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1.
Trop Doct ; 52(3): 427-430, 2022 Jul.
Article in English | MEDLINE | ID: mdl-35440256

ABSTRACT

To differentiate cavitary lung lesions caused by melioidosis and tuberculosis is challenging, especially in endemic countries. A study with a matched-sampling method (16 cavitary pulmonary melioidosis vs. 16 cavitary pulmonary tuberculosis) showed characteristics of bacterial infection more obvious and severe in the melioidosis patients, which were useful to distinguish two conditions.


Subject(s)
Bacterial Infections , Lung Diseases , Melioidosis , Tuberculosis, Pulmonary , Humans , Lung Diseases/diagnosis , Lung Diseases/epidemiology , Lung Diseases/microbiology , Melioidosis/diagnosis , Melioidosis/epidemiology , Melioidosis/microbiology , Tuberculosis, Pulmonary/diagnosis , Tuberculosis, Pulmonary/epidemiology
2.
Influenza Other Respir Viruses ; 12(6): 742-754, 2018 11.
Article in English | MEDLINE | ID: mdl-30044029

ABSTRACT

BACKGROUND: In temperate and subtropical climates, respiratory diseases exhibit seasonal peaks in winter. In the tropics, with no winter, peak timings are irregular. METHODS: To obtain a detailed picture of influenza-like illness (ILI) patterns in the tropics, we established an mHealth study in community clinics in Ho Chi Minh City (HCMC). During 2009-2015, clinics reported daily case numbers via SMS, with a subset performing molecular diagnostics for influenza virus. This real-time epidemiology network absorbs 6000 ILI reports annually, one or two orders of magnitude more than typical surveillance systems. A real-time online ILI indicator was developed to inform clinicians of the daily ILI activity in HCMC. RESULTS: From August 2009 to December 2015, 63 clinics were enrolled and 36 920 SMS reports were received, covering approximately 1.7M outpatient visits. Approximately 10.6% of outpatients met the ILI case definition. ILI activity in HCMC exhibited strong nonannual dynamics with a dominant periodicity of 206 days. This was confirmed by time series decomposition, stepwise regression, and a forecasting exercise showing that median forecasting errors are 30%-40% lower when using a 206-day cycle. In ILI patients from whom nasopharyngeal swabs were taken, 31.2% were positive for influenza. There was no correlation between the ILI time series and the time series of influenza, influenza A, or influenza B (all P > 0.15). CONCLUSION: This suggests, for the first time, that a nonannual cycle may be an essential driver of respiratory disease dynamics in the tropics. An immunological interference hypothesis is discussed as a potential underlying mechanism.


Subject(s)
Influenza, Human/epidemiology , Orthomyxoviridae/isolation & purification , Epidemiological Monitoring , Humans , Tropical Climate , Urban Population , Vietnam/epidemiology
3.
PLoS Negl Trop Dis ; 11(4): e0005498, 2017 04.
Article in English | MEDLINE | ID: mdl-28448490

ABSTRACT

BACKGROUND: Dengue is the most important mosquito-borne viral infection to affect humans. Although it usually manifests as a self-limited febrile illness, complications may occur as the fever subsides. A systemic vascular leak syndrome that sometimes progresses to life-threatening hypovolaemic shock is the most serious complication seen in children, typically accompanied by haemoconcentration and thrombocytopenia. Robust evidence on risk factors, especially features present early in the illness course, for progression to dengue shock syndrome (DSS) is lacking. Moreover, the potential value of incorporating serial haematocrit and platelet measurements in prediction models has never been assessed. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed data from a prospective observational study of Vietnamese children aged 5-15 years admitted with clinically suspected dengue to the Hospital for Tropical Diseases in Ho Chi Minh City between 2001 and 2009. The analysis population comprised all children with laboratory-confirmed dengue enrolled between days 1-4 of illness. Logistic regression was the main statistical model for all univariate and multivariable analyses. The prognostic value of daily haematocrit levels and platelet counts were assessed using graphs and separate regression models fitted on each day of illness. Among the 2301 children included in the analysis, 143 (6%) progressed to DSS. Significant baseline risk factors for DSS included a history of vomiting, higher temperature, a palpable liver, and a lower platelet count. Prediction models that included serial daily platelet counts demonstrated better ability to discriminate patients who developed DSS from others, than models based on enrolment information only. However inclusion of daily haematocrit values did not improve prediction of DSS. CONCLUSIONS/SIGNIFICANCE: Daily monitoring of platelet counts is important to help identify patients at high risk of DSS. Development of dynamic prediction models that incorporate signs, symptoms, and daily laboratory measurements, could improve DSS prediction and thereby reduce the burden on health services in endemic areas.


Subject(s)
Platelet Count/methods , Severe Dengue/diagnosis , Severe Dengue/pathology , Adolescent , Asian People , Child , Child, Preschool , Female , Humans , Male , Prognosis , Prospective Studies
4.
PLoS Negl Trop Dis ; 9(2): e0003528, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25680106

ABSTRACT

BACKGROUND: Dengue control programs commonly employ reactive insecticide spraying around houses of reported cases, with the assumption that most dengue virus (DENV) transmission occurs in the home. Focal household transmission has been demonstrated in rural settings, but it is unclear whether this holds true in dense and mobile urban populations. We conducted a prospective study of dengue clustering around households in highly urban Ho Chi Minh City, Vietnam. METHODS: We enrolled 71 index cases with suspected dengue (subsequently classified as 52 dengue cases and 19 non-dengue controls); each initiated the enrollment of a cluster of 25-35 household members and neighbors who were followed up over 14 days. Incident DENV infections in cluster participants were identified by RT-PCR, NS1-ELISA, and/or DENV-IgM/-IgG seroconversion, and recent infections by DENV-IgM positivity at baseline. PRINCIPAL FINDINGS/CONCLUSIONS: There was no excess risk of DENV infection within dengue case clusters during the two-week follow-up, compared to control clusters, but the prevalence of recent DENV infection at baseline was two-fold higher in case clusters than controls (OR 2.3, 95%CI 1.0-5.1, p = 0.05). Prevalence of DENV infection in Aedes aegypti was similar in case and control houses, and low overall (1%). Our findings are broadly consistent with household clustering of dengue risk, but indicate that any clustering is at a short temporal scale rather than sustained chains of localized transmission. This suggests that reactive perifocal insecticide spraying may have a limited impact in this setting.


Subject(s)
Aedes/virology , Dengue/epidemiology , Dengue/transmission , Insect Vectors/virology , Insecticides/administration & dosage , Adolescent , Adult , Animals , Child , Child, Preschool , Cities , Cluster Analysis , Dengue/prevention & control , Dengue Virus/classification , Enzyme-Linked Immunosorbent Assay , Female , Humans , Male , Middle Aged , Prospective Studies , Rural Population , Urban Population , Vietnam/epidemiology , Young Adult
5.
PLoS Negl Trop Dis ; 7(12): e2592, 2013.
Article in English | MEDLINE | ID: mdl-24349598

ABSTRACT

BACKGROUND: Dysregulated immune responses may contribute to the clinical complications that occur in some patients with dengue. FINDINGS: In Vietnamese pediatric dengue cases randomized to early prednisolone therapy, 81 gene-transcripts (0.2% of the 47,231 evaluated) were differentially abundant in whole-blood between high-dose (2 mg/kg) prednisolone and placebo-treated patients two days after commencing therapy. Prominent among the 81 transcripts were those associated with T and NK cell cytolytic functions. Additionally, prednisolone therapy was not associated with changes in plasma cytokine levels. CONCLUSION: The inability of prednisolone treatment to markedly attenuate the host immune response is instructive for planning future therapeutic strategies for dengue.


Subject(s)
Dengue/drug therapy , Immunologic Factors/therapeutic use , Prednisolone/therapeutic use , Adolescent , Child , Child, Preschool , Cytokines/blood , Female , Gene Expression Profiling , Humans , Immunomodulation , Killer Cells, Natural/immunology , Male , Placebos/administration & dosage , T-Lymphocytes, Cytotoxic/immunology , Treatment Failure , Vietnam , Young Adult
6.
PLoS One ; 8(1): e54538, 2013.
Article in English | MEDLINE | ID: mdl-23349922

ABSTRACT

BACKGROUND: Dengue is the most important arboviral infection of humans. Following an initial febrile period, a small proportion of infected patients develop a vasculopathy, with children at particular risk for severe vascular leakage and shock. Differentiation between dengue and other common childhood illnesses is difficult during the early febrile phase, and risk prediction for development of shock is poor. The presence of microalbuminuria is recognized as a useful early predictor for subsequent complications in a number of other disorders with vascular involvement. Significant proteinuria occurs in association with dengue shock syndrome and it is possible that early-phase microalbuminuria may be helpful both for diagnosis of dengue and for identification of patients likely to develop severe disease. METHODOLOGY/PRINCIPAL FINDINGS: We measured formal urine albumin to creatinine ratios (UACRs) in daily samples obtained from a large cohort of children with suspected dengue recruited at two outpatient clinics in Ho Chi Minh City, Vietnam. Although UACRs were increased in the 465 confirmed dengue patients, with a significant time trend showing peak values around the critical period for dengue-associated plasma leakage, urine albumin excretion was also increased in the comparison group of 391 patients with other febrile illnesses (OFI). The dengue patients generally had higher UACRs than the OFI patients, but microalbuminuria, using the conventional cutoff of 30 mg albumin/g creatinine discriminated poorly between the two diagnostic groups in the early febrile phase. Secondly UACRs did not prove useful in predicting either development of warning signs for severe dengue or need for hospitalization. CONCLUSION/SIGNIFICANCE: Low-level albuminuria is common, even in relatively mild dengue infections, but is also present in many OFIs. Simple point-of-care UACR tests are unlikely to be useful for early diagnosis or risk prediction in dengue endemic areas.


Subject(s)
Albumins/analysis , Albuminuria/diagnosis , Dengue/diagnosis , Dengue/urine , Adult , Child , Child, Preschool , Creatinine/urine , Dengue/epidemiology , Dengue/physiopathology , Dengue Virus/pathogenicity , Early Diagnosis , Female , Fever , Humans , Male , Vietnam/epidemiology
7.
Am J Trop Med Hyg ; 87(1): 165-170, 2012 Jul.
Article in English | MEDLINE | ID: mdl-22764309

ABSTRACT

Non-invasive specimens for dengue diagnosis may be preferable where venous blood is difficult to collect and/or process, such as community-based or remote settings or when sampling from young children. We evaluated the performance of oral swabs and dried blood spots (DBS), compared with plasma, in diagnosing acute dengue and screening for past dengue virus (DENV) exposure. DENV-specific immunoglobulin (Ig) M, IgG, and NS1 antigen were detected both in oral swabs and DBS from acute patients. Oral swabs were less sensitive (IgM: 68.7%, IgG: 91.9%, NS1: 64.7%), but retained good specificity (100%, 92.3%, 95.8%, respectively) compared with plasma. DBS displayed high sensitivity (IgM: 100%, IgG: 96%, NS1: 100%) and specificity (IgM: 75%, IgG: 93%). DENV RNA was amplified from DBS (sensitivity 95.6%) but not from oral swabs. DENV-IgG (indicative of past flavivirus exposure) were detected with moderate sensitivity (61.1%) but poor specificity (50%) in oral swabs from healthy volunteers. Dried blood spots allow sensitive and specific diagnosis of acute dengue by serological, molecular, and antigen detection methods. Oral swabs may be an adequate alternative where blood cannot be collected.


Subject(s)
Blood , Dengue/diagnosis , Saliva , Dengue Virus/genetics , Humans , RNA, Viral/blood
8.
PLoS Negl Trop Dis ; 6(6): e1679, 2012.
Article in English | MEDLINE | ID: mdl-22745839

ABSTRACT

BACKGROUND: As dengue spreads to new geographical regions and the force of infection changes in existing endemic areas, a greater breadth of clinical presentations is being recognised. Clinical experience suggests that adults manifest a pattern of complications different from those observed in children, but few reports have described the age-related spectrum of disease in contemporaneous groups of patients recruited at the same geographical location. METHODOLOGY/PRINCIPAL FINDINGS: Using detailed prospectively collected information from ongoing studies that encompass the full spectrum of hospitalised dengue cases admitted to a single hospital in southern Vietnam, we compared clinical and laboratory features, management, and outcome for 647 adults and 881 children with confirmed dengue. Signs of vascular leakage and shock were more frequent and more severe in children than adults, while bleeding manifestations and organ involvement were more common in adults. Additionally, adults experienced significantly more severe thrombocytopenia. Secondary infection but not serotype was independently associated with greater thrombocytopenia, although with a smaller effect than age-group. The effect of age-group on platelet count was also apparent in the values obtained several weeks after recovery, indicating that healthy adults have intrinsically lower counts compared to children. CONCLUSIONS/SIGNIFICANCE: There are clear distinctions between adults and children in the pattern of complications seen in association with dengue infection, and these depend partly on intrinsic age-dependent physiological differences. Knowledge of such differences is important to inform research on disease pathogenesis, as well as to encourage development of management guidelines that are appropriate to the age-groups at risk.


Subject(s)
Dengue/complications , Dengue/pathology , Hemorrhage/epidemiology , Thrombocytopenia/epidemiology , Adolescent , Adult , Age Factors , Child , Child, Preschool , Dengue/epidemiology , Female , Hospitals , Humans , Infant , Male , Prospective Studies , Risk Assessment , Vietnam/epidemiology , Young Adult
9.
J Immunol ; 184(12): 7281-7, 2010 Jun 15.
Article in English | MEDLINE | ID: mdl-20483770

ABSTRACT

Immune activation is a feature of dengue hemorrhagic fever (DHF) and CD8+ T cell responses in particular have been suggested as having a role in the vasculopathy that characterizes this disease. By phenotyping CD8+ T cells (CD38+/HLA-DR+, CD38+/Ki-67+, or HLA-DR+/Ki-67+) in serial blood samples from children with dengue, we found no evidence of increased CD8+ T cell activation prior to the commencement of resolution of viremia or hemoconcentration. Investigations with MHC class I tetramers to detect NS3(133-142)-specific CD8+ T cells in two independent cohorts of children suggested the commencement of hemoconcentration and thrombocytopenia in DHF patients generally begins before the appearance of measurable frequencies of NS3(133-142)-specific CD8+ T cells. The temporal mismatch between the appearance of measurable surface activated or NS3(133-142)-specific CD8+ T cells suggests that these cells are sequestered at sites of infection, have phenotypes not detected by our approach, or that other mechanisms independent of CD8+ T cells are responsible for early triggering of capillary leakage in children with DHF.


Subject(s)
CD8-Positive T-Lymphocytes/immunology , Capillary Permeability/immunology , Severe Dengue/immunology , Adolescent , Cell Separation , Child , Child, Preschool , Enzyme-Linked Immunosorbent Assay , Female , Flow Cytometry , Histocompatibility Antigens Class I/immunology , Humans , Lymphocyte Activation/immunology , Male , RNA Helicases/immunology , Reverse Transcriptase Polymerase Chain Reaction , Serine Endopeptidases/immunology , Severe Dengue/pathology , Viral Nonstructural Proteins/immunology
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