Peruvian horse sickness virus and Yunnan orbivirus, isolated from vertebrates and mosquitoes in Peru and Australia.

During 1997, two new viruses were isolated from outbreaks of disease that occurred in horses, donkeys, cattle and sheep in Peru. Genome characterization showed that the virus isolated from horses (with neurological disorders, 78% fatality) belongs to a new species the Peruvian horse sickness virus (PHSV), within the genus Orbivirus, family Reoviridae. This represents the first isolation of PHSV, which was subsequently also isolated during 1999, from diseased horses in the Northern Territory of Australia (Elsey virus, ELSV). Serological and molecular studies showed that PHSV and ELSV are very similar in the serotype-determining protein (99%, same serotype). The second virus (Rioja virus, RIOV) was associated with neurological signs in donkeys, cattle, sheep and dogs and was shown to be a member of the species Yunnan orbivirus (YUOV). RIOV and YUOV are also almost identical (97% amino acid identity) in the serotype-determining protein. YUOV was originally isolated from mosquitoes in China.

Contributions of woody and herbaceous vegetation to tropical savanna ecosystem productivity: a quasi-global estimate.

To estimate the relative contributions of woody and herbaceous vegetation to savanna productivity, we measured the 13C/12C isotopic ratios of leaves from trees, shrubs, grasses and the surface soil carbon pool for 22 savannas in Australia, Brazil and Ghana covering the full savanna spectrum ranging from almost pure grassland to closed woodlands on all three continents. All trees and shrubs sampled were of the C3 pathway and all grasses of the C4 pathway with the exception of Echinolaena inflexa (Poir.) Chase, a common C3 grass of the Brazilian cerrado. By comparing the carbon isotopic compositions of the plant and carbon pools, a simple model relating soil delta 13C to the relative abundances of trees + shrubs (woody plants) and grasses was developed. The model suggests that the relative proportions of a savanna ecosystem's total foliar projected cover attributable to grasses versus woody plants is a simple and reliable index of the relative contributions of grasses and woody plants to savanna net productivity. Model calibrations against woody tree canopy cover made it possible to estimate the proportion of savanna productivity in the major regions of the world attributable to trees + shrubs and grasses from ground-based observational maps of savanna woodiness. Overall, it was estimated that 59% of the net primary productivity (Np) of tropical savannas is attributable to C4 grasses, but that this proportion varies significantly within and between regions. The C4 grasses make their greatest relative contribution to savanna Np in the Neotropics, whereas in African regions, a greater proportion of savanna Np is attributable to woody plants. The relative contribution of C4 grasses in Australian savannas is intermediate between those in the Neotropics and Africa. These differences can be broadly ascribed to large scale differences in soil fertility and rainfall.

Suicide, assisted suicide and euthanasia: international perspectives.

Suicide, assisted suicide and euthanasia are elusive and controversial issues worldwide. To discuss such issues from only one perspective may be limiting. Therefore, this paper was written by authors from various regions, each of whom has been asked to reflect on the issues. The countries/cultures are: Australia, China, Cuba, Ireland, India, Japan, Russia, South Africa, The Netherlands, North America (Turtle Island) and United States. Historically and today, suicide is viewed differently. Assisted suicide and euthanasia are equally seen from multifarious perspectives. Highlighting development in the Netherlands, Australia's Northern Territory and Japan (ie. the famous Yamanouchi Case), the review shows growing re-examination of the right to die. There appear, however, to be no uniform legal and ethical positions. Further debate and discussion globally is needed to avoid myopic perspectives.

Two cases of mycetoma due to Nocardia brasiliensis in central Australia.

Comparatively few cases of mycetoma ("Madura foot") have been reported in Australia, and only one caused by Nocardia brasiliensis. We report two Aboriginal women from remote communities in central Australia who presented with longstanding mycetomas caused by this organism. Difficulties in diagnosis substantially delayed commencement of effective treatment, illustrating the need to consider this condition in chronic suppurative skin infection.

Genetically distinct dog-derived and human-derived Sarcoptes scabiei in scabies-endemic communities in northern Australia.

Overcrowding is a significant factor contributing to endemic infection with Sarcoptes scabiei in human and animal populations. However, since scabies mites from different host species are indistinguishable morphologically, it is unclear whether people can be infected from scabies-infested animals. Molecular fingerprinting was done using three S. scabiei-specific single locus hypervariable microsatellite markers, with a combined total of 70 known alleles. Multilocus analysis of 712 scabies mites from human and dog hosts in Ohio, Panama and Aboriginal communities in northern Australia now shows that genotypes of dog-derived and human-derived scabies cluster by host species rather than by geographic location. Because of the apparent genetic separation between human scabies and dog scabies, control programs for human scabies in endemic areas do not require resources directed against zoonotic infection from dogs.