Iceland’s scientific investigation into a mysterious respiratory illness that affected its horses shows the power of genomics to unravel the cause of a significant biosecurity threat, an expert says.
Dr Mark Davies, a University of Melbourne specialist in bacterial genomics, praised the microbial forensic work undertaken to get to the bottom of the 2010 outbreak.
Iceland is free of all major horses diseases thanks to a ban on importing horses into the country that has applied since 1882.
The country’s 77,000 iconic Icelandic horses have enjoying a relatively disease-free environment for the last 1000 years, which makes them particularly susceptible to any new bacteria or viruses that cross the border.
Strict biosecurity regulations are in place to protect them. However, in 2010, a mysterious respiratory infection swept through the horse population, spreading across the country within weeks. It also affected dogs and cats, and some people fell ill.
Horse transportation was brought to a halt in a bid to contain the spread of the infectious agent.
Davies said Sigríður Björnsdóttir and his colleagues employed the power and resolution of “genomic epidemiology” – the combination of whole genomic sequencing and epidemiological approaches – to examine the source and spread of the outbreak.
Intriguingly, the outbreak was not viral in origin, but linked to a bacterial Streptococcus equi subsp. zooepidemicus infection.
A national sampling strategy coupled with population genomics revealed that the outbreak was most likely driven by a S. equi subsp. zooepidemicus sequence type 209 (ST209) infection that spread nationally from a single source.
The research showed the power of genomics applied on a national scale to unravel the cause of a significant biosecurity threat, Davies wrote in a commentary in mBio, the journal published by the American Society for Microbiology.