Natural Hendra virus infection in flying-foxes - tissue tropism and risk factors

Hendra virus (HeV) is a lethal zoonotic agent that emerged in 1994 in Australia. Pteropid bats (flying-foxes) are the natural reservoir. To date, HeV has spilled over from flying-foxes to horses on 51 known occasions, and from infected horses to close-contact humans on seven occasions. We undertook screening of archived bat tissues for HeV by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Tissues were tested from 310 bats including 295 Pteropodiformes and 15 Vespertilioniformes. HeV was detected in 20 individual flying-foxes (6.4%) from various tissues including spleen, kidney, liver, lung, placenta and blood components. Detection was significantly higher in Pteropus Alecto and P. conspicillatus, identifying species as a risk factor for infection. Further, our findings indicate that HeV has a predilection for the spleen, suggesting this organ plays an important role in HeV infection. The lack of detections in the foetal tissues of HeV-positive females suggests that vertical transmission is not a regular mode of transmission in naturally infected flyingfoxes, and that placental and foetal tissues are not a major source of infection for horses. A better understanding of HeV tissue tropism will strengthen management of the risk of spillover from flying-foxes to horses and ultimately humans

Defining the risk of human exposure to Australian bat lyssavirus through potential non-bat animal infection

Human infection with Australian bat lyssavirus (ABLV) was first reported in November 1996, six months after the first identification of the virus in a flying fox in May 1996. Only two human cases of ABLV infection have been described to date, although hundreds of potential human exposures to ABLV have been reported. Current public health guidance considers the risk of transmission of ABLV from a dog or cat to a person is very low. Furthermore, owners are advised that although the animal has a remote possibility of being infected with ABLV, it should be observed closely for at least three months and to report any behavioural changes that occur. The authors present two cases where the behaviour of dogs after potential exposure to ABLV posed significant questions for veterinary and public health authorities

Global-Local Finite Element Analysis

114 σ.Η αναλυτική επίλυση πολύπλοκων προβλημάτων της μηχανικής στις μέρες μας καθίσταται δυσχερής εως αδύνατη χωρίς την εφαρμογή αριθμητικών μεθόδων και τη χρήση ηλεκτρονικού υπολογιστή. Η μέθοδος των πεπερασμένων στοιχείων αποτελεί σήμερα ένα ισχυρό εργαλείο για την επίλυση τέτοιων προβλημάτων και εξελίσσεται με μεγάλη ταχύτητα τόσο σε ακαδημαϊκό όσο και σε επαγγελματικό επίπεδο. Ενδεικτικά, αν και επινοήθηκε και χρησιμοποιήθηκε για τη στατική ανάλυση φορέων, έχει καθολικότερη εφαρμογή σε μια ευρύτερη κατηγορία προβλημάτων του μηχανικού, όπως στη ρευστομηχανική, στη μεταφορά θερμότητας, στην ακουστική, στον ηλεκτρομαγνητισμό και στην εμβιομηχανική. Επιπλέον, η εξέλιξη στων Η/Υ με τις ολοένα μεγαλύτερες δυνατότητες διαχείρισης όγκου δεδομένων αλλά και με την αύξηση της ταχύτητας εκτέλεσης των αριθμητικών πράξεων κατέστησε εφικτή την επίλυση σύνθετων προβλημάτων τα οποία θεωρούνταν απροσπέλαστα πριν μερικά χρόνια. Στην κατηγορία αυτή, των προβλημάτων αυξημένου υπολογιστικού κόστους, ανήκει και η καταστατική περιγραφή πολυφασικών υλικών. Είναι γεγονός ότι το μεγαλύτερο μέρος των παραγώμενων δομικών υλικών σήμερα, παρουσιάζει κάποιο είδος ανομοιογένειας, διακριτή ή μη στην κλίμακα δομικών έργων. Χαρακτηριστικά παραδείγματα αποτελούν τα κράματα μετάλλων, τα πορώδη, τα πολυκρυσταλλικά και τα σύνθετα υλικά στα οποία το μέγεθος, το σχήμα και οι ιδιότητες των συστατικών τους μερών καθορίζουν άμεσα τη συνολική τους μηχανική συμπεριφορά. Διάφορες τεχνικές έχουν αναπτυχθεί για την προσομοίωση και την περιγραφή της απόκρισης ανομοιογενών υλικών. Η παρούσα εργασία επικεντρώνεται στη μέθοδο ομογενοποίησης πολλαπλών κλιμάκων η οποία συνίσταται στην επίλυση δύο εμφωλευμένων προβλημάτων συνοριακών τιμών, για τη μακροκλίμακα και τη μικροκλίμακα αντίστοιχα. Τα βασικά χαρακτηριστικά μιας τέτοιας μεθόδου είναι ότι - Δεν απαιτείται η περιγραφή των καταστατικών νόμων του μακροφορέα. - Παρέχει τη δυνατότητα ενσωμάτωσης μεγάλων παραμορφώσεων και στροφών τόσο στην προσομοίωση της μικροκλίμακας όσο και του μακροφορέα. - Παρέχει τη δυνατότητα λεπτομερούς προσομοίωσης των συστατικών μερών της μικροκλίμακας. - Επιτρέπει οποιαδήποτε τεχνική επίλυσης στην κλίμακα του μικροφορέα. Αναλυτικά, σύμφωνα με τη μέθοδο αυτή. υπολογίζεται το διάνυσμα ανηγμένων παραμορφώσεων σε κάθε υλικό σημείο του μακροφορέα το οποίο στη συνέχεια χρησιμοποιείται για τη μόρφωση των συνοριακών συνθηκών του αντιπροσωπευτικού μικροφορέα στο αντίστοιχο σημείο. Μετά την επίλυση του προβλήματος συνοριακών τιμών της μικροκλίμακας, το διάνυσμα των τάσεων του μακροφορέα υπολογίζεται μέσα από τη διαδικασία ομογενοποίησης του πεδίου των τάσεων και κατά τον τρόπο αυτό υπολογίζεται η σχέση τάσεων ανηγμένων παραμορφώσεων για κάθε υλικό σημείο Ωστόσο, υπάρχουν κάποιοι περιορισμοί στην εφαρμογή της εν λόγω υπολογιστικής τεχνικής. Συγκεκριμένα, παρά το ότι κατά την προσομοίωση λαμβάνονται υπ' όψην οι διάφορες παράμετροι της μικροκλίμακας όπως το ποσοστό όγκου, η κατανομή και η μορφολογία των συστατικών μερών του υλικού, τα αποτελέσματα της μεθόδου είναι ανεξάρτητα από το απόλυτο μέγεθος του αντιπροσωπευτικού όγκου της μικροκλίμακας. Παρ' όλα αυτά, η τεχνική ομογενοποίησης στα πλαίσια ανάλυσης πολλαπλών κλιμάκων αποτελεί ένα σημαντικό εργαλείο για τον υπολογισμό των καταστατικών σχέσεων πολυφασικών υλικών στα οποία είναι αδύνατη η εφαρμογή οποιασδήποτε άλλης μεθόδου.Nowadays, analysis of complicated problems in the domain of mechanics consti- tutes a hard and even impossible task without the implementation of numerical methods and the employment of computational machines. Finite element method is a powerful tool for the solution of such problems and is rapidly developed in an academic and professional sense. Even if it was developed and implemented for structural analysis, it is widely employed in several domains such as in fluid mechanics, heat transfer, acoustics and electromagnetism. Furthermore, the development of computer hardware in terms of data processing, has significantly contributed to the solution of problems that were considered inaccessible a few years ago. Most of the materials produced in industry are heterogeneous on one or another spatial scale. Typical examples include metal alloy systems, porous media and polycrystalline materials and composites. The overall response of these micro heterogeneous materials depends strongly on the size, shape properties and spatial distribution of the microstructural components. Several techniques have been developed for the prediction of the macroscopic behavior of such materials. The present work is concentrated on the first order homogenization technique in the framework of a multi-scale approach which consists of the solution of two nested boundary value problems, for the macro-scale and the micro-scale respectively. Methods of this type - Do not require any constitutive assumption with respect to the overall ma- terial behavior. - Enable the incorporation of large deformations and rotations on both micro and macrolevel. - Provide the possibility to introduce detailed microstructural information. - Allow the use of any modelling technique at the microlevel. Concretely, according to this approach, the macroscopic deformation tensor is calculated for every integration point of the macrostructure and then is used to formulate the kinematic boundary conditions for the associated microstructural representative volume element (RVE). After the solution of the microstructural boundary value problem, the macroscopic stress tensor is computed by averaging the resulting microstructural stress field over the volume of the RVE and as a result, we obtain the stress-strain relation at every macroscopic point. However, there is a major disadvantage of the existing first-order computational homogenization. More specifically, this technique can account for the volume fraction, distribution and morphology of the micro-components however, it cannot take into account the absolute size of the microstructure making it thus impossible to treat microstructural size effects. Nevertheless, computational homogenization provides a significant strategy to obtain micro-macro structure-property relations for materials for which the overall macroscopic response cannot be computed by any other method.Κωνσταντινος Ε. Τατση

Extreme mobility of the world’s largest flying mammals creates key challenges for management and conservation

Effective conservation management of highly mobile species depends upon detailed knowledge of movements of individuals across their range; yet, data are rarely available at appropriate spatiotemporal scales. Flying-foxes (Pteropus spp.) are large bats that forage by night on floral resources and rest by day in arboreal roosts that may contain colonies of many thousands of individuals. They are the largest mammals capable of powered flight, and are highly mobile, which makes them key seed and pollen dispersers in forest ecosystems. However, their mobility also facilitates transmission of zoonotic diseases and brings them in conflict with humans, and so they require a precarious balancing of conservation and management concerns throughout their Old World range. Here, we analyze the Australia-wide movements of 201 satellite-tracked individuals, providing unprecedented detail on the inter-roost movements of three flying-fox species: Pteropus alecto, P. poliocephalus, and P. scapulatus across jurisdictions over up to 5 years

Genome Sequence Conservation of Hendra Virus Isolates during Spillover to Horses, Australia

Bat-to-horse transmission of Hendra virus has occurred at least 14 times. Although clinical signs in horses have differed, genome sequencing has demonstrated little variation among the isolates. Our sequencing of 5 isolates from recent Hendra virus outbreaks in horses found no correlation between sequences and time or geographic location of outbreaks

Evidence of Endemic Hendra Virus Infection in Flying-Foxes (Pteropus conspicillatus)—Implications for Disease Risk Management

This study investigated the seroepidemiology of Hendra virus in a spectacled flying-fox (Pteropus conspicillatus) population in northern Australia, near the location of an equine and associated human Hendra virus infection in late 2004. The pattern of infection in the population was investigated using a serial cross-sectional serological study over a 25-month period, with blood sampled from 521 individuals over six sampling sessions. Antibody titres to the virus were determined by virus neutralisation test. In contrast to the expected episodic infection pattern, we observed that seroprevalence gradually increased over the two years suggesting infection was endemic in the population over the study period. Our results suggested age, pregnancy and lactation were significant risk factors for a detectable neutralizing antibody response. Antibody titres were significantly higher in females than males, with the highest titres occurring in pregnant animals. Temporal variation in antibody titres suggests that herd immunity to the virus may wax and wane on a seasonal basis. These findings support an endemic infection pattern of henipaviruses in bat populations suggesting their infection dynamics may differ significantly from the acute, self limiting episodic pattern observed with related viruses (e.g. measles virus, phocine distemper virus, rinderpest virus) hence requiring a much smaller critical host population size to sustain the virus. These findings help inform predictive modelling of henipavirus infection in bat populations, and indicate that the life cycle of the reservoir species should be taken into account when developing risk management strategies for henipaviruses

Evidence of Endemic Hendra Virus Infection in Flying-Foxes (Pteropus conspicillatus)—Implications for Disease Risk Management

This study investigated the seroepidemiology of Hendra virus in a spectacled flying-fox (Pteropus conspicillatus) population in northern Australia, near the location of an equine and associated human Hendra virus infection in late 2004. The pattern of infection in the population was investigated using a serial cross-sectional serological study over a 25-month period, with blood sampled from 521 individuals over six sampling sessions. Antibody titres to the virus were determined by virus neutralisation test. In contrast to the expected episodic infection pattern, we observed that seroprevalence gradually increased over the two years suggesting infection was endemic in the population over the study period. Our results suggested age, pregnancy and lactation were significant risk factors for a detectable neutralizing antibody response. Antibody titres were significantly higher in females than males, with the highest titres occurring in pregnant animals. Temporal variation in antibody titres suggests that herd immunity to the virus may wax and wane on a seasonal basis. These findings support an endemic infection pattern of henipaviruses in bat populations suggesting their infection dynamics may differ significantly from the acute, self limiting episodic pattern observed with related viruses (e.g. measles virus, phocine distemper virus, rinderpest virus) hence requiring a much smaller critical host population size to sustain the virus. These findings help inform predictive modelling of henipavirus infection in bat populations, and indicate that the life cycle of the reservoir species should be taken into account when developing risk management strategies for henipaviruses

Henipavirus Infection in Fruit Bats (Pteropus giganteus), India

We tested 41 bats for antibodies against Nipah and Hendra viruses to determine whether henipaviruses circulate in pteropid fruit bats (Pteropus giganteus) in northern India. Twenty bats were seropositive for Nipah virus, which suggests circulation in this species, thereby extending the known distribution of henipaviruses in Asia westward by >1,000 km