Metapopulation structure for perpetuation of Francisella tularensis tularensis.
Metapopulation structure for perpetuation of Francisella tularensis tularensis.
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DOI：
10.1186/1471-2180-9-147
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发表时间：
2009-07-23
期刊：
影响因子：
4.2
通讯作者：
Telford SR 3rd
中科院分区：
文献类型：
--
作者：
Goethert HK;Saviet B;Telford SR 3rd
由土拉菌弗朗西斯菌引起的A型土拉菌病暴发通常是散发的和不稳定的，极大地阻碍了确定永存和人类风险的决定因素。马萨诸塞州的玛莎葡萄园岛爆发了持续了9年的A型土拉菌病。这种独特的情况使我们能够在那里进行长期的生态流行病学研究。我们的假设是，A型土拉菌病的病原体作为一个超种群而持续存在，具有许多小的孤立的自然传播灶。在传播增加期间，疫源地将合并，并发生更大规模的动物流行病，人类接触的可能性更大。我们对岛上两个自然疫源地的狗蜱进行了采样，并对它们进行了土拉菌病DNA检测。我们确定了两个焦点之间的传播力是否不同。此外，我们通过可变数字串联重复（VNTR）分析检查了蜱虫的土拉菌种群结构，该分析可以估计多样性，连锁不平衡和eBURST分析。两个地点的蜱虫中土拉菌病DNA的流行率明显不同：一个地点在研究过程中稳定，产生多达5.6%的阳性蜱虫。相比之下，来自比较地点的受感染蜱的流行率明显增加，从2003年的0.4%增加到2006年的3.9%。使用4个VNTR位点，我们记录了75种不同的单倍型（多样性= 0.91）。eBURST分析表明，稳定位点基本上是克隆的，而比较位点包含多个不相关的谱系。一般细菌种群是无性进化的（多位点不平衡），两个地点的细菌是生殖隔离的。即使在孤岛内，相距不超过15公里的土拉菌病自然疫源地也被独特地隔离开来。我们的一个地点有稳定的传播，另一个是紧急的。稳定位点的种群结构是循环细菌的克隆复合体，而新兴的焦点可能来自多个创始人。我们得出结论，土拉菌病病原体可能在小型稳定的自然疫源地中持续存在，并且由于这些稳定地点的溢出而出现新的疫源地。
Outbreaks of Type A tularemia due to Francisella tularensis tularensis are typically sporadic and unstable, greatly hindering identification of the determinants of perpetuation and human risk. Martha's Vineyard, Massachusetts has experienced an outbreak of Type A tularemia which has persisted for 9 years. This unique situation has allowed us to conduct long-term eco-epidemiologic studies there. Our hypothesis is that the agent of Type A tularemia is perpetuated as a metapopulation, with many small isolated natural foci of transmission. During times of increased transmission, the foci would merge and a larger scale epizootic would occur, with greater likelihood that humans become exposed. We sampled questing dog ticks from two natural foci on the island and tested them for tularemia DNA. We determined whether the force of transmission differed between the two foci. In addition, we examined the population structure of F. tularensis from ticks by variable number tandem repeat (VNTR) analysis, which allowed estimates of diversity, linkage disequilibrium, and eBURST analysis. The prevalence of tularemia DNA in ticks from our two field sites was markedly different: one site was stable over the course of the study yielding as many as 5.6% positive ticks. In contrast, infected ticks from the comparison site markedly increased in prevalence, from 0.4% in 2003 to 3.9% in 2006. Using 4 VNTR loci, we documented 75 different haplotypes (diversity = 0.91). eBURST analysis indicates that the stable site was essentially clonal, but the comparison site contained multiple unrelated lineages. The general bacterial population is evolving clonally (multilocus disequilibrium) and the bacteria in the two sites are reproductively isolated. Even within an isolated island, tularemia natural foci that are no more than 15 km apart are uniquely segregated. One of our sites has stable transmission and the other is emergent. The population structure at the stable site is that of a clonal complex of circulating bacteria, whereas the emerging focus is likely to be derived from multiple founders. We conclude that the agent of tularemia may perpetuate in small stable natural foci and that new foci emerge as a result of spillover from such stable sites.
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DOI：
10.1111/j.1574-695x.1996.tb00235.x
发表时间：
1996-03-01
影响因子：
--
作者：
Berdal, BP;Mehl, R;Scheel, O
通讯作者：
Scheel, O
影响因子：
6.7
作者：
Goethert HK;Telford SR 3rd
通讯作者：
Telford SR 3rd
DOI：
10.1196/annals.1409.013
发表时间：
2007-01-01
期刊：
FRANCISELLA TULARENSIS: BIOLOGY, PATHOGENICITY, EPIDEMIOLOGY, AND BIODEFENSE
影响因子：
--
作者：
Matyas, Bela I.;Nieder, Henry S.;Telford, Sam R., III
通讯作者：
Telford, Sam R., III
影响因子：
--
作者：
HOPLA, CE
通讯作者：
HOPLA, CE
影响因子：
4.2
作者：
Davis, S.;Klassovskiy, N.;Begon, M.
通讯作者：
Begon, M.