National influenza surveillance in Vietnam, 2006–2007

Nguyen, Hien Tran; Dharan, Nila; Le, Mai Thi Quynh; Nguyen, Nguyen B.; Nguyen, Chung Thanh; Hoang, Dong Van; Tran, Hau Phuc; Bui, Chien Trong; Dang, Dat Tuan; Pham, Dinh N; Nguyen, Hoa Thuy; Phan, Tu V; Dennis, David T.; Uyeki, Timothy M.; Mott, Joshua A.; Nguyen, Yen T.; Team, Evaluation

doi:10.1016/j.vaccine.2009.09.139

Cited by 34 publications

(74 citation statements)

References 17 publications

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“…Occurrence of two peaks of influenza in some years in some tropical countries can be sporadic, as seen and suggested in a recent study in Nicaragua [7 ]. The high proportion of influenza viruspositive samples demonstrated in the majority of months in short-term studies conducted in Vietnam and Cameroon is a strong indicator of year-round activity of influenza viruses in these countries, which need to be confirmed in long-term studies [13,17 ].…”

Section: Seasonality Of Influenza In Tropical Regionsmentioning

confidence: 97%

Influenza in the tropics

Moura

2010

Current Opinion in Infectious Diseases

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The seasonality of influenza is very diverse in tropical countries. Recent studies on the subject confirm the year-round activity of these viruses in many countries and the regular occurrence of epidemic outbreaks in others. The use of molecular diagnostic methods has led to prevalence rates comparable to those seen in temperate countries. Phylogenetic analysis of hemagglutinin of influenza isolates allows understanding of the evolution and divergence of avian (H5N1) and human influenza viruses (A/H1N1, A/H3N2, and B) in tropical settings. Influenza viruses resistant to oseltamivir and zanamivir have been detected in tropical countries despite the rare use of these drugs in the treatment of influenza in people living in these areas.

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Section: Seasonality Of Influenza In Tropical Regionsmentioning

confidence: 97%

Influenza in the tropics

Moura

2010

Current Opinion in Infectious Diseases

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“…A third question that has received less attention is whether syndromic influenza-like illness (ILI) surveillance has the same peaks and troughs as molecular surveillance for influenza virus in these regions. In temperate countries, public health agencies are able to rely on ILI reporting to signal the onset of the influenza season [20][21][22] , but it is not known if ILI and influenza correlate in tropical countries 23,24 .…”

Section: Introductionmentioning

confidence: 99%

“…The first one is ignoring absolute case counts and reporting only the percentage of samples (nose/throat swabs) that test positive for influenza 12,14,[24][25][26][27] . Ignoring case counts makes it impossible to determine if samples are being taken during a potential influenza season or outside of it.…”

Section: Introductionmentioning

confidence: 99%

“…Ignoring case counts makes it impossible to determine if samples are being taken during a potential influenza season or outside of it. The second one is underpowering the analysis by using a short time series or monthly data or both 23,24,[26][27][28][29][30][31][32] . Monthly data are normally too coarse to infer the presence of an annual transmission season or other periodic trends (if these exist) unless the time series is quite long.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Non-annual seasonality of influenza-like illness in a tropical urban setting

Lam

Wesolowski

Hung

et al. 2017

Preprint

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In temperate countries, influenza and other viral respiratory diseases often have distinct seasonal peaks occurring during colder, wintertime months. However, little is known about the dynamics of influenza and viral respiratory disease dynamics in the tropics, despite high morbidity and a clear epidemiological link between tropical and temperate countries. In temperate countries, the dynamics of influenza and other respiratory diseases are often analyzed using syndromic surveillance data describing influenza-like illness (ILI) as ILI is highly correlated with virological surveillance for influenza. To obtain a detailed picture of respiratory disease incidence patterns in a large tropical city, we established an mHealth study in community outpatient clinics in Ho Chi Minh City, Vietnam (11N latitude). From August 2009 through December 2015, clinics reported daily case numbers of ILI using standard mobile-phone SMS messaging. A subset of these clinics performed molecular diagnostics for influenza A and B viruses. Unlike the annual patterns seen in temperate countries, ILI activity in Ho Chi Minh City exhibited strong non-annual periodicity and was not correlated with PCR-confirmed influenza. The dominant periodicity in the data was approximately 200 days. This was confirmed by a time series decomposition, a step-wise regression analysis on annual and non-annual covariates, and a forecasting exercise showing that forecasting was 30% to 40% more accurate when a 200-day non-annual cycle was included in the forecast. This suggests, for the first-time, that a non-annual cycle may be an essential driver of ILI dynamics in the tropics. This raises new questions about the seasonality and drivers of respiratory disease transmission in tropical countries.

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“…In recent years, metal-organic coordination polymers based on metal ions and multifunctional ligands have been rapidly developed owning to their fascinating structural diversities [1,2] and potential applications in many fields such as gas absorption [3][4][5], luminescence [6,7], magnetism [8][9][10] and catalysis [11][12][13]. The rational design and construction of coordination polymers greatly depend on the judicious selection of the organic ligands and metal centers.…”

Section: Introductionmentioning

confidence: 99%