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New surveillance strategy for avian influenza

04 September 2018

Highly pathogenic avian influenza (HPAI) remains a serious threat to the global poultry industry, but a new and successful Canadian technique to detect presence of the disease in wild bird populations is already helping to prepare for and control outbreaks

Words Treena Hein

From 2014 to 2015, HPAI outbreaks across the US caused the deaths of more than 48 million birds, with costs reaching $3.3 billion. In 2018, outbreaks occurred in many European countries.

Epic Scotland (the Scottish government’s centre of expertise on animal disease outbreaks) notes on its website that this includes an HPAI H5N6 strain outbreak in England (Dorset), the Netherlands, Germany and Switzerland; HPAI H5N8 in Russia, Germany, Italy and Bulgaria; and HPAI H5N2 in Russia. An “avian influenza prevention zone” was declared in January across England and Wales and was lifted in May.

According to the Canadian Wildlife Health Cooperative, a cross-Canada network of partners and collaborators dedicated to wildlife health, AI surveillance strategies must, first and foremost, focus on wild waterfowl. “Wild waterfowl, which are generally asymptomatic carriers of the virus, are responsible for long-distance transmission of AI,” notes the agency on its website, “spreading the virus into new geographic areas during their migration.”

The cooperative points out that the overlap of global wild-bird migratory routes aids the reassortment of viruses’ genes, and that five North American AI outbreaks have been caused by a virus that contained a Eurasian H5 segment and a North American N2 segment. There is concern, it states, “that global warming and associated changes in migratory patterns might favour increased incursion of Eurasian viruses into North America. This is particularly problematic because Eurasian viruses tend to be more pathogenic for both people and poultry and could lead to an increase in the frequency and severity of North American AI outbreaks. It is of note that reassortment and long-distance movement of viruses in waterfowl makes it difficult to predict circulating virus strains, which, in turn, makes it difficult to develop effective vaccination programs for poultry.”

Surveillance programmes for wild waterfowl in Canada and the USA have involved the collection and testing of individual wild birds. However, in 2015, a new idea was explored by a group of experts from several agencies based in British Columbia, Canada, including the BC Ministry of Agriculture and the BC Centre for Disease Control. Instead of testing for the AI virus in wild birds, the approach involved testing sediments containing wild-bird faeces in wetland areas.

Many tests results have shown AI detected in a significant proportion of sediment samples. This detection rate is very high, notes the cooperative, compared to the Canadian national wild-bird influenza surveillance programme’s current rate of detection, which is less than 1 percent.

To further evaluate this surveillance approach, a new project called “Genomic analysis of wetland sediment as a tool for avian influenza surveillance and prevention” has just been given the green light. It is supported by an investment of more than $2.5 million provided by Genome BC, the BC Ministry of Agriculture, the Canadian Food Inspection Agency, the Sustainable Poultry Farming Group and others.

In this follow-up project, the team will determine how to move the technology from successful proof-of-concept to widespread implementation in provincial and national wild-waterfowl influenza surveillance programmes.

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