INFECTIOUS DISEASES
Flexible and
Opportunistic Dry Cough? Nasal Discharge? Keep S. zooepidemicus in the Differential for Respiratory Diseases
The organism, Streptococcus equi subspecies zooepidemicus is the bacterium that is most often recovered from a horse’s oropharynx even when healthy, which might suggest that it is not a serious threat, but Andrew Waller 3rd, PhD, the chief scientific officer at Intervacc in Sweden, thinks it is cause for concern. Several recent studies show that S. zooepidemicus is quite the opportunist and can cause a variety of diseases in many animals, including humans. Often by the time there are clinical signs, the organism has already spread around the barn, according to Dr. Waller. “The disease is often subclinical, so it can be quite tricky to pick up—sort of a bit like COVID—it can spread around without many signs, and then every now and then, you get a flare up of severe disease,” he explained. You might consider including it in the differential in an animal with obvious cough, he said, and be vigilant about biosecurity and wearing personal protective equipment (PPE). Not only does it spread swiftly among a group of horses, but it can sometimes affect B y
4
Issue 1/2022 | ModernEquineVet.com
M a r i e
the people caring for them. “It is something to watch out for,” he said at the American Association of Equine Practitioners Annual Convention 2021. “If you ever treat animals that are obviously coughing, just be aware that it can jump into humans. It's flexible and opportunistic, and it's got a variety of mechanisms to allow it to cause disease in different animal hosts.” Human cases of S. zooepidemicus can be extremely serious, he added, mentioning one case in a caregiver in Iceland during an outbreak who suffered septicemia and a miscarriage, and tested positive for the particular strain of S. zooepidemicus that was causing the outbreak. “It’s just something to bear in mind, if you go and see an animal that has obvious respiratory signs of disease, it might be worth wearing some sort of PPE,” he said. “The risk of it transferring to humans is really small, but when it does, it can cause really nasty disease.” Streptococci occur in many different animals, and they cause a variety of different diseases. Most veterinarians are familiar with S. equi, the cause of strangles, a com-
R o s e n t h a l ,
M S
