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African swine fever (ASF) is a viral disease that affects domestic and feral pigs. While not currently present in Australia, ASF outbreaks have been reported nearby in Indonesia, Timor-Leste, and Papua New Guinea. Feral pigs are found in all Australian states and territories and are distributed in a variety of habitats. To investigate the impacts of an ASF introduction event in Australia, we used a stochastic network-based metapopulation feral pig model to simulate ASF outbreaks in different regions of Australia. Outbreak intensity and persistence in feral pig populations was governed by local pig recruitment rates, population size, carcass decay period, and, if applicable, metapopulation topology. In Northern Australia, the carcass decay period was too short for prolonged persistence, while endemic transmission could possibly occur in cooler southern areas. Populations in Macquarie Marshes in New South Wales and in Namadgi National Park in the Australian Capital Territory had the highest rates of persistence. The regions had different modes of transmission that led to long-term persistence. Endemic Macquarie Marshes simulations were characterised by rapid transmission caused by high population density that required a fragmented metapopulation to act as a bottleneck to slow transmission. Endemic simulations in Namadgi, with low density and relatively slow transmission, relied on large, well-connected populations coupled with long carcass decay times. Despite the potential for endemic transmission, both settings required potentially unlikely population sizes and dynamics for prolonged disease survival. • Built a stochastic metapopulation ASF model with feral pig social structure. • Investigated ASF introduction in different Australian regions. • Persistence in Northern Australia unlikely due to reduced decay times. • Increased likelihood of endemic transmission in southern regions. • Southern feral pig population structure likely inhibits endemic transmission. [ABSTRACT FROM AUTHOR]

Various classifications of fuel accumulation models are used to describe the complex temporal relationship between fuel loads and vegetation dynamics. Fuel accumulation models are an important tool in wildfire management as fuel is the only component that can be directly controlled by fire managers. Here we discuss various strengths and limitations of analytical fuel accumulation models that exist in the literature, with a focus on those used in Australia. Early approaches to analytical or continuous models of fuel accumulation centred around the model introduced by Olson in 1963. This model assumes that the rate at which fuel accumulates is determined as a balance between the rate of fuel accession and the rate at which it decays. The Olson model has been shown to provide a reasonable description of litter accumulation, data sparsity issues notwithstanding, but can be of limited use in describing elevated fuels, or in forest stands that exhibitmore complex post-disturbance dynamics. Interactions between species and other disturbances have the potential to change the dynamics of fuel accumulation and decay processes. Moreover, post-fire vegetation stands are usually dominated by an understorey layer that eventually senesces as the dominant vegetation grows. Motivated by the critical differences between the models presented, a more general approach featuring vegetation density is proposed. A generic result is presented to indicate how the theoretical predictions of the model are able to emulate patterns of fuel accumulation that have been reported, and that can not be accounted for by the models commonly used in Australia. [ABSTRACT FROM AUTHOR]

Background The risk of progression to tuberculosis (TB) disease is greatest soon after infection, yet disease may occur many years or decades later. However, rates of TB reactivation long after infection remain poorly quantified. Australia has a low incidence of TB and most cases occur among migrants. We explored how TB rates in Australian migrants varied with time from migration, age, and gender. Methods We combined TB notifications in census years 2006, 2011, and 2016 with time- and country-specific estimates of latent TB prevalences in migrant cohorts to quantify postmigration reactivation rates. Results During the census years, 3246 TB cases occurred among an estimated 2 084 000 migrants with latent TB. There were consistent trends in postmigration reactivation rates, which appeared to be dependent on both time from migration and age. Rates were lower in cohorts with increasing time, until at least 20 years from migration, and on this background there also appeared to be increasing rates during youth (15–24 years of age) and in those aged 70 years and above. Within 5 years of migration, annual reactivation rates were approximately 400 per 100 000 (uncertainty interval [UI] 320–480), dropping to 170 (UI 130–220) from 5 to 10 years and 110 (UI 70–160) from 10 to 20 years, then sustaining at 60–70 per 100 000 up to 60 years from migration. Rates varied depending on age at migration. Conclusions Postmigration reactivation rates appeared to show dependency on both time from migration and age. This approach to quantifying reactivation risks will enable evaluations of the potential impacts of TB control and elimination strategies. [ABSTRACT FROM AUTHOR]

Background and objectives: Until recently, people in Australia with a history of injection drug use (IDU) were deferred indefinitely from donating blood. Knowledge gaps regarding policy non‐compliance and the prevalence of blood donation practices amongst people who inject drugs (PWID) precluded changes to this policy. We sought to address these gaps and to estimate the additional risk to Australia's blood supply associated with changing the indefinite deferral policy to 1 or 5 years since last injecting episode. Materials and methods: Data on blood donation amongst PWID were collected from 1853 interviews across two Australian studies of PWID conducted during 2015/16. Mathematical modelling was used to estimate the additional risk of hepatitis C (HCV)‐infected window period collections as a result of changing the deferral policy. Results: A very few (2–4%) study participants reported ever donating blood after ≥1 IDU episode. Changing the deferral policy from indefinite to 1 or 5 years was estimated to result in an additional 0·00000070 (95%CI: 0·00000033–0·00000165) or 0·00000020 (95%CI: 0·00000008–0·00000041) HCV‐positive window period collections per year, respectively. Conclusion: Changing Australia's indefinite deferral period to 1 or 5 years since last injecting episode poses a negligible increase in the risk of HCV‐infected window period collections from blood donors with a history of IDU. Our results informed a successful submission to the Australian regulator to change the deferral period from indefinite to 5 years since last injecting episode, a policy which came into effect in September 2018. [ABSTRACT FROM AUTHOR]

Since the emergence of SARS-CoV-2 in 2019 through to mid-2021, much of the Australian population lived in a COVID-19-free environment. This followed the broadly successful implementation of a strong suppression strategy, including international border closures. With the availability of COVID-19 vaccines in early 2021, the national government sought to transition from a state of minimal incidence and strong suppression activities to one of high vaccine coverage and reduced restrictions but with still-manageable transmission. This transition is articulated in the national 're-opening' plan released in July 2021. Here, we report on the dynamic modelling study that directly informed policies within the national re-opening plan including the identification of priority age groups for vaccination, target vaccine coverage thresholds and the anticipated requirements for continued public health measures-assuming circulation of the Delta SARS-CoV-2 variant. Our findings demonstrated that adult vaccine coverage needed to be at least 60% to minimize public health and clinical impacts following the establishment of community transmission. They also supported the need for continued application of test-trace-isolate-quarantine and social measures during the vaccine roll-out phase and beyond.

Background The aim of this study is to estimate the reduction in new HIV infections and resultant cost outcomes of providing antiretroviral treatment (ART) through Australia's 'universal access' health scheme to all temporary residents with HIV infection living legally in Australia, but currently deemed ineligible to access subsidised ART via this scheme.Methods: A mathematical model to estimate the number of new HIV infections averted and the associated lifetime costs over 5 years if all HIV-positive temporary residents in Australia had access to ART and subsidised medical care was developed. Input data came from a cohort of 180 HIV-positive temporary residents living in Australia who are receiving free ART donated by pharmaceutical companies for up to 4 years.Results: Expanding ART access to an estimated total 450 HIV+ temporary residents in Australia for 5 years could avert 80 new infections. The model estimated the total median discounted (5%) cost for ART and associated care to be A$36million, while the total savings in lifetime-discounted costs for the new infections averted was A$22million.Conclusions: It is estimated that expanded access to ART for all HIV-positive temporary residents in Australia will substantially reduce HIV transmission to their sexual partners at little additional cost. In the context of Australia's National HIV strategy and Australia's endorsement of global goals to provide universal access to ART for all people with HIV, this is an important measure to remove inequities in the provision of HIV-related treatment and care. [ABSTRACT FROM AUTHOR]

Pertussis resurgence has been reported from several developed countries with long-standing immunisation programs. Among these, Australia in 2003 discontinued an 18 months (fourth) booster dose in favour of an adolescent (fifth) dose. We developed a model to evaluate determinants of resurgence in Australia and alternative vaccine strategies for mitigation. Novel characteristics of our model included the use of seroepidemiologic data for calibration, and broad investigation of variables relevant to transmission of, and protection against, pertussis. We simulated multiple parameter combinations, retaining those consistent with observed data for subsequent use in predictive models comparing alternative vaccination schedules. Reproducing the early control of pertussis followed by late resurgence observed in Australia required natural immunity to last decades longer than vaccine-acquired immunity, with mean duration exceeding 50 years in almost 90% of simulations. Replacement of the dose at 18 months with an adolescent dose in 2003 resulted in a 40% increase in infections in the age group 18–47 months by 2013. A six dose strategy (2, 4, 6, 18 months, 4 and 15 years) yielded a reduction in infection incidence (pre-school 43%, infants 8%) greater than any alternative strategies considered for timing of five administered doses. Our finding that natural immunity drives long-term trends in pertussis cycles is relevant to a range of pertussis strategies and provides the necessary context in which to consider maternal vaccination. Comparatively short-lived vaccine-acquired immunity requires multiple boosters over the first two decades of life to maximise reduction in infections. [ABSTRACT FROM AUTHOR]

Currently, there is no road deterioration (RD) model that can address pavement performance with flooding. Therefore, the aim of this work was to develop an RD model that considers flooding and pre- and post-flood strategies. The case study is road group(s) in Queensland, Australia, based on the 34 000 km road database of its main roads authority, as Queensland was severely affected by floods in 2011. This paper provides a brief literature review and proposes an approach to develop an RD model based on a non-homogeneous Markov transition probability matrix. The new RD models are developed for a number of road groups based on roughness and rutting data collected since 2000. Detailed results on the derived roughness-based and rutting-based RD models with flooding for two selected road groups are highlighted. The new RD models show significant pavement deterioration at different probabilities of flooding events, especially at higher probabilities. It is believed that these results will help road authorities in managing flood-damaged roads with appropriate treatments and optimum budget. [ABSTRACT FROM AUTHOR]

The travel time reliability of buses has become increasingly important for public transit companies. In this study, a novel approach is proposed to evaluate and analyse the travel time reliability of bus services provided by TransLink in Queensland, Australia. In view of their stochastic features, the two components of travel time - dwell time and driving time - are represented by discrete distributed and normally distributed random variables respectively. Accordingly, the travel time could be described by Gaussian mixture models. Based on the proposed model, impact analysis shows that bus line reliability would increase by around 15% if onboard top-up for 'go cards' (electronic tickets) was not offered by TransLink. It was found that not providing this top-up method would not significantly harm the benefit of go card users, but it would substantially increase the total social benefit thanks to improved bus line reliability. [ABSTRACT FROM AUTHOR]

The macro-engineering project proposal exploits technologies that have the potential to quickly enliven the arid region surrounding Lake Eyre. The plan is focused on biosaline agriculture. The distinctive macro-project components are: Lake Eyre is gradually filled to a higher level by controlling evaporation and by pumping seawater from the nearby ocean using cheap tensioned textile tubes. Most of the necessary energy could be produced by photovoltaics, in a very attractive application without electricity storage requirements. Eventually, Lake Eyre is to be lidded with a floating impermeable plastic cap or with buoyant hollow plastic balls that reduce evaporation. Filled with seawater, Lake Eyre can be used as a reservoir for irrigation in biosaline agriculture. Elementary mathematical models for the proposed tasks and rough macro-economical estimations are presented. Based on overall results, we concluded that the macro-project is feasible with existing technologies and could become profitable in a few decades. But beyond paying off the capital investment, the greatest implementation benefit is the prospect of creating conditions for human settlement in the low-fertility soils of the Lake Eyre basin. Additional research directions are briefly presented. [ABSTRACT FROM AUTHOR]

When is a fertility treatment futile? This question has great practical importance, given the role futility plays in ethical, legal and clinical discussions. Here, we outline a novel method of determining futility for IVF treatments. Our approach is distinctive for considering the economic value attached to the intended aim of IVF treatments, i.e. the birth of a child, rather than just the effects on prospective parents and the health system in general. We draw on the commonly used metric, quality-adjusted life years (QALYs), to attach a monetary value to new lives created through IVF. We then define futility as treatments in which the chance of achieving a live birth is so low that IVF is no longer a cost-effective intervention given the economic value of new births. This model indicates that IVF treatments in which the chance of a live birth are <0.3% are futile. This suggests IVF becomes futile when women are aged between 47 and 49 years of age. This is notable older than ages currently considered as futile in an Australian context (∼45). In the UK, government subsidized treatment with the couple's own gametes stops at the age of 42, while privately funded treatments are self-regulated by individual providers. In most European countries and the USA, the 'age of futility' is likewise managed by clinical consensus., (© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Bioretention basins and permeable pavements are two widely implemented water sensitive urban design (WSUD) technologies. While their applications are extensive, their effectiveness as a result of changes in rainfall patterns is an emerging and important research question. This paper describes how these systems behave under varying rainfall conditions in Australian cities. To illustrate this, two design parameters, namely emptying times for permeable pavements and scour velocities for bioretention systems, were investigated. The study revealed that there are two groups of cities displaying almost similar peak flow characteristics - high (Darwin, Cairns, Brisbane, Townsville and Sydney) and low (Alice Springs, Hobart, Melbourne, Perth and Adelaide). It was shown that selection of an optimal storage size to ensure appropriate emptying times for permeable pavements requires a balance between managing dry periods, reuse demand and economic considerations. Increase of high flows increases the risk of scouring in bioretention basins, which is particularly significant for the first group of cities. Finally, the paper describes the importance of peak flow estimation method and appropriate selection of modelling time step for sustainable implementation of WSUD in Australia. [ABSTRACT FROM AUTHOR]

Abstract: We discuss the role and characteristics of water markets in Australia in facilitating efficient water allocation. Administrative, regulatory and/or political barriers to effective functioning of water markets are reviewed with a focus on the southern Murray-Darling Basin (MDB) region of Australia. A mathematical model is developed to estimate the costs of existing restrictions and the benefits from potential changes in water markets (e.g., removing barriers in temporary water markets). The modelling results reveal that expanding trade leads to an increase in mean annual net returns from AU $2502 million to AU $2590 million (i.e., an increase of AU $88 million). When the current volume restrictions, exchange rates, and trading charges are accounted for, mean annual net returns reduced from AU $2590 million to AU $2573 million (i.e., a reduction of AU $17 million). The exclusion of any of the three southern MDB states from the interstate water trading imposes significant costs. If South Australia, New South Wales or Victoria withdraws from the water market, net returns are reduced by AU $27 million, AU $31 million and $63 million, respectively. The paper outlines the policy implications of strategies to remove market barriers and to facilitate efficient and effective water trading. [Copyright &y& Elsevier]

The pedestrian planning work undertaken in preparation for the 2006 Commonwealth Games held in Melbourne is described. The paper considers why pedestrian modelling is needed and how it works. The work done in Melbourne is detailed and benefits and lessons learned are considered. [ABSTRACT FROM AUTHOR]

This article is an economic analysis of reallocating River Murray Basin water from agriculture to the environment with and without the possibility of interregional water trade. Acquiring environmental flows as an equal percentage of water allocations from all irrigation regions in the Basin is estimated to reduce returns to irrigation. When the same volume of water is taken from selected low-value regions only, the net revenue reduction is less. In all scenarios considered, net revenue gains from freeing trade are estimated to outweigh the negative revenue effects of reallocating water for environmental flows. The model accounts for how stochastic weather affects market water demand, supply and requirements for environmental flows. Net irrigation revenue is estimated to be 75 million less than the baseline level for a scenario involving reallocating a constant volume of water for the environment in both wet and dry years. For a more realistic scenario involving more water for the environment in wet and less in dry years, estimated net revenue loss is reduced by 48 per cent to 39 million. Finally, the external salinity-related costs of water trading are estimated at around 1 million per annum, a quite modest amount compared to the direct irrigation benefits of trade. [ABSTRACT FROM AUTHOR]

The use of native vegetation in the coastal regions of Australia has become increasingly popular for stabilising railway corridors built over expansive clays and compressive soft soils. The tree roots provide three stabilising functions: (a) they reinforce the soil; (b) they dissipate excess pore pressures; and (c) they establish sufficient matric suction to increase the shear strength. The matric suction generated within the tree root zone propagates radially into the soil matrix, as a function of the moisture content change. Considering soil conditions, the type of vegetation and atmospheric conditions, a mathematical model for the rate of root water uptake is developed. A conical shape is considered to represent the geometry of the tree root zone. Based on this model for the rate of root water uptake, the pore water pressure distribution and the movement of the ground adjacent to the tree are numerically analysed. Field measurements taken from the previously published literature are compared with the authors' numerical predictions. It is found that, given the approximation of the assumed model parameters, the agreement between the predicted results and field data is still promising. The study indicates that native vegetation improves the shear strength of the soil by increasing the matric suction, and also curtails soil movements. [ABSTRACT FROM AUTHOR]

Simple Summary: Feral cats (Felis catus) have a devastating impact on Australian native fauna. Several programs exist to control their numbers through lethal removal, using tools such as baiting with toxins. Adult male cats are especially difficult to control. We hypothesized that one way to capture these male cats is to lure them using female cats. As female cats are seasonal breeders, a method is needed to artificially induce reproductive (estrous) behavior so that they could be used for this purpose year-round (i.e., regardless of season). Estrogens can be given to cats to induce estrous behavior, but it is not known for how long this elevates the blood concentrations of estradiol. Following the administration of a long-acting estrogen, estradiol cypionate, to nine captive feral cats, blood estrogen concentrations remained elevated for several days. This information will be useful to ongoing studies that are investigating ways to reduce the abundance of feral cats in Australia, especially adult male cats. The control of feral cats (Felis catus) in Australia is a key biological conservation issue. Male cats are more difficult to control than female cats. Collared and tagged female cats displaying estrous behavior have been considered as a way to lure male cats and reveal their locations. As female cats are seasonal breeders, artificial induction of estrous behavior following the administration of a long-acting estrogen could improve their use for this purpose. Estradiol cypionate was intramuscularly administered to nine entire non-pregnant female feral cats, of unknown estrous status, at 0.1, 0.3, or 0.5 mg/kg. Mean peak serum concentrations of estradiol-17β were 365 pg/mL (0.1 mg/kg), 1281 pg/mL (0.3 mg/kg), and 1447 pg/mL (0.5 mg/kg). The time-course of estradiol-17β concentrations after various doses of estradiol cypionate was assessed using non-compartmental and non-linear mixed-effects methods. At the highest-studied dose (0.5 mg/kg), the 50th percentile of estradiol-17β concentrations exceeded 0.1 ng/mL for 11.8 days, and 0.05 ng/mL for 14.6 days. The duration increased with increasing dose. No signs of toxicity were noticed in any cat during the study. This information will be useful to ongoing studies that are investigating ways to reduce the abundance of feral cats in Australia, especially adult male cats. [ABSTRACT FROM AUTHOR]

Background & Aims: Elimination of HCV by 2030, as defined by the World Health Organization (WHO), is attainable with the availability of highly efficacious therapies. This study reports progress made in the timing of HCV elimination in 45 high-income countries between 2017 and 2019., Methods: Disease progression models of HCV infection for each country were updated with latest data on chronic HCV prevalence, and annual diagnosis and treatment levels, assumed to remain constant in the future. Modelled outcomes were analysed to determine the year in which each country would meet the WHO 2030 elimination targets., Results: Of the 45 countries studied, 11 (Australia, Canada, France, Germany, Iceland, Italy, Japan, Spain, Sweden, Switzerland, and United Kingdom) are on track to meet WHO's elimination targets by 2030; five (Austria, Malta, Netherlands, New Zealand, and South Korea) by 2040; and two (Saudi Arabia and Taiwan) by 2050. The remaining 27 countries are not expected to achieve elimination before 2050. Compared to progress in 2017, South Korea is no longer on track to eliminate HCV by 2030, three (Canada, Germany, and Sweden) are now on track, and most countries (30) saw no change., Conclusions: Assuming high-income countries will maintain current levels of diagnosis and treatment, only 24% are on track to eliminate HCV by 2030, and 60% are off track by at least 20 years. If current levels of diagnosis and treatment continue falling, achieving WHO's 2030 targets will be more challenging. With less than ten years remaining, screening and treatment expansion is crucial to meet WHO's HCV elimination targets., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The following case study aims to provide a broad overview of the initial Australian epidemiological situation of the novel coronavirus disease (COVID-19) pandemic. We provide a case presentation of Australia's current demographic characteristics and an overview of their health care system. The data we present on Australia's COVID-19 situation pertain to the initial wave of the pandemic from January through to 20 April 2020. The results of our study indicate the number of reported COVID-19 cases in Australia reduced, and Australia initially managed to successfully flatten the curve-from an initial doubling time of 3.4 days at the end of March 2020 to a doubling time of 112 days as of 20 April 2020. Using SEIR mathematical modelling, we investigate a scenario assuming infections increase once mitigation measures are lifted. In this case, Australia could experience over 15,000 confirmed cases by the end of April 2020. How Australia's government, health authorities and citizens adjust to preventative measures to reduce the risk of transmission as well as the risk of overburdening Australia's health care system is crucial. Our study presents the initial non-pharmaceutical intervention measures undertaken by the Australian health authorities in efforts to mitigate the rate of infection, and their observed and predicted outcomes. Finally, we conclude our study by presenting the observed and expected economic, social, and political disruptions Australians may endure as a result of the initial phase of the pandemic.

Objective: Following the outbreak of novel Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), and the disease named COVID-19, in Wuhan, China in late 2019, countries have implemented different interventions such as travel bans to slow the spread of this novel virus. This brief report evaluates the effect of travel bans imposed to prevent COVID-19 importation in the Australian context., Methods: We developed a stochastic meta-population model to capture the global dynamics and spread of COVID-19. By adjusting our model to capture the travel bans imposed globally and in Australia, the predicted COVID-19 cases imported to Australia were evaluated in comparison to observed imported cases., Results: Our modelling results closely aligned with observed cases in Australia and elsewhere. We observed a 79% reduction in COVID-19 importation and a delay of the COVID-19 outbreak in Australia by approximately one month. Further projection of COVID-19 to May 2020 showed spread patterns depending on the basic reproduction number., Conclusion: Imposing the travel ban was effective in delaying widespread transmission of COVID-19. However, strengthening of the domestic control measures is needed to prevent Australia from becoming another epicentre. Implications for public health: This report has shown the importance of border closure to pandemic control., (© 2020 The Authors.)

The aim of this article was to quantify socioeconomic inequalities in dental caries experience among Australian children and to identify factors that explain area-level socioeconomic inequalities in children's dental caries. We used data from the National Child Oral Health Survey conducted in Australia between 2012 and 2014 ( n = 24,664). Absolute and relative indices of socioeconomic inequalities in the dental caries experience in primary and permanent dentition (decayed, missing, and filled surfaces [dmfs] and DMFS, respectively) were estimated. In the first stage, we conducted multilevel negative binomial regressions to test the association between area-level Index of Relative Socioeconomic Advantage and Disadvantage (IRSAD) and dental caries experience (dmfs for 5- to 8-y-olds and DMFS for 9- to 14-y-olds) after adjustment for water fluoridation status, sociodemographics, oral health behaviors, pattern of dental visits, and sugar consumption. In the second stage, we performed Blinder-Oaxaca and Neumark decomposition analyses to identify factors that explain most of the area-level socioeconomic inequalities in dental caries. Children had a mean dmfs of 3.14 and a mean DMFS of 0.98 surfaces. Children living in the most disadvantaged and intermediately disadvantaged areas had 1.96 (95% confidence interval, 1.69-2.27) and 1.45 (1.26-1.68) times higher mean dmfs and 1.53 (1.36-1.72) and 1.43 (1.27-1.60) times higher mean DMFS than those living in the most advantaged areas, respectively. Water fluoridation status (33.6%), sugar consumption (22.1%), parental educational level (14.2%), and dental visit patterns (12.7%) were the main factors explaining area-level socioeconomic inequalities in dental caries in permanent dentition. Among all the factors considered, the factors that contributed most in explaining inequalities in primary dental caries were dental visits (30.3%), sugar consumption (20.7%), household income (20.0%), and water fluoridation status (15.9%). The inverse area-level socioeconomic inequality in dental caries was mainly explained by modifiable risk factors, such as lack of fluoridated water, high sugar consumption, and an unfavorable pattern of dental visits.

Sudden, large-scale infestations of house mice (Mus musculus domesticus) occur irregularly in the cereal-growing regions of Australia, resulting in substantial economic losses. Mathematical modelling has been used to evaluate the use of the liver nematode Capillaria hepatica as a potential agent for the biological control of mouse populations. The models suggest that C. hepatica is unlikely to be successful as a single-release control agent: instead, the parasite would need to be released when it becomes apparent that an outbreak is likely. Stage-structured models, including time delays and seasonal mouse demographic parameters, suggest that the parasite may be successful as a control agent, provided it can be introduced into the mouse population at least one year before an outbreak occurs. The optimum time for introduction is in summer or autumn. Some generalisations of this work are discussed. A parasite which affects fecundity alone is unlikely to be a good control agent, because it will destabilize the host population. Macroparasites may be unable to spread sufficiently rapidly to control sudden rises in vertebrate populations., (© OIE, 1993)