Vertical transmission of Mycoplasma haemolamae in alpacas (Vicugna pacos)

Abstract

The purpose of this study was to determine the frequency of vertical transmission of Mycoplasma haemolamae from dam to cria, whether colostral transmission of M. haemolamae occurs and provide preliminary data on colostral M. haemolamae specific antibody from pregnant alpacas on a farm with known prevalence of infection. M. haemolamae specific PCR was performed on blood and colostrum from pregnant alpacas and their cria (n=52 pairs). Indirect fluorescent antibody testing was performed on a subset (n=43) of the colostrum samples. Total immunoglobulin concentrations of colostrum and cria sera and M. haemolamae specific IgG (prior to and after ingesting colostrum) were determined by turbidometric immunoassay and indirect fluorescence antibody testing respectively. Sixteen of 52 dams (30.7%) pre-partum and one of 52 cria post-partum (1.9%; prior to ingesting colostrum) were PCR positive for M. haemolamae, while 36/52 dams (69%) and 51/52 cria (98%) tested negative for M. haemolamae by PCR. All 43 colostrum samples and 52 of 52 post-colostrum cria blood samples (100%) were negative by PCR. The dam giving birth to the M. haemolamae PCR positive cria was PCR negative. Statistically, it was no more likely for a PCR positive dam to give birth to a M. haemolamae, PCR positive cria (prior to colostrum ingestion) than a PCR negative dam (p=0.3077). M. haemolamae specific IgG was present in 22 of 43 (51%) of colostrum samples at a 1:10 dilution and 14 of 22 (64%) at a 1:100 dilution. There was no relationship between the PCR status of the dam and whether or not M. haemolamae specific antibodies were present in colostrum. Among the animals tested, in utero transmission of M. haemolamae was rare (1/52 pre-colostral alpaca cria), and all colostrum samples were negative for M. haemolamae by PCR. These data indicate that colostrum from positive dams is unlikely to harbor this parasite and therefore does not serve as a source of infection to newborn cria. Colostrum derived from both PCR positive and negative dams contained M. haemolamae specific antibodies. Our findings suggest that M. haemolamae specific antibodies may play a role in immunity to this hemoparasite; however, challenge studies are necessary to fully evaluate the role of M. haemolamae specific antibodies. Furthermore, antibody prevalence and detectable titers may provide different estimates than those available from current PCR based prevalence studies. Our findings also suggest that M. haemolamae isolates from geographically distinct regions do not differ significantly from each other.