Computer modelling central to NZ equine flu study

June 30, 2009

Sarah Rosanowski with Manfield. © Colin Louisson

How prepared is New Zealand for an outbreak of equine influenza, and how quickly is it likely to spread?

If you think it's the $64,000 question, think again. Australia discovered that the cost of the highly contagious virus to its economy was up to $A1 billion after the disease got loose from a quarantine station near Sydney in 2007.

Australia mounted a massive containment effort involving movement restrictions, buffer zones and a targeted vaccination programme which turned the tide against the disease.

However, jobs were lost and equine industries were hit hard as authorities worked to eradicate the disease.

Today, the aftermath continues, with major reforms of Australian biosecurity measures and ongoing debate over how the equine industry will pay for fighting future incursions of exotic diseases.

Now, Massey University masters student Sarah Rosanowski is about to explore just how prepared New Zealand is for equine flu and, using New Zealand-developed computer modelling software, will determine the likely course of any outbreak.

The computer model will also be able to determine the effectiveness of various containment and eradication measures, ranging from vaccination, movement bans and buffer zones.

The results should provide important strategic guidance should New Zealand face an exotic disease outbreak among horses.

The Ministry of Agriculture and Forestry recognised the likely value of such findings and has commissioned Rosanoswki's research.

Rosanowski's work is also likely to provide the country with arguably its most detailed snapshot to date of its equine population and, just as crucially, what people do with their horses.

Rosanowski graduated from Massey with a science degree in 2004. She has worked for five years in science, working for the Animal Health Group of AgRresearch, focusing on parasitology.

Now, her ongoing studies have set her on a path exploring a disease which is considered endemic in most parts of the world.

Only New Zealand, Australia and Iceland remain free of the disease among countries with significant equine populations.

Rosanowski's research will involve a postal survey of a cross-section of New Zealand horse owners.

Work has been under way developing thquestionnairere, which will go out to 3000 horse owners outside the racing sector within the next month. A later survey will target the racing sector.

Recipients have been randomly selected by computer from the Agribase database, where information is kept on what animals rural dwellers have indicated they keep on their properties.

The information being sought from owners includes the number of horses on their property, their uses, how often they take them from the property in a year, how far they travel, how often their animals mix with other horses and how often equine practitioners - ranging from vets, farriers and dentists to therapists - visit the horses.

Chris Rogers, an equine sciences lecturer at Massey who is supervising Rosanowski's research, says: "One of the major issues in New Zealand is that we have very limited information about how many horses there are and what they are used for."

Current estimates range from 70,000 to 120,000.

There is no central database covering the non-racing sector, which accounts for the majority of horses in the country.

He expects the data gathered will provide the most accurate snapshot yet of the non-racing sector in the country. "We should get a really accurate reflection of what we have," he says.

The information gathered in the survey will be input into software from Massey developed for a foot and mouth outbreak in Britain.

The software, called InterSpread Plus, has since been used for computer modelling around other disease outbreaks and scenarios.

Rosanowski says the software is readily adaptable and different variables can be entered to reflect the nature of each disease.

She says foot and mouth in fact has many parallels with equine influenza. Both can spread rapidly in a naive population and both can be dispersed by the movement of people and equipment.

Once survey data is entered into the software, Rosanowski will not only be able to explore the likely spread of the disease, but can input variables such as movement restrictions and vaccination programmes to see how they effect the potential rate of spread.

The result should be data on what measures are likely to be the most effective and viable in controlling an outbreak.

Rogers says the research is a collaborative project between the Ministry of Agriculture and Forestry and Massey. Later work will include an exploration of New Zealand's biosecurity preparedness and the potential economic impacts of an outbreak.

Rosanowski is working on what Rogers describes as a fairly tight timeframe, with initial findings expected from the middle of next year.

Rosanowski, who has been involved with horses all her life, said she followed the Australian equine flu outbreak with interest.

The Australian outbreak involved debate at the highest levels on what strategies should be employed, with some industry groups lobbying at one stage to abandon containment measures as the disease spread rapidly.

Rosanowski's findings should give the country's biosecurity officials the clearest picture yet of what direction they should take should New Zealand face a similar challenge.