The Epidemiology And Prophylaxis-Therapy Of Mycoplasma Ovipneumoniae Infection In Goats And Sheep

The Mycoplasma ovipneumoniae infection in sheep and goats was studied in epidemiology, isolation and identification of pathogen, diagnostic method and prophylaxis-therapy. The aim is to find methods for the control of the disease in production.1. The epidemiology of M. ovipneumoniae infection was researched by clinical investigation, pathological examination and serology. 243 of 586 detected sheep were positive with a positive rate of 41.5%. 79of 369 detected goats were positive with a positive rate of 21.4%. The positive rate of sheep is much higher than that of the goats. It showed that sheep is more liable to M. ovipneumoniae than goats. Tthe statistical analysis indicated that the sheep and goats under one year of age are the most liable; there is no significant difference between the male and female.2. 24 specimens were collected from the sheep with respiratory disease at Baoding, Langfang, Xingtai and Handan. After isolation and purification, 13 isolates were got. These isolates were proved to be the same serotype as the standard strain of M. ovipneumoniae Y98 by the identification of physical-chemical characteristics and serology. The experimental infection of sheep and goats with the isolate H1 indicated that the isolates are pathogenic, but its pathogenicity is different between sheep and goat. Electron microscopy revealed that the cell membrane of the pathogen has three layers and a large number of M. ovipneumoniae cells covered with an electron dense-stained amorphous material, suggesting that it was a capsule consisted of cilias.3. A polymerase chain reaction (PCR) assay for the detection of M. ovipneumoniae has been developed. According to nucleus acid sequence of 16S rRNA a pair of primers was designed. The premiers allowed an amplification of a 1050bp fragment from the standard strain Y98 and the isolates (H1 and H2). The same fragments didn't find with the reference strains of M. mycoides. Capri and M. pulmonis. The sensitivity by the PCR assay with the premier was 1 picogram of M. ovipneumoniae DNA. It indicated that the PCR assay is much more sensitive.4. The effects of ciprofloxacin, ofloxacin, danofloxacin, eromycin, tylosin, tilmicosin, tiamulin, tetracycline and doxycycline on M. ovipneumoniane Y98 in vitro were reported. Their minimal inhibitory concentrations (MIC) were respectively 0.026ug/mL , 0.042ug/mL , 0.073ug/mL , 0.583ug/mL, 0.167ug/mL, 0.042ug/mL, 0.042ug/mL, 0.292ug/mL, 0.208ug/mL. The fractional inhibitory concentration index (FIC) of tetracycline combined with eromycin was 1. The other FIC indexes were 0.5. The results showed that the combinations of tetracycline, doxycycilne with eromycin, tylosin, tilmicosin and tiamulin were synergism respectively. These results lay the basis for the further development of new high efficacious and low-priced compound against M. ovipneumoniae. The prophylactic and therapeutic efficacies of ciprofloxacin, danofloxacin, tiamulin and tilmicosin were observed in experimental and natural infection with M. ovipneumoniane in sheep. The results concluded that tiamulin and tilmicosin ware the first choice for the infection of M ovipneumoniane. By muscular injection the prophylactic dose is 5mg/kg body weight, while the theraprutic dose is 10mg/kg body weight with a treatment period of 1-2 weeks.