Deep vein thrombosis and air travel: record linkage study.
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OBJECTIVE: To investigate the time relations between long haul air travel and venous thromboembolism. DESIGN: Record linkage study using the case crossover approach. SETTING: Western Australia. PARTICIPANTS: 5408 patients admitted to hospital with venous thromboembolism and matched with data for arrivals of international flights during 1981-99. RESULTS: The risk of venous thromboembolism is increased for only two weeks after a long haul flight; 46 Australian citizens and 200 non-Australian citizens had an episode of venous thromboembolism during this so called hazard period. The relative risk during this period for Australian citizens was 4.17 (95% confidence interval, 2.94 to 5.40), with 76% of cases (n = 35) attributable to the preceding flight. A "healthy traveller" effect was observed, particularly for Australian citizens. CONCLUSIONS: The annual risk of venous thromboembolism is increased by 12% if one long haul flight is taken yearly. The average risk of death from flight related venous thromboembolism is small compared with that from motor vehicle crashes and injuries at work. The individual risk of death from flight related venous thromboembolism for people with certain pre-existing medical conditions is, however, likely to be greater than the average risk of 1 per 2 million for passengers arriving from a flight. Airlines and health authorities should continue to advise passengers on how to minimise risk. (+info)
Epizootic activity of Murray Valley encephalitis and Kunjin viruses in an aboriginal community in the southeast Kimberley region of Western Australia: results of mosquito fauna and virus isolation studies.
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We undertook annual surveys of flavivirus activity in the community of Billiluna in the southeast Kimberley region of Western Australia between 1989 and 2001 [corrected]. Culex annulirostris was the dominant mosquito species, particularly in years of above average rains and flooding. Murray Valley encephalitis (MVE) virus was isolated in 8 of the 13 years of the study from seven mosquito species, but more than 90% of the isolates were from Cx. annulirostris. The results suggest that MVE virus is epizootic in the region, w ith activity only apparent in years with average or above average rainfall and increased numbers of Cx. annulirostris. High levels of MVE virus activity and associated human cases were detected only once (in 1993) during the survey period. Activity of MVE virus could only be partially correlated with wet season rainfall and flooding, suggesting that a number of other factors must also be considered to accurately predict MVE virus activity at such communities. (+info)
Respiratory disease in non-smoking Western Australian goldminers.
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Respiratory symptoms, spirometry, and transfer factor were measured in 208 non-smoking Western Australian underground goldminers (mean age 32) to identify the presence of respiratory abnormalities resulting from underground work. These subjects were part of a larger group of 771 subjects attending for statutory periodic chest x ray examinations in the industry. They had worked underground for a median of three years. The prevalence odds ratios of bronchitis, dyspnoea, wheeze, and asthma all tended to be related to duration of underground employment, even after adjusting for age, those for wheeze and asthma reaching statistical significance. After adjusting for age and height the duration of employment also had a significant effect on TL/VA but not on FEV1, FVC, or TL. These changes are consistent with the presence of airway narrowing and non-specific lung fibrosis or emphysema in non-smoking underground goldminers. (+info)
Female reply strategies in a duetting Australian bushcricket, Caedicia sp. (Phaneropterinae: Tettigoniidae: Orthoptera).
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Duetting is common between the sexes of phaneropterine bushcrickets (Phaneropterinae: Tettigoniidae: Orthoptera). In this paper we describe the complex duet of an undescribed Australian species within the genus Caedicia: The male's call consists of three parts, of which the final part contains information of the species' identity and most reliably elicits the female's response. The timing of her reply usually occurs within a period of about 1 s after the male has completed his signal but may also start during the male's call. Females reply with brief clicks ranging from 1 to >10, adjusting this reply number to changes in male call duration and intensity. By using computer-synthesised calls, we discovered that the female times her reply both from cues within the male call, when she starts the reply before its conclusion, and from the end of the call, in the case where the reply follows the male call. As the number of clicks in the reply increases so the interval between clicks decreases; the female fits her entire reply within a critical time window following the male's call. The male call intensity had a marginal effect on female reply strategy. We suggest a model based on levels of female motivation, by which females may set the number of clicks in reply as well as the reply latency. (+info)
Ten-year risk of first recurrent stroke and disability after first-ever stroke in the Perth Community Stroke Study.
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BACKGROUND AND PURPOSE: Limited information exists on the long-term prognosis after first-ever stroke. We aimed to determine the absolute frequency of first recurrent stroke and disability and the relative frequency of recurrent stroke over 10 years after first-ever stroke in Perth, Western Australia. METHODS: For a 12-month period beginning February 1989, all individuals with suspected acute stroke or transient ischemic attack who lived in a geographically defined and representative region of Perth were registered prospectively. Patients with a definite first-ever stroke were followed up 10 years after the index event. RESULTS: Over 10 years of follow-up, the cumulative risk of a first recurrent stroke was 43% (95% confidence interval [CI], 34 to 51). After the first year after first-ever stroke, the average annual risk of recurrent stroke was approximately 4%. Case fatality at 30 days after first recurrent stroke was 41%, which was significantly greater than the case fatality at 30 days after first-ever stroke (22%) (P=0.003). For 30-day survivors of first-ever stroke, the 10-year cumulative risk of death or new institutionalization was 79% (95% CI, 73 to 85) and of death or new disability was 87% (95% CI, 81 to 92). CONCLUSIONS: Over 10 years of follow-up, the risk of first recurrent stroke is 6 times greater than the risk of first-ever stroke in the general population of the same age and sex, almost one half of survivors remain disabled, and one seventh require institutional care. Effective strategies for prevention of stroke need to be implemented early, monitored frequently, and maintained long term after first-ever stroke. (+info)
Prevalence of asthma in adults in Busselton, Western Australia.
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OBJECTIVE: To estimate whether the prevalence of asthma in adults increased over a nine year interval. DESIGN: Serial cross sectional studies of the population with a protocol that included both subjective and objective measurements. SETTING: Busselton, Western Australia. SUBJECTS: A random sample of 553 subjects aged 18-55 years in 1981, and of 1028 subjects aged 18-55 years in 1990. MAIN OUTCOME MEASURES: Respiratory symptoms measured by self administered questionnaire, bronchial responsiveness measured by bronchial challenge with histamine, and allergy measured by skin prick tests. RESULTS: Symptoms with increased prevalence were those with significant association with allergy in this population. Recent wheeze increased from 17.5% to 28.8% (p < 0.001) and diagnosed asthma increased from 9.0% to 16.3% (p < 0.001). The increase was greatest in subjects less than 30 years old. The prevalence of shortness of breath coming on at rest and of hay fever also increased significantly, but the prevalence of shortness of breath on exertion, chronic cough, bronchial hyperresponsiveness, current asthma (defined as recent wheeze plus bronchial hyperresponsiveness), and allergy did not increase. The severity of bronchial responsiveness did not change significantly in any symptom group. CONCLUSIONS: Young adults showed a significant increase in reporting of symptoms related to allergy but not in the prevalence of current asthma. The increase in symptoms may be due to increased awareness of asthma in this community, to changed treatment patterns, or to increased exposures to allergens. (+info)
Intestinal spirochaetes colonizing aborigines from communities in the remote north of Western Australia.
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Intestinal spirochaetal bacteria were isolated from 59 of 181 (32.6%) faecal samples obtained from Aboriginal children and a few adults living in communities in the Kimberley region in the north of Western Australia. Colonization was more common in young Aborigines between 2 and 18 years of age than it was in adults, or in babies and children less than 2 years of age. Three of 22 Aboriginal children who were sampled on two consecutive years were colonized on both occasions. None of four other children were found to be consistently colonized with the bacteria when sampled on three sequential years, but three were positive on two consecutive visits and the other child was positive on the first and third sampling. Most Aboriginal children had abnormal or watery stools, and both abnormal and watery stool samples were significantly more likely to contain spirochaetes than were normal samples. However, it was not possible to prove that the spirochaetes were the cause of the diarrhoea. In contrast, spirochaetes were only recovered from 8 of 695 (1.2%) faecal samples that were obtained from other mainly non-Aboriginal children and adults in Western Australia or the Northern Territory of Australia, even though most of these individuals were suffering from gastrointestinal disturbances. (+info)
Molecular diversity of rumen methanogens from sheep in Western Australia.
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The molecular diversity of rumen methanogens in sheep in Australia was investigated by using individual 16S rRNA gene libraries prepared from the rumen contents obtained from six merino sheep grazing pasture (326 clones), six sheep fed an oaten hay-based diet (275 clones), and five sheep fed a lucerne hay-based diet (132 clones). A total of 733 clones were examined, and the analysis revealed 65 phylotypes whose sequences (1,260 bp) were similar to those of cultivated methanogens belonging to the order Methanobrevibacter: Pasture-grazed sheep had more methanogen diversity than sheep fed either the oaten hay or lucerne hay diet. Methanobrevibacter strains SM9, M6, and NT7 accounted for over 90% of the total number of clones identified. M6 was more prevalent in grazing sheep, and SM9, despite being found in 16 of the 17 sheep, was more prevalent in sheep fed the lucerne-based diet. Five new species were identified. Two of these species exhibited very little sequence similarity to any cultivated methanogens and were found eight times in two of the six sheep that were grazing pasture. These unique sequences appear to represent a novel group of rumen archaea that are atypical for the rumen environment. (+info)