Factors associated with likelihood of horses having a high serum Streptococcus equi SeM-specific antibody titer

Abstract

Results indicated that older horses, horses other than Thoroughbreds and warmbloods, and horses that had been vaccinated with an attenuated-live intranasal S equi vaccine between 1 and 3 years previously had an increased likelihood of having a serum SeM-specific antibody titer > or = 1:1,600.

Update on Streptococcus equi subsp equi Infections

“…Titers greater than 1:1600 are Update on Streptococcus equi subsp equi Infections considered high enough such that vaccination may trigger immunologic reactions and likely reflect adequate immunity to disease. 4,30 Vaccination At this time, development of a truly protective vaccine for strangles is considered feasible but has not been fully achieved with the available products. There is significant research in this arena, and some characteristics of the routine microbe-host interaction suggest that vaccination can be successful.…”

“…SeM titers greater than 1:12,800 are most associated with metastatic strangles infection, and values of 1:3200 to 1:6400 are found with recent infection and recovery. 4,30 A subset of affected horses become persistent shedders of S equi after resolution of their primary disease. The infectious material is typically found within the GP, although it is also rarely reported to occur in the sinuses.…”

Comparison of Immunologic Responses Following Intranasal and Oral Administration of a USDA-Approved, Live-Attenuated Streptococcus equi Vaccine

“…Increased age, Quarter horse and other breeds compared to Thoroughbreds and warmbloods, and previous vaccination increased the odds of having a SeM titer >/= 1:1600 (Boyle et al 2009). …”

“…None of the 21 horses with an SeM titer of 1:1600 or of the 5 horses with an SeM titer of 1:3200 at the time of revaccination developed any signs of purpura hemorrhagica (Boyle et al 2009). antigens (antigens A and C) was compared to the SeM iELISA.…”

“…Because at pre-existing high SeM titer is associated with development of purpura hemorrhagica following vaccination, studies have determined factors that are associated with horses having high titers (Boyle et al 2009). …”