Although it is rare for humans to contract diseases from horses, it is important that as a horse owner you practice good hygiene to help limit the inherent risk. This is true also when the Streptococcus bacterium is concerned.
Normally, the Streptococcus zooepidemicus bacterium can be found in both healthy and sick equines. Typically, the Streptococcus bacterium is known to commonly cause respiratory conditions in horses -- and, uncommonly, other infections as well. The bacterium can also be found in the nose, mouth, and throat even in healthy horses.
However, this bacterium should not be confused with the Group A Streptococcus scientifically referred to as Streptococcus pyogenes which is a leading cause of “strep throat”, or Streptococcus pneumoniae that causes respiratory infections and meningitis in humans.
Although S. zooepidemicus is capable of causing disease in human beings, cases have been extremely rare. Contracting it can lead to ailments ranging from mild infections to severe eye infections and meningitis.
With horses, the good news is that this bacterium is very poorly adapted to infect humans. There have been very few cases of the bacteria in people considering how often this species of bacterium is found in both sick and healthy horses, and given the fact that humans have a lot of contact with their equine friends. But it is also important to note that horses are not the only source of this bacterium since some human infections of S. zooepidemicus have been linked to both dogs and guinea pigs as well.
Well, the risk appears to be quite low, but the fact that it is still not zero means that we should all be careful when handling our horses. Again, although a S. zooepidemicus infection is rarely serious, there is still very little knowledge about why the bacterium affects some people and not others -- another reason to be more careful.
So, what do you do to reduce the risk or eliminate it entirely? Maintain basic hygiene practices like hand-washing; limit your contact with sick horses; and wear your eye protection and mask whenever you are working closely with your equine partner if he is infected by a respiratory disease. This is more so for people with a compromised or naturally weak immune system.