Comparison of iatrogenic transmission of Anaplasma marginale in Holstein steers via needle and needle-free injection techniques

摘要

Objective-To compare iatrogenic transmission of Anaplasma marginate during sham vaccination between needle and needle-free injection techniques.Animals-26 Holstein steers confirmed negative for anaplasmosis by use of a competitive ELISA (cELISA) and an A margina/e-specific reverse transcription (RT)-PCR assay. Procedures An isolate of A marginate was propagated to a circulating parasitemia of 2.0% in a splenectomized steer. Sham vaccination was performed in the left cervical muscles of the splenectomized parasitemic steer with a hypodermic needle fitted to a multiple-dose syringe. The same needle and syringe were used to sham vaccinate a naive steer. This 2-step procedure was repeated until 10 naive steers (group ND) were injected. Similarly, sham vaccination of the right cervical muscles of the splenectomized parasitemic steer and another group of 10 naive steers (group NF) was performed by use of a needle-free injection system. Five control steers were not injected. Disease status was evaluated twice weekly for 61 days by use of light microscopy, a cELISA, and an A margina/e-specific RT-PCR assay.Results-latrogenic transmission was detected in 6 of 10 steers in group ND. Disease status did not change in the NF or control steers. Sensitivity of light microscopy, cELISA, and RT-PCR assay was 100% on days 41, 41, and 20 after sham vaccination, respectively; however, only cELISA and RT-PCR assay sustained a sensitivity of 100% thereafter.Conclusions and Clinical Relevance-Needle-free injection was superior to needle injection for the control of iatrogenic transmission of A marginate. (Am J Vet Res 2010;71: 1178-1188)