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The Pediatric Infectious Disease Journal 07/2012; 31(7):792. · 3.58 Impact Factor
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ABSTRACT: To investigate the relationship between risk of Ross River virus (RRV) infection and proximity to mosquito-breeding habitat surrounding a tidal wetland ecosystem in south-west Australia.
Geographic information systems (GIS) were used to spatially map cases of RRV disease in the Leschenault region between July 1995 and June 1996. Half kilometre buffer zones were constructed around the Leschenault Estuary and associated waterways; RRV disease case counts were calculated for each zone.
Different relationships between RRV disease incidence and proximity to saltmarsh mosquito habitat were observed east of the Leschenault Estuary compared with an urban region to the south. Disease incidence showed a decreasing trend away from eastern margins of the Estuary, particularly for the first 2 km. In the urban region, RRV disease risk was low close to the Estuary, but increased further out and remained steady across the remainder of that region.
The findings support an increased risk of contracting RRV disease for people residing close to eastern margins of the Leschenault Estuary.
This study highlights how historical data combined with GIS can improve understanding of the epidemiology of RRV disease. This has a valuable role in assessing the risk of mosquito-borne disease for land-use planning.
Australian and New Zealand Journal of Public Health 06/2012; 36(3):229-35. · 1.20 Impact Factor
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ABSTRACT: On 16 April 2009, a boat carrying 47 Afghan asylum seekers and 2 Indonesian crew exploded in Australian waters, resulting in mass casualties. Of these casualties, 23 persons who suffered significant burns were transferred to Royal Perth Hospital, Perth, Western Australia. One patient was subsequently shown to be a hepatitis B virus (HBV) carrier at the time of the explosion. Over the following months, 3 other patients received a diagnosis of acute hepatitis B, and an additional 4 patients showed serological evidence of recent HBV infection, including 1 patient who was transferred to another Australian city. Molecular typing determined that the strains from the HBV carrier and the acute and recent case patients formed a closely related cluster, and the investigation suggested that transmission occurred at or around the time of the boat explosion. This is the first report of confirmed transmission of HBV following a disaster, and it reinforces the importance of postexposure prophylaxis for HBV in mass casualty situations.
The Journal of Infectious Diseases 08/2011; 204(3):400-7. · 6.41 Impact Factor
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ABSTRACT: Indigenous and non-indigenous Western Australians with pandemic (H1N1) 2009 influenza (pH1N1) infection were compared for risk factors, influenza vaccination history, symptoms, use of antiviral medications, and hospitalisation. Data were collected systematically on 856 notified cases with laboratory confirmed pH1N1 infection during the first 10 weeks of pH1N1 virus transmission in Western Australia in 2009. Indigenous people with pH1N1 were approximately 3 times more likely to be hospitalised and were more likely to have a range of underlying medical conditions and be smokers, compared with non-Indigenous cases. Age (P < 0.001) and the presence of two or more co-morbidities (P < 0.001) were independent predictors of hospitalisation, while Indigenous status was not, indicating that higher pH1N1 hospitalisation rates in Indigenous Australians during the 2009 winter season were attributable to the higher prevalence of underlying chronic disease. These results underscore the need to ensure that influenza vaccination is delivered as widely as possible among those with chronic health conditions.
Communicable diseases intelligence 06/2011; 35(2):172-6.
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ABSTRACT: More than a year after an influenza pandemic was declared in June 2009, the World Health Organization declared the pandemic to be over. Evaluations of the pandemic response are beginning to appear in the public domain.
We argue that, despite the enormous effort made to control the pandemic, it is now time to acknowledge that many of the population-based public health interventions may not have been well considered. Prior to the pandemic, there was limited scientific evidence to support border control measures. In particular no border screening measures would have detected prodromal or asymptomatic infections, and asymptomatic infections with pandemic influenza were common. School closures, when they were partial or of short duration, would not have interrupted spread of the virus in school-aged children, the group with the highest rate of infection worldwide. In most countries where they were available, neuraminidase inhibitors were not distributed quickly enough to have had an effect at the population level, although they will have benefited individuals, and prophylaxis within closed communities will have been effective. A pandemic specific vaccine will have protected the people who received it, although in most countries only a small minority was vaccinated, and often a small minority of those most at risk. The pandemic vaccine was generally not available early enough to have influenced the shape of the first pandemic wave and it is likely that any future pandemic vaccine manufactured using current technology will also be available too late, at least in one hemisphere.
Border screening, school closure, widespread anti-viral prophylaxis and a pandemic-specific vaccine were unlikely to have been effective during a pandemic which was less severe than anticipated in the pandemic plans of many countries. These were cornerstones of the population-based public health response. Similar responses would be even less likely to be effective in a more severe pandemic. We agree with the recommendation from the World Health Organisation that pandemic preparedness plans need review.
BMC Public Health 02/2011; 11:78. · 2.00 Impact Factor
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ABSTRACT: To determine antibody levels and estimate incidence of infection with pandemic (H1N1) 2009 influenza in children and pregnant women during the 2009 winter in Western Australia.
Two cross-sectional serosurveys using stored specimens collected for unrelated pathology testing, from before and after (3 August to 30 November 2009) circulation of the pandemic virus, and before commencement of the pandemic vaccination program. Specimens were from three groups: children aged 1-4 years, older children and teenagers aged 5-19 years, and pregnant women aged 21-45 years. The groups were geographically representative of the WA population.
Reactivity against pandemic (H1N1) 2009 and seasonal A(H1N1) influenza viruses measured using haemagglutination inhibition (HI) assays.
Antibody titres were determined for 648 individuals in the prepandemic period and 736 in the postpandemic period. In the prepandemic period, HI titres ≥ 40 against the pandemic virus were found in 0 (95% CI, 0.0%-1.6%) children aged 1-4 years, 8.3% (95% CI, 5.3%-12.7%) of older children and teenagers, and 4.5% (95% CI, 2.4%-8.3%) of pregnant women. In postpandemic specimens collected from 1 September 2009 (when influenza activity had declined to near-baseline levels), estimated infection rates (subtracting prepandemic levels) were 25.4% (95% CI for difference, 18.6%-33.4%) in 1-4-year-old children, 39.4% (95% CI, 29.8%-48.5%) in older children and teenagers, and 10.2% (95% CI, 4.1%-17.1%) in pregnant women.
A quarter of preschool children and about 40% of school-aged children and older teenagers had serological evidence of pandemic influenza infection during winter 2009, indicating high levels of mild or asymptomatic infection. The infection rate in pregnant women was much lower. The high infection rates in children help explain the reduced impact of the pandemic virus during the 2010 winter. Augmented by vaccination, there should be sufficiently high levels of immunity in the Australian population to significantly reduce the impact of the virus in future influenza seasons.
The Medical journal of Australia 01/2011; 194(2):68-72. · 2.81 Impact Factor
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ABSTRACT: This article reviews the lessons that can be learned by the health sector, in particular, and the public sector, more generally, from the governmental response to pandemic (H1N1) 2009 influenza A (pH1N1) in Australia during 2009. It covers the period from the emergence of the epidemic to the release of the vaccine, and describes a range of impacts on the Western Australian health system, the government sector and the community. There are three main themes considered from a State government agency perspective: how decisions were influenced by prior planning; how the decision making and communication processes were intimately linked; and the interdependent roles of States and the Commonwealth Government in national programs. We conclude that: (a) communications were generally effective, but need to be improved and better coordinated between the Australian Government, States and general practice; (b) decision making was appropriately flexible, but there needs to be better alignment with expert advice, and consideration of the need for a national disease control agency in Australia; and (c) national funding arrangements need to fit with the model of state-based service delivery and to support critical workforce needs for surge capacity, as well as stockpile and infrastructure requirements.
Australian health review: a publication of the Australian Hospital Association 11/2010; 34(4):477-86. · 0.55 Impact Factor
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ABSTRACT: We compared confirmed pandemic (H1N1) 2009 influenza and seasonal influenza diagnosed in Western Australia during the 2009 influenza season. From 3,178 eligible reports, 984 pandemic and 356 seasonal influenza patients were selected; 871 (88.5%) and 288 (80.9%) were interviewed, respectively. Patients in both groups reported a median of 6 of 11 symptoms; the difference between groups in the proportion reporting any given symptom was < or =10%. Fewer than half the patients in both groups had > or =1 underlying condition, and only diabetes was associated with pandemic (H1N1) 2009 influenza (odds ratio [OR] 1.9, 95% confidence interval [CI] 1.1-3.5). A total of 129 (14.8%) persons with pandemic (H1N1) 2009 and 36 (12.5%) persons with seasonal influenza were hospitalized (p = 0.22). After controlling for age, we found that patient hospitalization was associated with pandemic (H1N1) 2009 influenza (OR 1.5; 95% CI 1.1-2.1). Contemporaneous pandemic and seasonal influenza infections were substantially similar in terms of patients' symptoms, risk factors, and proportion hospitalized.
Emerging Infectious Diseases 09/2010; 16(9):1388-95. · 6.79 Impact Factor
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ABSTRACT: School closure is often purported to reduce influenza transmission, but little is known about its effect on families. We surveyed families affected by pandemic (H1N1) 2009-related school closures in Perth, Western Australia, Australia. Surveys were returned for 233 (58%) of 402 students. School closure was deemed appropriate by 110 parents (47%); however, 91 (45%) parents of 202 asymptomatic students reported taking >or=1 day off work to care for their child, and 71 (35%) had to make childcare arrangements because of the class closures. During the week, 172 (74%) students participated in activities outside the home on >or=1 occasion, resulting in an average of 3.7 out-of-home activities for each student. In our survey, activities outside the home were commonly reported by students affected by school closure, the effect on families was substantial, and parental opinion regarding school closures as a means to mitigate the outbreak of pandemic (H1N1) 2009 was divided.
Emerging Infectious Diseases 02/2010; 16(2):205-11. · 6.79 Impact Factor
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ABSTRACT: In mid-June 2009 the State of Victoria in Australia appeared to have the highest notification rate of pandemic (H1N1) 2009 influenza in the world. We hypothesise that this was because community transmission of pandemic influenza was already well established in Victoria at the time testing for the novel virus commenced. In contrast, this was not true for the pandemic in other parts of Australia, including Western Australia (WA).
We used data from detailed case follow-up of patients with confirmed infection in Victoria and WA to demonstrate the difference in the pandemic curve in two Australian states on opposite sides of the continent. We modelled the pandemic in both states, using a susceptible-infected-removed model with Bayesian inference accounting for imported cases.
Epidemic transmission occurred earlier in Victoria and later in WA. Only 5% of the first 100 Victorian cases were not locally acquired and three of these were brothers in one family. By contrast, 53% of the first 102 cases in WA were associated with importation from Victoria. Using plausible model input data, estimation of the effective reproductive number for the Victorian epidemic required us to invoke an earlier date for commencement of transmission to explain the observed data. This was not required in modelling the epidemic in WA.
Strong circumstantial evidence, supported by modelling, suggests community transmission of pandemic influenza was well established in Victoria, but not in WA, at the time testing for the novel virus commenced in Australia. The virus is likely to have entered Victoria and already become established around the time it was first identified in the US and Mexico.
PLoS ONE 01/2010; 5(6):e11341. · 4.09 Impact Factor
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ABSTRACT: To describe a prolonged outbreak of mumps in the Kimberley region of Western Australia in 2007-2008.
Descriptive analysis of all mumps cases notified to the WA Notifiable Infectious Diseases Database for the period 1 July 2007 to 30 June 2008.
Notified cases of mumps by patients' place of residence, age, Indigenous or non-Indigenous ethnicity, vaccination status and method of diagnosis.
84% (153/183) of mumps notifications in WA over the study period occurred in the Kimberley region or were directly linked to Kimberley cases. Median age of patients was 18 years (range, 2-63 years), and 54% of patients were aged less than 20 years. Almost all (92%) were Australian Aboriginal people; 67% (102/153) had received at least one dose of mumps vaccine, and 52% had received two doses. The highest notification rate (1816 cases per 100,000 population) was in the Aboriginal 15-19-years age group, and 92% of these patients had received at least one dose of mumps vaccine. Almost all outbreak cases (94%) were laboratory confirmed. Genotyping was performed on 20 mumps virus isolates: all were genotype J.
A prolonged outbreak of mumps occurred in a well defined, highly vaccinated, predominantly young Aboriginal population in the remote Kimberley region of WA. This outbreak raises questions about the effectiveness and scheduling of the current vaccine (which is genotype A-derived), especially for Aboriginal people. Surveillance of circulating mumps virus genotypes and neutralisation studies will help in evaluating the protection provided by the current vaccine against genotypically different strains.
The Medical journal of Australia 10/2009; 191(7):398-401. · 2.81 Impact Factor
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ABSTRACT: Between May and June 2002 an outbreak of chickenpox (CP) occurred at a child care centre in Perth, Western Australia. An epidemiological study was undertaken in order to determine the characteristics of the outbreak, assess vaccine effectiveness, and to define the direct and indirect costs associated with CP infections in young children.
A cohort study of the outbreak utilising attendance records and a telephone survey of parents was conducted.
Of the 211 children attending the child care centre at the time of the outbreak, 44 contracted CP (attack rate 25.7%). In addition, two staff members, five secondary household contacts (secondary attack rate 38.5%) and four secondary non-household associated contacts were infected. There were no severe complications or any hospitalisations recorded in infected persons. Two cases had been vaccinated previously. Vaccine effectiveness for CP of any severity was 78.0% (95% CI 15.4-94.3%) while vaccine effectiveness against severe CP was 100%. Direct costs during this outbreak were estimated to be $54 per case and the total costs, including cost of parental time off work or study, were estimated to be $525.73 per case.
Although morbidity associated with CP in young children is not great, infection in childhood is almost universal. This study found that the average costs associated with each CP case were considerable. Since varicella vaccine affords good protection against CP, the recent inclusion of this vaccine in the Australian childhood vaccination schedule should save the community a considerable amount in direct and indirect costs if high coverage rates can be achieved.
Australian and New Zealand Journal of Public Health 05/2007; 31(2):113-9. · 1.20 Impact Factor
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ABSTRACT: Scarlet fever was associated with feared outbreaks and mortality in the 19th Century. It occurs sporadically in modern society and infection is readily treated with antibiotics. We report on a scarlet fever outbreak in children attending a primary school in Perth, Western Australia, in late 2003. A total of 13 cases were identified over a five week period. Six of the cases were pre-primary children (ages 4 to 5) from the same class of 26 children (attack rate 23.1%). Three of the remaining seven cases were older siblings of pre-primary cases who developed scarlet fever after their younger siblings. Screening of the children and teachers from the two pre-primary classes at the school yielded 12 positive pharyngeal swabs for group A Streptococcus. Emm-typing of the screening isolates indicated that a common strain was circulating within the outbreak pre-primary class, with four of six isolates identified as emm-type 3. The overall group A Streptococcus carriage rate in screened students in this class was 31.6 per cent and the carriage rate for emm-type 3 was 21.1 per cent. Carriers were treated with oral penicillin V to eradicate carriage and control the outbreak. No further cases of scarlet fever were reported after the treatment of pharyngeal carriers. Outbreaks of scarlet fever still occur in young children and identification and treatment of carriers may still be valuable.
Communicable diseases intelligence 02/2005; 29(4):386-90.
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ABSTRACT: To assess changes in and factors associated with recent malaria notifications in Western Australia (WA).
Retrospective analysis of the WA Notifiable Infectious Diseases Database and enhanced surveillance questionnaires completed by attending medical practitioners.
Cases of malaria notified between January 1990 and December 2001.
Annual notifications by demographic variables (including age, sex, occupation and place of residence), region/country of acquisition, chemoprophylaxis used, Plasmodium species and outcome.
482 patients were notified (mean age, 31 years; 80% male); 57% lived in Perth, 31% in country areas and 12% in an immigration detention centre. Comparison between the 6-year periods 1990-1995 and 1996-2001 showed that Plasmodium falciparum cases increased from 29 (14%) to 108 (44%; P < 0.001), while Plasmodium vivax cases decreased from 157 (77%) to 122 (50%; P < 0.001); immigrants in detention, defence force personnel and cases from Africa were increasingly represented (P < 0.05 in each case). Only 31% of patients took regular chemoprophylaxis and, among these, the regimen was appropriate in only a quarter. There was a median period of 3 days between symptom onset and diagnosis. One patient died.
There has been an increase in P. falciparum cases in WA since 1990. This reflects the influx of immigrants in detention, deployment of military personnel to East Timor and increasing numbers of cases from Africa. A significant number of Australian travellers who developed malaria had not taken chemoprophylaxis either regularly or at all, and, of those who had, the regimen was inadequate in most.
The Medical journal of Australia 02/2005; 182(4):164-7. · 2.81 Impact Factor
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ABSTRACT: On 16 February 2002, a total of 26 people presented to the emergency department of the local hospital in the rural town of Collie in southwest Western Australia with many infected scratches and pustules distributed over their bodies. All of the patients had participated in a "mud football" competition the previous day, in which there had been ~100 participants. One patient required removal of an infected thumbnail, and another required surgical debridement of an infected toe. Aeromonas hydrophila was isolated from all 3 patients from whom swab specimens were obtained. To prepare the mud football fields, a paddock was irrigated with water that was pumped from an adjacent river during the 1-month period before the competition. A. hydrophila was subsequently isolated from a water sample obtained from the river. This is the first published report of an outbreak of A. hydrophila wound infections associated with exposure to mud.
Clinical Infectious Diseases 05/2004; 38(8):1084-9. · 9.15 Impact Factor
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The Medical journal of Australia 181(11-12):710. · 2.81 Impact Factor
