| prevalence of equine onchocerciasis in southeastern and midwestern united states. | of 664 horses reported to have originated in southeastern and midwestern united states, 341 (51.4%) were positive for onchocerca cervicalis cutaneous microfilariasis. the highest prevalence of 68.8% was recorded for horses from virginia. horses with the highest concentrations of microfilariae (as high as 19,770 microfilariae/mg in 1 horse) were from the southeast (georgia, florida, tennessee, and alabama). for horses from south carolina, the prevalence of infection was 57.1%; from the midwest (k ... | 1985 | 4008301 |