Comparison of two modern vaccines and previous influenza infection against challenge with an equine influenza virus from the Australian 2007 outbreak

During 2007, large outbreaks of equine influenza (EI) caused by Florida sublineage Clade 1 viruses affected horse populations in Japan and Australia. The likely protection that would be provided by two modern vaccines commercially available in the European Union (an ISCOM-based and a canarypox-based vaccine) at the time of the outbreaks was determined. Vaccinated ponies were challenged with a representative outbreak isolate (A/eq/Sydney/2888-8/07) and levels of protection were compared. A group of ponies infected 18 months previously with a phylogenetically-related isolate from 2003 (A/eq/South Africa/4/03) was also challenged with the 2007 outbreak virus. After experimental infection with A/eq/Sydney/2888-8/07, unvaccinated control ponies all showed clinical signs of infection together with virus shedding. Protection achieved by both vaccination or long-term immunity induced by previous exposure to equine influenza virus (EIV) was characterised by minor signs of disease and reduced virus shedding when compared with unvaccinated control ponies. The three different methods of virus titration in embryonated hens’ eggs, EIV NP-ELISA and quantitative RT-PCR were used to monitor EIV shedding and results were compared. Though the majority of previously infected ponies had low antibody levels at the time of challenge, they demonstrated good clinical protection and limited virus shedding. In summary, we demonstrate that vaccination with current EIV vaccines would partially protect against infection with A/eq/Sydney/2888-8/07-like strains and would help to limit the spread of disease in our vaccinated horse population

The Economic Impact of Eradicating Peste des Petits Ruminants:A Benefit-Cost Analysis

Peste des petits ruminants (PPR) is an important cause of mortality and production loss among sheep and goats in the developing world. Despite control efforts in a number of countries, it has continued to spread across Africa and Asia, placing an increasing burden on the livelihoods of livestock keepers and on veterinary resources in affected countries. Given the similarities between PPR and rinderpest, and the lessons learned from the successful global eradication of rinderpest, the eradication of PPR seems appealing, both eliminating an important disease and improving the livelihoods of the poor in developing countries. We conducted a benefit-cost analysis to examine the conomic returns from a proposed programme for the global eradication of PPR. Based on our knowledge and experience, we developed the eradication strategy and estimated its costs. The benefits of the programme were determined from (i) the averted mortality costs, based on an analysis of the literature, (ii) the downstream impact of reduced mortality using a social accounting matrix, and (iii) the avoided control costs based on current levels of vaccination. The results of the benefit-cost analysis suggest strong economic returns from PPR eradication. Based on a 15-year programme with total discounted costs of US$2.26 billion, we estimate discounted benefits of US$76.5 billion, yielding a net benefit of US$74.2 billion. This suggests a benefit cost ratio of 33.8, and an internal rate of return (IRR) of 199%. As PPR mortality rates are highly variable in different populations, we conducted a sensitivity analysis based on lower and higher mortality scenarios. All the scenarios examined indicate that investment in PPR eradication would be highly beneficial economically. Furthermore, removing one of the major constraints to small ruminant production would be of considerable benefit to many of the most vulnerable communities in Africa and Asia

Managing the risks from new and emerging infectious disease: the \u27one health\u27 paradigm

The global risk from new and emerging infectious diseases continues to grow with recognition that, for the most part, the pathogens involved emerge from animals to infect humans. Recognizing the complexity of these interactions and the need for a strong interdisciplinary approach to effectively manage these risks, new partnerships are being forged under the general umbrella of \u27one health\u27. Involving human health, animal health, and environmental health exponents, solutions are sought for how to prevent as well as respond to the threats. But is this approach working? Whilst a number of key meetings continue to be held under the One Health umbrella, are we really seeing measureable progress in risk prevention and mitigation? Focusing research on the drivers for emergence, on modeling the risks, on improved diagnostics, and on targeted vaccines could considerably enhance our ability to prevent and respond. Ensuring the uptake and applications of new diagnostics and vaccines will be the key to prevention and response, but achieving this will require policies that drive further the One Health collaborations. Such policies should ensure that scant available resources are targeted toward the identified outcomes through research delivery and uptake, and that we genuinely work as "one world" in tackling the very real risks we fac

First international one health congress

More than 650 people from around 60 countries attended the 1st International One Health Conference, held in Melbourne from 14 to 16 February 2011. Scientists, clinicians, government and community members from a range of disciplines came together to discuss the benefits of working together to promote a One Health approach to human, animal and environmental health. One Health embraces systems thinking and recognising the interdependence of people, animals and environment. The conference was hosted by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and was supported by international agencies, the Australian and Canadian governments, and industry. The Organising Committee recognised from the outset, the need to provide a forum not just for scientific presentation, but for open discussion and dialogue around the policy and political issues, as well as the science that drives the One Health agenda. The Committee was also cognizant of the need to embrace a definition of One Health that includes food security and food safety and included the social and economic pressures that shapes this area. The meeting was therefore organised under four themes with plenary sessions followed by breakout parallel sessions for each of these. The themes covered Disease Emergence, Environmental Drivers, Trade, Food Security and Food Safety, and Science Policy and Political Action. The plenary session commenced with one or two keynote presentations by world leaders on the topic being covered, followed by panel discussions involving six to eight experts and involving all participants at the congress. Each of the panel members spoke briefly on the topic covered by the keynote speaker and were asked to be as provocative as possible. The discussions that followed allowed debate and discussion on the keynote presentations and the panel members comments. This was followed by six to eight parallel breakout sessions involving in depth papers on the session’s topic. Throughout the conference at various times, sponsored sessions dealt with particular areas of science or policy providing a further framework not only to learn current science but for debate and discussion. A full copy of all abstracts is available on the web at http://www.springerlink.com. In concluding the Congress recognised the interdependence of, and seeks to improve human, animal and environmental health; recognised that communication, collaboration and trust between human and animal health practitioners is at the heart of the One Health concept; agreed that a broad vision that includes other disciplines such as economics and social behaviour is essential to success. The Congress stressed the need to promote the ‘do-able’ such as improving surveillance and response for emerging infectious diseases whilst developing the broader approach. It identified a need to emphasise community participation and development of community capacity, and especially, an open transparent dialogue with both a ‘ground up’ and ‘top down’ approach that would lead to an improved understanding of our ecosystems, including molecular ecobiology, are an essential part of One Health

The immune response to bluetongue virus infection.

The outcome following the single, serial and simultaneous inoculation of different bluetongue virus (BTV) types into sheep and cattle was examined in terms of temperature, viraemia and neutralising antibody responses. Animals inoculated with one BTV type and challenged with the same type were shown to be protected from this challenge and to have produced only homotypic neutralising antibodies. Following the inoculation of one type and challenge with a different BTV type no protection could be demonstrated. When rechallenged these animals were found to be resistant to a third BTV type. Animals serially inoculated with two BTV types were shown to produce a transient heterotypic neutralising antibody response to a number of BTV types and although the level of this heterotypic response diminished with time the inoculation of a third BTV type gave rise to a further heterotypic response. The simultaneous inoculation of three BTV types however, resulted in replication of only two of the three inoculated viruses and a neutralising antibody response to only those two types. The ability of BTV to induce a cell-mediated immune response, in terms of the production of cytotoxic T lymphocytes (CTL's) was examined in both mice and sheep. After inoculation with live BTV, mice produced CTL's which showed virus and H[2] restriction. On secondary in vitro stimulation, specifically stimulated sensitised memory cells also produced high numbers of CTL's. Inactivation of virus preparations, either by BPL or glutaraldehyde induced only a low level response and the use of Freunds adjuvants and double immunisation procedures failed to improve that response. However, mice immunised with a single BTV type were shown to produce CTL's which cross-reacted with a number of BTV types. These cross-reactive CTL's could be induced by both primary in vivo and secondary in vitro stimulation and a varying degree of cross-reactivity occurred with the six BTV types examined. Following these observations in mice, the ability of BTV to induce CTL's in ovines was investigated. Presumptive ovine CTL's were shown to occur, their activity to be maximal around day 14 post inoculation (pi) of virus and their activity to be genetically restricted. BTV immune sera appeared incapable of participating in antibody dependent cell-mediated cytotoxicity (ADCC) reactions and although BTV induced high levels of interferon it was itself not susceptible to the effects of this interferon. Following the demonstration that the serial inoculation of two BTV types protected against challenge with a third type and that both the humoral and cellular components of the immune response were capable of heterotypic activity, work was carried out to evaluate the relative importance of antibody and CTL's in recovery and protection from reinfection with BTV. Using antibody transfer techniques it was possible to show that immune sera has a role to play in protection from challenge with homologous virus type although that protection did not appear to correlate with neutralising antibody levels and no protection could be demonstrated against heterologous virus challenge. Cellular transfer experiments in monozygotic sheep showed that BTV-induced thoracic duct lymphocytes were able to afford some degree of protection from homologous virus challenge and that this activity was probably T cell-mediated. It was also shown that this T cell-mediated response gave solid protection against challenge with a BTV type different from that used to induce these cells. The work in this thesis is discussed with relevance to other virus diseases, BTV immunology and the present BTV vaccine policies

Avian influenza from an ecohealth perspective

To understand and better control AI outbreaks, not only is it necessary to understand the biology of influenza viruses but also the natural history of the hosts in which these viruses multiply and the different environments in which the hosts and viruses interact. This includes the anthropogenic factors that have influenced where, whether and how avian influenza (AI) viruses can replicate and transmit between wild birds and poultry, and between poultry and mammals, including factors influencing uptake and application of appropriate control and preventive measures for AI. This disease represents one of the best examples of the need for a ‘One Health’ approach to understand and tackle disease with an increasing need to comprehend and unravel the environmental and ecology drivers that affect the virus host interactions. This forum piece seeks to bring together these aspects through a review of recent outbreaks and how a deeper understanding of all three aspects, the virus, the host and the environment, can help us better manage future outbreaks