Climate variability and Ross River virus transmission. (33/573)

OBJECTIVES: (1) To examine the feasibility to link climate data with monthly incidence of Ross River virus (RRv). (2) To assess the impact of climate variability on the RRv transmission. DESIGN: An ecological time series analysis was performed on the data collected between 1985 to 1996 in Queensland, Australia. METHODS: Information on the notified RRv cases was obtained from the Queensland Department of Health. Climate and population data were supplied by the Australian Bureau of Meteorology and the Australian Bureau of Statistics, respectively. Spearman's rank correlation analyses were performed to examine the relation between climate variability and the monthly incidence of notified RRv infections. The autoregressive integrated moving average (ARIMA) model was used to perform a time series analysis. As maximum and minimum temperatures were highly correlated with each other (r(s)=0.75), two separate models were developed. RESULTS: For the eight major cities in Queensland, the climate-RRv correlation coefficients were in the range of 0.12 to 0.52 for maximum and minimum temperatures, -0.10 to 0.46 for rainfall, and 0.11 to 0.52 for relative humidity and high tide. For the whole State, rainfall (partial regression coefficient: 0.017 (95% confidence intervals 0.009 to 0.025) in Model I and 0.018 (0.010 to 0.026) in Model II), and high tidal level (0.030 (0.006 to 0.054) in Model I and 0.029 (0.005 to 0.053) in Model II) seemed to have played significant parts in the transmission of RRv in Queensland. Maximum temperature was also marginally significantly associated with the incidence of RRv infection. CONCLUSION: Rainfall, temperature, and tidal levels may be important environmental determinants in the transmission cycles of RRv disease.  (+info)

A parvo-like virus in cultured redclaw crayfish Cherax quadricarinatus from Queensland, Australia. (34/573)

In the summer of 1999/2000, an epizootic occurred in cultured juvenile redclaw crayfish Cherax quadricarinatus on one commercial crayfish farm in northern Queensland, Australia. Mortalities occurred over 4 wk, with up to 96% cumulative mortalities in 2 earthen ponds stocked with juveniles. The crayfish were weak, anorexic and lethargic. A transmission trial was conducted, using filtered, cell-free extract prepared from infected crayfish as inoculum. The disease was reproduced, with on-going mortalities occurring in inoculated crayfish over 55 d. Experimentally inoculated crayfish showed gross signs of malaise, anorexia and disorientation before dying. Two types of intranuclear inclusion bodies (INIBs) were seen in tissues of endodermal, ectodermal and mesodermal origin by light microscopy with haematoxylin and eosin (H&E) stained sections. 'Early'-stage INIBs were eosinophilic, rounded and located centrally within slightly enlarged nuclei while 'late'-stage INIBs were well-rounded and deeply basophilic. The gills, cuticular epithelium and epithelial cells of the foregut, midgut and hindgut were the most heavily infected tissues. By transmission electron microscopy, virions with an average diameter of 19.5 nm were seen within electron-dense granular inclusion bodies within enlarged nuclei of both naturally and experimentally infected crayfish. The size of the virions and cytopathology are consistent with characteristics of viruses in the Family Parvoviridae. This is the first reported case of mass mortality caused by a parvo-like virus infection in C. quadricarinatus.  (+info)

Vertical transmission of gill-associated virus (GAV) in the black tiger prawn Penaeus monodon. (35/573)

Chronic gill-associated virus (GAV) infection is endemic in Penaeus monodon broodstock captured from north-east Queensland in Australia and in farmed shrimp produced from these. We investigated the role of vertical transmission in perpetuating the high prevalence of these chronic GAV infections. Reverse transcription (RT)-nested PCR detected GAV in spermatophores and mature ovarian tissue from broodstock and in fertilized eggs and nauplii spawned from wild-fertilized females. In laboratory-reared P. monodon (> 12 mo old) that had a high mortality rate, RT-nested PCR detected GAV in male spermatophores at levels significantly higher than that detected in the lymphoid organ. By transmission electron microscopy (TEM), GAV virions were detected in spermatophore seminal fluid, but not sperm cells. Histological evidence of hypertrophied cell foci (spheroids) and TEM observation of GAV nucleocapsids and virions in spheroid cells was also found in 100% of lymphoid organs of approximately 1.2 g juvenile P. monodon reared in the laboratory from postlarvae collected from commercial hatcheries. Sequence analysis of PCR amplicons from parental P. monodon and fertilized eggs of artificially inseminated broodstock indicated that GAV associated with eggs can originate from both the male and female parents. Although the female GAV genotype was predominant in eggs, there was some dependence on infection levels in the male and female shrimp as indicated by RT-PCR. RT-nested PCR data on GAV levels in eggs, nauplii, protozoea and PL5 progeny of the artificial matings suggests that vertically transmitted virus is most probably associated with the egg surface.  (+info)

Behavior of caregivers to protect their infants from exposure to the sun in Queensland, Australia. (36/573)

Exposure to the sun by infants has been demonstrated to increase the risk of the development of melanoma and other skin cancers later in life. A cohort of 508 women who delivered healthy Caucasian babies were followed up at 1 year to determine their knowledge, attitudes and practices regarding sun protection towards themselves and their child. In addition, the 1-year-old infants were assessed by a trained nurse for the number of nevi they had on their skin. Results indicate caregivers reported a high level of sun-protection practices towards their child, with 93% of the caregivers reporting usually or always placing the child in the shade when going outside. Further, 81% of the caregivers reported usually or always placing a hat on the child, while 64% reported usually or always applying sunscreen to the child's exposed skin. Interestingly, only 61% of the caregivers reported that they stayed in the shade to reduce sun exposure and only 42% wore a hat when out in the sun. Mother's own personal sun-protection methods predicted the method of sun protection that she would most likely use for the child. While children appear to be reasonably protected from the sun, they are influenced by their mother's own behaviors.  (+info)

Detection of Chlamydia trachomatis in an Australian high school student population. (37/573)

OBJECTIVE: To assess the prevalence of Chlamydia trachomatis infections among an Australian high school adolescent population. METHODS: Over a 4 year period, 14 high schools were selected in which an infertility prevention programme targeting C. trachomatis was delivered to senior student populations. Coded first catch urine specimens were analysed by Amplicor PCR and infected students treated. Data retrospectively obtained from chlamydia screening programmes conducted among disadvantaged young people detached from formal education were also collated for comparison. RESULTS: Of a total student test population of 1174, 15 (1.3%; 95% CI 0.7% to 2.1%) were diagnosed with C. trachomatis. Of 516 females and 658 males, 12 (2.3%; 95% CI 1.1% to 4.1%) and 3 (0.5%; 95% CI 0.1% to 1.4%) were tested positive respectively. Data collated for three populations of disadvantaged youth returned at total of 89 C. trachomatis infections out of 560 people (15.9% 95%CI 13.0-19.2%). CONCLUSION: The overall prevalence of C. trachomatis infection among this population of senior high school adolescents is low, and significantly differs from the higher chlamydia rates detected in disadvantaged adolescents detached from formal schooling (p<0.0001).  (+info)

A survey of skin disease among patients in an Australian nursing home. (38/573)

Although the number of nursing homes is increasing in Australia, few studies have investigated the dermatologic condition of their patients. To address this issue, we conducted one of the first skin disease investigations of nursing home residents in Queensland, Australia. METHODS: Our predominant data source was the attending physicians' medical reports, which are updated monthly following their physical examination of each patient. Specialist podiatrists' monthly progress notes were also used as were daily nursing reports. RESULTS: Just over half the patients (54.4%) had at least one skin disease registered among their medical records. Xerosis (dry skin) was the most common affliction, affecting 29.5% of the patients, followed by onychomycosis (tinea unguium) at 22.5% and dermatitis (8.9%). Skin cancer was recorded in 4.9%, while excoriation (3.1%) and unspecified keratosis (2.2%) were slightly less common. Being bedridden was identified as a risk factor for both xerosis (OR 3.9, 95% CI 1.8-8.7) and onychomycosis (OR 18.0, 95% Cl 7.5-49.0). CONCLUSION: Overall, our research suggests that skin diseases are reasonably common among Australian nursing home patients. The presence of certain dermatologic conditions differed from other reports.  (+info)

Roof gutters: a key container for Aedes aegypti and Ochlerotatus notoscriptus (Diptera: Culicidae) in Australia. (39/573)

The contribution of roof gutters to Aedes aegypti (L.) and Ochlerotatus notoscriptus (Skuse) pupal populations was quantified for the first time in Cairns, Australia. Concurrent yard and roof surveys yielded an estimated 6,934 mosquito pupae, comprising four species. Roof gutters were an uncommon but productive source of Ae. aegypti in both wet season (n = 11) and dry season (n = 2) surveys, producing 52.6% and 39.5% of the respective populations. First story gutters accounted for 92.3% of the positive gutters. Therefore, treatment of roof gutters is a critical element in Ae. aegypti control campaigns during dengue outbreaks. In wet season yards, the largest standing crops of Ae. aegypti occurred in garden accoutrements, discarded household items, and rubbish (36.4%, 28.0%, and 20.6%, respectively). In dry season yards, rubbish produced 79.6% of the Ae. aegypti pupae. The number of Ae. aegypti pupae/person was 2.36 and 0.59 for the wet and dry season surveys, respectively.  (+info)

Different responses of Ross River virus to climate variability between coastline and inland cities in Queensland, Australia. (40/573)

AIMS: To examine the potential impact of climate variability on the transmission of Ross River virus (RRv) infection, and to assess the difference in the potential predictors of RRv incidence in coastline and inland regions, Queensland, Australia. METHODS: Information on the RRv cases notified between 1985 to 1996 was obtained from the Queensland Department of Health. Climate and population data were supplied by the Australian Bureau of Meteorology and the Australia Bureau of Statistics, respectively. The function of cross correlations was used to compute a series of correlations between climate variables (rainfall, maximum temperature, minimum temperature, relative humidity, and high tide) and the monthly incidence of RRv disease over a range of time lags. Time series Poisson regression models were performed to adjust for the autocorrelations of the monthly incidences of RRv disease and the confounding effects of seasonality, the case notification time, and population sizes. RESULTS: The cross correlation function shows rainfall, maximum temperature, minimum temperature, and relative humidity at a lag of 1-2 months and high tide in the current month were significantly associated with the monthly incidence of RRv in the coastline region. Relative humidity and rainfall at a lag of two months was also significantly associated with the monthly incidence of RRv in the inland region. The results of Poisson regressive models show that the incidence of RRv disease was significantly associated with rainfall, maximum temperature, minimum temperature, relative humidity, and high tide in the coastline region, and with rainfall and relative humidity in the inland region. There was a significant interaction between climate variables and locality in RRv transmission. CONCLUSIONS: Climate variability may have played a significant role in the transmission of RRv. There appeared to be different responses of RRv to climate variability between coastline and inland cities in Queensland, Australia. Maximum temperature appeared to exhibit a greater impact on the RRv transmission in coastline than in inland cities. Minimum temperature and relative humidity at 3 pm inland seemed to affect the RRv transmission more than at the coastline. However, the relation between climate variables and RRv needs to be viewed within a wider context of other social and environmental factors, and further research is needed.  (+info)