Publications by authors named "Tran Hien Nguyen"

22 Publications

  • Page 1 of 1

Epidemiological and comparative genomic analysis of Bacillus anthracis isolated from northern Vietnam.

PLoS One 2020 21;15(2):e0228116. Epub 2020 Feb 21.

Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan.

To understand the epidemiological and genetic background of anthrax cases occurring in Vietnam from 2011 to 2015, we surveilled and genetically analyzed Bacillus anthracis isolated in the north of the country. Epidemiological surveillance showed that most human cutaneous anthrax cases occurred in association with animal dissection. Whole-genome sequences were obtained from six B. anthracis strains from human patients with cutaneous anthrax in the endemic area. Comparative genomic analysis showed that the genetic homogeneity among Vietnamese B. anthracis strains was very high. All Vietnamese B. anthracis strains belonged to the canSNP lineage of A.Br.011/009, which mostly consists of strains of the trans-Eurasian (TEA) group, including the most closely related strain, Carbosap. To clarify the genetic diversity of Vietnamese strains and strains belonging to A.Br.011/009 and A.Br.008/011 canSNP lineages, we applied a reference genome-based single-nucleotide polymorphism (SNP) and gene-by-gene genomic analysis (whole-genome MLST) strategy. The phylogeny from core genome SNPs revealed that the Vietnamese strains were positioned close to each other; moreover, several SNPs specific to Vietnamese B. anthracis were identified. Whole-genome MLST analysis revealed the differences in the number of SNPs between Vietnamese strains, which could enable discrimination at the strain level.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0228116PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7034820PMC
April 2020

Sero-Prevalence Surveillance to Predict Vaccine-Preventable Disease Outbreaks; A Lesson from the 2014 Measles Epidemic in Northern Vietnam.

Open Forum Infect Dis 2019 Mar 24;6(3):ofz030. Epub 2019 Jan 24.

Oxford University Clinical Research Unit, Wellcome Trust Asia Programme, Hanoi, Vietnam.

Background: During the first half of 2014, a severe outbreak of measles occurred in northern Vietnam, causing 15 033 confirmed cases and 146 deaths.

Methods: To evaluate the population-level seroprevalence of protection against measles in the period before the outbreak, we made use of an existing age-stratified serum bank, collected over the year before the outbreak, between November 2012 and December 2013, from 4 sites across the country (Hanoi, Hue, Dak Lak, and Ho Chi Minh City). Data from the UNICEF's Multiple Indicator Clustered Surveys (MICS), carried out in Vietnam during the first quarter of 2014, were used to assess the vaccine coverage in 6 ecological regions of Vietnam.

Results: Results revealed a large discrepancy between levels of protection, as estimated from the serology and vaccine coverage estimated by UNICEF's MICS. Variation in seroprevalence across locations and age groups corresponded with reported numbers of measles cases, most of which were among the 0-2-year-old age group and in the northern part of the country.

Conclusions: Our study presents a strong case in favor of a serosurveillance sentinel network that could be used to proactively tune vaccination policies and other public health interventions.
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http://dx.doi.org/10.1093/ofid/ofz030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6405937PMC
March 2019

Global Role and Burden of Influenza in Pediatric Respiratory Hospitalizations, 1982-2012: A Systematic Analysis.

PLoS Med 2016 Mar 24;13(3):e1001977. Epub 2016 Mar 24.

National Institute for Communicable Diseases, Johannesburg, South Africa.

Background: The global burden of pediatric severe respiratory illness is substantial, and influenza viruses contribute to this burden. Systematic surveillance and testing for influenza among hospitalized children has expanded globally over the past decade. However, only a fraction of the data has been used to estimate influenza burden. In this analysis, we use surveillance data to provide an estimate of influenza-associated hospitalizations among children worldwide.

Methods And Findings: We aggregated data from a systematic review (n = 108) and surveillance platforms (n = 37) to calculate a pooled estimate of the proportion of samples collected from children hospitalized with respiratory illnesses and positive for influenza by age group (<6 mo, <1 y, <2 y, <5 y, 5-17 y, and <18 y). We applied this proportion to global estimates of acute lower respiratory infection hospitalizations among children aged <1 y and <5 y, to obtain the number and per capita rate of influenza-associated hospitalizations by geographic region and socio-economic status. Influenza was associated with 10% (95% CI 8%-11%) of respiratory hospitalizations in children <18 y worldwide, ranging from 5% (95% CI 3%-7%) among children <6 mo to 16% (95% CI 14%-20%) among children 5-17 y. On average, we estimated that influenza results in approximately 374,000 (95% CI 264,000 to 539,000) hospitalizations in children <1 y-of which 228,000 (95% CI 150,000 to 344,000) occur in children <6 mo-and 870,000 (95% CI 610,000 to 1,237,000) hospitalizations in children <5 y annually. Influenza-associated hospitalization rates were more than three times higher in developing countries than in industrialized countries (150/100,000 children/year versus 48/100,000). However, differences in hospitalization practices between settings are an important limitation in interpreting these findings.

Conclusions: Influenza is an important contributor to respiratory hospitalizations among young children worldwide. Increasing influenza vaccination coverage among young children and pregnant women could reduce this burden and protect infants <6 mo.
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http://dx.doi.org/10.1371/journal.pmed.1001977DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4807087PMC
March 2016

Field evaluation of the establishment potential of wMelPop Wolbachia in Australia and Vietnam for dengue control.

Parasit Vectors 2015 Oct 28;8:563. Epub 2015 Oct 28.

Bio21 Institute and School of BioSciences, University of Melbourne, Parkville, Australia.

Background: Introduced Wolbachia bacteria can influence the susceptibility of Aedes aegypti mosquitoes to arboviral infections as well as having detrimental effects on host fitness. Previous field trials demonstrated that the wMel strain of Wolbachia effectively and durably invades Ae. aegypti populations. Here we report on trials of a second strain, wMelPop-PGYP Wolbachia, in field sites in northern Australia (Machans Beach and Babinda) and central Vietnam (Tri Nguyen, Hon Mieu Island), each with contrasting natural Ae. aegypti densities.

Methods: Mosquitoes were released at the adult or pupal stages for different lengths of time at the sites depending on changes in Wolbachia frequency as assessed through PCR assays of material collected through Biogents-Sentinel (BG-S) traps and ovitraps. Adult numbers were also monitored through BG-S traps. Changes in Wolbachia frequency were compared across hamlets or house blocks.

Results: Releases of adult wMelPop-Ae. aegypti resulted in the transient invasion of wMelPop in all three field sites. Invasion at the Australian sites was heterogeneous, reflecting a slower rate of invasion in locations where background mosquito numbers were high. In contrast, invasion across Tri Nguyen was relatively uniform. After cessation of releases, the frequency of wMelPop declined in all sites, most rapidly in Babinda and Tri Nguyen. Within Machans Beach the rate of decrease varied among areas, and wMelPop was detected for several months in an area with a relatively low mosquito density.

Conclusions: These findings highlight challenges associated with releasing Wolbachia-Ae. aegypti combinations with low fitness, albeit strong virus interference properties, as a means of sustainable control of dengue virus transmission.
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http://dx.doi.org/10.1186/s13071-015-1174-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4625535PMC
October 2015

Congenital rubella syndrome (CRS) in Vietnam 2011-2012--CRS epidemic after rubella epidemic in 2010-2011.

Vaccine 2015 Jul 15;33(31):3673-7. Epub 2015 Jun 15.

National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam.

Background: Rubella is endemic in Vietnam with epidemics occurring every 4-5 years. In 2011, Vietnam experienced the large nationwide rubella epidemic. During the rubella epidemic, many infants born with congenital rubella syndrome (CRS) were identified and reported from the neonatal units or cardiology departments of the national hospitals. To understand the burden of CRS, National Expanded Program on Immunization (NEPI) established sentinel CRS surveillance system.

Method: Three national paediatric hospitals in Hanoi and Ho Chi Minh City (HCMC) were selected as CRS sentinel surveillance sites. Blood specimens from the infants were collected for rubella specific IgM and ELISA testing was performed at the national measles and rubella laboratory.

Results: From January 2011 to December 2012, 424 infants with suspected CRS were identified and reported. Among them 406 (96%) had specimens obtained, 284 (70%) cases were IgM positive including 279 laboratory confirmed CRS and 5 Congenital Rubella Infection (CRI). 13 cases were clinically confirmed and 127 (30%) were discarded. Total 292 infants were confirmed as CRS. Of the 292 infants with CRS, 69% of mothers had a history of "fever and rash" during pregnancy, of which 85% was in the first trimester. The most common clinical defects were congenital heart disease and cataract(s). However, 81.9% of the infants had a combination of major and minor signs and symptoms. Low birth weight in full term infants with confirmed CRS was observed in 114 infants (39%).

Conclusions: The newly established CRS sentinel surveillance system documented the significant burden of CRS in Vietnam and provided evidence to the policy makers for the introduction of rubella containing vaccine (RCV) into Vietnam. This report highlights the importance of countries with rubella epidemic to establish CRS surveillance rapidly in order to support the introduction of RCV into the routine Expanded Programme on Immunization (EPI) immunization.
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http://dx.doi.org/10.1016/j.vaccine.2015.06.035DOI Listing
July 2015

Impact of Adverse Events Following Immunization in Viet Nam in 2013 on chronic hepatitis B infection.

Vaccine 2016 Feb 6;34(6):869-73. Epub 2015 Jun 6.

National Institute of Hygiene and Epidemiology, 1 Yersin Street, Hai Ba Trung, Ha Noi 10000, Viet Nam.

Adverse Events Following Immunization in Viet Nam in 2013 led to substantial reductions in hepatitis B vaccination coverage (both the birth dose and the three-dose series). In order to estimate the impact of the reduction in vaccination coverage on hepatitis B transmission and future mortality, a widely-used mathematical model was applied to the data from Viet Nam. Using the model, we estimated the number of chronic infections and deaths that are expected to occur in the birth cohort in 2013 and the number of excessive infections and deaths attributable to the drop in immunization coverage in 2013. An excess of 90,137 chronic infections and 17,456 future deaths were estimated to occur in the 2013 birth cohort due to the drop in vaccination coverage. This analysis highlights the importance of maintaining high vaccination coverage and swiftly responding to reported Adverse Events Following Immunization in order to regain consumer confidence in the hepatitis B vaccine.
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http://dx.doi.org/10.1016/j.vaccine.2015.05.067DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5357724PMC
February 2016

Differences in the Epidemiology of Human Cases of Avian Influenza A(H7N9) and A(H5N1) Viruses Infection.

Clin Infect Dis 2015 Aug 4;61(4):563-71. Epub 2015 May 4.

Division of Infectious Disease, Key Laboratory of Surveillance and Early-warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China.

Background: The pandemic potential of avian influenza viruses A(H5N1) and A(H7N9) remains an unresolved but critically important question.

Methods: We compared the characteristics of sporadic and clustered cases of human H5N1 and H7N9 infection, estimated the relative risk of infection in blood-related contacts, and the reproduction number (R).

Results: We assembled and analyzed data on 720 H5N1 cases and 460 H7N9 cases up to 2 November 2014. The severity and average age of sporadic/index cases of H7N9 was greater than secondary cases (71% requiring intensive care unit admission vs 33%, P = .007; median age 59 years vs 31, P < .001). We observed no significant differences in the age and severity between sporadic/index and secondary H5N1 cases. The upper limit of the 95% confidence interval (CI) for R was 0.12 for H5N1 and 0.27 for H7N9. A higher proportion of H5N1 infections occurred in clusters (20%) compared to H7N9 (8%). The relative risk of infection in blood-related contacts of cases compared to unrelated contacts was 8.96 for H5N1 (95% CI, 1.30, 61.86) and 0.80 for H7N9 (95% CI, .32, 1.97).

Conclusions: The results are consistent with an ascertainment bias towards severe and older cases for sporadic H7N9 but not for H5N1. The lack of evidence for ascertainment bias in sporadic H5N1 cases, the more pronounced clustering of cases, and the higher risk of infection in blood-related contacts, support the hypothesis that susceptibility to H5N1 may be limited and familial. This analysis suggests the potential pandemic risk may be greater for H7N9 than H5N1.
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http://dx.doi.org/10.1093/cid/civ345DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4542598PMC
August 2015

Thirty years of vaccination in Vietnam: Impact and cost-effectiveness of the national Expanded Programme on Immunization.

Vaccine 2015 May;33 Suppl 1:A233-9

National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.

Introduction: Countries like Vietnam transitioning to middle-income status increasingly bear the cost of both existing and new vaccines. However, the impact and cost-effectiveness of the Expanded Programme on Immunization (EPI) as a whole has never been assessed on a country level.

Methods: Data on vaccine-preventable disease incidence and mortality from Vietnam's national surveillance was analysed to estimate the likely impact that vaccination in 1980-2010 may have had. Adjustment for under-reporting was made by examining trends in reported mumps incidence and in case-fatality risks for each disease. The same data were separately analysed using the Lives Saved Tool (LiST) to give an alternative estimate of impact. The financial cost of EPI in 1996-2010 was also estimated from the perspective of service provider.

Results: National surveillance data suggests that up to 5.7 million diseases cases and 26,000 deaths may have been prevented by EPI. Analysis using LiST suggests that even more deaths (370,000) may have been prevented by measles and pertussis vaccination alone. The cost-effectiveness of EPI is estimated to be around $1000-$27,000 per death prevented.

Conclusion: Two separate approaches to assessing EPI impact in Vietnam give different quantitative results but a common conclusion: that EPI has made a substantial impact on mortality and represents good value for money.
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http://dx.doi.org/10.1016/j.vaccine.2014.12.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4428532PMC
May 2015

Determinants of influenza transmission in South East Asia: insights from a household cohort study in Vietnam.

PLoS Pathog 2014 Aug 21;10(8):e1004310. Epub 2014 Aug 21.

Oxford University Clinical Research Unit - Wellcome Trust Major Overseas Programme, Hanoi, Vietnam.

To guide control policies, it is important that the determinants of influenza transmission are fully characterized. Such assessment is complex because the risk of influenza infection is multifaceted and depends both on immunity acquired naturally or via vaccination and on the individual level of exposure to influenza in the community or in the household. Here, we analyse a large household cohort study conducted in 2007-2010 in Vietnam using innovative statistical methods to ascertain in an integrative framework the relative contribution of variables that influence the transmission of seasonal (H1N1, H3N2, B) and pandemic H1N1pdm09 influenza. Influenza infection was diagnosed by haemagglutination-inhibition (HI) antibody assay of paired serum samples. We used a Bayesian data augmentation Markov chain Monte Carlo strategy based on digraphs to reconstruct unobserved chains of transmission in households and estimate transmission parameters. The probability of transmission from an infected individual to another household member was 8% (95% CI, 6%, 10%) on average, and varied with pre-season titers, age and household size. Within households of size 3, the probability of transmission from an infected member to a child with low pre-season HI antibody titers was 27% (95% CI 21%-35%). High pre-season HI titers were protective against infection, with a reduction in the hazard of infection of 59% (95% CI, 44%-71%) and 87% (95% CI, 70%-96%) for intermediate (1∶20-1∶40) and high (≥1∶80) HI titers, respectively. Even after correcting for pre-season HI titers, adults had half the infection risk of children. Twenty six percent (95% CI: 21%, 30%) of infections may be attributed to household transmission. Our results highlight the importance of integrated analysis by influenza sub-type, age and pre-season HI titers in order to infer influenza transmission risks in and outside of the household.
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http://dx.doi.org/10.1371/journal.ppat.1004310DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4140851PMC
August 2014

A reduction in chronic hepatitis B virus infection prevalence among children in Vietnam demonstrates the importance of vaccination.

Vaccine 2014 Jan 24;32(2):217-22. Epub 2013 Nov 24.

World Health Organization, Western Pacific Regional Office, Manila, Philippines.

Background: Vietnam has high endemic hepatitis B virus infection with >8% of adults estimated to have chronic infection. Hepatitis B vaccine was first introduced in the national childhood immunization program in 1997 in high-risk areas, expanded nationwide in 2002, and included birth dose vaccination in 2003. This survey aimed to assess the impact of Vietnam's vaccination programme by estimating the prevalence of hepatitis B surface antigen (HBsAg) among children born during 2000-2008.

Methods: This nationally representative cross-sectional survey sampled children based on a stratified three-stage cluster design. Demographic and vaccination data were collected along with a whole blood specimen that was collected and interpreted in the field with a point-of-care HBsAg test.

Results: A total of 6,949 children were included in the survey analyses. The overall HBsAg prevalence among surveyed children was 2.70% (95% confidence interval (CI): 2.20-3.30). However, HBsAg prevalence was significantly higher among children born in 2000-2003 (3.64%) compared to children born 2007-2008 (1.64%) (prevalence ratio (PR: 2.22, CI 1.55-3.18)). Among all children included in the survey, unadjusted HBsAg prevalence among children with ≥3 doses of hepatitis B vaccine including a birth dose (1.75%) was significantly lower than among children with ≥3 doses of hepatitis B vaccine but lacked a birth dose (2.98%) (PR: 1.71, CI: 1.00-2.91) and significantly lower than among unvaccinated children (3.47%) (PR: 1.99, CI: 1.15-3.45). Infants receiving hepatitis B vaccine >7 days after birth had significantly higher HBsAg prevalence (3.20%) than those vaccinated 0-1 day after birth (1.52%) (PR: 2.09, CI: 1.27-3.46).

Conclusion: Childhood chronic HBV infection prevalence has been markedly reduced in Vietnam due to vaccination. Further strengthening of timely birth dose vaccination will be important for reducing chronic HBV infection prevalence of under 5 children to <1%, a national and Western Pacific regional hepatitis B control goal.
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http://dx.doi.org/10.1016/j.vaccine.2013.11.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4699283PMC
January 2014

Social contexts of risk behaviors for HIV among male, unskilled, unregistered laborers in urban Vietnam.

Qual Health Res 2012 Jul 7;22(7):871-9. Epub 2011 Nov 7.

Hanoi Medical University, Hanoi, Vietnam.

In Vietnam there has been relatively little success in controlling the HIV epidemic, in part because the subpopulations most exposed to the virus are often difficult to engage in prevention research and programs. In this qualitative study we explored social contexts shaping HIV risk behaviors among Vietnamese men involved in unskilled, unregistered, and low-income labor in urban settings. Based on self-disclosed behaviors, it is clear that these men were at high risk of sexually transmitted infection (STI). Evidence emerged from the interview data highlighting equivalent influences of individual psychological factors, social integration, social barriers, and accessibility regarding drug use and sexual risk behavior. Psychological influences such as tedium, distress, fatalism and revenge, and the strong effects of collective decision making and fear of social isolation appeared important for these men living on the economic and social margins of this rapidly urbanizing society. The study findings suggest directions for research and culturally appropriate HIV preventive education and services for these men.
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http://dx.doi.org/10.1177/1049732311424510DOI Listing
July 2012

H5N1-SeroDetect EIA and rapid test: a novel differential diagnostic assay for serodiagnosis of H5N1 infections and surveillance.

J Virol 2011 Dec 28;85(23):12455-63. Epub 2011 Sep 28.

Division of Viral Products, Center for Biologics Evaluation and Research, FDA, Bldg. 29B, Rm. 4NN02, 8800 Rockville Pike, Bethesda, MD 20892, USA.

Continuing evolution of highly pathogenic (HP) H5N1 influenza viruses in wild birds with transmission to domestic poultry and humans poses a pandemic threat. There is an urgent need for a simple and rapid serological diagnostic assay which can differentiate between antibodies to seasonal and H5N1 strains and that could provide surveillance tools not dependent on virus isolation and nucleic acid technologies. Here we describe the establishment of H5N1 SeroDetect enzyme-linked immunosorbent assay (ELISA) and rapid test assays based on three peptides in HA2 (488-516), PB1-F2 (2-75), and M2e (2-24) that are highly conserved within H5N1 strains. These peptides were identified by antibody repertoire analyses of H5N1 influenza survivors in Vietnam using whole-genome-fragment phage display libraries (GFPDLs). To date, both platforms have demonstrated high levels of sensitivity and specificity in detecting H5N1 infections (clade 1 and clade 2.3.4) in Vietnamese patients as early as 7 days and up to several years postinfection. H5N1 virus-uninfected individuals in Vietnam and the United States, including subjects vaccinated with seasonal influenza vaccines or with confirmed seasonal virus infections, did not react in the H5N1-SeroDetect assays. Moreover, sera from individuals vaccinated with H5N1 subunit vaccine with moderate anti-H5N1 neutralizing antibody titers did not react positively in the H5N1-SeroDetect ELISA or rapid test assays. The simple H5N1-SeroDetect ELISA and rapid tests could provide an important tool for large-scale surveillance for potential exposure to HP H5N1 strains in both humans and birds.
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http://dx.doi.org/10.1128/JVI.06023-11DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3209361PMC
December 2011

Social contact patterns in Vietnam and implications for the control of infectious diseases.

PLoS One 2011 Feb 14;6(2):e16965. Epub 2011 Feb 14.

Oxford University Clinical Research Unit, Hanoi, Vietnam.

Background: The spread of infectious diseases from person to person is determined by the frequency and nature of contacts between infected and susceptible members of the population. Although there is a long history of using mathematical models to understand these transmission dynamics, there are still remarkably little empirical data on contact behaviors with which to parameterize these models. Even starker is the almost complete absence of data from developing countries. We sought to address this knowledge gap by conducting a household based social contact diary in rural Vietnam.

Methods And Findings: A diary based survey of social contact patterns was conducted in a household-structured community cohort in North Vietnam in 2007. We used generalized estimating equations to model the number of contacts while taking into account the household sampling design, and used weighting to balance the household size and age distribution towards the Vietnamese population. We recorded 6675 contacts from 865 participants in 264 different households and found that mixing patterns were assortative by age but were more homogenous than observed in a recent European study. We also observed that physical contacts were more concentrated in the home setting in Vietnam than in Europe but the overall level of physical contact was lower. A model of individual versus household vaccination strategies revealed no difference between strategies in the impact on R(0).

Conclusions And Significance: This work is the first to estimate contact patterns relevant to the spread of infections transmitted from person to person by non-sexual routes in a developing country setting. The results show interesting similarities and differences from European data and demonstrate the importance of context specific data.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0016965PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3038933PMC
February 2011

Isolation and molecular characterization of Banna virus from mosquitoes, Vietnam.

Emerg Infect Dis 2008 Aug;14(8):1276-9

Department of Virology, Institute of Tropical Medicine, Nagasaki University, Nagasaki City, Japan.

We isolated and characterized a Banna virus from mosquitoes in Vietnam; 5 strains were isolated from field-caught mosquitoes at various locations; Banna virus was previously isolated from encephalitis patients in Yunnan, China, in 1987. Together, these findings suggest widespread distribution of this virus throughout Southeast Asia.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2600385PMC
http://dx.doi.org/10.3201/eid1408.080100DOI Listing
August 2008

Person-to-person transmission of influenza A (H5N1).

Lancet 2008 Apr 8;371(9622):1392-4. Epub 2008 Apr 8.

National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.

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http://dx.doi.org/10.1016/S0140-6736(08)60494-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7135816PMC
April 2008

A hidden HIV epidemic among women in Vietnam.

BMC Public Health 2008 Jan 28;8:37. Epub 2008 Jan 28.

Faculty of Public Health, Hanoi Medical University, Hanoi, Vietnam.

Background: The HIV epidemic in Vietnam is still concentrated among high risk populations, including IDU and FSW. The response of the government has focused on the recognized high risk populations, mainly young male drug users. This concentration on one high risk population may leave other populations under-protected or unprepared for the risk and the consequences of HIV infection. In particular, attention to women's risks of exposure and needs for care may not receive sufficient attention as long as the perception persists that the epidemic is predominantly among young males. Without more knowledge of the epidemic among women, policy makers and planners cannot ensure that programs will also serve women's needs.

Methods: More than 300 documents appearing in the period 1990 to 2005 were gathered and reviewed to build an understanding of HIV infection and related risk behaviors among women and of the changes over time that may suggest needed policy changes.

Results: It appears that the risk of HIV transmission among women in Vietnam has been underestimated; the reported data may represent as little as 16% of the real number. Although modeling predicted that there would be 98,500 cases of HIV-infected women in 2005, only 15,633 were accounted for in reports from the health system. That could mean that in 2005, up to 83,000 women infected with HIV have not been detected by the health care system, for a number of possible reasons. For both detection and prevention, these women can be divided into sub-groups with different risk characteristics. They can be infected by sharing needles and syringes with IDU partners, or by having unsafe sex with clients, husbands or lovers. However, most new infections among women can be traced to sexual relations with young male injecting drug users engaged in extramarital sex. Each of these groups may need different interventions to increase the detection rate and thus ensure that the women receive the care they need.

Conclusion: Women in Vietnam are increasingly at risk of HIV transmission but that risk is under-reported and under-recognized. The reasons are that women are not getting tested, are not aware of risks, do not protect themselves and are not being protected by men. Based on this information, policy-makers and planners can develop better prevention and care programs that not only address women's needs but also reduce further spread of the infection among the general population.
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http://dx.doi.org/10.1186/1471-2458-8-37DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2248180PMC
January 2008

Sexual risk and bridging behaviors among young people in Hai Phong, Vietnam.

AIDS Behav 2008 Jul 18;12(4):643-51. Epub 2007 Jul 18.

National Institute of Hygiene and Epidemiology, No. 1, Yersin Street, Ha Noi 10000, Vietnam.

The risk of the HIV epidemic spreading from high-risk groups to the general population in Vietnam depends on sexual risk and bridging behaviors between high- and low-risk individuals. A cross-sectional study was used to describe sexual activities of youth aged 18-29 years. Nearly half (41.4%) were sexually active. Premarital sex was reported by 43.3% of them; 78.3% of sexually active males and 13.5% of sexually active females. Multiple sex partners were reported by 31.0%; 56.7% of males and 9.2% of females. Almost 27% of males and 5% of females engaged in sexual bridging behaviors. Being unmarried was significantly associated with having sex with non-regular partners. Being unmarried and early age at first intercourse were associated with having sex with a sex worker. Consistent condom use was high with commercial sex workers but low with regular partners. Education to delay early sexual debut, increased employment, and strategies to inform young sexually active people to adopt safer behaviors are urgently needed.
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http://dx.doi.org/10.1007/s10461-007-9265-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2938170PMC
July 2008

Lack of transmission of H5N1 avian-human reassortant influenza viruses in a ferret model.

Proc Natl Acad Sci U S A 2006 Aug 31;103(32):12121-6. Epub 2006 Jul 31.

Influenza Branch, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.

Avian influenza A H5N1 viruses continue to spread globally among birds, resulting in occasional transmission of virus from infected poultry to humans. Probable human-to-human transmission has been documented rarely, but H5N1 viruses have not yet acquired the ability to transmit efficiently among humans, an essential property of a pandemic virus. The pandemics of 1957 and 1968 were caused by avian-human reassortant influenza viruses that had acquired human virus-like receptor binding properties. However, the relative contribution of human internal protein genes or other molecular changes to the efficient transmission of influenza viruses among humans remains poorly understood. Here, we report on a comparative ferret model that parallels the efficient transmission of H3N2 human viruses and the poor transmission of H5N1 avian viruses in humans. In this model, an H3N2 reassortant virus with avian virus internal protein genes exhibited efficient replication but inefficient transmission, whereas H5N1 reassortant viruses with four or six human virus internal protein genes exhibited reduced replication and no transmission. These findings indicate that the human virus H3N2 surface protein genes alone did not confer efficient transmissibility and that acquisition of human virus internal protein genes alone was insufficient for this 1997 H5N1 virus to develop pandemic capabilities, even after serial passages in a mammalian host. These results highlight the complexity of the genetic basis of influenza virus transmissibility and suggest that H5N1 viruses may require further adaptation to acquire this essential pandemic trait.
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http://dx.doi.org/10.1073/pnas.0605134103DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1567706PMC
August 2006

Avian influenza A (H5N1) infection in humans.

N Engl J Med 2005 Sep;353(13):1374-85

National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Md, USA.

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http://dx.doi.org/10.1056/NEJMra052211DOI Listing
September 2005

HIV/AIDS epidemics in Vietnam: evolution and responses.

AIDS Educ Prev 2004 Jun;16(3 Suppl A):137-54

Faculty of Public Health, Department of Epidemiology, Hanoi Medical University, Hanoi, Vietnam.

The goal of this study was to describe the evolution of the HIV epidemic in Vietnam and its responses. Surveillance was conducted in 8 provinces in 1994, expanded to 12 in 1995, 20 in 1996, and 30 in 2001. Sentinel populations were sexually transmitted disease (STD) patients, female sex workers (FSWs), injection drug users (IDUs), tuberculosis (TB) patients, antenatal women, and military conscripts. Vietnam is in the concentrated epidemic stage. HIV prevalence had increased significantly in all surveillance population groups in the 1990s. HIV prevalence in the south is higher than in other regions of the country. The national HIV prevalence increased from 10.1% in 1996 to 32% in 2002 among IDUs, from 0.6% in 1994 to 6.6% in 2002 among FSWs, from 0.4% in 1994 to 2.4% in 2002 among STD patients, from 0.03% in 1994 to 0.34% in 2002 among pregnant women, from 0% in 1994 to 0.7% in 2002 among army military recruits, and from 0.5% in 1994 to 3.6% in 2002 among TB patients. The government has a strong commitment to control the epidemic and has implemented many activities for HIV prevention and control. Vietnam's HIV epidemic is predominantly among IDUs. Current intervention activities have not been sufficient to reduce HIV transmission. Vietnam needs to strengthen responses by scaling up the best practices in the most affected population groups by implementing internationally recognised effective interventions appropriately.
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http://dx.doi.org/10.1521/aeap.16.3.5.137.35527DOI Listing
June 2004

Intravenous drug use among street-based sex workers: a high-risk behavior for HIV transmission.

Sex Transm Dis 2004 Jan;31(1):15-9

National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.

Background: HIV prevalence among sex workers in Ho Chi Minh City has increased rapidly, from 6.5% in 1999 to 18.1% in 2000. This study examined whether injecting drug use among street-based sex workers (SSWs) in Ho Chi Minh City is a high-risk factor for HIV infection.

Goal: The goal of this study was to determine the correlates and prevalence of intravenous drug users among SSWs in Ho Chi Minh City.

Study Design: A cross-sectional study was conducted among SSWs in Ho Chi Minh City during December 2000. The SSWs were interviewed and tested for HIV-1.

Results: HIV-1 seroprevalence was 16.3%. Regression analysis indicated that injecting drugs and being younger than 25 years of age were independently associated with HIV seropositivity.

Conclusion: Young SSWs who inject drugs are at the greatest risk of contracting HIV and acting as a bridge for HIV to the sexually active population.
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http://dx.doi.org/10.1097/01.OLQ.0000105002.34902.B5DOI Listing
January 2004