Epizootic vesicular stomatitis in Colorado, 1982: epidemiologic studies along the northern Colorado front range.

The research explores an outbreak of vesicular stomatitis, a viral disease in animals, in Colorado in 1982. The study found that the risk of infection was higher in those who had close physical contact with infected animals, with incidence rates highest in horses.

Epidemiologic Evaluations

• The research began with epidemiologic evaluations on farm personnel on premises affected by vesicular stomatitis along the front range of the Rocky Mountains in Colorado.
• The researchers noted a similarity between the antibody prevalence in farm personnel, veterinarians and other professionals involved in animal health who were involved with this outbreak.
• They concluded that the risk of infection appeared to increase with “intimate physical contact” with infected animals, particularly horses and cows.

Infection Rates

• The research found that the incidence and infection rates were considerably higher in horses at 45% compared to cows with a much lower infection rate of only 5%.
• This significant difference in infection rates between the two species suggests that in this specific outbreak, horses were significantly more susceptible to the disease.

Insights from the Equine Ranch Study

• To further understand the spread of the disease, a detailed study was conducted at a ranch with horses.
• The researchers found that the pasture was tied to the highest risk of infection with a 100% infection rate; while horses held in open pens and barns were at a lower risk of contracting the disease.
• This points towards possible factors in the environment of the pasture that may facilitate the spread of the disease.

Antibody Responses and Maternal Antibody

• Severe clinical disease in horses resulted in higher neutralizing antibody titers (a measure of how much antibody an organism is producing) compared to cases of mild or non-apparent infection.
• This indicates that severity of the disease appears to correspond to the immune response of the affected animal.
• The research also detected maternal antibody (antibodies passed from mother to offspring) in foals, up to 4 months of age.
• The antibody level in each foal reflected the antibody level in the mother, suggesting that the maternal immune response could influence the immune response in offspring.