METHODOLOGY/PRINCIPAL FINDINGS: We performed a literature review, whole genome sequencing on 145 GBS isolates collected from six Southeast Asian countries, and phylogenetic analysis on 7,468 GBS sequences including 227 variants of ST283 from humans and animals. Although almost absent outside Asia, ST283 was found in all invasive Asian collections analysed, from 1995 to 2017. It accounted for 29/38 (76%) human isolates in Lao PDR, 102/139 (73%) in Thailand, 4/13 (31%) in Vietnam, and 167/739 (23%) in Singapore. ST283 and its variants were found in 62/62 (100%) tilapia from 14 outbreak sites in Malaysia and Vietnam, in seven fish species in Singapore markets, and a diseased frog in China.
CONCLUSIONS: GBS ST283 is widespread in Southeast Asia, where it accounts for a large proportion of bacteraemic GBS, and causes disease and economic loss in aquaculture. If human ST283 is fishborne, as in the Singapore outbreak, then GBS sepsis in Thailand and Lao PDR is predominantly a foodborne disease. However, whether transmission is from aquaculture to humans, or vice versa, or involves an unidentified reservoir remains unknown. Creation of cross-border collaborations in human and animal health are needed to complete the epidemiological picture.
METHODOLOGY/PRINCIPAL FINDINGS: Photos of urine samples were taken in a customized photo booth, then processed using Adobe Photoshop to index urine colour into the red, green, and blue (RGB) colour space and assigned a unique RGB value. The RGB values were then correlated with patients' clinical and laboratory hydration indices using Pearson's correlation and multiple linear regression. There were strong correlations between urine osmolality and the RGB of urine colour, with r = -0.701 (red), r = -0.741 (green), and r = -0.761 (blue) (all p-value <0.05). There were strong correlations between urine specific gravity and the RGB of urine colour, with r = -0.759 (red), r = -0.785 (green), and r = -0.820 (blue) (all p-value <0.05). The blue component had the highest correlations with urine specific gravity and urine osmolality. There were moderate correlations between RGB components and serum urea, at r = -0.338 (red), -0.329 (green), -0.360 (blue). In terms of urine biochemical parameters linked to dehydration, multiple linear regression studies showed that the green colourimetry code was predictive of urine osmolality (β coefficient -0.082, p-value <0.001) while the blue colourimetry code was predictive of urine specific gravity (β coefficient -2,946.255, p-value 0.007).
CONCLUSIONS/SIGNIFICANCE: Urine colourimetry using mobile phones was highly correlated with the hydration status of dengue patients, making it a potentially useful hydration status tool.
METHODOLOGY/PRINCIPLE FINDINGS: Here we report on the distribution of B. pseudomallei sequence types (STs) in Malaysia and how the STs are related to STs globally. We obtained 84 culture-confirmed B. pseudomallei from confirmed septicaemic melioidosis patients from all over Malaysia. Prior to performing Multi Locus Sequence Typing, the isolates were subjected to antimicrobial susceptibility testing and detection of the YLF/BTFC genes and BimA allele. Up to 90.5% of the isolates were sensitive to all antimicrobials tested while resistance was observed for antimicrobials typically administered during the eradication stage of treatment. YLF gene cluster and bimABp allele variant were detected in all the isolates. The epidemiological distribution patterns of the Malaysian B. pseudomallei isolates were analysed in silico using phylogenetic tools and compared to Southeast Asian and world-wide isolates. Genotyping of the 84 Malaysian B. pseudomallei isolates revealed 29 different STs of which 6 (7.1%) were novel. ST50 was identified as the group founder followed by subgroup founders ST376, ST211 and ST84. A low-level diversity is noted for the B. pseudomallei isolates described in this study while phylogenetic analysis associated the Malaysian STs to Southeast Asian isolates especially isolates from Thailand. Further analysis also showed a strong association that implicates agriculture and domestication activities as high-risk routes of infection.
CONCLUSIONS/SIGNIFICANCE: In conclusion, MLST analysis of B. pseudomallei clinical isolates from all states in Malaysia revealed low diversity and a close association to Southeast Asian isolates.
METHODS: A decision-analytic Markov model was developed to simulate the impact of S. suis infection and its major complications: death, meningitis and infective endocarditis among Thai people in 2019 with starting age of 51 years. Transition probabilities, and inputs pertaining to costs, utilities and productivity impairment associated with long-term complications were derived from published sources. A lifetime time horizon with follow-up until death or age 100 years was adopted. The simulation was repeated assuming that the cohort had not been infected with S.suis. The differences between the two set of model outputs in years of life, QALYs, and PALYs lived reflected the impact of S.suis infection. An annual discount rate of 3% was applied to both costs and outcomes. One-way sensitivity analyses and Monte Carlo simulation modeling technique using 10,000 iterations were performed to assess the impact of uncertainty in the model.
KEY RESULTS: This cohort incurred 769 (95% uncertainty interval [UI]: 695 to 841) years of life lost (14% of predicted years of life lived if infection had not occurred), 826 (95% UI: 588 to 1,098) QALYs lost (21%) and 793 (95%UI: 717 to 867) PALYs (15%) lost. These equated to an average of 2.46 years of life, 2.64 QALYs and 2.54 PALYs lost per person. The loss in PALYs was associated with a loss of 346 (95% UI: 240 to 461) million Thai baht (US$11.3 million) in GDP, which equated to 1.1 million Thai baht (US$ 36,033) lost per person.
CONCLUSIONS: S.suis infection imposes a significant economic burden both in terms of health and productivity. Further research to investigate the effectiveness of public health awareness programs and disease control interventions should be mandated to provide a clearer picture for decision making in public health strategies and resource allocations.
METHODS: A high-throughput LAMP assay targeting a P. vivax mitochondrial gene and deploying colorimetric detection in a 96-well plate format was developed and evaluated in the laboratory. Diagnostic accuracy was compared against microscopy, antigen detection tests and PCR and validated in samples from malaria patients and community controls in a district hospital setting in Sabah, Malaysia.
RESULTS: The high throughput LAMP-P. vivax assay (HtLAMP-Pv) performed with an estimated limit of detection of 1.4 parasites/ μL. Assay primers demonstrated cross-reactivity with P. knowlesi but not with other Plasmodium spp. Field testing of HtLAMP-Pv was conducted using 149 samples from symptomatic malaria patients (64 P. vivax, 17 P. falciparum, 56 P. knowlesi, 7 P. malariae, 1 mixed P. knowlesi/P. vivax, with 4 excluded). When compared against multiplex PCR, HtLAMP-Pv demonstrated a sensitivity for P. vivax of 95% (95% CI 87-99%); 61/64), and specificity of 100% (95% CI 86-100%); 25/25) when P. knowlesi samples were excluded. HtLAMP-Pv testing of 112 samples from asymptomatic community controls, 7 of which had submicroscopic P. vivax infections by PCR, showed a sensitivity of 71% (95% CI 29-96%; 5/7) and specificity of 93% (95% CI87-97%; 98/105).
CONCLUSION: This novel HtLAMP-P. vivax assay has the potential to be a useful field applicable molecular diagnostic test for P. vivax infection in elimination settings.
METHODS: Over six months in 2018, we recruited 368 adults who met the WHO 2009 criteria for probable dengue infection. They underwent the following blood tests: full blood count, dengue virus (DENV) rapid diagnostic test (RDT), ELISA (dengue IgM and IgG), nested RT-PCR for dengue, multiplex qRT-PCR for Zika, Chikungunya and dengue as well as PCR tests for Leptopspira spp., Japanese encephalitis and West Nile virus.
RESULTS: Laboratory-confirmed dengue infections (defined by positive tests in NS1, IgM, high-titre IgG or nested RT-PCR) were found in 167 (45.4%) patients. Of these 167 dengue patients, only 104 (62.3%) were positive on rapid diagnostic testing. Dengue infection was significantly associated with the following features: family or neighbours with dengue in the past week (AOR: 3.59, 95% CI:2.14-6.00, p<0.001), cutaneous rash (AOR: 3.58, 95% CI:1.77-7.23, p<0.001), increased temperature (AOR: 1.33, 95% CI:1.04-1.70, p = 0.021), leucopenia (white cell count < 4,000/μL) (AOR: 3.44, 95% CI:1.72-6.89, p<0.001) and thrombocytopenia (platelet count <150,000/μL)(AOR: 4.63, 95% CI:2.33-9.21, p<0.001). Dengue infection was negatively associated with runny nose (AOR: 0.47, 95% CI:0.29-0.78, p = 0.003) and arthralgia (AOR: 0.42, 95% CI:0.24-0.75, p = 0.004). Serotyping by nested RT-PCR revealed mostly mono-infections with DENV-2 (n = 64), DENV-1 (n = 32) and DENV-3 (n = 17); 14 co-infections occurred with DENV-1/DENV-2 (n = 13) and DENV-1/DENV-4 (n = 1). Besides dengue, none of the pathogens above were found in patients' serum.
CONCLUSIONS: Acute undifferentiated febrile infections are a diagnostic challenge for community-based clinicians. Rapid diagnostic tests are increasingly used to diagnose dengue infection but negative tests should be interpreted with caution as they fail to detect a considerable proportion of dengue infection. Certain clinical features and haematological parameters are important in the clinical diagnosis of dengue infection.
METHODS: We determined the ability of B. pseudomallei to invade and survive intracellularly in A549 human lung epithelial cells, and also investigated the early transcriptional responses using an Illumina HumanHT-12 v4 microarray platform, after three hours of exposure to live B. pseudomallei (BCMS) and its secreted proteins (CCMS).
RESULTS: We found that the ability of B. pseudomallei to invade and survive intracellularly correlated with increase of multiplicity of infection and duration of contact. Activation of host carbohydrate metabolism and apoptosis as well as suppression of amino acid metabolism and innate immune responses both by live bacteria and its secreted proteins were evident. These early events might be linked to initial activation of host genes directed towards bacterial dissemination from lungs to target organs (via proposed in vivo mechanisms) or to escape potential sensing by macrophages.
CONCLUSION: Understanding the early responses of A549 cells toward B. pseudomallei infection provide preliminary insights into the likely pathogenesis mechanisms underlying melioidosis, and could contribute to development of novel intervention strategies to combat B. pseudomallei infections.
METHODS: We used transmission electron microscopy (TEM) to investigate post-mortem tissue sections of patients with clinical melioidosis to identify the localisation of a recently identified gut microbiome, B. pseudomallei within host cells. The intranuclear presence of B. pseudomallei was confirmed using transmission electron microscopy (TEM) of experimentally infected guinea pig spleen tissues and Live Z-stack, and ImageJ analysis of fluorescence microscopy analysis of in vitro infection of A549 human lung epithelial cells.
RESULTS: TEM investigations revealed intranuclear localization of B. pseudomallei in cells of infected human lung and guinea pig spleen tissues. We also found that B. pseudomallei induced actin polymerization following infection of A549 human lung epithelial cells. Infected A549 lung epithelial cells using 3D-Laser scanning confocal microscopy (LSCM) and immunofluorescence microscopy confirmed the intranuclear localization of B. pseudomallei.
CONCLUSION: B. pseudomallei was found within the nuclear compartment of host cells. The nucleus may play a role as an occult or transient niche for persistence of intracellular pathogens, potentially leading to recurrrent episodes or recrudescence of infection.
METHODOLOGY/PRINCIPAL FINDINGS: We used 13 nuclear microsatellite loci (on 911 individuals) and mitochondrial COI sequences to gain a better understanding of the historical and contemporary movements of Ae. albopictus in the Indo-Pacific region and to characterize its population structure. Approximate Bayesian computation (ABC) was employed to test competing historical routes of invasion of Ae. albopictus within the Southeast (SE) Asian/Australasian region. Our ABC results show that Ae. albopictus was most likely introduced to New Guinea via mainland Southeast Asia, before colonizing the Solomon Islands via either Papua New Guinea or SE Asia. The analysis also supported that the recent incursion into northern Australia's Torres Strait Islands was seeded chiefly from Indonesia. For the first time documented in this invasive species, we provide evidence of a recently colonized population (the Torres Strait Islands) that has undergone rapid temporal changes in its genetic makeup, which could be the result of genetic drift or represent a secondary invasion from an unknown source.
CONCLUSIONS/SIGNIFICANCE: There appears to be high spatial genetic structure and high gene flow between some geographically distant populations. The species' genetic structure in the region tends to favour a dispersal pattern driven mostly by human movements. Importantly, this study provides a more widespread sampling distribution of the species' native range, revealing more spatial population structure than previously shown. Additionally, we present the most probable invasion history of this species in the Australasian region using ABC analysis.