Study highlights ‘unbridled globetrotting’ of the strangles pathogen in horses

In the largest ever study of its kind into an equine pathogen, scientists in 18 countries used the latest DNA sequencing techniques to track the bacteria responsible for a disease called 'strangles’ in horses around the world.

Horse. Photo: Nicky/Pixabay

The results provide evidence of the important role played by the movement of horses in spreading this disease, providing new opportunities for interventions that will prevent future outbreaks.

Strangles, caused by the bacteria Streptococcus equi, is the most frequently diagnosed infectious disease of horses.

Streptococcus equi invades the lymph nodes of head and neck of horses, causing them to swell and form abscesses that can, in around 2% of cases, literally strangle the horse to death. Some of the horses that recover from strangles remain persistently infected.

These apparently healthy animals shed bacteria into the environment and spread the disease to other horses that they come into contact with.

Using standard diagnostic testing, the Streptococcus equi strains look almost identical. But by carefully examining the DNA of the bacteria, the team were able to track different variants as they spread across the world.

The research used the new online Pathogenwatch resource, developed at the Wellcome Sanger Institute, to visualise and share genome data to track the course of infections.

“Piecing the puzzle together, we showed that cases in Argentina, the United Kingdom and the United Arab Emirates were closely linked. Along with other examples, we provide evidence that the global trade and movement of horses is helping to spread the disease,” said Professor Matthew Holden of the University of St Andrews, who was involved in the study.

"This study shows once again the power of genomic data to uncover the fine detail of pathogen transmission locally and globally,” said Professor Julian Parkhill in the University of Cambridge’s Department of Veterinary Medicine, who was involved in the study.

He added: “Using whole genome sequences we can track the movement of pathogens with very high precision, showing how and where to intervene to prevent the disease spreading."

Strangles was first described in Medieval times and, with the exception of Iceland, affects horses in all corners of the world. The freedom from this disease enjoyed by Iceland is by virtue of a ban on the import of horses, which has been in place for over 1,000 years.

Horses are transported all over the world as they move to new premises or attend competitions and events. New cases of Strangles can be prevented by treating carriers before they pass on the bacteria. (University of Cambridge)

YOU MAY ALSO LIKE

Universe Might Be One Big Neural Network

In a thought-provoking new paper, a physicist suggests the whole universe could be a single neural network—a competing “theory of everything” that could unite quantum and classical mechanics, he says.

World's oldest DNA reveals how ice age mammoths evolved

Discovery of new lineage, insights into when and how fast mammoths adapted to cold climate.

Through the looking glass: artificial ‘molecules’ open door to ultrafast devices

Researchers from the University of Cambridge and Skoltech in Russia have shown that polaritons, the quirky (...)

Sea ice kept oxygen from reaching deep ocean during last ice age

Sea ice is like a closed window for the ocean.

Scientists discover how DNA fragments can trigger inflammation in sickle cell disease

Researchers have discovered that DNA from the mitochondria acts as a danger signal in the body and triggers (...)

Cuttlefish show their intelligence by snubbing sub-standard snacks

A study has found that cuttlefish can pass a fishy version of the ‘marshmallow test’ – and those that can delay gratification the longest are the most intelligent.