The respiratory infections group analysed the early progression of the epidemic of 2009 pandemic influenza (2009 H1N1) in Ho Chi Minh City, Vietnam from 26 May 2009 until the establishment of community transmission in the second half of July 2009
Data sources included all available health reports from the Ministry of Health and relevant health authorities as well as clinical and laboratory data from the first confirmed cases isolated at the Hospital for Tropical Diseases in Ho Chi Minh City. Extensive molecular diagnostics (RT-PCR) on serial samples, viral culture, susceptibility testing, and sequencing were performed on a subset of confirmed cases. Virological and epidemiological data were combined to reconstruct the initial outbreak. From 27 April to 24 July 2009, approximately 760,000 passengers who entered Ho Chi Minh City on international flights were screened at the airport by a body temperature scan and symptom questionnaire. Approximately 0.15% of incoming passengers were intercepted, 200 of whom tested positive for
2009 H1N1. An additional 121 out of 169 nontravelers tested positive after self-reporting or contact tracing. These 321 patients spent 79% of their PCR-positive days in isolation; 60% of PCR-positive days were spent treated and in isolation. Influenza-like illness was noted in 61% of patients and no patients experienced pneumonia or severe outcomes. Viral clearance times were similar among patient groups with differing time intervals from illness onset to treatment, with estimated median clearance times between 2.6 and 2.8 d post-treatment for illness-to-treatment intervals of 1–4 d, and 2.0 d (95% confidence interval 1.5–2.5) when treatment was started on the first day of illness.
The patients described here represent a cross-section of infected individuals that were identified by at the airport, as well as mildly symptomatic to moderately ill patients who self-reported to hospitals.
Data are observational and, although they are suggestive, it is not possible to be certain whether the containment efforts delayed community transmission in Vietnam. Viral clearance data showed a rapid therapeutic response to oseltamivir when given in the first four days of illness. (PLoS Med 7(5): e1000277.
doi:10.1371/journal.pmed.1000277)
Figure caption: 321 PCR-confirmed 2009 H1N1 cases and 298 PCR-negative suspected 2009 H1N1 cases admitted to hospitals in HCMC between early May 2009 and 20 July 2009. All 619 individuals are classified either as travelers (those who recently entered HCMC on a commercial flight from a foreign country) or residents; travelers are shown above the axis and residents below the axis. Graph is organized in a stacked fashion, so that the height of each colored area corresponds to the number of patients of a particular status (e.g., circulating, isolated) on a particular day. Graph is cut off on 20 July 2009 as the data were more sparse after this date.
Miss Duy An received an MSc from the University of Science, Ho Chi Minh City, in November 2009. Her research project , which was conducted at OUCRU, has been on fluoroquinolone resistance mechanisms in Mycobacterium tuberculosis. As resistance to the classic first line drugs for TB becomes more widespread, fluoroquinolones are increasingly important drugs in TB treatment and are currently under trial for use in first line regimens. However, resistance has already been documented and is an important step in the generation of extremely drug resistant T B (XDR TB), which is very difficult to treat. Duy An has been working on mechanisms of fluoroquinolone resistance in isolates from Vietnam and the relationship between fluoroquinolone resistance mechanisms, MIC and bacterial genotype in Mycobacterium tuberculosis. She has published 2 papers on this work: (1) Duong, D.A., et al., Antimicrob Agents Chemother, 2009. 53(11): p. 4835-9 and (2) van Doorn, H.R., et al. Int J Tuberc Lung Dis, 2008. 12(7): p. 736-42
Ms Hong Duyen received an MSc from the University of Science, Ho Chi Minh City in March 2010. Her research project, which was conducted at OUCRU, has been developing Variable number tandem repeat typing (VNTR) optimised to Vietnamese isolates of Mycobacterium tuberculosis. Classic genotyping techniques for M.tuberculosis- RFLP and spoligotyping- are poorly discriminartory for the major clades of Mycobacterium tuberculosis found in Vietnam, the Indo-Oceanic and Beijing genotyopes. This hampers efforts to understand virulence and transmission patterms of M.tuberculosis here. Her project has shown that VNTR typing can significantly improve discriminatory power of M.tuberculosis typing and will contribute to future work on virulence and transmission in Asian isolates of M.tuberculosis. Hong Duyen has been an author on several publications: (1) Caws, M., et al., PLoS Pathog, 2008. 4(3): p. e1000034. (2)Caws, M., et al. J Clin Microbiol, 2006. 44(11): p. 3934-9.(3) Duong, D.A., et al., Antimicrob Agents Chemother, 2009. 53(11): p. 4835-9.(4) Thwaites, G., et al. J Clin Microbiol, 2008. 46(4): p. 1363-8.