Seroprevalence of antibodies to Sarcocystis neurona in horses residing in Ohio.

OBJECTIVE

To determine the seroprevalence of serum antibodies to Sarcocystis neurona in horses residing in Ohio.

DESIGN

Prevalence survey.

SAMPLE POPULATION

Serum from samples from 1,056 horses. Serum was collected on every 36th sample submitted to the Ohio State Diagnostic Laboratory for testing for equine infectious anemia.

PROCEDURE

Serum was frozen at -80 C and analyzed for antibodies to S neurona, using a western blot. Information regarding blood sample collection, age, breed, sex, and geographic location was recorded for each horse. Data were analyzed, using multivariable logistic regression.

RESULTS

Horses of 37 breeds from 81 of Ohio's 88 counties were included in the study population. There were 481 females, 133 males, and 442 geldings ranging in age from 3 months to 27 years; > 48% were < 5.6 years old. More than 53% of samples were seropositive for antibodies to S neurona. A gender or breed effect on seroprevalence was not identified. There was a significant effect of age (P < or = 0.0001; with older horses more likely to be affected), and of location (statistical and extension districts; P = 0.02 and P = 0.03, respectively) on seroprevalence. Location effects appeared to be correlated to the number of days with temperatures below freezing (P < 0.05).

CLINICAL IMPLICATIONS

The high seroprevalence of antibodies to S neurona found in the sample population emphasizes the importance of examining CSF for S neurona-specific antibodies when establishing a diagnosis of equn protozoal myeloencephalitis.