University of Kentucky researchers have found evidence that cases involving the form of equine herpes virus-1 (EHV-1) capable of causing disease in nervous tissue are growing.

Scientists at the Maxwell H. Gluck Equine Research Centre, in the Department of Veterinary Science at the university, studied 426 archived EHV-1 samples collected from 1951 to 2006 from equine abortions.

All strains of EHV-1 can cause respiratory disease and abortion, but a possible genetic mutation in one sub-strain of the disease can cause severe neurological symptoms and is frequently fatal.

Their findings revealed that the viruses with the neuropathogenic genotype—capable of causing disease in nervous tissue—had existed in the 1950s and increased in prevalence from 3.3 percent in the 1960s to 14.4 percent in the 1990s.

Further investigation indicates that its prevalence from 2000 to 2006 had risen to 19.4 percent.