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Ross River (ross + river)
Selected AbstractsCritical review of the vector status of Aedes albopictusMEDICAL AND VETERINARY ENTOMOLOGY, Issue 3 2004N. G. Gratz Abstract., The mosquito Aedes (Stegomyia) albopictus (Skuse) (Diptera: Culicidae), originally indigenous to South-east Asia, islands of the Western Pacific and Indian Ocean, has spread during recent decades to Africa, the mid-east, Europe and the Americas (north and south) after extending its range eastwards across Pacific islands during the early 20th century. The majority of introductions are apparently due to transportation of dormant eggs in tyres. Among public health authorities in the newly infested countries and those threatened with the introduction, there has been much concern that Ae. albopictus would lead to serious outbreaks of arbovirus diseases (Ae. albopictus is a competent vector for at least 22 arboviruses), notably dengue (all four serotypes) more commonly transmitted by Aedes (Stegomyia) aegypti (L.). Results of many laboratory studies have shown that many arboviruses are readily transmitted by Ae. albopictus to laboratory animals and birds, and have frequently been isolated from wild-caught mosquitoes of this species, particularly in the Americas. As Ae. albopictus continues to spread, displacing Ae. aegypti in some areas, and is anthropophilic throughout its range, it is important to review the literature and attempt to predict whether the medical risks are as great as have been expressed in scientific journals and the popular press. Examination of the extensive literature indicates that Ae. albopictus probably serves as a maintenance vector of dengue in rural areas of dengue-endemic countries of South-east Asia and Pacific islands. Also Ae. albopictus transmits dog heartworm Dirofilaria immitis (Leidy) (Spirurida: Onchocercidae) in South-east Asia, south-eastern U.S.A. and both D. immitis and Dirofilaria repens (Raillet & Henry) in Italy. Despite the frequent isolation of dengue viruses from wild-caught mosquitoes, there is no evidence that Ae. albopictus is an important urban vector of dengue, except in a limited number of countries where Ae. aegypti is absent, i.e. parts of China, the Seychelles, historically in Japan and most recently in Hawaii. Further research is needed on the dynamics of the interaction between Ae. albopictus and other Stegomyia species. Surveillance must also be maintained on the vectorial role of Ae. albopictus in countries endemic for dengue and other arboviruses (e.g. Chikungunya, EEE, Ross River, WNV, LaCrosse and other California group viruses), for which it would be competent and ecologically suited to serve as a bridge vector. [source] Population structure of the peridomestic mosquito Ochlerotatus notoscriptus in AustraliaMEDICAL AND VETERINARY ENTOMOLOGY, Issue 2 2004D. H. Foley Abstract.,Ochlerotatus notoscriptus (Skuse) (Diptera: Culicidae) is the predominant peridomestic mosquito in Australia where it is the primary vector of dog heartworm, Dirofilaria immitis (Leidy), and a potentially important vector of arboviruses (Barmah Forest, Ross River) with geographical variation of vector competence. Although widespread, Oc. notoscriptus has low dispersal ability, so it may have isolated subpopulations. The identification of gene flow barriers may assist in understanding arbovirus epidemiology and disease risk, and for developing control strategies for this species. We investigated the population structure of Oc. notoscriptus from 17 sites around Australia, using up to 31 putative allozyme loci, 11 of which were polymorphic. We investigated the effect of larval environment and adult morphology on genetic variation. At least five subpopulations were found, four in New South Wales (NSW) and one unique to Darwin. Perth samples appear to be a product of recent colonization from the Australian east coast. For NSW sites, a Mantel test revealed an isolation by distance effect and spatial autocorrelation analysis revealed an area of effective gene flow of 67 km, which is high given the limited dispersal ability of this species. No consistent difference was observed between ,urban' and ,sylvan' habitats, which suggests frequent movement between these sites. However, a finer-scaled habitat study at Darwin revealed small but significant allele frequency differences, including for Gpi. No fixed allozyme differences were detected for sex, size, integument colour or the colour of species-diagnostic pale scales on the scutum. The domestic habit of Oc. notoscriptus and assisted dispersal have helped to homogenize this species geographically but population structure is still detectable on several levels associated with geographical variation of vector competence. [source] Environmental and entomological factors determining Ross River virus activity in the River Murray Valley of South AustraliaAUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH, Issue 3 2009Craig R. Williams Abstract Objectives: 1) To determine whether environmental and mosquito abundance variables could be used to explain fluctuations in the activity of Ross River (RR) virus, in the River Murray Valley of South Australia (SA). 2) To develop models at the local government spatial scale to understand local variability in RR activity factors. Method: Notification data of RR virus positive serology, mosquito surveillance, meteorological and river height data were analysed for the period 1999 to 2006. Stepwise multiple regression was used to determine significant environmental factors and to create descriptive models. Results: The three models developed for different regions of the Valley explained significant amounts of variation in notification rates (R2 0.77 , 0.98). Regional variation in the models was observed, with differences in significant mosquito species evident. Rainfall was a significant predictor of RR virus activity in two of the models, while the height of the River Murray was significant in the third. An overall model for the entire SA section of the Valley contained only time-lagged mosquito abundance variables (R2 0.52). Conclusion: Although rainfall, river height and mosquito abundance are significant factors in determining RR virus activity, there are regional differences in this relationship. Implications: The regional variability of RR virus activity drivers has been defined, and has implications for the forecasting of future activity in this part of SA. The models provided here can provide the foundation for an effective RR virus early warning system, but only if criteria for action, lines of responsibility and the resources required have been determined. [source] Spatial distribution of vectors of Ross River virus and Barmah Forest virus on Russell Island, Moreton Bay, QueenslandAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 4 2002Jason AL Jeffery Abstract We used a network of 20 carbon dioxide- and octenol-supplemented light traps to sample adult mosquitoes throughout Russell Island in southern Moreton Bay, south-east Queensland. Between February and April 2001, an estimated 1365 564 adult female mosquitoes were collected. In contrast to an average catch of 9754 female mosquitoes per trap night on Russell Island, reference traps set on Macleay Island and on the mainland returned average catches of 3172 and 222, respectively. On Russell Island, Ochlerotatus vigilax (Skuse), Coquillettidia linealis (Skuse), Culex annulirostris Skuse and Verrallina funerea (Theobald), known or suspected vectors of Ross River (RR) and/or Barmah Forest (BF) viruses, comprised 89.6% of the 25 taxa collected. When the spatial distributions of the above species were mapped and analysed using local spatial statistics, all were found to be present in highest numbers towards the southern end of the island during most of the 7 weeks. This indicated the presence of more suitable adult harbourage sites and/or suboptimal larval control efficacy. As immature stages and the breeding habitat of Cq. linealis are as yet undescribed, this species in particular presents a considerable impediment to proposed development scenarios. The method presented here of mapping the numbers of mosquitoes throughout a local government area allows specific areas that have high vector numbers to be defined. [source] Vector competence of Coquillettidia linealis (Skuse) (Diptera: Culicidae) for Ross River and Barmah Forest virusesAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 4 2002Jason AL Jeffery AbstractCoquillettidia linealis is a severe pest on some of the Moreton Bay islands in Queensland, Australia, but little is known of its breeding habitats and biology. Because of its high abundance and its association with Ross River (RR) and Barmah Forest (BF) viruses by field isolation, its vector competence was evaluated in the laboratory by feeding dilutions of both viruses in blood. For RR, Cq. linealis was of comparable efficiency to Ochlerotatus vigilax (Skuse), recognised as being a major vector. Results were as follows for Cq. linealis and Oc. vigilax, respectively: dose to infect 50%, 102.2 and <101.7 CCID50/mosquito; 88% and 90% disseminated infection at 4 days postinfection; transmission at 4 days with rates of 68,92% and 25,60%. For BF dose to infect 50%, 102.7 and 102.0; disseminated infection rates on first transmission day (day 6), 40% and 70%; transmission rates of 8,16% and 0,10%. As a capillary-tube method was used rather than suckling mice to demonstrate transmission, transmission rates may be underestimates. This, the first study of the vector competence of Cq. linealis in Australia, demonstrates that this species deserves control on the southern Moreton Bay islands. [source] Assessment of the potential of dogs and cats as urban reservoirs of Ross River and Barmah Forest virusesAUSTRALIAN VETERINARY JOURNAL, Issue 1-2 2002AM BOYD Objective To determine whether dogs and cats are potential reservoirs of Ross River (RR) and Barmah Forest (BF) viruses Method Young seronegative female dogs and cats were experimentally exposed to the viruses using Ochlerotatus vigilax(Skuse) mosquitoes. Results Only one of the 10 dogs and one of the 10 cats exposed to RR developed neutralising antibody. None of the animals developed detectable viraemia or clinical signs. One dog and three cats exposed to BF developed neutralising antibody. In addition, a serological survey of sera obtained from domestic dogs and cats residing in the Brisbane region indicated that 23.7% and 1.3% of dogs, and 14% and 2% of cats, had neutralising antibodies to RR and BF respectively. Conclusions Although dogs and cats are exposed naturally to these viruses, and can become infected, they are unlikely to be important urban reservoirs of either virus. [source] Assessment of the potential of dogs and cats as urban reservoirs of Ross River and Barmah Forest virusesAUSTRALIAN VETERINARY JOURNAL, Issue 1 2002AM BOYD Objective To determine whether dogs and cats are potential reservoirs of Ross River (RR) and Barmah Forest (BF) viruses Method Young seronegative female dogs and cats were experimentally exposed to the viruses using Ochlerotatus vigilax(Skuse) mosquitoes. Results Only one of the 10 dogs and one of the 10 cats exposed to RR developed neutralising antibody. None of the animals developed detectable viraemia or clinical signs. One dog and three cats exposed to BF developed neutralising antibody. In addition, a serological survey of sera obtained from domestic dogs and cats residing in the Brisbane region indicated that 23.7% and 1.3% of dogs, and 14% and 2% of cats, had neutralising antibodies to RR and BF respectively. Conclusions Although dogs and cats are exposed naturally to these viruses, and can become infected, they are unlikely to be important urban reservoirs of either virus. [source] | |||||||||||||