Vesicular stomatitis (VS) is a viral disease primarily affecting livestock, particularly horses, cattle, and swine, though it can also affect llamas and alpacas. Caused by the Vesicular Stomatitis Virus (VSV), this illness is characterized by blister-like lesions on the mouth, teats, and feet of infected animals. The disease circulates in warmer climates and occurs sporadically in the temperate regions of the Western Hemisphere. Vesicular Stomatitis is considered a zoonotic disease.
The Zoonotic Nature of Vesicular Stomatitis
The causative agent is the Vesicular Stomatitis Virus (VSV), which belongs to the Rhabdoviridae family of viruses. While the virus primarily causes widespread outbreaks in livestock, human infection is possible, typically occurring in people who have close contact with infected animals.
Human cases are generally rare compared to animal outbreaks but pose a recognized risk for certain occupational groups. This mandatory reporting requirement for livestock highlights the seriousness of potential spread.
Transmission Pathways and High-Risk Exposure
Transmission occurs mainly through direct contact with infectious materials, including saliva, nasal secretions, and fluid or tissue from ruptured blisters (vesicles) on the animals. The virus enters the human body through abrasions or cuts on the skin, or via contact with mucous membranes (eyes, nose, or mouth).
Indirect transmission is also possible through contaminated objects, such as feed buckets, halters, or other equipment used for infected animals. Biting insects, such as sand flies and black flies, are also suspected to play a role in viral spread.
Individuals who work closely with livestock are at the highest risk of exposure. This includes veterinarians, technicians, handlers, farmers, and farriers. Risk increases for those who examine the oral cavity of infected animals or have open wounds during contact. Transmission can also occur through the inhalation of infectious aerosols in a laboratory setting.
Symptoms and Human Health Impact
When humans become infected with the Vesicular Stomatitis Virus, the disease typically manifests as an acute, self-limiting illness. The incubation period is short, lasting from one to six days. The initial phase often resembles a mild case of the flu.
Common symptoms include a sudden onset of fever, headache, muscle aches, and general weakness. Some individuals may also develop characteristic vesicular lesions (blisters) that appear in the mouth, on the lips, or on the hands and fingers.
The illness is usually mild and runs its course within four to seven days. Complete recovery is expected, and severe complications, such as inflammation of the brain, are extremely uncommon.
Protective Measures and Post-Exposure Management
Preventing human infection with Vesicular Stomatitis Virus relies on implementing strict personal hygiene and biosecurity measures when working with potentially infected animals. Individuals who must handle or examine animals with suspected lesions should use appropriate Personal Protective Equipment (PPE). This equipment includes disposable gloves, gowns, and eye protection or face shields to prevent contact with infectious fluids and materials.
Frequent and thorough handwashing is a fundamental practice for controlling the spread of this disease. Controlling insect populations, particularly biting flies and midges, is also a preventive action, as these vectors can spread the virus. Insect control programs should focus on reducing breeding areas and using approved insecticides.
If exposure is suspected or confirmed, the management of the illness in humans is primarily supportive, as there is no specific antiviral treatment for Vesicular Stomatitis. Supportive care involves managing symptoms with over-the-counter pain relievers for fever and muscle aches, and ensuring adequate hydration. Individuals who have been in contact with affected animals should report their illness to their physician. Simultaneously, any animal suspected of having the disease must be reported immediately to a veterinarian or state animal health authorities, as Vesicular Stomatitis is a reportable condition.