No abstract

Vaccination of chickens with a commercially available killed H5N2 vaccine was being evaluated as an additional tool to enhanced biosecurity measures and intensive surveillance for control of highly pathogenic avian influenza subtype H5N1 disease in Hong Kong in 2002. In December 2002 to January 2003, there were outbreaks of H5N1 disease in waterfowl in two recreational parks, wild water birds, several poultry markets and five chicken farms. In addition to quarantine, depopulation of the affected sheds and increased biosecurity, vaccination of the unaffected sheds and surrounding unvaccinated farms was undertaken on three farms. In at least two farms, infection spread to the recently vaccinated sheds with low rates of H5N1 mortality in sheds when the chickens were between 9 and 18 days post-vaccination. However, after 18 days post-vaccination no more deaths from H5N1 avian influenza occurred and intensive monitoring by virus culture on these farms showed no evidence of asymptomatic shedding of the virus. This provides evidence that H5 vaccine can interrupt virus transmission in a field setting.

Faces are perceived via an orientation-dependent expert mechanism. We previously showed that inversion impaired perception of the spatial relations of features more in the lower face than in the (more salient) upper face, suggests a failure to rapidly process this type of structural data from the entire face. In this study we wished to determine if this interaction between inversion and regional salience, which we consider a marker for efficient whole-face processing, was specific to second-order (coordinate) spatial relations or also affected other types of structural information in faces. We used an oddity paradigm to test the ability of seventeen subjects to discriminate changes in feature size, feature spatial relations, and external contour in both the upper and lower face. We also tested fourteen subjects on perception of two different types of spatial relations: second-order changes that create plausible alternative faces, and illegal spatial changes that transgress normal rules of facial geometry. In both experiments we examined for asymmetries between upper-face and lower-face perceptual accuracy with brief stimulus presentations. While all structural changes were less easily discerned in inverted faces, only changes to spatial relations showed a marked asymmetry between the upper and lower face, with far worse performance in the mouth region. Furthermore, this asymmetry was found only for second-order spatial relations and not illegal spatial changes. These results suggest that the orientation-dependent face mechanism has a rapid whole-face processing capacity specific to the internal second-order (coordinate) spatial relations of facial features.