Strangles is a highly contagious bacterial disease primarily affecting horses and other equids worldwide. This condition often raises questions among horse owners and enthusiasts about potential risks to human health. This article clarifies whether humans can contract Strangles and addresses human health considerations when interacting with horses.
Understanding Equine Strangles
Strangles is an infectious disease of the upper respiratory tract in horses, caused by the bacterium Streptococcus equi subspecies equi (S. equi equi). This bacterium leads to characteristic swelling and abscess formation in the lymph nodes, particularly those located in the head and neck region, which can sometimes obstruct breathing. Clinical signs typically appear after an incubation period of 3 to 8 days and can include fever, lethargy, loss of appetite, and nasal discharge that often becomes thick and pus-like.
The spread of S. equi equi occurs through direct contact with infected animals or indirectly via contaminated environments. Infected horses shed the bacteria through nasal discharge and material from ruptured abscesses. This can contaminate water sources, feed, equipment, and even human hands and clothing. While the prognosis for uncomplicated cases is generally good, some horses can become carriers, harboring the bacteria in their guttural pouches and intermittently shedding it.
Is Strangles a Human Disease?
Streptococcus equi subspecies equi, the specific bacterium responsible for Strangles in horses, is highly host-specific to equids, including horses, donkeys, and mules. This means the bacterium has evolved to thrive and cause disease almost exclusively within these animal species. The biological mechanisms that allow S. equi equi to infect and multiply efficiently are uniquely adapted to the equine host, making it generally unable to establish infection in humans.
Documented cases of S. equi equi causing disease in humans are rare. When reported, they typically involve individuals who are severely immunocompromised or who experienced unusual circumstances involving direct inoculation of the bacteria into a compromised site. General contact with horses, even those infected, does not typically lead to human infection with S. equi equi.
Human Health Risks and Prevention
While Streptococcus equi subspecies equi rarely infects humans, other Streptococcus species found in horses can pose a risk. Streptococcus equi subspecies zooepidemicus (S. zooepidemicus) is a distinct bacterium commonly found in horses that can cause infections in humans. Unlike S. equi equi, S. zooepidemicus is an opportunistic pathogen in horses and has a broader host range, occasionally causing severe infections in humans. Human infections with S. zooepidemicus have been linked to direct contact with infected animal fluids or through the consumption of unpasteurized dairy products. Symptoms in humans can range from localized infections to more severe conditions like meningitis, endocarditis, or kidney issues.
To minimize health risks when interacting with horses, especially sick ones, practicing good biosecurity and hygiene is important. Thorough hand washing with soap and water is recommended after handling horses, their tack, or their environment. Avoiding contact with nasal discharge or abscess material from sick animals is also a precaution. If direct contact with potentially contaminated materials is unavoidable, wearing protective gear, such as gloves, can provide safety. These measures help prevent the transmission of various pathogens, including S. zooepidemicus, that can be carried by horses.
When to Seek Medical Advice
If you have been around horses, particularly sick ones, and begin to experience concerning symptoms, seeking medical advice is prudent. Symptoms such as swollen lymph nodes, fever, or respiratory issues are common to many human illnesses, including viral infections or other bacterial infections, and are not specific indicators of a horse-related disease.
When consulting a healthcare professional, providing information about any recent animal contact, including horses, can be helpful for diagnosis. This context allows the doctor to consider a wider range of potential causes for your symptoms. Any persistent or severe symptoms should always be evaluated by a healthcare professional. Prompt medical attention is advised for deep wounds, severe bleeding, or signs of infection such as increasing pain, redness, swelling, or pus.