Epidemiologic studies of Lyme disease in horses and their public health significance.

The research paper is focused on studying the prevalence of Lyme disease in horses in the New Jersey-Pennsylvania area, its epidemiology, and its potential implications on public health.

Geographical Spread and Prevalence of Lyme Disease in Horses

• The paper discusses an investigation of horses in the New Jersey-Pennsylvania area. It found that around ten percent of the horses surveyed had significant serum antibody levels to Borrelia burgdorferi, the bacterium that causes Lyme disease. These statistics, however, varied with location. In an area of central New Jersey that is a hotbed for the disease, almost sixty percent of the mares and yearlings on one particular farm were seropositive.

Temporal Variation of Lyme Disease Prevalence

• Observing the same farm longitudinally, researchers saw in 1983 that only 12% of the mares and 35% of the yearlings were positive for Borrelia burgdorferi. In 1985, however, a more focused study on individual yearlings over a six-month period found that 34% of them declined during this period.

Emergence of a New Clinical Syndrome

• Researchers discovered a new clinical syndrome associated with Lyme disease within the horse population of the studied farm between 1985 and 1987. Initially, the syndrome was characterized by leg edema and dermatitis in about 19.2% of the foals, with a concentration of cases suggesting an infection source beyond just arthropods. By 1986, the syndrome had developed into arthritis in 14.6% of the foals, proving resistant to antibiotics in some cases.

Experimental Infection of a Pony

• As a part of the study, researchers also experimentally infected a pony with triturated B. burgdorferi-infected tick material. The emergence of low specific antibody levels, starting from the ninth day and continuing for three weeks, was observed. However, after challenging the pony after six months with primary B. burgdorferi cultures, the animal showed a quick and significant booster effect within just four days of the challenge.