Ngounda P, Manso-Silván L, Thiaucourt F
Laboratoire central vétérinaire (LACEVET), Ministère de l'élevage et de la santé animale (MESA) BP 786 Bangui, République centrafricaine.
CIRAD, UMR ASTRE, F-34398 Montpellier, France.
Med Trop Sante Int. 2021 May 17;1(2). doi: 10.48327/mtsibulletin.2021.100. eCollection 2021 Jun 30.
The aim of this study was to analyse the current situation of Contagious Bovine Pleuropneumonia (CBPP) in the Central African Republic (CAR) by seroprevalence analysis, as well as isolation and characterization of strains of the etiologic agent, (Mmm), circulating in livestock breeding regions.
The strains obtained were subjected to whole genome sequencing by Illumina technology and genotyped using the eMLST technique based on 62 genes of the Mmm core genome. Their sensitivity to tetracycline was assessed by determination of the minimum inhibitory concentration (MIC) on agar. A seroprevalence analysis by competitive ELISA was conducted in livestock breeding regions (West, Centre and East CAR), including both zebu and taurine cattle breeds, and both males and females.
The three strains isolated in the three regions of the CAR shared exactly the same genomic sequence. Phylogenetic analysis showed that they were closely related to a strain isolated in the CAR in 1991, also sequenced in this study, and clustered with Mmm strains originating from East and Central Africa. The recent isolates presented increased MIC values, though they were still sensitive to tetracycline. The global CBPP prevalence in the CAR was estimated at 12.5% with no significant differences observed between cattle breeding regions, nor between males and females. However, a significantly higher prevalence was observed in zebu compared to taurine cattle, most likely in relation to their herding system based on cattle transhumance and nomadic pastoralism.
CBPP is enzootic in the CAR in spite of control campaigns based on use of the live T1 vaccines, which have shown little efficacy due to poor implementation in the field. New strategies combining controlled use of antibiotics and inactivated vaccines, with increased thermostability, should be well received by livestock keepers and allow a better control of CBPP in the region. The fact that the recent Mmm isolates are still resistant to tetracycles is encouraging.
本研究旨在通过血清流行率分析以及对在畜牧养殖地区循环的病原体丝状支原体丝状亚种（Mmm）菌株进行分离和鉴定，来分析中非共和国（CAR）牛传染性胸膜肺炎（CBPP）的现状。
使用Illumina技术对获得的菌株进行全基因组测序，并基于Mmm核心基因组的62个基因，采用eMLST技术进行基因分型。通过测定琼脂上的最低抑菌浓度（MIC）来评估它们对四环素的敏感性。在畜牧养殖地区（CAR西部、中部和东部）开展了竞争性ELISA血清流行率分析，涉及瘤牛和黄牛品种，以及雄性和雌性牛。
在CAR三个地区分离出的三株菌株具有完全相同的基因组序列。系统发育分析表明，它们与1991年在CAR分离出的一株菌株密切相关，本研究中也对该菌株进行了测序，并且与源自东非和中非的Mmm菌株聚类。最近分离出的菌株MIC值有所增加，不过它们对四环素仍然敏感。CAR的CBPP总体流行率估计为12.5%，在不同的养牛地区之间以及雄性和雌性之间均未观察到显著差异。然而，与黄牛相比，瘤牛的流行率显著更高，这很可能与基于牛群季节性迁移和游牧畜牧业的放牧系统有关。
尽管开展了基于使用活T1疫苗的防控行动，但由于在实地实施效果不佳，这些行动成效甚微，CBPP在CAR仍是地方流行性疾病。结合可控使用抗生素和热稳定性更高的灭活疫苗的新策略应该会受到畜牧养殖者的欢迎，并有助于更好地控制该地区的CBPP。最近分离出的Mmm菌株仍然对四环素耐药这一事实令人鼓舞。
