An elderly woman in the Seattle area died this year from a bacterial infection that usually only affects horses after she had close contact with an ill animal, according to a recent CDC report.
Streptococcus equi zooepidemicus "rarely causes human illness," and is usually associated with eating unpasteurized dairy products or coming in contact with horses.
In this case, a 71-year-old woman visited her daughter who runs a horse boarding and riding facility in King County, Wash. One of the horses at the facility had been ill, started taking antibiotics, and recovered. The mother had been in contact with the horse before it began treatment, and she developed symptoms including vomiting and diarrhea before being found unconscious and was transferred to the hospital, where she later died.
Lab testing showed she had been infected with the same strain of S. zooepidemicus that the horse had.
It is possible that older adults could be at higher risk of contracting an S. zooepidemicus infection, according to the CDC report.
"This outbreak highlights the need for more research regarding risk factors for zoonotic transmission and spectrum of human illness associated with S. zooepidemicus," the report concluded.
Editor's note: The headline to this story was updated to remove reference to horseback riding, as the infection was in fact linked to close contact with a sick horse. We regret the incorrect implication.