Pham Hong Thang

National Institute of Hygiene and Epidemiology, Hà Nội, Ha Nội, Vietnam

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Publications (15)39.93 Total impact

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    ABSTRACT: HIV in Vietnam remains a concentrated epidemic, with high HIV prevalence among people who inject drugs, female sex workers, and men who have sex with men, whereas low HIV prevalence is found among pregnant women and military recruits. People who inject drugs are the main drivers for the HIV epidemic in Vietnam. The HIV epidemic tends to significantly decrease or stabilize among people who inject drugs in most provinces, despite the high prevalence level and geographical diversity. People who inject drugs reported multiple risks, including sharing of needles and syringes, sexual intercourse with female sex workers, and inconsistent condom use. The activity of sharing needles and syringes showed a decreasing trend over time among people who inject drugs in most provinces, but the numbers remain at a high level. Prevention and intervention programs appear to reach and effectively reduce high-risk behavior and HIV prevalence among this population. However, the coverage of intervention and prevention programs remains low. HIV intervention and prevention programs need to be improved and scaled up for sustainable impact. Program designs need to be based on a local context.
    Full-text · Article · Mar 2015
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    ABSTRACT: In this report we describe a new approach in HIV sentinel surveillance that was piloted in Viet Nam in 2009 and is currently being rolled out in all provinces. It comprises a brief behavioural questionnaire added to the HIV sentinel surveillance surveys conducted routinely among people who inject drugs, female sex workers and men who have sex with men. Timely reporting of data from this system has resulted in improvements to HIV prevention efforts for most at-risk populations.
    Full-text · Article · Feb 2015
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    ABSTRACT: Given the overlapping modes of transmission of HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV), understanding the burden and relationship of these infections is critical for an effective response. Representative data on these infections among males who inject drugs (MWID), the key high-risk population for HIV in Vietnam, are currently lacking. Data and stored specimens from Vietnam's 2009-2010 Integrated Biologic and Behavioral Survey, a cross-sectional study among high-risk populations, were used for this analysis. Plasma samples were tested for HIV, HBV, and HCV using commercial assays. A questionnaire was administered to provide demographic, behavior, and service-uptake information. Provincial-level analyses were conducted to profile MWID enrollees and to provide estimates on the prevalence of HIV, HBV, and HCV infection. Among 3010 MWID sampled across 10 provinces, the median (range) HIV prevalence was 28.1% (1.0%-55.5%). Median prevalence for current HBV infection (HBsAg+) was 14.1% (11.7%-28.0%), for previous exposure to HBV (total anti-HBc+) was 71.4% (49.9%-83.1%), and for current or past HCV infection (HCV Ag/Ab+) was 53.8% (10.9%-80.8%). In adjusted analysis, HBsAg+ (aOR: 2.09, 1.01-4.34) and HCV Ag/Ab+ (aOR: 19.58, 13.07-29.33) status were significantly associated with HIV infection; the association with total anti-HBc+ approached significance (aOR: 1.29, 0.99-1.68). The prevalence and association between HIV, HBV, and HCV are high among MWID in Vietnam. These findings indicate the need for integrated policies and practice that for the surveillance, prevention, screening, and treatment of both HIV and viral hepatitis among MWID in Vietnam.
    Full-text · Article · Feb 2015 · PLoS ONE
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    ABSTRACT: Background: HIV sentinel surveillance (HSS) is conducted annually among 6 key populations in 41 provinces in Viet Nam to monitor HIV prevalence trends. The HSS system began collecting risk taking behaviors among men who have sex with men (MSM) in 2010 for better understanding the HIV epidemic. The aims of this study were to determine the association between drug injection and selling sex among MSM and HIV infection in Viet Nam. Methods: Two-stage cluster sampling was applied to recruit participants based on geographic mapping where they gathering and through peer educators and local health staff. Following informed consent, respondents were interviewed with a short questionnaire consists of 30 behavioral questions and agreed to take a blood draw for HIV test. Results: There were 900, 800, and 800 MSM sampled in Ha Noi, An Giang, and Ho Chi Minh city (HCMC) combined during 2010, 2011 and 2012, respectively. HIV prevalence among MSM was 6.0%, 6.7%, and 6.5% in Ha Noi; 2.0%, 3.0%, and 2.0% in An Giang; 16%, 14.0%, and 7.3% in HCMC in 2010, 2011 and 2012 respectively. HIV infection was found to be associated with drug injecting behavior in HCMC in 2010 (OR: 9.5; 95% CI: 4.7-19.2) and in 2011 (OR: 5.3; 95% CI: 2.6-10.8), and in An Giang in 2011 (OR: 5.2; 95% CI: 0.9 - 30.4); and with selling sex behavior in An Giang in 2011 (OR: 8.2; 95% CI: 1.4 - 46.5) and 2012 (OR: 7.7; 95% CI: 1.1 - 56.5) respectively. Conclusions: MSM practice multiple risk behaviors including drug injecting and selling sex. HIV prevalence was found to be associated with drug injecting and selling sex behaviors. HIV prevention efforts needs to be broadened with a focus on drug injecting and selling sex MSM. The application of integrating a short behavioral questionnaire into routine sentinel surveillance provides essential information for better understanding the HIV epidemic in Viet Nam.
    Full-text · Conference Paper · Jul 2014
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    ABSTRACT: Background: HIV sentinel surveillance (HSS) is conducted annually among 6 key populations in 41 provinces in Vietnam to monitor HIV prevalence. To obtain national and global indicators on risk behavior and coverage of prevention services, short behavioral questionnaire was added to HSS since 2010 among female sex workers (FSWs), injecting drug users (IDUs), and men who have sex with men (MSM). This reports data among FSWs. Methods: Two-stage cluster sampling was applied to recruit participants based on geographic mapping where they gathering and through peer educators and local health staff. There were 5466, 7983, and 8140 FSWs sampled in 2010, 2011 and 2012. Following informed consent, respondents were interviewed with a short questionnaire about 30 questions and agreed to take a blood draw for HIV test. Results: Overall, 7%, 3%, and 2.3% of FSWs used drugs, of whom 82%, 81%, and 70% had injected drug in the past month in 2010, 2011, and 2012 respectively. HIV prevalence among drug injecting FSWs was 29%, 22%, and 15.5% vesus HIV prevalence among overall FSWs was 4%, 2.9%, 2.7% in 2010, 2011, and 2012 respectively. The last sex condom use with client was 88.0%, 90.0%, 88.9% in 2010, 2011, and 2012. Among those injecting FSW, clean syringe needles use in the last injection was 97.5%, 92.3%, and 94.7% in 2010 and 2011. Receiving free condom in the last month was 81%, 78%, and 58.7% in 2010, 2011, and 2012. Receiving free needles among drug injecting FSWs were 46%, 58%, and 54% in 2010, 2011, and 2012. Receiving STI screening in the last 3 months was 47.3%, 32.0%, and 50.0% in 2010, 2011, and 2012. Knowing HIV test result in the last test was 52.1%, 54.3%, and 40% in 2010, 2011, and 2012. Conclusions: HIV prevalence among injecting FSWs was much higher than among overall FSWs and closely related to drug injection. Harm reduction programs was in place but the coverage was at low level especially among injecting drug FSWs. HIV prevention efforts should increase and focus on injecting FSWs. The application of integrating a short behavioral questionnaire into HSS provides essential information for planning and evaluation.
    Full-text · Conference Paper · Jul 2014
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    ABSTRACT: An estimated 120,000 HIV-associated cryptococcal meningitis (CM) cases occur each year in South and Southeast Asia; early treatment may improve outcomes. The World Health Organization (WHO) recently recommended screening HIV-infected adults with CD4<100 cells/mm(3) for serum cryptococcal antigen (CrAg), a marker of early cryptococcal infection, in areas of high CrAg prevalence. We evaluated CrAg prevalence and cost-effectiveness of this screening strategy in HIV-infected adults in northern and southern Vietnam. Serum samples were collected and stored during 2009-2012 in Hanoi and Ho Chi Minh City, Vietnam, from HIV-infected, ART-naïve patients presenting to care in 12 clinics. All specimens from patients with CD4<100 cells/mm(3) were tested using the CrAg lateral flow assay. We obtained cost estimates from laboratory staff, clinicians and hospital administrators in Vietnam, and evaluated cost-effectiveness using WHO guidelines. Sera from 226 patients [104 (46%) from North Vietnam and 122 (54%) from the South] with CD4<100 cells/mm(3) were available for CrAg testing. Median CD4 count was 40 (range 0-99) cells/mm(3). Nine (4%; 95% CI 2-7%) specimens were CrAg-positive. CrAg prevalence was higher in South Vietnam (6%; 95% CI 3-11%) than in North Vietnam (2%; 95% CI 0-6%) (p = 0.18). Cost per life-year gained under a screening scenario was $190, $137, and $119 at CrAg prevalences of 2%, 4% and 6%, respectively. CrAg prevalence was higher in southern compared with northern Vietnam; however, CrAg screening would be considered cost-effective by WHO criteria in both regions. Public health officials in Vietnam should consider adding cryptococcal screening to existing national guidelines for HIV/AIDS care.
    Full-text · Article · Apr 2013 · PLoS ONE
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    ABSTRACT: : Decreased memory B-cell maintenance during HIV-1 infection has been associated with the viraemia-induced accumulation of activated memory B cells, sensitive to Fas-mediated apoptosis. We aimed at clarifying whether other B-cell subsets might also be affected by an increased Fas expression in HIV-1-infected patients, and we studied the possible contribution of viraemia, lymphopenia or T-cell activation in Fas upregulation on B cells. We analysed whether Fas upregulation might have collaborative effects with the dysregulation of other B-cell modulatory molecules, leukocyte-associated immunoglobulin-like receptor 1 (LAIR1) and programmed cell death protein 1 (PD-1), on B-cell homeostasis. : Fas, LAIR1 and PD-1 were analysed on B-cell subpopulations in HIV-1-infected patients who were treatment naive, nonlymphopenic; antiretroviral therapy (ART)-treated, nonlymphopenic; or ART-treated, lymphopenic or in noninfected controls. : Flow cytometry was used to study B-cell subsets and Milliplex for serum cytokines. : Fas expression increased on all B-cell subpopulations of viraemic or lymphopenic individuals. The decreased ratio of resting memory B cells and their increased Fas expression were not normalized by ART. Cytokines associated with T-cell activation might influence Fas expression on the naive and transitional B cells. LAIR1 expression decreased in all HIV-1-infected patients, but only on memory B cells, whereas PD-1 increased on resting memory B cells in viraemic patients. : Fas is regulated by the concerted action of viraemia, lymphopenia and T-cell activation during HIV-1 infection, and Fas expression is altered on all peripheral B-cell subsets. Resting memory B-cell homeostasis shows the highest sensitivity to HIV-1-induced perturbations.
    No preview · Article · Jan 2013 · AIDS (London, England)
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    ABSTRACT: One important pathogenic feature of human immunodeficiency virus (HIV)-1 infection is chronic immune activation and impaired survival of T and B cells. A decline of resting memory B cells was reported to occur in both children and adults infected with HIV-1; these cells are responsible for maintaining an adequate serological response to antigens previously encountered in life through natural infection or vaccination. Further understanding of the mechanisms leading to impaired B cell differentiation and germinal center reaction might be essential to design new HIV vaccines and therapies that could improve humoral immune responses in HIV-1 infected individuals. In the present article we summarize the literature and present our view on critical mechanisms of B cell development impaired during HIV-1 infection. We also discuss the impact of microbial translocation, a driving force for persistent inflammation during HIV-1 infection, on survival of terminally differentiated B cells and how the altered expression of cytokines/chemokines pivotal for communication between T and B cells in lymphoid tissues may impair formation of memory B cells.
    Full-text · Article · Jan 2011 · Frontiers in Immunology
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    P H Thang · N Ruffin · D Brodin · B Rethi · P D Cam · N T Hien · L Lopalco · N Vivar · F Chiodi
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    ABSTRACT: Interleukin (IL)-7 is a key cytokine in T-cell homeostasis. Stromal cells, intestinal epithelial cells and keratinocytes are known to produce this cytokine. The mechanisms and cellular factors regulating IL-7 production are still unclear. We assessed whether IL-1beta and interferon (IFN)-gamma, cytokines produced during inflammatory conditions, may impact on IL-7 production. We used human intestinal epithelial cells (DLD-1 cell line) and bone marrow stromal cells (HS27 cell line), known to produce IL-7; IL-7 production was evaluated at the mRNA and protein levels. To assess whether treatment of HS27 cells with IL-1beta and/or IFN-gamma leads to changes in the gene expression of cytokines, Toll-like receptors (TLRs) and chemokines, we analysed gene expression profiles using the whole-genome microarray Human Gene 1.0 ST. We found that IFN-gamma enhanced the expression of IL-7 mRNA (P < 0.001) in both cell lines. IL-1beta treatment led to a significant down-regulation (P < 0.001) of IL-7 mRNA expression in both cell lines. The IL-7 concentration in supernatants collected from treated DLD-1 and HS27 cell cultures reflected the trend of IL-7 mRNA levels. The gene profiles revealed dramatic changes in expression of cytokines and their receptors (IL-7/IL-7R alpha; IL-1alpha,IL-1beta/IL-1R1; IFN-gamma/IFN-gammaR1), of IFN regulatory factors (IRF-1 and 2), of TLRs and of important chemo-attractants for T cells. The microarray results were verified by additional methods. Our results are discussed in the setting of inflammation and T-cell survival in the gut compartment during HIV-1 infection where stromal and epithelial cells may produce factors that contribute to impaired IL-7 homeostasis and homing of T cells.
    Full-text · Article · Apr 2010 · Journal of Internal Medicine
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    ABSTRACT: To estimate the epidemic history of HIV-1 CRF01_AE in Vietnam and adjacent Guangxi, China, we determined near full-length nucleotide sequences of CRF01_AE from a total of 33 specimens collected in 1997–1998 from different geographic regions and risk populations in Vietnam. Phylogenetic and Bayesian molecular clock analyses were performed to estimate the date of origin of CRF01_AE lineages. Our study reconstructs the timescale of CRF01_AE expansion in Vietnam and neighboring regions and suggests that the series of CRF01_AE epidemics in Vietnam arose by the sequential introduction of founder strains into new locations and risk groups. CRF01_AE appears to have been present among heterosexuals in South-Vietnam for more than a decade prior to its epidemic spread in the early 1990s. In the late 1980s, the virus spread to IDUs in Southern Vietnam and subsequently in the mid-1990s to IDUs further north. Our results indicate the northward dissemination of CRF01_AE during this time.
    Full-text · Article · Aug 2009 · Virology
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    ABSTRACT: A household-based population study interviewed 2,553 women and 1,984 men aged 15-49 years in urban (Ho Chi Minh City) and rural (Thai Binh) provinces in Viet Nam between July and August 2005. The survey response rate was high--approximately 97% of households and 93% of adults overall, with a >92% acceptance of HIV testing among eligible adults. The unadjusted estimated population HIV prevalence was 0.3% (confidence interval [CI]: 0.1-0.6%) in Thai Binh and 0.7% (CI: 0.3-1.3) in Ho Chi Minh City (HCMC), compared with the national estimates and projections of 0.352% and 1.250%, respectively, for 2005. The ratio of male-to-female prevalence was 10.5:1 in Thai Binh and 1.3:1 in HCMC. A low level of men reported purchasing sex in the last 12 months (2.4%) and there were low self-reports of sexually transmitted infections in all adults (5%). A correct knowledge of HIV/AIDS prevention methods was high in both provinces (83%), although only 24.8% of women knew of the use of antiretroviral therapy to prevent vertical transmission of HIV. The observed population prevalence was consistent with recent projections in Thai Binh, although lower than expected in HCMC, indicating the substantial downward revisions of projected population HIV prevalence may need to be extended. The unequal sex prevalence ratio is consistent with the projected trends of increasing male-to-female sexual transmission in urban areas. The results and experience of this study will inform future population based surveys in Viet Nam and the broader Asian region.
    No preview · Article · Sep 2008 · AIDS research and human retroviruses
  • Nancy Vivar · Pham Hong Thang · Ann Atlas · Francesca Chiodi · Bence Rethi
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    ABSTRACT: As CD8+CD28- T cells have been associated with dendritic and T cell suppression, we analyzed whether an increase in CD8+CD28- T cell numbers during HIV-1 infection could lead to impaired T cell responses. In contrast to the in-vitro generated CD8+CD28- suppressors, peripheral blood CD8+CD28- T cells of both HIV-infected and noninfected individuals promoted dendritic cell activation. The CD8+CD28- T cell accumulation during HIV-1 infection may thus contribute to accelerated inflammatory reactions and immune activation.
    No preview · Article · May 2008 · AIDS (London, England)
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    ABSTRACT: Serum IL-7 levels correlate with T-cell depletion in HIV-infected individuals. In some patients, we observed that serum IL-7 decreases upon progression to AIDS, suggesting a role for IL-7 in T-cell maintenance in sporadic cases. Interestingly, IL-7 levels were significantly lower in stable long-term non-progressors (LTNP) than in patients who lost the LTNP status in a 3-year follow-up (P < 0.001), indicating that the serum IL-7 concentration might be a valuable marker for maintenance of the LTNP state.
    No preview · Article · May 2007 · AIDS
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    ABSTRACT: To study patterns and determinants of HIV prevalence and risk-behaviour characteristics in different population groups in four border provinces of Viet Nam. We surveyed four population groups during April-June 2002. We used stratified random-cluster sampling and collected data concomitantly on HIV status and risk behaviours. The groups included were female sex workers (n = 2023), injecting drug users (n = 1391), unmarried males aged 15-24 years (n = 1885) and different categories of mobile groups (n = 1923). We found marked geographical contrasts in HIV prevalence, particularly among female sex workers (range 0-24%). The HIV prevalence among injecting drug users varied at high levels in all provinces (range 4-36%), whereas lower prevalences were found among both unmarried young men (range 0-1.3%) and mobile groups (range 0-2.5%). All groups reported sex with female sex workers. Less than 40% of the female sex workers had used condoms consistently. The strongest determinants of HIV infection among female sex workers were inconsistent condom use (adjusted odds ratio [OR], 5.3; 95% confidence interval [CI], 2.4-11.8), history of injecting drug use and mobility, and, among injecting drug users, sharing of injection equipment (adjusted OR, 7.3; 95% CI, 2.3-24.0) and sex with non-regular partners (adjusted OR 3.4; 95% CI 1.4-8.5). The finding of marked geographical variation in HIV prevalence underscores the value of understanding local contexts in the prevention of HIV infection. Although lacking support from data from all provinces, there would appear to be a potential for sex work to drive a self-sustaining heterosexual epidemic. That the close links to serious injecting drug use epidemics can have an accelerating effect in increasing the spread of HIV merits further study.
    Full-text · Article · Feb 2007 · Bulletin of the World Health Organisation

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Publication Stats

127 Citations
39.93 Total Impact Points

Institutions

  • 2007-2015
    • National Institute of Hygiene and Epidemiology
      Hà Nội, Ha Nội, Vietnam
  • 2007-2011
    • Karolinska Institutet
      • Department of Microbiology, Tumor and Cell Biology (MTC)
      Solna, Stockholm, Sweden
  • 2008
    • Ministry of Health, Vietnam
      Hà Nội, Ha Nội, Vietnam