Iceland is free of all major equine infectious diseases, so Icelandic horses are particularly susceptible to any new bacteria or virus that enters the country. | Photo: iStock

Researchers from the Animal Health Trust (AHT), in partnership with British and Icelandic research and veterinary institutions, have identified the cause of an epidemic of respiratory disease which infected not only Iceland’s native horse population, but also dogs, cats, and humans.

The respiratory disease epidemic in early 2010 was characterized by coughing and nasal discharge. The disease spread through the population of 77,000 Icelandic horses within weeks, leading to a self-imposed ban on their export and significant economic cost to the country. Initially, due to the speed at which the disease had spread, a viral cause was suspected. Investigations by researchers at the University of Iceland showed that only Streptococcus zooepidemicus, was consistently recovered from coughing horses and rare fatal cases of infection. However, this bacterium was also often found in healthy horses.

Scientists from the AHT and the Wellcome Trust Sanger Institute, in Cambridge, England, were brought in to investigate