Modelling the progression of pandemic influenza A (H1N1) in Vietnam and the opportunities for reassortment with other influenza viruses

BACKGROUND: A novel variant of influenza A (H1N1) is causing a pandemic and, although the illness is usually mild, there are concerns that its virulence could change through reassortment with other influenza viruses. This is of greater concern in parts of Southeast Asia, where the population density is high, influenza is less seasonal, human-animal contact is common and avian influenza is still endemic. METHODS: We developed an age- and spatially-structured mathematical model in order to estimate the potential impact of pandemic H1N1 in Vietnam and the opportunities for reassortment with animal influenza viruses. The model tracks human infection among domestic animal owners and non-owners and also estimates the numbers of animals may be exposed to infected humans. RESULTS: In the absence of effective interventions, the model predicts that the introduction of pandemic H1N1 will result in an epidemic that spreads to half of Vietnam's provinces within 57 days (interquartile range (IQR): 45-86.5) and peaks 81 days after introduction (IQR: 62.5-121 days). For the current published range of the 2009 H1N1 influenza's basic reproductive number (1.2-3.1), we estimate a median of 410,000 cases among swine owners (IQR: 220,000-670,000) with 460,000 exposed swine (IQR: 260,000-740,000), 350,000 cases among chicken owners (IQR: 170,000-630,000) with 3.7 million exposed chickens (IQR: 1.9 M-6.4 M), and 51,000 cases among duck owners (IQR: 24,000 - 96,000), with 1.2 million exposed ducks (IQR: 0.6 M-2.1 M). The median number of overall human infections in Vietnam for this range of the basic reproductive number is 6.4 million (IQR: 4.4 M-8.0 M). CONCLUSION: It is likely that, in the absence of effective interventions, the introduction of a novel H1N1 into a densely populated country such as Vietnam will result in a widespread epidemic. A large epidemic in a country with intense human-animal interaction and continued co-circulation of other seasonal and avian viruses would provide substantial opportunities for H1N1 to acquire new genes

Viral Etiology of Encephalitis in Children in Southern Vietnam: Results of a One-Year Prospective Descriptive Study

Viral encephalitis is associated with high morbidity and mortality in Vietnam. However little is known about the causes of the disease due to a lack of diagnostic facilities in this relatively resource-poor setting. Knowledge about the etiologies and clinical outcome of viral encephalitis is necessary for future design of intervention studies targeted at improvement of clinical management, treatment and prevention of the disease. We report the viral agents, clinical outcome and prognostic factors of mortality of encephalitis in children admitted to a referral hospital for children in southern Vietnam. We show that about one third of the enrolled patients die acutely, and that mortality is independently associated with patient age and Glasgow Coma Scale on admission. Japanese encephalitis, dengue virus and enterovirus (including enterovirus 71) are the major viruses detected in our patients. However, more than half of the patients remain undiagnosed, while mortality in this group is as high as in the diagnosed group. This study will benefit clinicians and public health in terms of clinical management and prevention of childhood encephalitis in Vietnam

Reentrant nematic and columnar phases in disc-like liquid crystals at atmospheric pressure

We describe the first example of reentrant ND nematic and D r columnar mesophases at atmospheric pressure in a pure disc-like compound.Un composé discoïde présente, pour la première fois, deux mésophases « rentrantes » à la pression atmosphérique : une phase nématique ND et une phase en colonne Dr

Phasmids : a new class of liquid crystals

Two hexa-alkoxy derivatives (7a and 7b) of terephthal-bis-[4-benzoyloxyaniline] are described. They exhibit two new types of mesophase for which the term phasmidic is proposed : one has an hexagonal 2D lattice and the second an oblique 2D lattice.On décrit deux dérivés hexa alcoxy de la téréphtal-bis-[benzoyloxy-4-aniline] 7a et 7b. Ils présentent deux nouveaux types de mésophases pour lesquelles le qualificatif (phases) phasmidiques est proposé. L'une de ces mésophases possède un réseau bidimensionnel hexagonal, l'autre un réseau bidimensionnel oblique

Biforked mesogens : a new type of thermotropic liquid crystals

Some biforked mesogens belonging to five series were prepared and studied. They exhibit an interesting polymorphism in which both columnar and lamellar mesomorphic orders coexist at different temperatures. The short chains lead to the classical nematic phase and/or the smectic C phase. The long ones give evidence of a hexagonal columnar mesophase similar to the Φh phasmidic phase. One cyclohexane derivative shows a body centered cubic phase and a hexagonal columnar phase with a large lattice parameter corresponding to twice the molecular length .On décrit quelques mésogènes bifourchus dérivant des cinq séries : téréphtalates (IlIa) et transcyclohexanedicarboxylates-1 4 (IIIb) de bis-[(dialcoxy-3,4 benzoyloxy)-4'phényle], téréphtalates (IIIc) et trans-cyclohexanedicarboxylates-1,4 (IIId) de bis-[N-(dialcoxy-3,4 benzylidène)amino-4' phényle] et téréphtal-bis-[(dialcoxy-3,4 benzoyloxy)-4' aniline] (IIIe ). Ils présentent un polymorphisme original où coexistent phases colonnaires et phases lamellaires à des températures différentes. La phase nématique et/ou la phase smectique C s'observent avec les composés à chaînes courtes, tandis que les composés à chaînes longues présentent une phase colonnaire hexagonale semblable à celle des phasmides (Φh). Une phase cubique centrée et une phase hexagonale à grand paramètre (égal à deux longueurs moléculaires) sont observées chez un dérivé du cyclohexane

Nouvelle série de mésogènes à phase smectique F. Ordre de succession des smectiques

Four new compounds exhibit smectic B, F, C and nematic phases. The smectic mesophases follow each other in the order E, G, B, F, C, D, A when the temperature increases.Quatre composés nouveaux présentent des phases smectiques B, F, C et nématiques. Les mésophases smectiques se succèdent dans l'ordre E, G, B, F, C, D, A quand la température croît

On the rectangular-hexagonal columnar phase transition in disc-like liquid crystals

We report the isobaric binary phase diagram for two disc-like mesogens, hexa-n-octyloxytriphenylene and hexa-n-octanoyloxytriphenylene, which was studied by means of optical texture observations, differential scanning calorimetry and X-ray diffraction measurements. They all confirm the presence of a direct transition between an hexagonal ordered columnar phase and a rectangular disordered columnar phase; this kind of transition is also described in a pure disc-like mesogen : hexa-n-decanoate of truxene. Furthermore we show, within the binary phase diagram, a strongly non-ideal behaviour with a marked maximum of the spindle between the isotropic and the mesomorphic phase. The existence domain of the hexagonal ordered phase versus temperature and concentration is discussed from a structural point of view.Le diagramme binaire isobare pour deux mésogènes discoïdes, l'hexa-n-octyloxytriphénylène et l'hexa-n-octanoyloxytriphénylène, est étudié par l'examen des textures optiques, l'analyse enthalpique différentielle et la diffraction des rayons X. Ces trois techniques confirment l'existence d'une transition directe entre mésophase en colonnes hexagonale ordonnée et mésophase en colonnes rectangle désordonnée ; ce type de transition est également décrit dans un corps pur discoïde : l'hexa-n-décanoate de truxène. Par ailleurs on révèle, dans le diagramme binaire, un comportement fortement non-idéal avec la présence d'un fuseau à maximum à la transition colonne-isotrope. Le domaine d'existence de la phase en colonnes hexagonale ordonnée dans un espace concentration-température est discuté d'un point de vue structural