Use of a polymerase chain reaction assay to study response to oxytetracycline treatment in experimental Candidates Mycoplasma haemolamae infection in alpacas
ABSTRACT To develop a PCR assay for Candidatus Mycoplasma haemolamae (CMhl) infection in alpacas and use it to study the efficacy of oxytetracycline treatment and development of a subclinical carrier state.
8 healthy adult alpacas.
Alpacas initially had negative results for CMhl in blood samples via PCR assay and were experimentally infected with CMhl; 4 were treated with oxytetracycline, and 4 were not treated. All were monitored regularly via PCR assay, blood smear examination, PCV, rectal temperature, and physical examination. At 6 months after treatment, all alpacas were immunosuppressed by administration of dexamethasone and tested for CMhl.
7 of 8 alpacas had positive PCR assay results 4 to 6 days after experimental infection. When organisms were detectable on a blood smear, they were seen 2 to 6 days after positive results of PCR assay. Infection was often associated with mild anemia that was usually transient. No alpacas became hypoglycemic. Oxytetracycline treatment was not associated with faster clearance of organisms or resolution of anemia, and 4 of 4 treated alpacas still had positive results of PCR assay when immunosuppressed 6 months later; 0 of 3 nontreated alpacas had positive results of PCR assay following immunosuppression. Transient fever was detected in 3 alpacas during immunosuppression.
The PCR assay was more sensitive than blood smear examination for detection of infection. Clinical signs, anemia, and fever were not necessarily associated with infection. Oxytetracyline administration did not consistently clear CMhl infection. Although treated with oxytetracycline, infected alpacas remained chronic carriers.
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- "This suggests a component of the dam's immune system is capable of reducing the number of parasites to below the threshold for detection, while producing antibodies specific to this organism. This is also compatible with prior reports (Tornquist et al., 2009, 2011). It is therefore possible that prior infection may provide the immunologic mechanisms necessary to clear infection and protect the newborn that acquires the organism early in life while colostral antibodies are still in circulation. "
ABSTRACT: 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.Small Ruminant Research 08/2012; 106(2-3):181-188. DOI:10.1016/j.smallrumres.2012.02.021 · 1.10 Impact Factor
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ABSTRACT: Mycoplasma haemolamae is a hemotropic mycoplasma that affects red blood cells of llamas (Lama glama) and alpacas (Lama pacos). It is variably associated with anemia, and most infections are subclinical. Development of a polymerase chain reaction assay has facilitated detection of this infection in llamas and alpacas in the United States and other countries. Whether the infection occurs in camelids in South America has previously been unknown. The current study documents a 15.8% infection rate among 76 Peruvian llamas, a 19.3% infection rate among Peruvian alpacas at one site, and a 9.26% infection rate in 108 Chilean alpacas from selected herds. All of the camelids tested appeared to be clinically healthy. No gender or species predilection was found. Only 1 positive camelid younger than 18 months was found. Infection is not associated with anemia, and the mean packed cell volume (PCV) in positive Peruvian camelids was slightly higher than the mean PCV in negative Peruvian camelids. In the Chilean alpacas, the positive alpacas had a slightly lower PCV than the negative alpacas, although the mean PCV was not in the anemic range in any of the groups.Journal of veterinary diagnostic investigation: official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc 09/2010; 22(5):766-9. DOI:10.1177/104063871002200520 · 1.23 Impact Factor
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ABSTRACT: Two alpacas from a herd in southwest Switzerland died for unknown reasons. Necropsy revealed chronic weight loss and pale mucous membranes. Infection with hemotropic mycoplasmas was suspected and subsequently confirmed by molecular methods. In order to investigate the epidemiological situation in this herd, a real-time TaqMan(®) qPCR assay for the specific detection and quantification of hemoplasma infection in South American camelids was developed. This assay was based on the 16S rRNA gene and amplified 'Candidatus Mycoplasma haemolamae' DNA, but not DNA from other hemoplasmas or non-hemotropic mycoplasma species. The lower detection limit was one copy/PCR, and the amplification efficiency was 97.4%. In 11 out of 24 clinically healthy herd mates of the two infected alpacas, 'Candidatus M. haemolamae' infection was confirmed. No correlation was found between bacterial load and clinical signs or anemia. The assay described herein enables to detect and quantify 'Candidatus M. haemolamae' and may be used in future studies to investigate the prevalence, pathogenesis and treatment follow-up of hemoplasma infections in South American camelids.Veterinary Microbiology 12/2010; 146(3-4):290-4. DOI:10.1016/j.vetmic.2010.05.029 · 2.73 Impact Factor