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Roberts T, Silisouk J, Sengdatka D, Sibounheuang B, Seljuk R, Vang X, Sengduangphachanh A, Davong V, Vongsouvath M, Malou N, Ferreyra C, Ashley EA, Simpson AJH. OUP accepted manuscript. JAC Antimicrob Resist 2022; 4:dlac006. [PMID: 35146428 PMCID: PMC8826549 DOI: 10.1093/jacamr/dlac006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 01/06/2022] [Indexed: 11/14/2022] Open
Abstract
Background There is a need for simple microbiology diagnostics to enable antimicrobial resistance surveillance in low- and middle-income countries. Objectives To investigate the field utility of InTray COLOREX plates for urine culture and ESBL detection. Methods Clinical urine samples from Mahosot Hospital, Vientiane, Lao PDR were inoculated onto chromogenic media and InTray COLOREX Screen plates between June and August 2020. Urine and isolates from other clinical specimens were inoculated onto COLOREX ESBL plates. A simulated field study investigating the field utility of the InTray COLOREX plates was also completed. Results In total, 355 urine samples were inoculated onto standard chromogenic agar and InTray COLOREX Screen plates, and 154 urine samples and 54 isolates from other clinical specimens on the COLOREX ESBL plates. Growth was similar for the two methods (COLOREX Screen 41%, standard method 38%) with 20% discordant results, mainly due to differences in colony counts or colonial appearance. Contamination occurred in 13% of samples, with the COLOREX Screen plates showing increased contamination rates, potentially due to condensation. ESBL producers were confirmed from 80% of isolates from the COLOREX ESBL plates, and direct plating provided rapid detection of presumptive ESBL producers. Burkholderia pseudomallei also grew well on the ESBL plates, a relevant finding in this melioidosis-endemic area. Conclusions The InTray COLOREX Screen and ESBL plates were simple to use and interpret, permitting rapid detection of uropathogens and ESBLs, and have the potential for easy transport and storage from field sites and use in laboratories with low capacity.
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Affiliation(s)
- Tamalee Roberts
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Corresponding author. E-mail:
| | - Joy Silisouk
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Davanh Sengdatka
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Bountoy Sibounheuang
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Ranoy Seljuk
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Xao Vang
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Amphonesavanh Sengduangphachanh
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Viengmon Davong
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Manivanh Vongsouvath
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | | | | | - Elizabeth A. Ashley
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Andrew J. H. Simpson
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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Mayxay M, Paboriboune P, Xaiyaphet X, Kunlaya K, Vongsouvath M, Sibounheuang B, Dubot-Pérès A, Simpson AJH, Robinson MT, Choumlivong K, Dittaphong V, Thongsana M, Chanthamavong A, Sayasene P, Soumphonphakdy B, Soutthisombat K, Phoumindr B, Phetsouvanh R, Xangsayarath P, Ashley EA. A pilot study to investigate the risk of SARS-CoV-2 household transmission following hospital discharge of confirmed cases in Vientiane Capital, Lao PDR. Valasan Kanphaet Lao 2021; 12:67-70. [PMID: 37868344 PMCID: PMC7615233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
Background Global guidelines from the World Health Organization on discharging patients diagnosed with COVID-19 changed in 2021 to a symptom-based rather than negative PCR-based approach. Studies have shown that shedding of viable virus continues for approximately eight days after symptom onset in most patients. In Vientiane, Laos, until now, patients diagnosed with asymptomatic or mild COVID-19 are hospitalised for 2 weeks and then, if they still test PCR positive for SARS-CoV-2, stay for a further week in a designated quarantine hotel before being discharged home. Objective The aim of this pilot study was to investigate the risk of transmission of SARS-CoV-2 to household contacts of discharged patients who are still PCR-positive following 2-3 weeks quarantine in Vientiane, Lao PDR. Methods Adult participants, who were resident in Vientiane Capital and who were about to be discharged from hospital (after 2 weeks hospitalisation), or from a quarantine hotel, following a further one-week quarantine, were screened to assess eligibility for the study. The household of each case was visited a maximum of 48 hours before or up to 24 hours after the participant was discharged and a nasopharyngeal swab was taken from all household members. Repeat nasopharyngeal swabs from cases and contacts were taken on day 7 and day 14 after discharge home of each case. Results Between 20th May 2021 and 27th August 2021, 55 cases and 84 contacts in 27 households were enrolled in the study. The median [range] age of all 139 included participants was 26.5 years [3 months to 83 years] and 83 (60%) were female. By household, the median [range] number of cases and contacts were 1 [1-6] and 3 [1-13] respectively. At discharge home 32/48 (67%) cases tested positive for SARS-CoV-2. By day 7 11 of 47 cases (23%) still tested positive for SARS-CoV-2 by PCR and by day 14 this number was 2/24 (8%). No contacts tested positive during follow up and the numbers tested at the time of discharge of the case, 7 days later and 2 weeks later were 56, 57 and 37 respectively. Loss to follow up at day 7 and day 14 ranged from 15-50% (participants not at home at the time of visits). Conclusion In this pilot study we found no evidence of onward transmission of SARS-CoV-2 to contacts of cases discharged home with a positive PCR result. This suggests the current discharge policy for mild to moderate COVID-19 case following 2 weeks in hospital in the Lao PDR is safe.
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Affiliation(s)
- Mayfong Mayxay
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane Capital, Lao PDR
- Institute of Research and Education Development (IRED), University of Health Sciences, Ministry of Health, Vientiane Lao PDR
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Phimpha Paboriboune
- Centre d'Infectiologie Lao-Christophe Mérieux (CILM), Ministry of Health, Lao PDR
| | - Xaipasong Xaiyaphet
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane Capital, Lao PDR
| | - Khamfong Kunlaya
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane Capital, Lao PDR
| | - Manivanh Vongsouvath
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane Capital, Lao PDR
| | - Bountoy Sibounheuang
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane Capital, Lao PDR
| | - Audrey Dubot-Pérès
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane Capital, Lao PDR
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Unité des Virus Émergents (UVE: Aix-Marseille Univ-IRD 190-Inserm 1207), Marseille, France
| | - Andrew J. H. Simpson
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane Capital, Lao PDR
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Matthew T. Robinson
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane Capital, Lao PDR
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | | | | | | | | | | | | | | | - Bouathep Phoumindr
- Department of Health Care and Rehabilitation, Ministry of Health, Lao PDR
| | | | | | - Elizabeth A Ashley
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane Capital, Lao PDR
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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Dubot-Pérès A, Mayxay M, Phetsouvanh R, Lee SJ, Rattanavong S, Vongsouvath M, Davong V, Chansamouth V, Phommasone K, Moore C, Dittrich S, Lattana O, Sirisouk J, Phoumin P, Panyanivong P, Sengduangphachanh A, Sibounheuang B, Chanthongthip A, Simmalavong M, Sengdatka D, Seubsanith A, Keoluangkot V, Phimmasone P, Sisout K, Detleuxay K, Luangxay K, Phouangsouvanh I, Craig SB, Tulsiani SM, Burns MA, Dance DAB, Blacksell SD, de Lamballerie X, Newton PN. Management of Central Nervous System Infections, Vientiane, Laos, 2003-2011. Emerg Infect Dis 2019; 25:898-910. [PMID: 31002063 PMCID: PMC6478220 DOI: 10.3201/eid2505.180914] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
During 2003–2011, we recruited 1,065 patients of all ages admitted to Mahosot Hospital (Vientiane, Laos) with suspected central nervous system (CNS) infection. Etiologies were laboratory confirmed for 42.3% of patients, who mostly had infections with emerging pathogens: viruses in 16.2% (mainly Japanese encephalitis virus [8.8%]); bacteria in 16.4% (including Orientia tsutsugamushi [2.9%], Leptospira spp. [2.3%], and Rickettsia spp. [2.3%]); and Cryptococcus spp. fungi in 6.6%. We observed no significant differences in distribution of clinical encephalitis and meningitis by bacterial or viral etiology. However, patients with bacterial CNS infection were more likely to have a history of diabetes than others. Death (26.3%) was associated with low Glasgow Coma Scale score, and the mortality rate was higher for patients with bacterial than viral infections. No clinical or laboratory variables could guide antibiotic selection. We conclude that high-dependency units and first-line treatment with ceftriaxone and doxycycline for suspected CNS infections could improve patient survival in Laos.
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SoukAloun D, Douangbouphaa V, Phetsouvanh R, Sibounheuang B, Vongsouvat M, Chanmala K, Vongphachanh T, Maniphonh S, Phouangsouvanh I, Fox K, Logronio J, Grabovac V, Heffelfinger J, Jeong H, Kim K, Nyambat B. Rotavirus diarrhea in hospitalized children under 5 years of age in Vientiane, Lao PDR, 2009-2015. Vaccine 2018; 36:7878-7882. [PMID: 29739715 DOI: 10.1016/j.vaccine.2018.04.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 03/14/2018] [Accepted: 04/03/2018] [Indexed: 10/17/2022]
Abstract
BACKGROUND Diarrhea is a leading cause of death in children <5 years worldwide, causing an estimated 215,000 deaths in 2013. This evaluation tracks the epidemiologic patterns and most common rotavirus genotypes among hospitalized children in this age group with acute gastroenteritis in Lao PDR. METHODS Children <5 years in a central tertiary hospital in the capital city were prospectively enrolled into the surveillance platform during January 2009-December 2015. We collected information regarding clinical characteristics of enrolled children. Stool samples were obtained within 24 h of hospital admission and tested for rotavirus using rotavirus antigen detection enzyme immunoassay. Samples were sent to the regional reference laboratories in Australia and South Korea for genotyping. Bivariate analyses compared demographic and clinical characteristics between rotavirus positive and negative children using Chi-square statistical testing. Seasonality of rotavirus and annual genotype distribution are also described. RESULTS We enrolled 1853 children <5 years with acute gastroenteritis during the surveillance period and collected 1772 fecal specimens, 982 (55%) of which tested positive for rotavirus. A higher proportion of rotavirus acute gastroenteritis was observed among children 12-23 months of age as compared to rotavirus negative children in the same age group, 41% vs 36%. Eighty-six percent of rotavirus positive children experienced vomiting, as compared to 65% of rotavirus negative children. Eighty-five percent (n = 830/982) of rotavirus positive specimens occurred during the dry season (January-April). The most common genotypes identified were G1, G2, G3 and P8 and P4. The most prevalent combined genotype differed annually during the surveillance period. CONCLUSION Surveillance continues to be important in documenting the burden of rotavirus in children <5 years in Lao PDR as well as providing a baseline for determining the impact of rotavirus vaccine once it is introduced into Lao PDR's national immunization schedule.
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Affiliation(s)
- Douangdao SoukAloun
- Department of Pediatrics, Mahosot Hospital, Vientiane, Lao Democratic People's Republic.
| | - Vannida Douangbouphaa
- Department of Pediatrics, Mahosot Hospital, Vientiane, Lao Democratic People's Republic.
| | | | - Bountoy Sibounheuang
- Microbiology Section, Mahosot Hospital, Vientiane, Lao Democratic People's Republic
| | - Manivanh Vongsouvat
- Microbiology Section, Mahosot Hospital, Vientiane, Lao Democratic People's Republic
| | - Keomany Chanmala
- Department of Pediatrics, Mahosot Hospital, Vientiane, Lao Democratic People's Republic
| | - Thonglay Vongphachanh
- Department of Pediatrics, Mahosot Hospital, Vientiane, Lao Democratic People's Republic
| | - Soudalinh Maniphonh
- Department of Pediatrics, Mahosot Hospital, Vientiane, Lao Democratic People's Republic
| | | | - Kimberley Fox
- WHO Western Pacific Regional Office, Manila, Philippines
| | | | - Varja Grabovac
- WHO Western Pacific Regional Office, Manila, Philippines
| | | | - Hyesook Jeong
- Division of Vaccine Research, Korea Centers of Disease Control and Prevention, Seoul, Republic of Korea
| | - Kisang Kim
- Division of Vaccine Research, Korea Centers of Disease Control and Prevention, Seoul, Republic of Korea
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Castonguay-Vanier J, Klitting R, Sengvilaipaseuth O, Piorkowski G, Baronti C, Sibounheuang B, Vongsouvath M, Chanthongthip A, Thongpaseuth S, Mayxay M, Phommasone K, Douangdala P, Inthalath S, Souvannasing P, Newton PN, de Lamballerie X, Dubot-Pérès A. Molecular epidemiology of dengue viruses in three provinces of Lao PDR, 2006-2010. PLoS Negl Trop Dis 2018; 12:e0006203. [PMID: 29377886 PMCID: PMC5805359 DOI: 10.1371/journal.pntd.0006203] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 02/08/2018] [Accepted: 01/02/2018] [Indexed: 01/12/2023] Open
Abstract
Few data on dengue epidemiology are available for Lao PDR. Here, we provide information on the complexity of dengue epidemiology in the country, demonstrating dynamic circulation that varies over space and time, according to serotype. We recruited 1,912 consenting patients presenting with WHO dengue criteria at Mahosot Hospital, Vientiane (central Laos), between 2006 and 2010. Between 2008 and 2010, 1,413 patients with undifferentiated fever were also recruited at Luang Namtha (LNT) Provincial Hospital (northern Laos) and 555 at Salavan (SV) Provincial Hospital (southern Laos). We report significant variations in Dengue virus (DENV) circulation between the three sites. Peaks of DENV infection were observed in the rainy seasons, although 11% of confirmed cases in the provinces and 4.6% in the capital were detected during the dry and cool seasons (between December and February). Four DENV serotypes were detected among the 867 RT-PCR positive patients: 76.9% DENV-1, 9.6% DENV-2, 7.7% DENV-4 and 5.3% DENV-3. DENV-1 was the predominant serotype throughout the study except in LNT in 2008 and 2009 when it was DENV-2. Before July 2009, DENV-2 was not detected in SV and only rarely detected in Vientiane. DENV-3 and DENV-4 were commonly detected in Vientiane, before 2008 for DENV-4 and after 2009 for DENV-3. The phylogenetic analyses of DENV envelope sequences suggest concurrent multiple introductions of new strains as well as active DENV circulation throughout Laos and with neighboring countries. It is therefore of great importance to develop and strengthen a year-round nation-wide surveillance network in order to collect data that would allow anticipation of public health issues caused by the occurrence of large dengue outbreaks. Dengue is a mosquito-borne disease that can be caused by 4 viruses. It is a flu-like disease but can sometime be more severe and cause hemorrhage or death. An estimated 390 million people are infected every year, mainly in the Western Pacific and in South-East Asia. In Laos, where our study was conducted from 2006 to 2010, little was known on the circulation of the different dengue viruses. A total of 1,912 patients were recruited at Mahosot Hospital, Vientiane (central Laos), 1,413 patients at Luang Namtha Provincial Hospital (northern Laos) and 555 at Salavan Provincial Hospital (southern Laos). Although most Dengue virus infections were detected during rainy seasons (where mosquitoes are the most active) in all three provinces, some patients were also infected during the dryer months. All 4 dengue viruses were detected with different distributions: mostly type 1 in the capital and in the South, and type 1 and 2 in equal proportion in the north. Type 3 and 4 were not detected in Luang Namtha and rarely in Salavan. Comparison of Dengue virus sequences from Laos with sequences collected worldwide showed an active year-round circulation of dengue within Laos and with neighboring countries. It is hence of great importance to develop and strengthen a year-round nation-wide surveillance network in order to collect data that would allow anticipation of public health issues caused by the occurrence of large dengue outbreaks.
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Affiliation(s)
- Josée Castonguay-Vanier
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine & Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Raphaëlle Klitting
- UMR "Unité des Virus Emergents" (UVE: Aix-Marseille Univ–IRD 190 –Inserm 1207 –IHU Méditerranée Infection), Marseille, France
| | - Onanong Sengvilaipaseuth
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Géraldine Piorkowski
- UMR "Unité des Virus Emergents" (UVE: Aix-Marseille Univ–IRD 190 –Inserm 1207 –IHU Méditerranée Infection), Marseille, France
| | - Cécile Baronti
- UMR "Unité des Virus Emergents" (UVE: Aix-Marseille Univ–IRD 190 –Inserm 1207 –IHU Méditerranée Infection), Marseille, France
| | - Bountoy Sibounheuang
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Manivanh Vongsouvath
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Anisone Chanthongthip
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Soulignasack Thongpaseuth
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Mayfong Mayxay
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine & Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
- Faculty of Postgraduate Studies, University of Health Sciences, Vientiane, Lao PDR
| | - Koukeo Phommasone
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | | | - Saythong Inthalath
- Luang Namtha Provincial Hospital, Luang Namtha, Luang Namtha Province, Lao PDR
| | | | - Paul N. Newton
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine & Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Xavier de Lamballerie
- UMR "Unité des Virus Emergents" (UVE: Aix-Marseille Univ–IRD 190 –Inserm 1207 –IHU Méditerranée Infection), Marseille, France
| | - Audrey Dubot-Pérès
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine & Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
- UMR "Unité des Virus Emergents" (UVE: Aix-Marseille Univ–IRD 190 –Inserm 1207 –IHU Méditerranée Infection), Marseille, France
- * E-mail:
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Mayxay M, Castonguay-Vanier J, Chansamouth V, Dubot-Pérès A, Paris DH, Phetsouvanh R, Tangkhabuanbutra J, Douangdala P, Inthalath S, Souvannasing P, Slesak G, Tongyoo N, Chanthongthip A, Panyanouvong P, Sibounheuang B, Phommasone K, Dohnt M, Phonekeo D, Hongvanthong B, Xayadeth S, Ketmayoon P, Blacksell SD, Moore CE, Craig SB, Burns MA, von Sonnenburg F, Corwin A, de Lamballerie X, González IJ, Christophel EM, Cawthorne A, Bell D, Newton PN. Causes of non-malarial fever in Laos: a prospective study. Lancet Glob Health 2015; 1:e46-54. [PMID: 24748368 PMCID: PMC3986032 DOI: 10.1016/s2214-109x(13)70008-1] [Citation(s) in RCA: 181] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Background Because of reductions in the incidence of Plasmodium falciparum malaria in Laos, identification of the causes of fever in people without malaria, and discussion of the best empirical treatment options, are urgently needed. We aimed to identify the causes of non-malarial acute fever in patients in rural Laos. Methods For this prospective study, we recruited 1938 febrile patients, between May, 2008, and December, 2010, at Luang Namtha provincial hospital in northwest Laos (n=1390), and between September, 2008, and December, 2010, at Salavan provincial hospital in southern Laos (n=548). Eligible participants were aged 5–49 years with fever (≥38°C) lasting 8 days or less and were eligible for malaria testing by national guidelines. Findings With conservative definitions of cause, we assigned 799 (41%) patients a diagnosis. With exclusion of influenza, the top five diagnoses when only one aetiological agent per patient was identified were dengue (156 [8%] of 1927 patients), scrub typhus (122 [7%] of 1871), Japanese encephalitis virus (112 [6%] of 1924), leptospirosis (109 [6%] of 1934), and bacteraemia (43 [2%] of 1938). 115 (32%) of 358 patients at Luang Namtha hospital tested influenza PCR-positive between June and December, 2010, of which influenza B was the most frequently detected strain (n=121 [87%]). Disease frequency differed significantly between the two sites: Japanese encephalitis virus infection (p=0·04), typhoid (p=0·006), and leptospirosis (p=0·001) were more common at Luang Namtha, whereas dengue and malaria were more common at Salavan (all p<0·0001). With use of evidence from southeast Asia when possible, we estimated that azithromycin, doxycycline, ceftriaxone, and ofloxacin would have had significant efficacy for 258 (13%), 240 (12%), 154 (8%), and 41 (2%) of patients, respectively. Interpretation Our findings suggest that a wide range of treatable or preventable pathogens are implicated in non-malarial febrile illness in Laos. Empirical treatment with doxycycline for patients with undifferentiated fever and negative rapid diagnostic tests for malaria and dengue could be an appropriate strategy for rural health workers in Laos. Funding Wellcome Trust, WHO–Western Pacific Region, Foundation for Innovative New Diagnostics, US Centers for Disease Control and Prevention.
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Affiliation(s)
- Mayfong Mayxay
- Lao Oxford Mahosot Hospital Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
- Faculty of Postgraduate Studies, University of Health Sciences, Vientiane, Laos
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Josée Castonguay-Vanier
- Lao Oxford Mahosot Hospital Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - Vilada Chansamouth
- Lao Oxford Mahosot Hospital Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - Audrey Dubot-Pérès
- Lao Oxford Mahosot Hospital Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
- UMR_D 190 “Emergence des Pathologies Virales”, Aix-Marseille University, IRD French Institute of Research for Development, EHESP French School of Public Health, Marseille, France
| | - Daniel H Paris
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
- Mahidol–Oxford Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok
| | - Rattanaphone Phetsouvanh
- Lao Oxford Mahosot Hospital Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | | | | | - Saythong Inthalath
- Luang Namtha Provincial Hospital, Luang Namtha, Luang Namtha Province, Laos
| | | | - Günther Slesak
- Tropical Hospital Paul-Lechler-Krankenhaus, Tübingen, Germany
| | - Narongchai Tongyoo
- Mahidol–Oxford Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok
| | - Anisone Chanthongthip
- Lao Oxford Mahosot Hospital Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - Phonepasith Panyanouvong
- Lao Oxford Mahosot Hospital Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - Bountoy Sibounheuang
- Lao Oxford Mahosot Hospital Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - Koukeo Phommasone
- Lao Oxford Mahosot Hospital Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - Michael Dohnt
- WHO/FAO/OIE Collaborating Centre for Leptospirosis Reference and Research, Queensland, Australia
- School of Biomedical Sciences, Queensland University of Technology, Queensland, Australia
| | - Darouny Phonekeo
- National Centre for Laboratory and Epidemiology, Vientiane, Laos
| | | | | | | | - Stuart D Blacksell
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
- Mahidol–Oxford Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok
| | - Catrin E Moore
- Lao Oxford Mahosot Hospital Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Scott B Craig
- WHO/FAO/OIE Collaborating Centre for Leptospirosis Reference and Research, Queensland, Australia
- School of Biomedical Sciences, Queensland University of Technology, Queensland, Australia
| | - Mary-Anne Burns
- WHO/FAO/OIE Collaborating Centre for Leptospirosis Reference and Research, Queensland, Australia
- School of Biomedical Sciences, Queensland University of Technology, Queensland, Australia
| | - Frank von Sonnenburg
- Department of Infectious Diseases and Tropical Medicine, University of Munich, Munich, Germany
| | - Andrew Corwin
- Centers for Disease Control and Prevention, US Embassy, Vientiane, Laos
| | - Xavier de Lamballerie
- UMR_D 190 “Emergence des Pathologies Virales”, Aix-Marseille University, IRD French Institute of Research for Development, EHESP French School of Public Health, Marseille, France
| | - Iveth J González
- Foundation for Innovative New Diagnostics (FIND), Geneva, Switzerland
| | | | - Amy Cawthorne
- WHO–Regional Office for the Western Pacific, Manila, Philippines
| | - David Bell
- Foundation for Innovative New Diagnostics (FIND), Geneva, Switzerland
| | - Paul N Newton
- Lao Oxford Mahosot Hospital Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
- Correspondence to: Dr Paul Newton, Lao Oxford Mahosot Hospital Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
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7
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Keita AK, Dubot-Pérès A, Phommasone K, Sibounheuang B, Vongsouvath M, Mayxay M, Raoult D, Newton PN, Fenollar F. High prevalence of Tropheryma whipplei in Lao kindergarten children. PLoS Negl Trop Dis 2015; 9:e0003538. [PMID: 25699514 PMCID: PMC4336285 DOI: 10.1371/journal.pntd.0003538] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 01/13/2015] [Indexed: 12/18/2022] Open
Abstract
Background Tropheryma whipplei is a bacterium commonly found in feces of young children in Africa, but with no data from Asia. We estimated the prevalence of T. whipplei carriage in feces of children in Lao PDR (Laos). Methods/Principal Findings Using specific quantitative real-time PCR, followed by genotyping for each positive specimen, we estimated the prevalence of T. whipplei in 113 feces from 106 children in Vientiane, the Lao PDR (Laos). T. whipplei was detected in 48% (51/106) of children. Those aged ≤4 years were significantly less frequently positive (17/52, 33%) than older children (34/54, 63%; p< 0.001). Positive samples were genotyped. Eight genotypes were detected including 7 specific to Laos. Genotype 2, previously detected in Europe, was circulating (21% of positive children) in 2 kindergartens (Chompet and Akad). Genotypes 136 and 138 were specific to Chompet (21% and 15.8%, respectively) whereas genotype 139 was specific to Akad (10.55%). Conclusions/Significance T. whipplei is a widely distributed bacterium, highly prevalent in feces of healthy children in Laos. Further research is needed to identify the public health significance of this finding. Tropheryma whipplei is a common bacterium carried in feces of young children. Here, using specific PCR, we estimated the prevalence of T. whipplei in 113 feces from 106 children in Vientiane, the Lao PDR (Laos). T. whipplei was detected in 48% (51/106) of children. Eight genotypes were detected, including 7 specific to Laos. Genotype 2, previously detected in Europe, was circulating (21% of positive children) in 2 kindergartens (Chompet and Akad). Genotypes 136 and 138 were specific to Chompet (21% and 15.8%, respectively), whereas genotype 139 was specific to Akad (10.55%). Long regarded as a rare bacterium, now we can affirm that T. whipplei is a widely distributed bacterium, highly prevalent in feces including those from children in Vientiane.
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Affiliation(s)
- Alpha Kabinet Keita
- Aix Marseille Université, URMITE, UM63, CNRS 7278, IRD 198, Inserm 1095, Marseille, France
| | - Audrey Dubot-Pérès
- UMR_D 190, Aix Marseille Univ-IRD-EHESP, Medical University, Marseille, France
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, Churchill Hospital, University of Oxford, Oxford, United Kingdom
| | - Koukeo Phommasone
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Bountoy Sibounheuang
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Manivanh Vongsouvath
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Mayfong Mayxay
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, Churchill Hospital, University of Oxford, Oxford, United Kingdom
| | - Didier Raoult
- Aix Marseille Université, URMITE, UM63, CNRS 7278, IRD 198, Inserm 1095, Marseille, France
| | - Paul N. Newton
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, Churchill Hospital, University of Oxford, Oxford, United Kingdom
| | - Florence Fenollar
- Aix Marseille Université, URMITE, UM63, CNRS 7278, IRD 198, Inserm 1095, Marseille, France
- * E-mail:
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8
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Nguyen VH, Sibounheuang B, Phommasone K, Vongsouvath M, Newton PN, Piorkowski G, Baronti C, de Lamballerie X, Dubot-Pérès A. First isolation and genomic characterization of enterovirus A71 and coxsackievirus A16 from hand foot and mouth disease patients in the Lao PDR. New Microbes New Infect 2014; 2:170-2. [PMID: 25566395 PMCID: PMC4265048 DOI: 10.1002/nmi2.63] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 08/07/2014] [Accepted: 08/11/2014] [Indexed: 11/27/2022] Open
Abstract
Enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16) are major aetiological agents of hand,
foot and mouth disease in Asia. We established the first genomic characterization of strains
isolated in 2011 from Lao patients. Isolates were related to EV-A71 genotype C4 and CV-A16 genotype
B1a that circulated in neighbouring countries during the same period. This confirms the regional
character of hand, foot and mouth disease epidemiology and makes plausible the occurrence of severe
disease in the Lao population.
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Affiliation(s)
- V H Nguyen
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health ; IHU Méditerranée Infection, APHM Public Hospitals of Marseille Marseille, France
| | - B Sibounheuang
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital Vientiane, Lao PDR
| | - K Phommasone
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital Vientiane, Lao PDR
| | - M Vongsouvath
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital Vientiane, Lao PDR
| | - P N Newton
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital Vientiane, Lao PDR ; Centre for Tropical Medicine, Nuffield Department of Medicine, Churchill Hospital, University of Oxford Oxford, United Kingdom
| | - G Piorkowski
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health ; IHU Méditerranée Infection, APHM Public Hospitals of Marseille Marseille, France
| | - C Baronti
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health
| | - X de Lamballerie
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health ; IHU Méditerranée Infection, APHM Public Hospitals of Marseille Marseille, France
| | - A Dubot-Pérès
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health ; Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital Vientiane, Lao PDR ; Centre for Tropical Medicine, Nuffield Department of Medicine, Churchill Hospital, University of Oxford Oxford, United Kingdom
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9
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Dubot-Pérès A, Tan CYQ, de Chesse R, Sibounheuang B, Vongsouvath M, Phommasone K, Bessaud M, Gazin C, Thirion L, Phetsouvanh R, Newton PN, de Lamballerie X. SYBR green real-time PCR for the detection of all enterovirus-A71 genogroups. PLoS One 2014; 9:e89963. [PMID: 24651608 PMCID: PMC3961242 DOI: 10.1371/journal.pone.0089963] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 01/21/2014] [Indexed: 11/18/2022] Open
Abstract
Enterovirus A71 (EV-A71) has recently become an important public health threat, especially in South-East Asia, where it has caused massive outbreaks of Hand, Foot and Mouth disease every year, resulting in significant mortality. Rapid detection of EV-A71 early in outbreaks would facilitate implementation of prevention and control measures to limit spread. Real-time RT-PCR is the technique of choice for the rapid diagnosis of EV-A71 infection and several systems have been developed to detect circulating strains. Although eight genogroups have been described globally, none of these PCR techniques detect all eight. We describe, for the first time, a SYBR Green real-time RT-PCR system validated to detect all 8 EV-A71 genogroups. This tool could permit the early detection and shift in genogroup circulation and the standardization of HFMD virological diagnosis, facilitating networking of laboratories working on EV-A71 in different regions.
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Affiliation(s)
- Audrey Dubot-Pérès
- Unité Mixte de Recherche_D 190 “Emergence des Pathologies Virales” (Aix-Marseille University, IRD French Institute of Research for Development, EHESP French School of Public Health), Marseille, France
- Lao-Oxford-Mahosot Hospital–Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
- * E-mail:
| | - Charlene Y. Q. Tan
- Unité Mixte de Recherche_D 190 “Emergence des Pathologies Virales” (Aix-Marseille University, IRD French Institute of Research for Development, EHESP French School of Public Health), Marseille, France
| | - Reine de Chesse
- Unité Mixte de Recherche_D 190 “Emergence des Pathologies Virales” (Aix-Marseille University, IRD French Institute of Research for Development, EHESP French School of Public Health), Marseille, France
| | - Bountoy Sibounheuang
- Lao-Oxford-Mahosot Hospital–Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Manivanh Vongsouvath
- Lao-Oxford-Mahosot Hospital–Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Koukeo Phommasone
- Lao-Oxford-Mahosot Hospital–Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Maël Bessaud
- Unité Mixte de Recherche_D 190 “Emergence des Pathologies Virales” (Aix-Marseille University, IRD French Institute of Research for Development, EHESP French School of Public Health), Marseille, France
| | - Céline Gazin
- Laboratory of Clinical Microbiology, AP-HM Timone, University Hospital Institute for Infectious Disease and Tropical Medicine, Marseille, France
| | - Laurence Thirion
- Unité Mixte de Recherche_D 190 “Emergence des Pathologies Virales” (Aix-Marseille University, IRD French Institute of Research for Development, EHESP French School of Public Health), Marseille, France
| | - Rattanaphone Phetsouvanh
- Lao-Oxford-Mahosot Hospital–Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Paul N. Newton
- Lao-Oxford-Mahosot Hospital–Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Xavier de Lamballerie
- Unité Mixte de Recherche_D 190 “Emergence des Pathologies Virales” (Aix-Marseille University, IRD French Institute of Research for Development, EHESP French School of Public Health), Marseille, France
- Laboratory of Clinical Microbiology, AP-HM Timone, University Hospital Institute for Infectious Disease and Tropical Medicine, Marseille, France
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10
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Phetsouvanh R, Thojaikong T, Phoumin P, Sibounheuang B, Phommasone K, Chansamouth V, Lee SJ, Newton PN, Blacksell SD. Inter- and intra-operator variability in the reading of indirect immunofluorescence assays for the serological diagnosis of scrub typhus and murine typhus. Am J Trop Med Hyg 2013; 88:932-936. [PMID: 23478577 PMCID: PMC3752761 DOI: 10.4269/ajtmh.12-0325] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Inter- and intra-observer variation was examined among six microscopists who read 50 scrub typhus (ST) and murine typhus (MT) indirect immunofluorescence assay (IFA) immunoglobulin M (IgM) slides. Inter-observer agreement was moderate (κ = 0.45) for MT and fair (κ = 0.32) for ST, and was significantly correlated with experience (P = 0.03 and P = 0.004, respectively); κ-scores for intra-observer agreement between morning and afternoon readings (range = 0.35–0.86) were not correlated between years of experience for ST and MT IFAs (Spearman's ρ = 0.31, P = 0.54 and P = 0.14, respectively; P = 0.78). Storage at 4°C for 2 days showed a change from positive to negative in 20–32% of slides. Although the titers did not dramatically change after 14 days of storage, the final interpretation (positive to negative) did change in 36–50% of samples, and it, therefore, recommended that slides should be read as soon as possible after processing.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Stuart D. Blacksell
- *Address correspondence to Stuart D. Blacksell, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Rd., Bangkok 10400, Thailand. E-mail:
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