Dao Huy Manh

Chikungunya fever is an acute febrile illness caused by the chikungunya virus (CHIKV), which is transmitted by Aedes mosquitoes. Since 1965, only a few studies with limited scope have been conducted on CHIKV in Vietnam. Thus, this study aimed to determine the seroprevalence and molecular epidemiology of CHIKV infection among febrile patients in Vietnam from 2017 to 2019. A total of 1063 serum samples from 31 provinces were collected and tested for anti-CHIKV IgM and IgG ELISA. The 50% focus reduction neutralization test (FRNT₅₀) was used to confirm CHIKV-neutralizing antibodies. Quantitative real-time RT–PCR (RT–qPCR) was performed to confirm the presence of the CHIKV genome. The results showed that 15.9% (169/1063) of the patients had anti-CHIKV IgM antibodies, 20.1% (214/1063) had anti-CHIKV IgG antibodies, 10.4% (111/1063) had CHIKV-neutralizing antibodies, and 27.7% (130/469) of the samples were positive in RT–qPCR analysis. The E1 CHIKV genome sequences were detected among the positive RT–qPCR samples. Our identified sequences belonged to the East/Central/South/African (ECSA) genotype, which has been prevalent in Vietnam previously, suggesting CHIKV has been maintained and is endemic in Vietnam. This study demonstrates a high prevalence of CHIKV infection in Vietnam and calls for an annual surveillance program to understand its impact.

: Relatively little is known about the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG antibodies and COVID-19-related behaviors in the general population in Vietnam, where the first case of COVID-19 was detected on January 22, 2020. We surveyed a group of 885 blood donors at community blood donation sessions in Ho Chi Minh City from August 27 to November 7, 2020. Blood was collected to test for SARS-CoV-2 IgG antibodies using the plaque reduction neutralization test. We adjusted the seroprevalence by weight for ages 18 to 59 years old obtained from the 2019 population census. The weighted seroprevalence estimate for SARS-CoV-2 neutralizing IgG antibodies was 0.20% (95% CI, 0.05–0.81). Reports of usually or always using a mask in public places were observed at high levels of 28.6% and 67.5%, respectively. The percentages of usually or always washing hands with soap or disinfecting with hand sanitizer after touching items in public places were 48.0% and 37.6%, respectively. Although our findings suggest undocumented exposure to the virus, the seroprevalence of SARS-CoV-2 IgG antibodies among blood donors was low in this city.

Genome‐wide analysis of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) strains is essential to better understand infectivity and virulence and to track coronavirus disease 2019 (COVID‐19) cases and outbreaks. We performed whole‐genome sequencing of 27 SARS‐CoV‐2 strains isolated between January 2020 and April 2020. A total of 54 mutations in different genomic regions was found. The D614G mutation, first detected in March 2020, was identified in 18 strains and was more likely associated with a lower cycle threshold (<25) in real‐time reverse‐transcription polymerase chain reaction diagnostic tests than the original D614 (prevalence ratio = 2.75; 95% confidence interval, 1.19–6.38). The integration of sequencing and epidemiological data suggests that SARS‐CoV‐2 transmission in both quarantine areas and in the community in Vietnam occur at the beginning of the epidemic although the country implemented strict quarantine quite early, with strict contact tracing, and testing. These findings provide insights into the nature of the epidemic, as well as shape strategies for COVID‐19 prevention and control in Vietnam.

Background: The protective or pathogenic role of T lymphocytes during the acute phase of dengue virus (DENV) infection has not been fully understood despite its importance in immunity and vaccine development. Objectives: This study aimed to clarify the kinetics of T lymphocyte subsets during the clinical course of acute dengue patients. Study design: In this hospital-based cohort study, 59 eligible Vietnamese dengue patients were recruited and admitted. They were investigated and monitored for T cell subsets and a panel of clinical and laboratory parameters every day until discharged and at post-discharge from the hospital. Results: We described for the first time the kinetics of T cell response during the clinical course of DENV infection. Severe cases showed significantly lower levels of effector CD8⁺ T cells compared to mild cases at day −1 (p = 0.017) and day 0 (p = 0.033) of defervescence. After defervescence, these cell counts in severe cases increased rapidly to equalize with the levels of mild cases. Our results also showed a decline in total CD4⁺ T, Th1, Th1/17 cells during febrile phase of dengue patients compared to normal controls or convalescent phase. On the other hand, Th2 cells increased during DENV infection until convalescent phase. Cytokines such as interferon-γ, IL-12p70, IL-5, IL-23, IL-17A showed tendency to decrease on day 0 and 1 compared with convalescence and only IL-5 showed significance indicating the production during acute phase was not systemic. Conclusion: With a rigorous study design, we uncovered the kinetics of T cells in natural DENV infection. Decreased number of effector CD8⁺ T cells in the early phase of infection and subsequent increment after defervescence day probably associated with the T cell migration in DENV infection.

Objectives This study aimed to investigate the knowledge, behaviour and attitudes towards Chagas disease (CD) among Latin American migrants in Japan and to evaluate the effectiveness of an educational activity (EA) in increasing knowledge of CD. Design A cross-sectional, mixed-methods study employing a preknowledge and postknowledge test and focus group discussion, conducted from March 2018 to June 2018. Participants Seventy-two participants were included, all born in Bolivia and residents in four Japanese cities. Fifty-nine of them participated in the EA. Interventions The EA comprised showing three videos about CD and a group discussion covering different dimensions of CD and was evaluated with questionnaires to analyse the knowledge of the participants before and after. Results Seventy-two participants were enrolled, predominantly from highly endemic CD areas of Bolivia. Though most participants were familiar with vector-borne transmission, epidemiology and symptomatology of CD, the baseline knowledge of CD was low. Less than 10% of them had been tested prior for CD. The dominant factors associated with better knowledge were living in Japan for more than 10 years (OR=8.42, 95% CI 1.56 to 48.62) and previously testing for CD (OR=11.32; 95% CI 1.52 to 105.9). The EA significantly improved the CD knowledge of the participants (p value Conclusion EA with an integrative approach is useful to increase the knowledge of CD within the Bolivian migrant population living in Japan. The activity brings the possibility to explore not only the level of knowledge but also to reveal experiences and to understand the needs of the people at risk. Considering them as actors towards healthcare solutions could lead to better outcomes for the success of future policies and interventions aimed to decrease the global burden.

In January 2020, we identified two severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2)‐infected patients in a familial cluster with one person coming from Wuhan, China. The complete genome sequences of two SARS‐CoV‐2 strains isolated from these patients were identical and 99.98% similar to strains isolated in Wuhan. This is genetically suggestive of human‐to‐human transmission of SARS‐CoV‐2 and indicates Wuhan as the most plausible origin of the early outbreak in Vietnam. The younger patient had a mild upper respiratory illness and a brief viral shedding, whereas the elderly with multi‐morbidity had pneumonia, prolonged viral shedding, and residual lung damage. The evidence of nonsynonymous substitutions in the ORF1ab region of the viral sequence warrants further studies.

Background: Chagas disease (CD), typically confined to the Latin America (LA) region, is emerging as a global health problem. In Japan, as in the rest of world, the under-diagnose rate of CD is alarmingly high. Various studies have highlighted the importance of informed knowledge in the seeking behavior. Educational integrative activities, with consideration for socio-cultural factors, can help increase the knowledge of the participants. There has been no studies that analyze the difference in knowledge, before and after these educational activities. This study aimed to qualitatively and quantitatively investigate the knowledge, behavior and attitude toward CD among LA migrants in Japan and to evaluate the effectiveness of the community educational activity in increasing knowledge of CD. Methodology: This cross-sectional study involved two questionnaires to analyze the knowledge of the LA migrant participants before and after the community activity (CA) in four cities in Japan (Oizumi, Suzuka, Hadano, and Nagoya). Principal Findings: A total of 75 participants were enrolled, predominantly Bolivians from hyperendemic areas. The baseline knowledge of CD was low. However, most of them were familiar with the disease although less than 10% of them had been tested for CD before. Living in Japan for more than 10 years and previously being tested for CD were the factors associated with better knowledge. The conducted CA significantly improved the knowledge of the participants. They associated the term “Chagas” mostly with fear and concern. In contrast to other studies, the level of stigmatization was low. The barriers in care seeking behavior were language, migration process and difficulties to access to the healthcare system. Conclusion: Educational activities with integrative approach are useful to increase knowledge of CD. The activity brings the possibility to explore not only the level of knowledge, but also to reveal the experience and to understand the needs of the people at risk. Author Summary: Though the incident rate of Chagas disease (CD) has fallen, more than 7 million people are affected worldwide. The CD prevalence is under-estimated because just 1% of these affected people can access to the diagnosis and treatment. This situation is maintaining mainly for the lack of implication of socio-cultural factors in the interventions to decrease the burden of the disease. Educational activities with integral approach are useful to increase the knowledge of the people at risk. People that have being tested for CD before or living in Japan for more than 10 years have better knowledge about the disease, suggesting the importance of knowledge in the seeking behavior. The authors recommend the implementation of educational activities with integral approach as a strategy to improves the knowledge of Chagas disease among Latin America migrants in Japan.

Considerable progress has been made in dengue management, however the lack of appropriate predictors of severity has led to huge number of unwanted admissions mostly decided on the grounds of warning signs. Apoptosis related mediators, among others, are known to correlate with severe dengue (SD) although no predictive validity is established. The objective of this study was to investigate the association of plasma cell-free DNA (cfDNA) with SD, and evaluate its prognostic value in SD prediction at acute phase. This was a hospital-based prospective cohort study conducted in Vietnam. All the recruited patients were required to be admitted to the hospital and were strictly monitored for various laboratory and clinical parameters (including progression to SD) until discharged. Plasma samples collected during acute phase (6–48 h before defervescence) were used to estimate the level of cfDNA. Of the 61 dengue patients, SD patients (n = 8) developed shock syndrome in 4.8 days (95% CI 3.7–5.4) after the fever onset. Plasma cfDNA levels before the defervescence of SD patients were significantly higher than the non-SD group (p = 0.0493). From the receiver operating characteristic (ROC) curve analysis, a cut-off of > 36.9 ng/mL was able to predict SD with a good sensitivity (87.5%), specificity (54.7%), and area under the curve (AUC) (0.72, 95% CI 0.55–0.88; p = 0.0493). Taken together, these findings suggest that cfDNA could serve as a potential prognostic biomarker of SD. Studies with cfDNA kinetics and its combination with other biomarkers and clinical parameters would further improve the diagnostic ability for SD.

The lack of an appropriate model has been a serious concern in dengue research pertinent to immune response and vaccine development. It remains a matter of impediment in dengue virus (DENV) studies when it comes to an in vitro model, which requires adequate quantity of dendritic cells (DC) with uniform characters. Other sources of DC, mostly monocyte derived DC (moDC), have been used despite their limitations such as quantity, proliferation, and donor dependent characters. Recent development of human iPS cells with consistent proliferation for long, stable, functional characteristics and desired HLA background has certainly offered added advantages. Therefore, we hypothesised that iPS derived cells would be a reliable alternative to the traditional DCs to be used with an in vitro DENV system. To develop a DENV infection and T cell activation model, we utilised iPS cells (HLA-A*24) as the source of DC. iPS-ML-DC was prepared and DENV infectivity was assessed apart from the major surface markers expression and cytokine production potential. Our iPS-ML-DC had major DC markers expression, DENV infection efficiency and cytokine production properties similar to that of moDC. Moreover, DENV infected iPS-ML-DC demonstrated the ability to activate HLA-matched T cell (but not mismatched) in vitro as evidenced by significantly higher proportion of IFN-γ+ CD69+ T cells compared to non-infected iPS-ML-DC. This affirmed the antigen-specific T cell activation by iPS-ML-DC as a function of antigen presenting cells. To conclude, maturation potential, DENV infection efficiency and T cell activation ability collectively suggest that iPS-ML-DC serves as an attractive option of DC for use in DENV studies in vitro.