Koukeo Phommasone

Murine typhus, caused by Rickettsia typhi , is a globally distributed flea-borne disease. Antimicrobial susceptibility data are largely based on reference strains, with little evaluation of variability across clinical isolates. The plaque assay, the gold standard for antibiotic susceptibility testing, requires up to 14 days to complete. Quantitative real-time PCR (qPCR) offers a rapid alternative for determining minimum inhibitory concentrations (MICs). Although qPCR-based susceptibility testing has been described, formal statistical assessment of agreement between methods remains limited. We estimated the MICs for azithromycin, doxycycline, and amoxicillin using qPCR and plaque assay on 24 R. typhi isolates (8 laboratory strains and 16 Lao clinical isolates) cultured in Vero cells. Heat-inactivated R. typh i (56°C, 30 min) served as a control. MIC was defined as the lowest concentration preventing plaque formation (plaque assay) or producing a Ct value greater than or equal to that of the heat-inactivated sample (qPCR). The mean MIC from three independent experiments was taken to represent each isolate. Agreement between methods was assessed using Bland-Altman analysis. Median qPCR MICs (MIC ₅₀ ) of all isolates were 0.130 mg/L (IQR, 0.104–0.240 mg/L) for azithromycin, 0.130 mg/L (IQR, 0.065–0.224 mg/L) for doxycycline, and 256 mg/L (IQR, 234.7–341.3 mg/L) for amoxicillin. Corresponding plaque assay MICs ₅₀ were 0.383 mg/L (IQR, 0.194–0.807 mg/L), 0.037 mg/L (IQR, 0.026–0.073 mg/L), and 170.7 mg/L (IQR, 112–256 mg/L), respectively. Bias was −0.3452 (−1.146, 0.4558) for azithromycin, 0.0969 (−0.2297, 0.4235) for doxycycline, and 85.33 (−187.3, 358) for amoxicillin. These findings demonstrate inter-isolate variability and quantitative agreement between methods. IMPORTANCE: Murine typhus is a treatable febrile illness caused by Rickettsia typhi , transmitted to humans via fleas. The plaque assay, which detects bacterial-induced host cell death in the presence or absence of antibiotics, is the reference method for testing drug susceptibility. However, the method requires approximately 2 weeks to obtain results. Detection of bacterial nucleic acid provides an alternative laboratory approach that reduces the assay duration to approximately 1 week, thereby improving research efficiency and throughput when testing multiple isolates. Compared with plaque assays, quantitative real-time PCR allows downstream analysis following sample inactivation, reducing prolonged high-containment handling. In this study, we compared the antibiotic susceptibility of 24 R. typhi isolates using both methods. We tested antibiotics commonly used to treat R. typhi infection (doxycycline and azithromycin), along with amoxicillin as a negative control. Both showed comparable results for all antibiotics tested, further supporting nucleic acid detection as a reliable and faster alternative.

Objectives Thalassaemia, a genetic blood disorder, is a major public health burden. Most affected individuals reside in low-and-middle-income countries (LMICs). Screening programmes can reduce incidence, but in resource-constrained settings cost-effectiveness is important. This work aimed to investigate how economic evaluations of thalassaemia screening programmes have been conducted globally, to identify best practices for future evaluation suited to a LMIC context. Design Systematic literature review. Data sources The original review was undertaken between May and July 2023; an update was completed between November and December 2025. Electronic databases (MEDLINE, Embase, National Health Service Economic Evaluation Database, Health Technology Assessment Database, Cochrane Database of Systematic Reviews), economic databases (Cost-Effectiveness Analysis Registry) and grey literature (including conference proceedings) were searched. Additional validation searches were conducted in Google Scholar to identify relevant studies not indexed in the electronic databases. Eligibility criteria Studies were screened against pre-specified criteria by two independent reviewers. Eligible articles reported an economic evaluation of a thalassaemia screening programme for pregnant women or children aged 2 years or younger in any geographic setting. Data extraction and synthesis Data extraction for each included article was performed by one author and verified by a second. Findings were interpreted within the context of LMICs, given the high prevalence and resource limitations in these settings. The quality of each article was assessed using the Critical Appraisal Skills Programme Economic Evaluation Checklist; quality assessment for each article was performed by one author and verified by a second. Results Of 2112 publications identified from database searches, ten were ultimately included: three cost-effectiveness analyses (CEAs), six cost-benefit analyses (CBAs) and one cost-utility analysis. Study quality varied widely, with most not reporting methodological details such as discounting rates and time horizon. Additionally, no studies employed standard cost-effectiveness metrics, such as quality-adjusted life-years. Seven studies adopted simplified approaches to evaluating thalassaemia screening programmes, relying on basic cost comparisons without formal modelling. Three studies used a decision tree model structure based on the chronological sequence of steps during the screening process. Of these, two Thailand-based studies were notable, given their robust decision tree model, explicit adoption of a lifetime time horizon, application of a discounting rate in line with Thai Health Technology Assessment Guidelines, and performance of sensitivity analyses using recognised methods. Conclusions The frequent use of simple cost comparisons likely reflects the complexities surrounding modelling of thalassaemia screening programmes. While traditional CEAs are predominantly used in cost-effectiveness research, practical and ethical challenges associated with calculating health utility differences in this context may limit their use. However, the absence of standard metrics does not preclude a robust economic evaluation, as evidenced by the two high-quality Thailand-based studies. The methods outlined in these papers can be used as a starting point for future economic evaluations, provided the evaluation is further tailored to the local setting. If development of a model is not possible, a simpler CBA with a robust, comprehensive approach could be used. In any case, it is vital to capture the societal benefits of screening programmes; any future evaluation within this context should therefore include a broad societal perspective. PROSPERO registration number CRD42023445001.

We used 2492 whole genome sequences from Laos to investigate the molecular epidemiology of SARS-CoV-2 from 2021 through 2024, covering the major waves of COVID-19 disease in Laos including time periods of travel restrictions and after relaxation of travel across international borders. We identify successive waves of COVID-19 caused by shifts in the dominant lineage, beginning with the Alpha variant in April 2021 and continuing through the Delta and Omicron variants. We quantify a shift from a small number of viral introductions responsible for widespread transmission in early waves to a larger number of introductions for each variant after travel restrictions were lifted, and identify potential routes of introduction into the country. Our study underscores the importance of genomic surveillance to public health responses to characterize viral transmission dynamics during pandemics.

Introduction: In many low- and middle-income countries, there is widespread use of point-of-care tests (POCTs) to diagnose a variety of infectious diseases, even in hospitals due to weak laboratory capacity. Often, POCT use is unregulated and expensive while the use of substandard tests is common. A cost-effectiveness analysis was conducted to investigate which POCTs for non-malarial febrile illness (NMFI) represent the best use of resources in Lao PDR in outpatient settings, assuming best-in-class POCTs are used. Methods: A decision-tree cost-effectiveness analysis was conducted to simulate use of POCTs of interest for outpatients presenting with NMFI, compared to clinical assessment alone. The analyses were performed from both healthcare provider’s perspective and a limited societal perspective, which included cost estimates of the contribution of antibiotic consumption by class to future AMR costs. Deterministic and probabilistic analyses were performed. Results: In probabilistic and deterministic analyses, dengue and rickettsia POCTs were consistently cost-effective and the most cost-effective of the four POCTs evaluated. Deterministic analyses estimated that typhoid and leptospirosis POCTs were cost-effective compared with clinical assessment alone. However, in probabilistic analyses, clinical assessment was more likely to be cost-effective than typhoid or leptospirosis POCTs at the estimated cost-effectiveness threshold in the Lao PDR. Conclusions: This evaluation was able to make use of comprehensive primary data from fever studies in Lao PDR, giving an understanding of the aetiology and prescribing behaviour of physicians for undifferentiated NMFI. However, sensitivity analyses showed that there was substantial uncertainty about which strategy would be most cost-effective and if substandard POCTs were analysed then it is more likely that clinical assessment alone would be the most cost-effective strategy. This research shows that there is good reason to be cautious about the overuse of POCTs for NMFI and whether they represent good value for money in low-income contexts compared with clinical assessment alone.

Murine typhus, caused by infection with Rickettsia typhi , is a neglected disease contributing to infectious disease burden in south- and southeast Asia. Despite its importance, we have minimal knowledge of the genomics of R. typhi , with only four complete genomes being sequenced prior to this work. We sequenced a further 25 genomes including historical strains collected before 1976 from both human and rat hosts, and recent genomes isolated from patients at a single hospital in Laos. Whole genome SNP analysis reveals extremely low levels of genetic diversity across the 29 genomes, with overall nucleotide diversity (π) of 1.27e ^-05 and evidence of purifying selection, and a minimal pan-genome. Phylogenetic analysis shows clustering of the genome by historic or modern origin, with the exception of one modern strain which is most closely related to historic strains from Thailand, and no clustering by host origin. The highly conserved genome of R. typhi suggests strong constraints on genome evolution in this obligate intracellular parasite, and has implications for the design of future murine typhus diagnostic tools and vaccines.

Intensive care unit registries, which aim to improve the quality of intensive care unit care through benchmarking and quality improvement initiatives, are active worldwide, with considerable dishomogeneity. We aimed to map core datasets, additional variables, and research activities of these registries. A cross-sectional survey was disseminated to registry leads between October 2023 and June 2024. The survey was structured into four main topics: registry characteristics and coverage, core dataset features, additional modules, and registry-enabled research. Leads of 34/42 national registries responded (response rate 81%), covering 3,337 intensive care units, with a larger representation from South America. Systematized nomenclature of medicine, clinical terms, and customized categorical classifications were the main nomenclatures used. All registries except one employed a severity of illness score/risk prediction model. The SOFA score was reported by 88% of registries. Organ support measures were often recorded, including mechanical ventilation (97%), vasopressor administration (86%) and renal replacement therapy (86%). Three out of four intensive care unit registries coded interventions such as intubations, intravenous lines and tracheostomies. Additional datasets differed, with many use cases for nosocomial infection burden, bed availability and staffing resources. Over half of intensive care unit registries had current structured quality improvement initiatives. Registry-enabled observational research was reported in 46% of registries, while interventional studies were reported in only 22%. Over three thousand intensive care units in 35 countries participate in an intensive care unit registry. Despite heterogeneity in coding systems, risk models, and additional datasets, we identify several areas of convergence that may inform a future shared core dataset. There is potential for further intensive care unit registry-based research, particularly interventional.

Background: Lao PDR reported a low number of confirmed SARS-CoV-2 cases until the introduction of COVID-19 vaccines in April 2021. This raised doubts about whether the reported number reflected the true situation and questioned about possible pre-existing immunity against SARS-CoV-2. Methods: We retrospectively analyzed leftover blood donor samples collected in 2003–2004, 2015, and 2018 in Vientiane Capital, as well as samples collected in 2020 and between February and August 2021 across 18 provinces in Lao PDR to better understand the epidemiology of the infection. The samples were first screened using an anti-SARS-CoV-2 IgG ELISA (Euroimmun). The presence of anti-SARS-CoV-2 antibodies was then confirmed or refuted by testing positive and equivocal samples using anti-SARS-CoV-2 IgG CLIA (Beckman Coulter) targeting anti-Spike antibodies and SARS-CoV-2 virus neutralization test. Results: All pre-pandemic sera from Vientiane capital (79 in 2003−2004, 406 in 2015 and 191 in 2018), and all 2,225 sera collected in 2020 from eight provinces, tested negative. A total of 3,663 sera were collected prospectively in 2021 from 14 provinces. Bokeo and Oudomxay had the highest prevalence, each at 19.8%, followed by Luang Namtha at 16.1% and Salavan at 15.5%. However, the majority of samples collected from those four provinces were obtained after the outbreak surge and the introduction of COVID-19 vaccines in mid-April. Conclusion: There was no evidence of cross-reactive neutralizing antibodies prior to the COVID-19 pandemic and the seroprevalence of SARS-CoV-2 was confirmed to be low in Lao PDR before the introduction of COVID-19 vaccines and the surge in infections from May 2021.

Murine typhus, caused by infection with Rickettsia typhi , is a neglected disease contributing to infectious disease burden in south- and southeast Asia. Despite its importance, we have minimal knowledge of the genomics of R. typhi , with only four complete genomes being sequenced prior to this work. We sequenced a further 25 genomes including historical strains collected before 1976 from both human and rat hosts, and recent genomes isolated from patients at a single hospital in Laos. Whole genome SNP analysis reveals extremely low levels of genetic diversity across the 29 genomes, with overall nucleotide diversity (π) of 1.27e ⁻⁰⁵ and evidence of purifying selection, and a minimal pan-genome. Phylogenetic analysis shows clustering of the genome by historic or modern origin, with the exception of one modern strain which is most closely related to historic strains from Thailand, and no clustering by host origin. The highly conserved genome of R. typhi suggests strong constraints on genome evolution in this obligate intracellular parasite, and has implications for the design of future murine typhus diagnostic tools and vaccines. Impact Statement: Rickettsia typhi is the causative agent of murine typhus, an infectious disease that causes morbidity and mortality in humans. This study has expanded the genomic dataset from a small number of genomes to a comprehensive collection of 29 complete genomes. The genome comparison includes historic and modern strains and reveals a clonal population structure with minimal genetic diversity across time. This shows the evolutionary stability of R. typhi , which is most likely due to strong purifying selection and an intracellular lifestyle. This extremely low genomic variation has significant impacts for the development of murine typhus vaccines and robust diagnostic assays.

With the advent of highly sensitive real-time PCR, multiple pathogens have been identified from nasopharyngeal swabs of patients with acute respiratory infections (ARIs). However, the detection of microorganisms in the upper respiratory tract does not necessarily indicate disease causation. We conducted a matched case–control study, nested within a broader fever aetiology project, to facilitate determination of the aetiology of ARIs in hospitalised patients in Northeastern Laos. Consenting febrile patients of any age admitted to Xiengkhuang Provincial Hospital were included if they met the inclusion criteria for ARI presentation (at least one of the following: cough, rhinorrhoea, nasal congestion, sore throat, difficulty breathing, and/or abnormal chest auscultation). One healthy control for each patient, matched by sex, age, and village of residence, was recruited for the study. Nasopharyngeal swabs were collected from participants and tested for 33 pathogens by probe-based multiplex real-time RT-PCR (FastTrack Diagnostics Respiratory pathogen 33 kit). Attributable fraction of illness for a given microorganism was calculated by comparing results between patients and controls (= 100 * [OR − 1]/OR) (OR = odds ratio). Between 24th June 2019 and 24th June 2020, 205 consenting ARI patients and 205 matching controls were recruited. After excluding eight pairs due to age mismatch, 197 pairs were included in the analysis. Males were predominant with sex ratio 1.2:1 and children < 5 years old accounted for 59% of participants. At least one potential pathogen was detected in 173 (88%) patients and 175 (89%) controls. ARI in admitted patients were attributed to influenza B virus, influenza A virus, human metapneumovirus (HMPV), and respiratory syncytial virus (RSV) in 17.8%, 17.2%, 7.5%, and 6.5% of participants, respectively. SARS-CoV-2 was not detected in any cases or controls. Determining ARI aetiology in individual patients remains challenging. Among hospitalised patients with ARI symptoms presenting to a provincial hospital in Northeastern Laos, half were determined to be caused by one of several respiratory viruses, in particular influenza A virus, influenza B virus, HMPV, and RSV.

Background: Although Southeast Asia is one of the most leptospirosis afflicted regions, little is known about the diversity and molecular epidemiology of the causative agents of this widespread and emerging zoonotic disease. Methodology/Principal findings: We used whole genome sequencing to examine genetic variation in 75 Leptospira strains isolated from patients in the Lao PDR (Laos) between 2006 and 2017. Eleven serogroups from 4 Leptospira species and 43 cgMLST-defined clonal groups (CGs) were identified. The most prevalent CG was CG272 (n = 18, 26.8%), composed of L. interrogans serogroup Autumnalis isolates. This genotype was recovered throughout the 12-year period and was associated with deaths, and with a large outbreak in neighbouring Thailand. Genome analysis reveals that the CG272 strains form a highly clonal group of strains that have, for yet unknown reasons, recently spread in Laos and Thailand. Additionally, accessory genes clearly discriminate CG272 strains from the other Leptospira strains. Conclusions/Significance: The present study reveals a high diversity of Leptospira genotypes in Laos, thus extending our current knowledge of the pan- and core-genomes of these life-threatening pathogens. Our results demonstrate that the CG272 strains belong to a unique clonal group, which probably evolved through clonal expansion following niche adaptation. Additional epidemiological studies are required to better evaluate the spread of this genotype in Southeast Asia. To further investigate the key factors driving the virulence and spread of these pathogens, more intense genomic surveillance is needed, combining detailed clinical and epidemiological data.