Overview of the 2007 Australian outbreak of equine influenza

In August 2007 equine influenza (EI) was diagnosed in Australia's horse population following the failure to contain infection in quarantine after the importation of one or more infected horses. The response had many unique features, and addressed financial, social, economic, human and animal health, trade and recovery issues. The outbreak and the associated control measures had a vast impact on individual horse owners, the horse industry and associated sectors in both infected and uninfected states.     

Overview of the epidemiology of equine influenza in the Australian outbreak

This overview of the equine influenza (EI) epidemic as it occurred in two Australian states, New South Wales and Queensland, in 2007 describes the functions and activities of the epidemiology teams that were engaged during the outbreak and also identifies key features of the epidemiology of EI during the outbreak.     

High-level coordination and strategy in the 2007 equine influenza outbreak response

The equine influenza (EI) outbreak presented many challenges that required high-level coordination and decision making, as well as the development of new approaches for satisfactory and consistent resolution. This paper outlines the elements of the national coordination arrangements, preparatory arrangements in place prior to the outbreak that facilitated national coordination, and some of the issues faced and resolved in the response.     

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.     

Factors associated with high psychological distress in horse industry participants during the 2007 Australian equine influenza outbreak and evidence of recovery after 1 year

This short report summarises data on the prevalence of high psychological distress in horse industry participants during the 2007 Australian equine influenza (EI) outbreak and the statistical analysis undertaken to identify the factors associated with this high psychological distress. In addition, follow-up data collected 1 year later are reported briefly.     

Role of the diagnostic laboratories during the 2007 equine influenza outbreak in Australia

During the 2007 equine influenza (EI) outbreak in Australia, diagnostic laboratories and the use of appropriate tests played a pivotal role in the response to the crisis. This role began with the detection of EI virus in New South Wales (NSW) on the evening of 24 August 2007 and culminated in providing the final 'proof of freedom' from EI in March 2008. The tests that were used during the EI response were able to provide results quickly, and with high sensitivity and specificity. This section of the supplement describes the roles and functions of the Australian laboratories; tests used and their performance characteristics; improvements made and methods used to validate assays; strategies that were followed during the response; the characterisation of viruses detected; and the resources that were available to laboratories.     

Insights into the economic consequences of the 2007 equine influenza outbreak in Australia

We estimate and describe the financial costs of the equine influenza (EI) outbreak in Australia, including the costs of emergency response measures and lost income/assets to businesses, associations and private horse owners. Costs to associations, governments and industry are discussed. We identify a lack of reliable data about the financial costs of the EI outbreak to the non-racing sectors of the horse industry.     

Vaccination program in the response to the 2007 equine influenza outbreak in Australia

At the time of the initial notification of the occurrence of equine influenza (EI) in Australia in August 2007, vaccination was restricted to horses for which it was an import requirement and only with the approval of the state or territory Chief Veterinary Officer. This paper describes the complexities involved in the selection of a vaccine and its distribution. A combination of ring, predictive and blanket vaccination was implemented during the response. The specific vaccination programs, including its use in buffer zones and for movement of horses, the performance of the vaccine, any adverse reactions and the effect on exposure of vaccinated horses to circulating virus, are also described. Vaccination is considered to have made a valuable contribution to the containment and subsequent eradication of EI from Australia and to risk management in the resumption of horse activities in affected areas from December 2007. Movement restrictions and other biosecurity measures were critically important in controlling the spread of EI and contributing to its eventual eradication, and vaccination was an aid to these measures.     

An insider's view of the lockdown at Moonbi during the Australian equine influenza outbreak

Participants in the 1- and 2-day Tamworth Dressage Club (TDC) annual dressage championships arrived in Moonbi, New South Wales (NSW) as reports of the equine influenza outbreak surfaced on 25 August 2007. Three horses who had attended a competition in Maitland the weekend before had been showing flu-like symptoms and the next day the site was declared a suspect premise. On 27 August, infection was confirmed and the site was placed in total quarantine. Although most participants had travelled long distances to compete and did not have provisions for them or their horses, the quarantine was not lifted until 3 October, having a great social and personal impact on all those trapped in Moonbi.     

Industry liaison officers in the infected states of Australia during the 2007 equine influenza outbreak

We describe the activities of persons who were formally employed as industry liaison officers (ILOs) in the infected states of Australia during the 2007 equine influenza outbreak. The knowledge and communication skills of ILOs allowed them to function very effectively, despite most of them having received no prior training. It is arguable, however, that if ILOs had received prior training, they would have performed more effectively sooner. We suggest that more individuals need ILO training in 'peacetime' and that 'just-in-time' training packages require preparation and trial prior to outbreaks to be effective.     

Impact of the Australian equine influenza outbreak on a small business that was not infected

At the outbreak of equine influenza (EI) we chose to close our horse-based business, as we did not want to risk our horses contracting the disease and the demand for our services ceased. We report our experiences of the outbreak.     

Infection of dogs with equine influenza virus: evidence for transmission from horses during the Australian outbreak

During the equine influenza (EI) outbreak, respiratory disease was observed in dogs that were in close proximity to infected horses. Investigations were undertaken to exclude influenza virus infection. Of the 23 dogs that were seropositive in tests using the influenza A/Sydney/2007 virus as the test antigen, 10 showed clinical signs. EI virus appeared to be readily transmitted to dogs that were held in close proximity to infected horses, but there was no evidence of lateral transmission of the virus to other dogs that did not have contact with or were not held in close proximity to horses.     

Assessment of the proportion of under-reporting during the 2007 equine influenza outbreak in New South Wales, Australia

During the 2007 equine influenza (EI) outbreak in Australia, there was no objective information about the possible under-reporting of cases by horse owners either so that they would avoid movement restrictions or because of their inability to detect infection. This investigation aimed to estimate the proportion of under-reporting during the outbreak based on the results of surveillance undertaken in conjunction with vaccination. The results provided improved estimates of morbidity during the outbreak and indicated the level of under-reporting likely to occur in future outbreaks of other infectious diseases in horses in Australia.     

Attack risk on infected properties during the 2007 equine influenza outbreak in New South Wales, Australia

The aim of this preliminary study was to estimate the proportions of seropositive horses on infected premises (IPs) in order to assess the attack risk of the disease. Logistic regression analyses were conducted to evaluate the differences in attack risks between enterprise sizes and predefined spatial clusters/regions. The average attack risk experienced during the outbreak was 96.88% (median 100%), but it differed according to the size of the enterprise and other geographic and demographic conditions. The highest attack risks were observed in the Dubbo cluster/region and the lowest in the Narrabri-Northern cluster. Properties with fewer horses were generally more likely to have higher attack risks than larger enterprises, though this was not true for all cluster/regions.