. This study determined the seroprevalence of immunoglobulin G (IgG) antibodies to rickettsial species in different regions of Myanmar. Methods Seven hundred leftover blood samples from patients of all ages in primary care clinics and hospitals in seven regions of Myanmar were collected. Samples were screened for scrub typhus group (STG), typhus group (TG) and spotted fever group (SFG) IgG antibodies using enzyme-linked immunosorbent assays (ELISA). Immunofluorescence assays were performed for the same rickettsial groups to confirm seropositivity if ELISA optical density ≥0.5. Results Overall IgG seroprevalence was 19% [95% confidence interval (CI) 16–22%] for STG, 5% (95% CI 3–7%) for TG and 3% (95% CI: 2–5%) for SFG. The seroprevalence of STG was particularly high in northern and central Myanmar (59% and 19–33%, respectively). Increasing age was associated with higher odds of STG and TG seropositivity [per 10-year increase, adjusted odds ratio estimate 1.68 (p < 0.01) and 1.24 (p = 0.03), respectively]. Conclusion Rickettsial infections are widespread in Myanmar, with particularly high seroprevalence of STG IgG antibodies in central and northern regions. Healthcare workers should consider rickettsial infections as common causes of fever in Myanmar.
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Affiliation(s)
| | | | | | - Alistair R D McLean
- Myanmar Oxford Clinical Research Unit, Yangon, Myanmar; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | | | - Kyaw Soe
- Myanmar Oxford Clinical Research Unit, Yangon, Myanmar
| | | | - Ampai Tanganuchitcharnchai
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Thel K Hla
- Myanmar Oxford Clinical Research Unit, Yangon, Myanmar; Medical Action Myanmar, Yangon, Myanmar
| | - Ni Ni Tun
- Medical Action Myanmar, Yangon, Myanmar
| | - Thin Thin Nwe
- Magway General Hospital and University of Medicine, Magway, Myanmar; University of Medicine 2, Yangon, Myanmar
| | - Myat Myat Moe
- Magway General Hospital and University of Medicine, Magway, Myanmar
| | - Win May Thein
- Mandalay General Hospital and University of Medicine, Mandalay, Myanmar
| | - Ni Ni Zaw
- Mandalay General Hospital and University of Medicine, Mandalay, Myanmar
| | | | - Htun Linn
- Monywa General Hospital, Monywa, Myanmar
| | | | - Frank M Smithuis
- Myanmar Oxford Clinical Research Unit, Yangon, Myanmar; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom; Medical Action Myanmar, Yangon, Myanmar
| | - Stuart D Blacksell
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom; Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Elizabeth A Ashley
- Myanmar Oxford Clinical Research Unit, Yangon, Myanmar; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom; Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao Democratic People's Republic.
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17
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The Isolation of Orientia tsutsugamushi and Rickettsia typhi from Human Blood through Mammalian Cell Culture: a Descriptive Series of 3,227 Samples and Outcomes in the Lao People's Democratic Republic. J Clin Microbiol 2020; 58:JCM.01553-20. [PMID: 32999008 PMCID: PMC7685894 DOI: 10.1128/jcm.01553-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 09/23/2020] [Indexed: 11/20/2022] Open
Abstract
In the Lao People’s Democratic Republic (Laos), rickettsial infections, including scrub and murine typhus, account for a significant burden of fevers. The Mahosot Hospital Microbiology Laboratory in Vientiane, Laos, routinely performs rickettsial isolation from hospitalized patients with suspected rickettsioses using mammalian cell culture systems. We review the clinical and laboratory factors associated with successful Orientia tsutsugamushi and Rickettsia typhi isolations from this laboratory over a period of 6 years between 2008 and 2014. In the Lao People’s Democratic Republic (Laos), rickettsial infections, including scrub and murine typhus, account for a significant burden of fevers. The Mahosot Hospital Microbiology Laboratory in Vientiane, Laos, routinely performs rickettsial isolation from hospitalized patients with suspected rickettsioses using mammalian cell culture systems. We review the clinical and laboratory factors associated with successful Orientia tsutsugamushi and Rickettsia typhi isolations from this laboratory over a period of 6 years between 2008 and 2014. The overall isolation success was 7.9% for all samples submitted and 17.3% for samples for which the patient had a positive O. tsutsugamushi or R. typhi rapid diagnostic test (RDT), serology, or PCR. The frequency of successful isolation was highest for samples submitted in November, at the end of the wet season (28.3%). A longer median duration of reported illness, a positive result for a concurrent Orientia or Rickettsia spp. quantitative PCR, and the use of antibiotics by the patient in the week before admission were significantly associated with isolation success (P < 0.05). Buffy coat inoculation and a shorter interval between sample collection and inoculation in the laboratory were associated with a higher frequency of isolation (both P < 0.05). This frequency was highest if cell culture inoculation occurred on the same day as blood sample collection. Factors related to the initial rickettsial bacterial concentration are likely the main contributors to isolation success. However, modifiable factors do contribute to the rickettsial isolation success, especially delays in inoculating patient samples into culture.
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Kala D, Gupta S, Nagraik R, Verma V, Thakur A, Kaushal A. Diagnosis of scrub typhus: recent advancements and challenges. 3 Biotech 2020; 10:396. [PMID: 32834918 PMCID: PMC7431554 DOI: 10.1007/s13205-020-02389-w] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 08/10/2020] [Indexed: 02/07/2023] Open
Abstract
Scrub typhus is a mite-borne, acute febrile illness caused by the bacterium Orientia tsutsugamushi. It is a re-emerging infectious disease of the tsutsugamushi triangle. Scrub typhus is transmitted through bites of contaminated chiggers (larval stage). Diagnosis of scrub typhus is challenging as its symptoms mimic with other acute febrile illnesses. Several methods are effectual for diagnosis of scrub typhus that includes enzyme-linked immunosorbent assay (ELISA), immunofluorescence assay (IFA), immunochromatographic test (ICT), Weil-Felix, polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP). Weil-Felix test was initially used for the diagnosis of scrub typhus in underdeveloped countries but not preferred due to a lack of both specificity and sensitivity. Other immuno-based methods like IFA and ELISA are most outrank for detection of scrub typhus due to their higher sensitivity and specificity, but not vigorous to lay bare the infection at early stages and need the convalescent sampling for verification of positive samples. On another deed, PCR based methods becoming acceptable over era due to its dexterity of early-stage diagnosis with higher specificity and sensitivity but lack its applicability in circumstances of scrub typhus due to the variegated genetic makeup of Orientia tsutsugamushi among its serotypes. The present review focused on various detection methods along with their advantages and disadvantages used in the diagnosis of scrub typhus. A comparison between available methods of diagnosis with challenges in the detection of scrub typhus is also summarized.
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Affiliation(s)
- Deepak Kala
- Amity Center of Nanotechnology, Amity University, Haryana, 122413 India
| | | | | | | | - Atul Thakur
- Amity Center of Nanotechnology, Amity University, Haryana, 122413 India
| | - Ankur Kaushal
- Amity Center of Nanotechnology, Amity University, Haryana, 122413 India
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Prevalence of scrub typhus in a tertiary care centre in Telangana, south India. IRANIAN JOURNAL OF MICROBIOLOGY 2020; 12:204-208. [PMID: 32685116 PMCID: PMC7340608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND AND OBJECTIVES Scrub typhus is re-emerging as an important cause of acute undifferentiated fever in the last decade from various parts of India. Complexity in performing the "gold standard" immunofluorescent assay and the unreliable nature of Weil Felix test often results in delayed or misdiagnosis in a majority of cases. The present study seeks to integrate the results of rapid diagnostic tests, clinical and laboratory features to aid the diagnosis and management of scrub typhus patients. MATERIALS AND METHODS A total of 645 serum samples with suspected scrub typhus sent to the Department of Microbiology were included in the study. Scrub typhus was tested by rapid immunochromatographic test (SD Diagnostics) and IgM ELISA (Inbios International, USA). Clinical features, laboratory parameters and final outcome were analysed from the clinical records of positive patients. RESULTS Scrub typhus was diagnosed in 13.7% of patients and majority of them were observed in the month of August. 58.6% of scrub typhus patients presented with fever of one to two weeks duration. Eschar was documented in 13.7% of patients and 24% of patients gave a history of working outdoors or exposure to vegetation. All the patients responded to Doxycycline treatment and there was no mortality. CONCLUSION High index of suspicion for scrub typhus is necessary in febrile patients not responding to conventional antibiotics especially during outbreak situations. Rapid immunochromatographic tests with excellent specificity and acceptable sensitivity can be used as potential point of care tests for quick diagnosis of scrub typhus especially in delayed presentation.
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Pokharel S, White LJ, Aguas R, Celhay O, Pellé KG, Dittrich S. Algorithm in the Diagnosis of Febrile Illness Using Pathogen-specific Rapid Diagnostic Tests. Clin Infect Dis 2020; 70:2262-2269. [PMID: 31313805 PMCID: PMC7245147 DOI: 10.1093/cid/ciz665] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 07/16/2019] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND In the absence of proper guidelines and algorithms, available rapid diagnostic tests (RDTs) for common acute undifferentiated febrile illnesses are often used inappropriately. METHODS Using prevalence data of 5 common febrile illnesses from India and Cambodia, and performance characteristics (sensitivity and specificity) of relevant pathogen-specific RDTs, we used a mathematical model to predict the probability of correct identification of each disease when diagnostic testing occurs either simultaneously or sequentially in various algorithms. We developed a web-based application of the model so as to visualize and compare output diagnostic algorithms when different disease prevalence and test performance characteristics are introduced. RESULTS Diagnostic algorithms with appropriate sequential testing predicted correct identification of etiology in 74% and 89% of patients in India and Cambodia, respectively, compared with 46% and 49% with simultaneous testing. The optimally performing sequential diagnostic algorithms differed in India and Cambodia due to varying disease prevalence. CONCLUSIONS Simultaneous testing is not appropriate for the diagnosis of acute undifferentiated febrile illnesses with presently available tests, which should deter the unsupervised use of multiplex diagnostic tests. The implementation of adaptive algorithms can predict better diagnosis and add value to the available RDTs. The web application of the model can serve as a tool to identify the optimal diagnostic algorithm in different epidemiological settings, while taking into account the local epidemiological variables and accuracy of available tests.
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Affiliation(s)
- Sunil Pokharel
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom
- Foundation for Innovative New Diagnostics, Geneva, Switzerland
| | - Lisa J White
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Ricardo Aguas
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Olivier Celhay
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Karell G Pellé
- Foundation for Innovative New Diagnostics, Geneva, Switzerland
| | - Sabine Dittrich
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom
- Foundation for Innovative New Diagnostics, Geneva, Switzerland
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21
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Bhattarai T, Poudel SC, Pokharel N, Bhattarai S. Scrub typhus as a rare cause of acute pyelonephritis: case report. BMC Infect Dis 2020; 20:322. [PMID: 32375669 PMCID: PMC7201669 DOI: 10.1186/s12879-020-05050-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 04/23/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Scrub typhus can present with atypical signs and symptoms such as those of acute kidney injury, gastroenteritis, pneumonitis, and acute respiratory distress syndrome. Meningitis, encephalitis, and hepatic dysfunction have also been reported, particularly in severe cases with multisystem involvement. Scrub typhus has never been reported in the literature to cause urinary tract infections (UTIs) which includes cystitis and pyelonephritis. CASE PRESENTATION A 45-year old male presenting to the outpatient unit with fever, right flank pain, and burning micturition for three days was initially treated for UTI. However, he returned to the hospital on the fourth day of illness with persistent symptoms. He was hospitalized, with intravenous (IV) ceftriaxone. Computerized tomography scan of his abdomen-pelvis showed features of acute pyelonephritis, so his antibiotics were upgraded to meropenem and teicoplanin. Despite this, the patient's condition deteriorated. Laboratory investigations showed multisystem involvement: decreasing platelets, raised creatinine, and deranged liver panel. As Kathmandu was hit by dengue epidemic during the patient's hospitalization, on the seventh day of his illness, blood samples were sent for tropical fever investigation. All tests came out negative except for scrub typhus-IgM antibodies positive on rapid diagnostic test. The patient's symptoms subsided after 48 h of starting doxycycline and he became fully asymptomatic four days later. Fever did not recur even after discontinuing other IV antibiotics, favoring scrub typhus disease rather than systemic bacterial sepsis. CONCLUSIONS Scrub typhus is an emerging infectious disease of Nepal. Therefore, every unexplained fever cases (irrespective of clinical presentation) should be evaluated for potential Rickettsiosis. Moreover, for cases with acute pyelonephritis, atypical causative agents should be investigated, for example scrub typhus in this case.
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Affiliation(s)
- Tulsi Bhattarai
- Department of Internal Medicine, Kathmandu Medical College, Kathmandu, Nepal
| | | | | | - Suraj Bhattarai
- Global Institute for Interdisciplinary Studies/Gandaki Medical College Teaching Hospital, Post Box: 24560, Sundhara, Kathmandu, Nepal.
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22
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Gautam R, Parajuli K, Tshokey T, Stenos J, Sherchand JB. Diagnostic evaluation of IgM ELISA and IgM Immunofluorescence assay for the diagnosis of Acute Scrub Typhus in central Nepal. BMC Infect Dis 2020; 20:138. [PMID: 32054525 PMCID: PMC7020552 DOI: 10.1186/s12879-020-4861-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 02/06/2020] [Indexed: 06/15/2024] Open
Abstract
Background Scrub typhus is an acute febrile illness caused by the obligate intracellular bacterium, Orientia tsutsugamushi. Immunochromatography (ICT) and IgM ELISA are two of the routinely employed antibody based assays for diagnosis of Scrub typhus fever in Nepal, although the recommended gold standard diagnostic test is IgM Immunofluorescence assay (IFA). This study evaluated InBios Scrub Typhus Detect™ Immunoglobulin M (IgM) ELISA and IgM Immunofluorescence assays in single serum sample at the time of admission. Method Study participants (1585 suspected cases), were enrolled based on acute febrile illness with suspected scrub typhus cases in central Nepal. Blood sample was collected from the suspected patients of scrub typhus, presenting with acute febrile illness. IgM antibody to Orientia tsusugamushi was detected by using Scrub Typhus Detect™ Kit and an in-house IgM IFA. The IFA assay was performed with the Gilliam, Karp, Kato strains and O. chuto antigens following the ARRL protocol. Result Statistical analysis of IgM ELISA results when compared to reference test, IgM IFA results demonstrated the following characteristics, sensitivity 84.0% (95%CI: 79.73–87.68%), specificity 94.82% (95% CI: 93.43–95.99%), positive likelihood ratio 16.21% (95% CI: 12.71–20.67%), negative likelihood ratio 0.17% (95% CI: 0.13–0.21%), disease prevalence 22.08% (95% CI: 20.06 -24.21%), positive predictive value 82.12% (95% CI: 78.28–85.42%) and negative predictive value 95.44% (95% CI: 94.27–96.38%) respectively. Conclusion Although IgM IFA is considered the gold standard test for the diagnosis of scrub typhus cases, it is relatively expensive, requires trained personal and a microscope with fluorescence filters. Scrub typhus IgM ELISA may be the best alternative test and possible viable option for resource limited endemic countries like Nepal.
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Affiliation(s)
- Rajendra Gautam
- Department of Microbiology, Maharajgunj Medical Campus, Institute of Medicine, Kathmandu, Nepal.
| | - Keshab Parajuli
- Department of Microbiology, Maharajgunj Medical Campus, Institute of Medicine, Kathmandu, Nepal
| | - Tshokey Tshokey
- Australian rickettsial reference laboratory, Geelong, Victoria, Australia
| | - John Stenos
- Australian rickettsial reference laboratory, Geelong, Victoria, Australia
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23
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Phanichkrivalkosil M, Tanganuchitcharnchai A, Jintaworn S, Kantipong P, Laongnualpanich A, Chierakul W, Paris DH, Richards AL, Wangrangsimakul T, Day NPJ, Blacksell SD. Determination of Optimal Diagnostic Cut-Offs for the Naval Medical Research Center Scrub Typhus IgM ELISA in Chiang Rai, Thailand. Am J Trop Med Hyg 2020; 100:1134-1140. [PMID: 30860022 PMCID: PMC6493932 DOI: 10.4269/ajtmh.18-0675] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
In this diagnostic accuracy study, we evaluated data from 135 febrile patients from Chiang Rai, to determine the optimal optical density (OD) cutoffs for an in-house scrub typhus IgM ELISA. Receiver operating characteristic curves were generated using a panel of reference assays, including an IgM immunofluorescence assay (IFA), PCR, in vitro isolation, presence of an eschar, or a combination of these. Altogether, 33 patients (24.4%) were diagnosed as having scrub typhus. Correlation between positivity by IFA and increasing OD values peaked at a cutoff of 2.0, whereas there was little association between positivity by culture or eschar with increasing ELISA cutoffs—cutoffs of 3.0 and 4.0 were demonstrated to be optimal for the total absorbance of the OD at dilutions 1:100, 1:400, 1:1,600, and 1:6,400, for admission and convalescent samples, respectively. The optimal cutoff at a 1:100 dilution was found to be between 1.85 and 2.22 for admission samples and convalescent-phase samples, respectively. Sensitivities for the cutoffs varied from 57.1% to 90.0% depending on the reference test and sample timing, whereas specificities ranged from 85.2% to 99.0%. We therefore recommend a cutoff of around 2.0, depending on the sensitivity and specificity desired in clinical or epidemiological settings. The results demonstrate the ELISA to be a valuable diagnostic tool, suitable for use in resource-limited endemic regions, especially when used in combination with other diagnostic modalities such as the presence of an eschar.
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Affiliation(s)
- Meghna Phanichkrivalkosil
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Ampai Tanganuchitcharnchai
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Suthatip Jintaworn
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | | | | | - Wirongrong Chierakul
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Daniel H Paris
- Faculty of Medicine, University of Basel, Basel, Switzerland.,Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Department of Medicine, Swiss Tropical and Public Health Institute, Basel, Switzerland.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Allen L Richards
- Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, Maryland.,Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland
| | - Tri Wangrangsimakul
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom.,Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Nicholas P J Day
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom.,Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Stuart D Blacksell
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom.,Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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24
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Yang SL, Tsai KH, Chen HF, Luo JY, Shu PY. Evaluation of Enzyme-Linked Immunosorbent Assay Using Recombinant 56-kDa Type-Specific Antigens Derived from Multiple Orientia tsutsugamushi Strains for Detection of Scrub Typhus Infection. Am J Trop Med Hyg 2020; 100:532-539. [PMID: 30526730 DOI: 10.4269/ajtmh.18-0391] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Scrub typhus is caused by the intracellular bacterium Orientia tsutsugamushi. The 56-kDa type-specific antigen (TSA) displays a significant antigenic variation across different O. tsutsugamushi strains. To minimize the influence of the antigenic diversity of TSA on assay sensitivity, we developed a mixed-TSA enzyme-linked immunosorbent assay (mixed-TSA ELISA) using a mixture of recombinant TSAs of prototype (Karp, Gilliam, and Kato) and local (TW-1, TW-10, TW-19, and TW-22) O. tsutsugamushi strains as antigens to detect immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against O. tsutsugamushi. These four local strains covered a major part of the total genetic diversity of TSA gene of O. tsutsugamushi in Taiwan. A total of 109 acute-phase serum samples from O. tsutsugamushi polymerase chain reaction-positive, scrub typhus patients, and 82 negative control serum samples from non-scrub typhus cases were used for evaluation of the recombinant TSA-based ELISA. We compared the performance of the mixed-TSA ELISA with immunofluorescence assay (IFA), which is considered the gold standard method for the serological diagnosis of scrub typhus. The results indicated that the sensitivity of IgM mixed-TSA ELISA (80.7%) was significantly higher than that of IgM IFA (68.8%). We demonstrated that the mixed-TSA ELISA had a high sensitivity and specificity and can be used for screening of scrub typhus patient in the early phase of the disease.
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Affiliation(s)
- Su-Lin Yang
- Center for Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taipei, Republic of China
| | - Kun-Hsien Tsai
- Department of Public Health and Institute of Environmental Health, College of Public Health, National Taiwan University, Taipei, Republic of China
| | - Hsiang-Fei Chen
- Center for Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taipei, Republic of China
| | - Jun-Yu Luo
- Center for Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taipei, Republic of China
| | - Pei-Yun Shu
- Center for Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taipei, Republic of China
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25
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Trung NV, Hoi LT, Dien VM, Huong DT, Hoa TM, Lien VN, Van Luan P, Lewycka SO, Choisy M, Bryant JE, Nadjm B, Rogier van Doorn H, Richards AL, Van Kinh N. Clinical Manifestations and Molecular Diagnosis of Scrub Typhus and Murine Typhus, Vietnam, 2015-2017. Emerg Infect Dis 2019; 25. [PMID: 30882318 PMCID: PMC6433017 DOI: 10.3201/eid2504.180691] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Scrub typhus was the predominant rickettsial disease diagnosed among hospitalized patients with acute undifferentiated fever in northern Vietnam. Rickettsioses are endemic to Vietnam; however, only a limited number of clinical studies have been performed on these vectorborne bacteria. We conducted a prospective hospital-based study at 2 national referral hospitals in Hanoi to describe the clinical characteristics of scrub typhus and murine typhus in northern Vietnam and to assess the diagnostic applicability of quantitative real-time PCR assays to diagnose rickettsial diseases. We enrolled 302 patients with acute undifferentiated fever and clinically suspected rickettsiosis during March 2015–March 2017. We used a standardized case report form to collect clinical information and laboratory results at the time of admission and during treatment. We confirmed scrub typhus in 103 (34.1%) patients and murine typhus in 12 (3.3%) patients. These results highlight the need for increased emphasis on training for healthcare providers for earlier recognition, prevention, and treatment of rickettsial diseases in Vietnam.
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26
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Katoh S, Cuong NC, Hamaguchi S, Thuy PT, Cuong DD, Anh LK, Anh NTH, Anh DD, Sando E, Suzuki M, Fujita H, Yasunami M, Yoshihara K, Yoshida LM, Paris DH, Ariyoshi K. Challenges in diagnosing scrub typhus among hospitalized patients with undifferentiated fever at a national tertiary hospital in northern Vietnam. PLoS Negl Trop Dis 2019; 13:e0007928. [PMID: 31805053 PMCID: PMC6917290 DOI: 10.1371/journal.pntd.0007928] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 12/17/2019] [Accepted: 11/14/2019] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Scrub typhus (ST) is a leading cause of non-malarial febrile illness in Southeast Asia, but evidence of its true disease burden is limited because of difficulties of making the clinical diagnosis and lack of adequate diagnostic tests. To describe the epidemiology and clinical characteristics of ST, we conducted an observational study using multiple diagnostic assays at a national tertiary hospital in Hanoi, Vietnam. METHODOLOGY/PRINCIPAL FINDINGS We enrolled 1,127 patients hospitalized with documented fever between June 2012 and May 2013. Overall, 33 (2.9%) patients were diagnosed with ST by PCR and/or screening of ELISA for immunoglobulin M (IgM) with confirmatory tests: 14 (42.4%) were confirmed by indirect immunoperoxidase assay (IIP), and 19 (57.6%) were by IIP and PCR. Living by farming, conjunctival injection, eschar, aspartate aminotransferase elevation, and alanine aminotransferase elevation were significantly associated with ST cases (adjusted odds ratios (aORs): 2.8, 3.07, 48.8, 3.51, and 4.13, respectively), and having a comorbidity and neutrophilia were significantly less common in ST cases (aORs: 0.29 and 0.27, respectively). The majority of the ST cases were not clinically diagnosed with rickettsiosis (72.7%). Dominant IIP reactions against a single antigen were identified in 15 ST cases, whereas indistinguishably high reactions against multiple antigens were seen in 11 ST cases. The most frequently observed dominant IIP reaction was against Karp antigen (eight cases) followed by Gilliam (four cases). The highest diagnostic accuracy of IgM ELISA in acute samples was 78%. In a phylogenetic analysis of the 56-kDa type-specific antigen gene, the majority (14 cases) were located in the Karp-related branch followed by the Gilliam-related (two cases), Kato-related (two cases), and TA763-related clades (one case). CONCLUSIONS/SIGNIFICANCE Both the clinical and laboratory diagnoses of ST remain challenging at a tertiary hospital. Implementation of both serological and nucleic acid amplification assays covering endemic O. tsutsugamushi strains is essential.
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Affiliation(s)
- Shungo Katoh
- Department of Clinical Medicine, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
- Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
- Department of General Internal Medicine, Nagasaki Rosai Hospital, Nagasaki, Japan
| | - Ngo Chi Cuong
- Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
- Department of Infectious Diseases, Bach Mai Hospital, Hanoi, Vietnam
| | - Sugihiro Hamaguchi
- Department of General Internal Medicine, Fukushima Medical University, Fukushima, Japan
| | - Pham Thanh Thuy
- Department of Infectious Diseases, Bach Mai Hospital, Hanoi, Vietnam
- The Partnership for Health Advancement in Vietnam (HAIVN), Hanoi, Vietnam
| | - Do Duy Cuong
- Department of Infectious Diseases, Bach Mai Hospital, Hanoi, Vietnam
| | - Le Kim Anh
- Vietnam Research Station, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Hanoi, Vietnam
| | | | - Dang Duc Anh
- National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
| | - Eiichiro Sando
- Department of Clinical Medicine, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
- Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
- Department of General Internal Medicine, Kameda Medical Center, Chiba, Japan
| | - Motoi Suzuki
- Department of Clinical Medicine, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
| | - Hiromi Fujita
- Mahara Institute of Medical Acarology, Tokushima, Japan
| | - Michio Yasunami
- Department of Clinical Medicine, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
- Saga-Ken Medical Centre Koseikan, Saga, Japan
| | - Keisuke Yoshihara
- Department of Paediatric Infectious Diseases, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
| | - Lay-Myint Yoshida
- Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
- Department of Paediatric Infectious Diseases, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
| | - Daniel Henry Paris
- Department of Medicine, Swiss Tropical and Public Health Institute, Basel, Switzerland
- Faculty of Medicine, University of Basel, Basel, Switzerland
| | - Koya Ariyoshi
- Department of Clinical Medicine, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
- Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
- * E-mail:
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Chaudhry R, Thakur CK, Gupta N, Sagar T, Bahadur T, Wig N, Sood R, Misra MC. Mortality due to scrub typhus - report of five cases. Indian J Med Res 2019; 149:790-794. [PMID: 31496533 PMCID: PMC6755786 DOI: 10.4103/ijmr.ijmr_1314_18] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Scrub typhus is largely ignored in India particularly during outbreaks of viral fever. The disease course is often complicated leading to fatalities in the absence of treatment. However, if diagnosed early and a specific treatment is initiated, the cure rate is high. We report here five cases of scrub typhus to highlight the fact that high clinical suspicion for such a deadly disease is an absolute necessity.
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Affiliation(s)
- Rama Chaudhry
- Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India
| | - Chandan Kumar Thakur
- Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India
| | - Nitin Gupta
- Department of Microbiology; Department of Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Tanu Sagar
- Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India
| | - Tej Bahadur
- Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India
| | - Naveet Wig
- Department of Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Rita Sood
- Department of Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Mahesh Chandra Misra
- Department of Surgery, All India Institute of Medical Sciences, New Delhi, India
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28
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Trung NV, Hoi LT, Cuong DD, Ha DT, Hoa TM, Lien VN, Hoa NT, Hoa LNM, Huong DT, Bich VTN, van Doorn HR, Nadjm B, Richards AL. Analysis of the 56-kDa type specific antigen gene of Orientia tsutsugamushi from northern Vietnam. PLoS One 2019; 14:e0221588. [PMID: 31469878 PMCID: PMC6716651 DOI: 10.1371/journal.pone.0221588] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 08/09/2019] [Indexed: 11/24/2022] Open
Abstract
Scrub typhus has been documented since 1932 in Vietnam, however, the disease burden of scrub typhus remains poorly understood in the country. We conducted this study to describe the phylogenetic analysis of the 56-kDa type-specific antigen (TSA) gene of Orientia tsutsugamushi associated with PCR positive cases of scrub typhus. Of 116 positive samples, 65 type-specific antigen gene sequences were obtained and classified into 3 genogroups: Karp, Kato and Gilliam. The Karp genogroup was the most frequently detected phylogenetic cluster in the study with 30 samples (46%), followed by Kato and Gilliam with 20 (31%) and 15 (23%), respectively. All sequences showed 94–100% nucleotide similarity to reference sequences collected in the central part of Vietnam in 2017. Patients infected with Karp genogroup were more likely to have significant thrombocytopenia than the other genogroups. These results suggest that any scrub typhus vaccine considered for use in Vietnam should provide protection against each of these 3 genogroups.
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Affiliation(s)
- Nguyen Vu Trung
- National Hospital for Tropical Diseases, Hanoi, Vietnam
- Hanoi Medical University, Hanoi, Vietnam
| | - Le Thi Hoi
- National Hospital for Tropical Diseases, Hanoi, Vietnam
| | | | | | - Tran Mai Hoa
- National Hospital for Tropical Diseases, Hanoi, Vietnam
| | - Vu Ngoc Lien
- National Hospital for Tropical Diseases, Hanoi, Vietnam
| | | | | | | | - Vu Thi Ngoc Bich
- Oxford University Clinical Research Unit, Wellcome Trust Asia Program, Hanoi, Vietnam
| | - H. Rogier van Doorn
- Oxford University Clinical Research Unit, Wellcome Trust Asia Program, Hanoi, Vietnam
| | - Behzad Nadjm
- Oxford University Clinical Research Unit, Wellcome Trust Asia Program, Hanoi, Vietnam
| | - Allen L. Richards
- Naval Medical Research Center, Silver Spring, Maryland, United States of America
- Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
- * E-mail:
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Bhatia M, Kumar P, Gupta P, Gupta PK, Dhar M, Kalita D. Serological evidence of human leptospirosis in patients with acute undifferentiated febrile illness from Uttarakhand, India: A pilot study. J Lab Physicians 2019; 11:11-16. [PMID: 30983796 PMCID: PMC6437824 DOI: 10.4103/jlp.jlp_121_18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
CONTEXT: To the best of our knowledge, there are no reports of serological evidence of human leptospirosis from Uttarakhand state in India. AIMS: The aim of this study was to screen for serological evidence of leptospirosis in patients with acute undifferentiated febrile illness at a tertiary care teaching hospital in Uttarakhand. SETTINGS AND DESIGN: A pilot study was conducted from March to November 2017. SUBJECTS AND METHODS: Fifty-three adult patients who presented in Medicine outpatient Department with a history of fever of ≥7 up to 14 days duration with or without other associated symptoms such as a headache, rashes, myalgia, arthralgia, and conjunctival suffusion were enrolled in the study using convenience sampling technique. Blood samples of these patients were collected and subjected to peripheral smear examination for malaria parasites, dengue immunoglobulin M (IgM) immunochromatographic card test, IgM Typhidot, Leptospira and Scrub typhus IgM ELISA, respectively. Aerobic blood culture was performed in 24 cases. Relevant clinico-epidemiological details were obtained as per the pro forma formulated in accordance with the modified Faine's criteria. STATISTICAL ANALYSIS USED: Descriptive statistics. RESULTS: The study population consisted of 50.94% of males and 49.06% of females with a mean age ± standard deviation of 34.2 ± 15.2 years. Fifty febrile patients had additional symptoms of which myalgia was the most common (81.1%) followed by arthralgia (22.6%). Peripheral smears of all patients were negative for malaria parasites. Dengue and Typhidot IgM positivity was observed in two and eight patients, respectively. Six and five patients were tested positive by leptospira and scrub typhus IgM ELISA, respectively. Salmonella Typhi was isolated from blood sample of only one patient. Serum samples of two patients showed dual positivity. All six leptospira seropositive patients satisfied modified Faine's criteria. CONCLUSIONS: Leptospirosis is a seemingly unexplored infection in Uttarakhand and should be considered as a differential diagnosis in patients with acute undifferentiated febrile illness.
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Affiliation(s)
- Mohit Bhatia
- Department of Microbiology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
| | - Pradeep Kumar
- Department of Microbiology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
| | - Pratima Gupta
- Department of Microbiology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
| | - Puneet Kumar Gupta
- Department of Microbiology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
| | - Minakshi Dhar
- Department of Microbiology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
| | - Deepjyoti Kalita
- Department of Microbiology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
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Saraswati K, Phanichkrivalkosil M, Day NPJ, Blacksell SD. The validity of diagnostic cut-offs for commercial and in-house scrub typhus IgM and IgG ELISAs: A review of the evidence. PLoS Negl Trop Dis 2019; 13:e0007158. [PMID: 30716070 PMCID: PMC6382213 DOI: 10.1371/journal.pntd.0007158] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 02/20/2019] [Accepted: 01/15/2019] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Scrub typhus is a neglected tropical disease that causes acute febrile illness. Diagnosis is made based upon serology, or detection of the causative agent-Orientia tsutsugamushi-using PCR or in vitro isolation. The enzyme-linked immunosorbent assay (ELISA) is an objective and reproducible means of detecting IgM or IgG antibodies. However, lack of standardization in ELISA methodology, as well as in the choice of reference test with which the ELISA is compared, calls into question the validity of cut-offs used in diagnostic accuracy studies and observational studies. METHODOLOGY/PRINCIPAL FINDINGS A PubMed search and manual screening of reference lists identified 46 studies that used ELISA antibody cut-offs to diagnose scrub typhus patients, 22 of which were diagnostic accuracy studies. Overall, 22 studies (47.8%) provided little to no explanation as to how the ELISA cut-off was derived, and 7 studies (15.2%) did not even state the cut-off used. Variation was seen locally in reference standards used, in terms of both the diagnostic test and cut-off titer. Furthermore, with the exception of studies using ELISAs manufactured by InBios, there was no standardization of the selection of antigenic strains. As a result, no consensus was found for determining a cut-off, ELISA methodology, or for a single value diagnostic cut-off. CONCLUSIONS/SIGNIFICANCE We have concluded that there is a lack of consensus in the determination of a cut-off. We recommend interpreting the results from these studies with caution. Further studies will need to be performed at each geographic location to determine region-specific cut-offs, taking into consideration background antibody levels to discriminate true disease from healthy individuals.
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Affiliation(s)
- Kartika Saraswati
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Eijkman-Oxford Clinical Research Unit, Eijkman Institute for Molecular Biology, Jakarta, Indonesia
| | - Meghna Phanichkrivalkosil
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Nicholas P. J. Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Stuart D. Blacksell
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
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Blacksell SD, Kingston HWF, Tanganuchitcharnchai A, Phanichkrivalkosil M, Hossain M, Hossain A, Ghose A, Leopold SJ, Dondorp AM, Day NPJ, Paris DH. Diagnostic Accuracy of the InBios Scrub Typhus Detect™ ELISA for the Detection of IgM Antibodies in Chittagong, Bangladesh. Trop Med Infect Dis 2018; 3:tropicalmed3030095. [PMID: 30274491 PMCID: PMC6160969 DOI: 10.3390/tropicalmed3030095] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 08/20/2018] [Accepted: 08/27/2018] [Indexed: 11/16/2022] Open
Abstract
Here we estimated the accuracy of the InBios Scrub Typhus Detect™ immunoglobulin M (IgM) ELISA to determine the optimal optical density (OD) cut-off values for the diagnosis of scrub typhus. Patients with undifferentiated febrile illness from Chittagong, Bangladesh, provided samples for reference testing using (i) qPCR using the Orientia spp. 47-kDa htra gene, (ii) IFA ≥1:3200 on admission, (iii) immunofluorescence assay (IFA) ≥1:3200 on admission or 4-fold rise to ≥3200, and (iv) combination of PCR and IFA positivity. For sero-epidemiological purposes (ELISA vs. IFA ≥1:3200 on admission or 4-fold rise to ≥3200), the OD cut-off for admission samples was ≥1.25, resulting in a sensitivity (Sn) of 91.5 (95% confidence interval (95% CI: 96.8–82.5) and a specificity (Sp) of 92.4 (95% CI: 95.0–89.0), while for convalescent samples the OD cut-off was ≥1.50 with Sn of 66.0 (95% CI: 78.5–51.7) and Sp of 96.0 (95% CI: 98.3–92.3). Comparisons against comparator reference tests (ELISA vs. all tests including PCR) indicated the most appropriate cut-off OD to be within the range of 0.75–1.25. For admission samples, the best Sn/Sp compromise was at 1.25 OD (Sn 91.5%, Sp 92.4%) and for convalescent samples at 0.75 OD (Sn 69.8%, Sp 89.5%). A relatively high (stringent) diagnostic cut-off value provides increased diagnostic accuracy with high sensitivity and specificity in the majority of cases, while lowering the cut-off runs the risk of false positivity. This study underlines the need for regional assessment of new diagnostic tests according to the level of endemicity of the disease given the high levels of residual or cross-reacting antibodies in the general population.
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Affiliation(s)
- Stuart D Blacksell
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithee Road, Bangkok 10400, Thailand.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7FZ, UK.
| | - Hugh W F Kingston
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithee Road, Bangkok 10400, Thailand.
| | - Ampai Tanganuchitcharnchai
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithee Road, Bangkok 10400, Thailand.
| | - Meghna Phanichkrivalkosil
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithee Road, Bangkok 10400, Thailand.
| | | | - Amir Hossain
- Chittagong Medical College Hospital, Chittagong, Bangladesh.
| | - Aniruddha Ghose
- Chittagong Medical College Hospital, Chittagong, Bangladesh.
| | - Stije J Leopold
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithee Road, Bangkok 10400, Thailand.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7FZ, UK.
| | - Arjen M Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithee Road, Bangkok 10400, Thailand.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7FZ, UK.
| | - Nicholas P J Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithee Road, Bangkok 10400, Thailand.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7FZ, UK.
| | - Daniel H Paris
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithee Road, Bangkok 10400, Thailand.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7FZ, UK.
- Department of Medicine, Swiss Tropical and Public Health Institute, 4056 Basel, Switzerland.
- Faculty of Medicine, University of Basel, 4003 Basel, Switzerland.
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Saraswati K, Day NPJ, Mukaka M, Blacksell SD. Scrub typhus point-of-care testing: A systematic review and meta-analysis. PLoS Negl Trop Dis 2018; 12:e0006330. [PMID: 29579046 PMCID: PMC5892940 DOI: 10.1371/journal.pntd.0006330] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 04/10/2018] [Accepted: 02/21/2018] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Diagnosing scrub typhus clinically is difficult, hence laboratory tests play a very important role in diagnosis. As performing sophisticated laboratory tests in resource-limited settings is not feasible, accurate point-of-care testing (POCT) for scrub typhus diagnosis would be invaluable for patient diagnosis and management. Here we summarise the existing evidence on the accuracy of scrub typhus POCTs to inform clinical practitioners in resource-limited settings of their diagnostic value. METHODOLOGY/PRINCIPAL FINDINGS Studies on POCTs which can be feasibly deployed in primary health care or outpatient settings were included. Thirty-one studies were identified through PubMed and manual searches of reference lists. The quality of the studies was assessed with the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). About half (n = 14/31) of the included studies were of moderate quality. Meta-analysis showed the pooled sensitivity and specificity of commercially available immunochromatographic tests (ICTs) were 66.0% (95% CI 0.37-0.86) and 92.0% (95% CI 0.83-0.97), respectively. There was a significant and high degree of heterogeneity between the studies (I2 value = 97.48%, 95% CI 96.71-98.24 for sensitivity and I2 value = 98.17%, 95% CI 97.67-98.67 for specificity). Significant heterogeneity was observed for total number of samples between studies (p = 0.01), study design (whether using case-control design or not, p = 0.01), blinding during index test interpretation (p = 0.02), and QUADAS-2 score (p = 0.01). CONCLUSIONS/SIGNIFICANCE There was significant heterogeneity between the scrub typhus POCT diagnostic accuracy studies examined. Overall, the commercially available scrub typhus ICTs demonstrated better performance when 'ruling in' the diagnosis. There is a need for standardised methods and reporting of diagnostic accuracy to decrease between-study heterogeneity and increase comparability among study results, as well as development of an affordable and accurate antigen-based POCT to tackle the inherent weaknesses associated with serological testing.
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Affiliation(s)
- Kartika Saraswati
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Eijkman-Oxford Clinical Research Unit, Eijkman Institute for Molecular Biology, Jakarta, Indonesia
- Centre for Tropical Medicine & Global Health, Nuffield Department of Medicine, University of Oxford, Old Road Campus, Oxford, United Kingdom
| | - Nicholas P. J. Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine & Global Health, Nuffield Department of Medicine, University of Oxford, Old Road Campus, Oxford, United Kingdom
| | - Mavuto Mukaka
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine & Global Health, Nuffield Department of Medicine, University of Oxford, Old Road Campus, Oxford, United Kingdom
| | - Stuart D. Blacksell
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine & Global Health, Nuffield Department of Medicine, University of Oxford, Old Road Campus, Oxford, United Kingdom
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Pote K, Narang R, Deshmukh P. Diagnostic Performance of Serological Tests to Detect Antibodies Against Acute Scrub Typhus Infection in Central India. Indian J Med Microbiol 2018; 36:108-112. [DOI: 10.4103/ijmm.ijmm_17_405] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Xu G, Walker DH, Jupiter D, Melby PC, Arcari CM. A review of the global epidemiology of scrub typhus. PLoS Negl Trop Dis 2017; 11:e0006062. [PMID: 29099844 PMCID: PMC5687757 DOI: 10.1371/journal.pntd.0006062] [Citation(s) in RCA: 257] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 11/15/2017] [Accepted: 10/21/2017] [Indexed: 12/18/2022] Open
Abstract
Scrub typhus is a serious public health problem in the Asia-Pacific area. It threatens one billion people globally, and causes illness in one million people each year. Caused by Orientia tsutsugamushi, scrub typhus can result in severe multiorgan failure with a case fatality rate up to 70% without appropriate treatment. The antigenic heterogeneity of O. tsutsugamushi precludes generic immunity and allows reinfection. As a neglected disease, there is still a large gap in our knowledge of the disease, as evidenced by the sporadic epidemiologic data and other related public health information regarding scrub typhus in its endemic areas. Our objective is to provide a systematic analysis of current epidemiology, prevention and control of scrub typhus in its long-standing endemic areas and recently recognized foci of infection.
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Affiliation(s)
- Guang Xu
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Preventive Medicine and Community Health, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - David H. Walker
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Daniel Jupiter
- Department of Preventive Medicine and Community Health, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Peter C. Melby
- Department of Internal Medicine, Division of Infectious Diseases, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Christine M. Arcari
- Department of Preventive Medicine and Community Health, The University of Texas Medical Branch, Galveston, Texas, United States of America
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Woods K, Nic-Fhogartaigh C, Arnold C, Boutthasavong L, Phuklia W, Lim C, Chanthongthip A, Tulsiani SM, Craig SB, Burns MA, Weier SL, Davong V, Sihalath S, Limmathurotsakul D, Dance DAB, Shetty N, Zambon M, Newton PN, Dittrich S. A comparison of two molecular methods for diagnosing leptospirosis from three different sample types in patients presenting with fever in Laos. Clin Microbiol Infect 2017; 24:1017.e1-1017.e7. [PMID: 29092789 PMCID: PMC6125144 DOI: 10.1016/j.cmi.2017.10.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 10/16/2017] [Accepted: 10/18/2017] [Indexed: 02/01/2023]
Abstract
OBJECTIVES To compare two molecular assays (rrs quantitative PCR (qPCR) versus a combined 16SrRNA and LipL32 qPCR) on different sample types for diagnosing leptospirosis in febrile patients presenting to Mahosot Hospital, Vientiane, Laos. METHODS Serum, buffy coat and urine samples were collected on admission, and follow-up serum ∼10 days later. Leptospira spp. culture and microscopic agglutination tests (MAT) were performed as reference standards. Bayesian latent class modelling was performed to estimate sensitivity and specificity of each diagnostic test. RESULTS In all, 787 patients were included in the analysis: 4/787 (0.5%) were Leptospira culture positive, 30/787 (3.8%) were MAT positive, 76/787 (9.7%) were rrs qPCR positive and 20/787 (2.5%) were 16SrRNA/LipL32 qPCR positive for pathogenic Leptospira spp. in at least one sample. Estimated sensitivity and specificity (with 95% CI) of 16SrRNA/LipL32 qPCR on serum (53.9% (33.3%-81.8%); 99.6% (99.2%-100%)), buffy coat (58.8% (34.4%-90.9%); 99.9% (99.6%-100%)) and urine samples (45.0% (27.0%-66.7%); 99.6% (99.3%-100%)) were comparable with those of rrs qPCR, except specificity of 16SrRNA/LipL32 qPCR on urine samples was significantly higher (99.6% (99.3%-100%) vs. 92.5% (92.3%-92.8%), p <0.001). Sensitivities of MAT (16% (95% CI 6.3%-29.4%)) and culture (25% (95% CI 13.3%-44.4%)) were low. Mean positive Cq values showed that buffy coat samples were more frequently inhibitory to qPCR than either serum or urine (p <0.001). CONCLUSIONS Serum and urine are better samples for qPCR than buffy coat, and 16SrRNA/LipL32 qPCR performs better than rrs qPCR on urine. Quantitative PCR on admission is a reliable rapid diagnostic tool, performing better than MAT or culture, with significant implications for clinical and epidemiological investigations of this global neglected disease.
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Affiliation(s)
- K Woods
- National Infection Service, Public Health England, London, UK; Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos.
| | - C Nic-Fhogartaigh
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos; Bart's Health Division of Infection, Pathology and Pharmacy Department, Royal London Hospital, London, UK
| | - C Arnold
- National Infection Service, Public Health England, London, UK
| | - L Boutthasavong
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - W Phuklia
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - C Lim
- Mahidol-Oxford-Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - A Chanthongthip
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - S M Tulsiani
- Queensland Health Forensic and Scientific Service, WHO Collaborating Centre for Reference and Research on Leptospirosis, Brisbane, Qld, Australia
| | - S B Craig
- Queensland Health Forensic and Scientific Service, WHO Collaborating Centre for Reference and Research on Leptospirosis, Brisbane, Qld, Australia; University of the Sunshine Coast, Faculty of Science Health, Education and Engineering, Sippy Downs, Qld, Australia; Faculty of Health, Queensland University of Technology, Brisbane, Qld, Australia
| | - M-A Burns
- Queensland Health Forensic and Scientific Service, WHO Collaborating Centre for Reference and Research on Leptospirosis, Brisbane, Qld, Australia
| | - S L Weier
- Faculty of Health, Queensland University of Technology, Brisbane, Qld, Australia
| | - V Davong
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - S Sihalath
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - D Limmathurotsakul
- Mahidol-Oxford-Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, England, UK
| | - D A B Dance
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, England, UK; Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - N Shetty
- National Infection Service, Public Health England, London, UK
| | - M Zambon
- National Infection Service, Public Health England, London, UK
| | - P N Newton
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, England, UK
| | - S Dittrich
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, England, UK; Foundation for Innovative New Diagnostics, Geneva, Switzerland
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State of the art of diagnosis of rickettsial diseases: the use of blood specimens for diagnosis of scrub typhus, spotted fever group rickettsiosis, and murine typhus. Curr Opin Infect Dis 2017; 29:433-9. [PMID: 27429138 PMCID: PMC5029442 DOI: 10.1097/qco.0000000000000298] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
PURPOSE OF REVIEW With improved malaria control, acute undifferentiated febrile illness studies in tropical regions reveal a startling proportion of rickettsial illnesses, especially scrub typhus, murine typhus, and spotted fever group rickettsioses. Laboratory diagnosis of these infections evolved little over the past 40 years, but combinations of technologies like PCR and loop-mediated isothermal amplification, with refined rapid diagnostic tests and/or ELISA, are promising for guidance for early antirickettsial treatment. RECENT FINDINGS The long-term reliance on serological tests - useful only late in rickettsial infections - has led to underdiagnosis, inappropriate therapies, and undocumented morbidity and mortality. Recent approaches integrate nucleic acid amplification and recombinant protein-based serological tests for diagnosing scrub typhus. Optimized using Bayesian latent class analyses, this strategy increases diagnostic confidence and enables early accurate diagnosis and treatment - a model to follow for lagging progress in murine typhus and spotted fever. SUMMARY A laboratory diagnostic paradigm shift in rickettsial infections is evolving, with replacement of indirect immunofluorescence assay by the more objective ELISA coupled with nucleic acid amplification assays to expand the diagnostic window toward early infection intervals. This approach supports targeted antirickettsial therapy, reduces morbidity and mortality, and provides a robust evidence base for further development of diagnostics and vaccines.
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Anitharaj V, Stephen S, Pradeep J, Pooja P, Preethi S. Validation of Geno-Sen's Scrub Typhus Real Time Polymerase Chain Reaction Kit by its Comparison with a Serological ELISA Test. J Glob Infect Dis 2017; 9:108-112. [PMID: 28878522 PMCID: PMC5572194 DOI: 10.4103/jgid.jgid_158_16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Background: In the recent past, scrub typhus (ST) has been reported from different parts of India, based on Weil-Felix/enzyme-linked immunosorbent assay (ELISA)/indirect immunofluorescence assay (IFA). Molecular tests are applied only by a few researchers. Aims: Evaluation of a new commercial real time polymerase chain reaction (PCR) kit for molecular diagnosis of ST by comparing it with the commonly used IgM ELISA is our aim. Settings and Design: ST has been reported all over India including Puducherry and surrounding Tamil Nadu and identified as endemic for ST. This study was designed to correlate antibody detection by IgM ELISA and Orientia tsutsugamushi DNA in real time PCR. Materials and Methods: ST IgM ELISA (InBios Inc., USA) was carried out for 170 consecutive patients who presented with the symptoms of acute ST during 11 months (November, 2015– September, 2016). All 77 of these patients with IgM ELISA positivity and 49 of 93 IgM ELISA negative patients were subjected to real time PCR (Geno-Sen's ST real time PCR, Himachal Pradesh, India). Statistical Analysis: Statistical analysis for clinical and laboratory results was performed using IBM SPSS Statistics 17 for Windows (SPSS Inc., Chicago, USA). Chi-square test with Yates correction (Fisher's test) was employed for a small number of samples. Results and Conclusion: Among 77 suspected cases of acute ST with IgM ELISA positivity and 49 IgM negative patients, 42 and 7 were positive, respectively, for O. tsutsugamushi 56-kDa type-specific gene in real time PCR kit. Until ST IFA, the gold standard diagnostic test, is properly validated in India, diagnosis of acute ST will depend on both ELISA and quantitative PCR.
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Affiliation(s)
- Velmurugan Anitharaj
- Department of Microbiology, Mahatma Gandhi Medical College and Research Institute, Puducherry, India
| | - Selvaraj Stephen
- Department of Microbiology, Mahatma Gandhi Medical College and Research Institute, Puducherry, India
| | - Jothimani Pradeep
- Department of Microbiology, Mahatma Gandhi Medical College and Research Institute, Puducherry, India
| | - Pratheesh Pooja
- Department of Genomics and Proteomics, Central Interdisciplinary Research Facility, Mahatma Gandhi Medical College and Research Institute, Puducherry, India
| | - Sridharan Preethi
- Department of Genomics and Proteomics, Central Interdisciplinary Research Facility, Mahatma Gandhi Medical College and Research Institute, Puducherry, India
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Sumonwiriya M, Paris DH, Sunyakumthorn P, Anantatat T, Jenjaroen K, Chumseng S, Im-erbsin R, Tanganuchitcharnchai A, Jintaworn S, Blacksell SD, Chowdhury FR, Kronsteiner B, Teparrukkul P, Burke RL, Lombardini ED, Richards AL, Mason CJ, Jones JW, Day NPJ, Dunachie SJ. Strong interferon-gamma mediated cellular immunity to scrub typhus demonstrated using a novel whole cell antigen ELISpot assay in rhesus macaques and humans. PLoS Negl Trop Dis 2017; 11:e0005846. [PMID: 28892515 PMCID: PMC5608426 DOI: 10.1371/journal.pntd.0005846] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 09/21/2017] [Accepted: 08/01/2017] [Indexed: 01/30/2023] Open
Abstract
Scrub typhus is a febrile infection caused by the obligate intracellular bacterium Orientia tsutsugamushi, which causes significant morbidity and mortality across the Asia-Pacific region. The control of this vector-borne disease is challenging due to humans being dead-end hosts, vertical maintenance of the pathogen in the vector itself, and a potentially large rodent reservoir of unclear significance, coupled with a lack of accurate diagnostic tests. Development of an effective vaccine is highly desirable. This however requires better characterization of the natural immune response of this neglected but important disease. Here we implement a novel IFN-γ ELISpot assay as a tool for studying O. tsutsugamushi induced cellular immune responses in an experimental scrub typhus rhesus macaque model and human populations. Whole cell antigen for O. tsutsugamushi (OT-WCA) was prepared by heat inactivation of Karp-strain bacteria. Rhesus macaques were infected intradermally with O. tsutsugamushi. Freshly isolated peripheral blood mononuclear cells (PBMC) from infected (n = 10) and uninfected animals (n = 5) were stimulated with OT-WCA, and IFN-γ secreting cells quantitated by ELISpot assay at five time points over 28 days. PBMC were then assayed from people in a scrub typhus-endemic region of Thailand (n = 105) and responses compared to those from a partially exposed population in a non-endemic region (n = 14), and to a naïve population in UK (n = 12). Mean results at Day 0 prior to O. tsutsugamushi infection were 12 (95% CI 0-25) and 15 (2-27) spot-forming cells (SFC)/106 PBMC for infected and control macaques respectively. Strong O. tsutsugamushi-specific IFN-γ responses were seen post infection, with ELISpot responses 20-fold higher than baseline at Day 7 (mean 235, 95% CI 200-270 SFC/106 PBMC), 105-fold higher at Day 14 (mean 1261, 95% CI 1,097-1,425 SFC/106 PBMC), 125-fold higher at Day 21 (mean 1,498, 95% CI 1,496-1,500 SFC/106 PBMC) and 118-fold higher at Day 28 (mean 1,416, 95% CI 1,306-1,527 SFC/106 PBMC). No significant change was found in the control group at any time point compared to baseline. Humans from a scrub typhus endemic region of Thailand had mean responses of 189 (95% CI 88-290) SFC/106 PBMC compared to mean responses of 40 (95% CI 9-71) SFC/106 PBMC in people from a non-endemic region and 3 (95% CI 0-7) SFC/106 PBMC in naïve controls. In summary, this highly sensitive assay will enable field immunogenicity studies and further characterization of the host response to O. tsutsugamushi, and provides a link between human and animal models to accelerate vaccine development.
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Affiliation(s)
| | - Daniel H. Paris
- Mahidol Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Department of Medicine, Swiss Tropical and Public Health Institute, Basel, Switzerland
- Faculty of Medicine, University of Basel, Basel, Switzerland
| | - Piyanate Sunyakumthorn
- Department of Veterinary Medicine, Armed Forces Research Institute of Medical Sciences (AFRIMS), Bangkok, Thailand
| | - Tippawan Anantatat
- Mahidol Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
| | - Kemajittra Jenjaroen
- Mahidol Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
| | - Suchintana Chumseng
- Mahidol Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
| | - Rawiwan Im-erbsin
- Department of Veterinary Medicine, Armed Forces Research Institute of Medical Sciences (AFRIMS), Bangkok, Thailand
| | | | - Suthatip Jintaworn
- Mahidol Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
| | - Stuart D. Blacksell
- Mahidol Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
| | - Fazle R. Chowdhury
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, United Kingdom
| | - Barbara Kronsteiner
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, United Kingdom
| | - Prapit Teparrukkul
- Department of Medicine, Sappasithiprasong Hospital, Ubon Ratchathani, Thailand
| | - Robin L. Burke
- Department of Veterinary Medicine, Armed Forces Research Institute of Medical Sciences (AFRIMS), Bangkok, Thailand
| | - Eric D. Lombardini
- Department of Veterinary Medicine, Armed Forces Research Institute of Medical Sciences (AFRIMS), Bangkok, Thailand
| | - Allen L. Richards
- Department of Viral & Rickettsial Diseases, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- Preventive Medicine and Biometrics Department, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Carl J. Mason
- Department of Enteric Diseases, Armed Forces Research Institute of Medical Sciences (AFRIMS), Bangkok, Thailand
| | - James W. Jones
- Department of Veterinary Medicine, Armed Forces Research Institute of Medical Sciences (AFRIMS), Bangkok, Thailand
- Department of Enteric Diseases, Armed Forces Research Institute of Medical Sciences (AFRIMS), Bangkok, Thailand
| | - Nicholas P. J. Day
- Mahidol Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Susanna J. Dunachie
- Mahidol Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, United Kingdom
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Abstract
Scrub typhus is an acute febrile illness in the “tsutsugamushi triangle”, transmitted by chiggers that can be treated effectively if detected early. Laboratory testing, including molecular and serological assays, is needed for confirming the diagnosis, especially in the absence of the pathognomonic eschar. In this review, factors that play a role in disease occurrence and clinical clues for diagnosis, in addition to risk factors contributing to disease severity, including mortality, are discussed in detail. Moreover, issues related to diagnostic assays, treatment, and mixed infections are also enumerated and described.
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Chao CC, Zhang Z, Belinskaya T, Thipmontree W, Tantibhedyangkul W, Silpasakorn S, Wongsawat E, Suputtamongkol Y, Ching WM. An ELISA assay using a combination of recombinant proteins from multiple strains of Orientia tsutsugamushi offers an accurate diagnosis for scrub typhus. BMC Infect Dis 2017; 17:413. [PMID: 28601091 PMCID: PMC5466769 DOI: 10.1186/s12879-017-2512-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 06/01/2017] [Indexed: 12/02/2022] Open
Abstract
Background Scrub typhus (ST) is a disease caused by an obligate intracellular bacterium, Orientia tsutsugamushi, an organism that requires a BSL3 laboratory for propagation. The disease is hallmarked by an eschar at the site of the chigger bite, followed by the development of fever, malaise, myalgia, anorexia, and papulomacular rash. Indirect immunofluorescent assay (IFA) is the gold standard for scrub typhus diagnosis, however, the subjectivity of the assay, the need for a specialized laboratory and instruments has limited the wide use of the test in resource limited areas. Methods A recombinant-protein based enzyme linked immunosorbent assay (ELISA) using the most abundant and immunodominant protein for the detection of Orientia specific antibodies in serum has been developed. The performance of the assay was evaluated using prospectively collected acute sera from 248 randomly selected patients in Thailand. The ELISA assay was evaluated using two different cutoff values. Results The receiver operating characteristic (ROC) curve generated cutoff values gave slightly better consistency with diagnosis of ST than those cutoff values established by averaging ELISA optical density of known negatives at 99% confidence interval. Both cutoff values provided similar statistical parameters when compared with the diagnosis of ST, indicating the validity of both calculations to derive cutoff values. These results suggest that both IgG and IgM ELISA performed well to accurately diagnose scrub typhus cases in endemic areas using only acute serum samples. Conclusions We have successfully developed an ELISA assay for the detection of Orientia-specific antibodies in serum that could provide effective screening of acute sera under clinical setup and it is also a useful assay to estimate seroprevalence in various endemic areas. Electronic supplementary material The online version of this article (doi:10.1186/s12879-017-2512-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Chien-Chung Chao
- Viral and Rickettsial Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD, USA. .,Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.
| | - Zhiwen Zhang
- Viral and Rickettsial Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD, USA.,Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Tatyana Belinskaya
- Viral and Rickettsial Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD, USA.,Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Wilawan Thipmontree
- Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.,Department of Medicine, Maharat Nakhon Ratchasima Hospital, Nakhon Ratchasima, Thailand
| | - Wiwit Tantibhedyangkul
- Department of Immunology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Saowaluk Silpasakorn
- Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Ekkarat Wongsawat
- Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Yupin Suputtamongkol
- Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Wei-Mei Ching
- Viral and Rickettsial Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD, USA.,Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
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Trung NV, Hoi LT, Thuong NTH, Toan TK, Huong TTK, Hoa TM, Fox A, van Kinh N, van Doorn HR, Wertheim HFL, Bryant JE, Nadjm B. Seroprevalence of Scrub Typhus, Typhus, and Spotted Fever Among Rural and Urban Populations of Northern Vietnam. Am J Trop Med Hyg 2017; 96:1084-1087. [PMID: 28500808 PMCID: PMC5417199 DOI: 10.4269/ajtmh.16-0399] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 01/17/2017] [Indexed: 12/02/2022] Open
Abstract
AbstractRickettsial infections are recognized as important causes of fever throughout southeast Asia. Herein, we determined the seroprevalence to rickettsioses within rural and urban populations of northern Vietnam. Prevalence of individuals with evidence of prior rickettsial infections (IgG positive) was surprisingly low, with 9.14% (83/908) testing positive to the three major rickettsial serogroups thought to circulate in the region. Prevalence of typhus group rickettsiae (TG)-specific antibodies (6.5%, 58/908) was significantly greater than scrub typhus group orientiae (STG)- or spotted fever group rickettsiae (SFG)-specific antibodies (P < 0.05). The majority of TG seropositives were observed among urban rather than rural residents (P < 0.05). In contrast, overall antibody prevalence to STG and SFG were both very low (1.1%, 10/908 for STG; 1.7%, 15/908 for SFG), with no significant differences between rural and urban residents. These results provide data on baseline population characteristics that may help inform development of Rickettsia serological testing criteria in future clinical studies.
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Affiliation(s)
| | - Le Thi Hoi
- National Hospital for Tropical Diseases, Hanoi, Vietnam
| | - Nguyen Thi Hong Thuong
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
| | | | - Tran Thi Kieu Huong
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
| | - Tran Mai Hoa
- National Hospital for Tropical Diseases, Hanoi, Vietnam
| | - Annette Fox
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
- Department of Microbiology and Immunology, Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Australia
| | | | - H. Rogier van Doorn
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
- Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Heiman F. L. Wertheim
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
- Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
- Department of Medical Microbiology, Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Juliet E. Bryant
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
- Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Behzad Nadjm
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
- Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
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First Identification and Description of Rickettsioses and Q Fever as Causes of Acute Febrile Illness in Nicaragua. PLoS Negl Trop Dis 2016; 10:e0005185. [PMID: 28036394 PMCID: PMC5201229 DOI: 10.1371/journal.pntd.0005185] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 11/15/2016] [Indexed: 11/19/2022] Open
Abstract
Background Rickettsial infections and Q fever present similarly to other acute febrile illnesses, but are infrequently diagnosed because of limited diagnostic tools. Despite sporadic reports, rickettsial infections and Q fever have not been prospectively studied in Central America. Methodology/Principal Findings We enrolled consecutive patients presenting with undifferentiated fever in western Nicaragua and collected epidemiologic and clinical data and acute and convalescent sera. We used ELISA for screening and paired sera to confirm acute (≥4-fold rise in titer) spotted fever and typhus group rickettsial infections and Q fever as well as past (stable titer) infections. Characteristics associated with both acute and past infection were assessed. Conclusions/Significance We enrolled 825 patients and identified acute rickettsial infections and acute Q fever in 0.9% and 1.3%, respectively. Clinical features were non-specific and neither rickettsial infections nor Q fever were considered or treated. Further study is warranted to define the burden of these infections in Central America. Rickettsial infections and Q fever cause illness characterized by fever and non-specific symptoms and signs. Not only are these infections difficult to recognize, they are also difficult to diagnose because of limitations in existing tests for them. Despite sporadic reports, rickettsial infections and Q fever have not been prospectively studied in Central America. We enrolled consecutive patients presenting with undifferentiated fever in western Nicaragua and collected data regarding potential risk factors as well as symptoms and signs associated with the illnesses. Additionally, we collected blood samples at the initial visit and 2 to 4 weeks thereafter. We used serologic assays to differentiate new (rising antibody titers) vs. old (stable antibody titers) infections. Characteristics associated with both acute and past infection were assessed. We enrolled 825 patients and identified acute (new) rickettsial infections and acute Q fever in 0.9% and 1.3%, respectively. Clinical features were non-specific and neither rickettsial infections nor Q fever were considered nor treated. Further study is warranted to define the burden of these infections in Central America.
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Abstract
The obligate intracellular bacterium Orientia tsutsugamushi is responsible for more than one million cases of scrub typhus annually throughout the Asia-Pacific region. Human infection occurs via the bite of the larval form (chigger) of several species of trombiculid mites. While in some patients the result of infection is a mild, febrile illness, others experience severe complications, which may even be fatal. This review discusses the genome and biology of the causative agent, the changing epidemiology of scrub typhus, the challenges of its diagnosis, and current treatment recommendations.
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Affiliation(s)
- Sunil Thomas
- Lankenau Institute for Medical Research, Wynnewood, Pennsylvania USA
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44
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Chanana L, Atre K, Galwankar S, Kelkar D. State of the Globe: What's the Right Test for Diagnosing Rickettseal Diseases. J Glob Infect Dis 2016; 8:95-6. [PMID: 27621558 PMCID: PMC4997799 DOI: 10.4103/0974-777x.188581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Lakshay Chanana
- Honourable Fellow of the Academic College of Emergency Experts, Vellore, India
| | | | - Sagar Galwankar
- Department of Emergency Medicine, University of Florida, Jacksonville, USA
| | - Dhanashree Kelkar
- Department of Emergency Medicine, Section of Infectious Diseases, Winter Haven Hospital Division, University of Florida, Jacksonville, USA
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Gupta N, Chaudhry R, Thakur CK. Determination of Cutoff of ELISA and Immunofluorescence Assay for Scrub Typhus. J Glob Infect Dis 2016; 8:97-9. [PMID: 27621559 PMCID: PMC4997800 DOI: 10.4103/0974-777x.188584] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Background: The most common method employed for diagnosis of scrub typhus is serology. It is widely known that demonstration of ≥4-fold rise in titers of antibody in paired sera is required for diagnosis. However, for guidance of initial treatment, there is a need for rapid diagnosis at the time of admission. Therefore, there is a need for standardized region specific cutoff titers at the time of admission. Materials and Methods: A total of 258 patients of all age groups with clinically suspected scrub typhus over a period of 24 months (October 2013-October 2015) were enrolled. Serum samples of these patients were subjected to immunofluorescent antibody (IFA) for immunoglobulin M (IgM) (Fuller Labs, USA) with dilutions of 1:64, 1:128, 1:256, and 1:512. Serum samples of all 258 patients were subjected to IgM ELISA (Inbios Inc., USA). Any patient with response to antibiotics within 48 h accompanied by either presence of an eschar or positivity by polymerase chain reaction was taken as positive. Receiver operating characteristic (ROC) curve was drawn to generate cutoff for these tests. Results: A total of 20 patients were diagnosed as cases of scrub typhus. The ROC curve analysis revealed a cutoff optical density value of 0.87 with sensitivity and specificity of 100% and 94.12%, respectively. ROC curve analysis of IFA revealed sensitivity and specificity of 100% and 93.5%, respectively at 1:64 dilution. Conclusion: Considering cost constraints, centers in and around New Delhi region can use the cutoffs we determined for the diagnosis of scrub typhus.
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Affiliation(s)
- Nitin Gupta
- Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India
| | - Rama Chaudhry
- Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India
| | - Chandan Kumar Thakur
- Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India
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Lubell Y, Althaus T, Blacksell SD, Paris DH, Mayxay M, Pan-Ngum W, White LJ, Day NPJ, Newton PN. Modelling the Impact and Cost-Effectiveness of Biomarker Tests as Compared with Pathogen-Specific Diagnostics in the Management of Undifferentiated Fever in Remote Tropical Settings. PLoS One 2016; 11:e0152420. [PMID: 27027303 PMCID: PMC4814092 DOI: 10.1371/journal.pone.0152420] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 03/14/2016] [Indexed: 01/21/2023] Open
Abstract
Background Malaria accounts for a small fraction of febrile cases in increasingly large areas of the malaria endemic world. Point-of-care tests to improve the management of non-malarial fevers appropriate for primary care are few, consisting of either diagnostic tests for specific pathogens or testing for biomarkers of host response that indicate whether antibiotics might be required. The impact and cost-effectiveness of these approaches are relatively unexplored and methods to do so are not well-developed. Methods We model the ability of dengue and scrub typhus rapid tests to inform antibiotic treatment, as compared with testing for elevated C-Reactive Protein (CRP), a biomarker of host-inflammation. Using data on causes of fever in rural Laos, we estimate the proportion of outpatients that would be correctly classified as requiring an antibiotic and the likely cost-effectiveness of the approaches. Results Use of either pathogen-specific test slightly increased the proportion of patients correctly classified as requiring antibiotics. CRP testing was consistently superior to the pathogen-specific tests, despite heterogeneity in causes of fever. All testing strategies are likely to result in higher average costs, but only the scrub typhus and CRP tests are likely to be cost-effective when considering direct health benefits, with median cost per disability adjusted life year averted of approximately $48 USD and $94 USD, respectively. Conclusions Testing for viral infections is unlikely to be cost-effective when considering only direct health benefits to patients. Testing for prevalent bacterial pathogens can be cost-effective, having the benefit of informing not only whether treatment is required, but also as to the most appropriate antibiotic; this advantage, however, varies widely in response to heterogeneity in causes of fever. Testing for biomarkers of host inflammation is likely to be consistently cost-effective despite high heterogeneity, and can also offer substantial reductions in over-use of antimicrobials in viral infections.
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Affiliation(s)
- Yoel Lubell
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- * E-mail:
| | - Thomas Althaus
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Stuart D. Blacksell
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Daniel H. Paris
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Mayfong Mayxay
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Mahosot Hospital, Vientiane, Laos
- Faculty of Postgraduate Studies, University of Health Sciences, Vientiane, Laos
| | - Wirichada Pan-Ngum
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Lisa J. White
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Nicholas P. J. Day
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Paul N. Newton
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Mahosot Hospital, Vientiane, Laos
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Optimal Cutoff and Accuracy of an IgM Enzyme-Linked Immunosorbent Assay for Diagnosis of Acute Scrub Typhus in Northern Thailand: an Alternative Reference Method to the IgM Immunofluorescence Assay. J Clin Microbiol 2016; 54:1472-1478. [PMID: 27008880 PMCID: PMC4879268 DOI: 10.1128/jcm.02744-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 03/08/2016] [Indexed: 01/03/2023] Open
Abstract
The enzyme-linked immunosorbent assay (ELISA) has been proposed as an alternative serologic diagnostic test to the indirect immunofluorescence assay (IFA) for scrub typhus. Here, we systematically determine the optimal sample dilution and cutoff optical density (OD) and estimate the accuracy of IgM ELISA using Bayesian latent class models (LCMs). Data from 135 patients with undifferentiated fever were reevaluated using Bayesian LCMs. Every patient was evaluated for the presence of an eschar and tested with a blood culture for Orientia tsutsugamushi, three different PCR assays, and an IgM IFA. The IgM ELISA was performed for every sample at sample dilutions from 1:100 to 1:102,400 using crude whole-cell antigens of the Karp, Kato, and Gilliam strains of O. tsutsugamushi developed by the Naval Medical Research Center. We used Bayesian LCMs to generate unbiased receiver operating characteristic curves and found that the sample dilution of 1:400 was optimal for the IgM ELISA. With the optimal cutoff OD of 1.474 at a sample dilution of 1:400, the IgM ELISA had a sensitivity of 85.7% (95% credible interval [CrI], 77.4% to 86.7%) and a specificity of 98.1% (95% CrI, 97.2% to 100%) using paired samples. For the ELISA, the OD could be determined objectively and quickly, in contrast to the reading of IFA slides, which was both subjective and labor-intensive. The IgM ELISA for scrub typhus has high diagnostic accuracy and is less subjective than the IgM IFA. We suggest that the IgM ELISA may be used as an alternative reference test to the IgM IFA for the serological diagnosis of scrub typhus.
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Diagnostic Accuracy of the InBios Scrub Typhus Detect Enzyme-Linked Immunoassay for the Detection of IgM Antibodies in Northern Thailand. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2015; 23:148-54. [PMID: 26656118 PMCID: PMC4744921 DOI: 10.1128/cvi.00553-15] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2015] [Accepted: 12/04/2015] [Indexed: 11/29/2022]
Abstract
In this study, we examined the diagnostic accuracy of the InBios Scrub Typhus Detect IgM enzyme-linked immunosorbent assay (ELISA) and determined the optimal diagnostic optical density (OD) cutoffs for screening and diagnostic applications based on prospectively collected, characterized samples from undifferentiated febrile illness patients in northern Thailand. Direct comparisons with the serological gold standard, indirect immunofluorescence assay (IFA), revealed strong statistical correlation of ELISA OD values and IFA IgM titers. Determination of the optimal ELISA cutoff for seroepidemiology or screening purposes compared to the corresponding IFA reciprocal titer of 400 as previously described for Thailand was 0.60 OD, which corresponded to a sensitivity (Sn) of 84% and a specificity (Sp) of 98%. The diagnostic performance against the improved and more-stringent scrub typhus infection criteria (STIC), correcting for low false-positive IFA titers, resulted in an Sn of 93% and an Sp of 91% at an ELISA cutoff of 0.5 OD. This diagnostic ELISA cutoff corresponds to IFA reciprocal titers of 1,600 to 3,200, which greatly reduces the false-positive rates associated with low-positive IFA titers. These data are in congruence with the recently improved serodiagnostic positivity criteria using the Bayesian latent class modeling approach. In summary, the InBios Scrub Typhus Detect IgM ELISA is affordable and easy-to-use, with adequate diagnostic accuracy for screening and diagnostic purposes, and should be considered an improved alternative to the gold standard IFA for acute diagnosis. For broader application, regional cutoff validation and antigenic composition for consistent diagnostic accuracy should be considered.
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Optimal Cutoff Titers for Indirect Immunofluorescence Assay for Diagnosis of Scrub Typhus. J Clin Microbiol 2015; 53:3663-6. [PMID: 26354819 PMCID: PMC4609688 DOI: 10.1128/jcm.01680-15] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Accepted: 08/29/2015] [Indexed: 11/20/2022] Open
Abstract
We determined the optimal cutoff titers in admission and convalescent-phase samples for scrub typhus indirect immunofluorescence assay using Bayesian latent class models. Cutoff titers of ≥1:3,200 in an admission sample or of a ≥4-fold rise to ≥1:3,200 in a convalescent-phase sample provided the highest accuracy (sensitivity, 81.6%; specificity, 100%).
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Comparative Accuracy of the InBios Scrub Typhus Detect IgM Rapid Test for the Detection of IgM Antibodies by Using Conventional Serology. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2015; 22:1130-2. [PMID: 26291089 PMCID: PMC4580738 DOI: 10.1128/cvi.00390-15] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 07/23/2015] [Indexed: 12/18/2022]
Abstract
This study investigated the comparative accuracy of a recombinant 56-kDa type-specific antigen-based rapid diagnostic test (RDT) for scrub typhus for the detection of IgM antibodies by using conventional serology in well-characterized serum samples from undifferentiated febrile illness patients. The RDT showed high specificity and promising comparative accuracy, with 82% sensitivity and 98% specificity for samples defined positive at an IgM indirect immunofluorescence assay positivity cutoff titer of ≥1:1,600 versus 92% and 95% at ≥1:6,400, respectively.
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