Pre-Columbian Origins for North American Anthrax

Abstract

Disease introduction into the New World during colonial expansion is well documented and had a major impact on indigenous populations; however, few diseases have been associated with early human migrations into North America. During the late Pleistocene epoch, Asia and North America were joined by the Beringian Steppe ecosystem which allowed animals and humans to freely cross what would become a water barrier in the Holocene. Anthrax has clearly been shown to be dispersed by human commerce and trade in animal products contaminated with Bacillus anthracis spores. Humans appear to have brought B. anthracis to this area from Asia and then moved it further south as an ice-free corridor opened in central Canada ∼13,000 ybp. In this study, we have defined the evolutionary history of Western North American (WNA) anthrax using 2,850 single nucleotide polymorphisms (SNPs) and 285 geographically diverse B. anthracis isolates. Phylogeography of the major WNA B. anthracis clone reveals ancestral populations in northern Canada with progressively derived populations to the south; the most recent ancestor of this clonal lineage is in Eurasia. Our phylogeographic patterns are consistent with B. anthracis arriving with humans via the Bering Land Bridge. This northern-origin hypothesis is highly consistent with our phylogeographic patterns and rates of SNP accumulation observed in current day B. anthracis isolates. Continent-wide dispersal of WNA B. anthracis likely required movement by later European colonizers, but the continent's first inhabitants may have seeded the initial North American populations.

Genomic characterization of theBacillus cereussensu lato species: Backdrop to the evolution ofBacillus anthracis

“…genome projects (Table 1B). To avoid over-representing B. anthracis, which has undergone a recent clonal expansion (Zwick et al 2005;Van Ert et al 2007;Kenefic et al 2009), we chose to include only one genome sequence from this species, the canonical Ames ancestor strain ). We used the locus tag suffix of the genomes (Table 1A,B) as a naming code to simplify descriptions in this manuscript.…”

Bovine Bacillus anthracis in Cameroon

“…They showed a strong homogeneity, and they belong, together with strains from Chad, to cluster A␤, which appears to be predominant in western Africa. However, one strain that belongs to a newly defined clade (D) and cluster (D1) is penicillin resistant and shows certain phenotypes typical of Bacillus cereus.Extensive genetic analysis of a large number of strains of Bacillus anthracis, the causative agent of anthrax, led to robust molecular epidemiological data, making this bacterium a model for microbial evolution and the global spread of pathogens and even making it possible for researchers to follow migration or movement of its hosts or host products (5)(6)(7)(8)15). This is possible by virtue of the large data set based on canonical single nucleotide polymorphisms (canSNPs), which classify B. anthracis strains into clades (22), and on multiple-locus variable-number tandem-repeat (VNTR) analysis (MLVA), which groups them further into clusters (6).…”

Anthrax and the Geochemistry of Soils in the Contiguous United States

“…Animal outbreaks of anthrax are a common occurrence in the contiguous United States, and they are typically constrained to a few geographical regions (e.g., Texas, Minnesota, Montana and the Dakotas). The "Ames" or "Ames-like" clade has caused periodic outbreaks in southern Texas and is believed to have been introduced through the importation of infected livestock during European colonization [7,8]. The WNA clade is genetically most similar to isolates of the Eurasian clade and account for ~89% of non-human cases in North America [7].…”

“…The "Ames" or "Ames-like" clade has caused periodic outbreaks in southern Texas and is believed to have been introduced through the importation of infected livestock during European colonization [7,8]. The WNA clade is genetically most similar to isolates of the Eurasian clade and account for ~89% of non-human cases in North America [7]. It is believed that the WNA clade was introduced to the Americas by human migration across the Bering Strait that occurred prior to ~11,000 years ago when the land bridge between Asia and North America last closed at the end of the Younger Dryas [7,9,10].…”

“…The WNA clade is genetically most similar to isolates of the Eurasian clade and account for ~89% of non-human cases in North America [7]. It is believed that the WNA clade was introduced to the Americas by human migration across the Bering Strait that occurred prior to ~11,000 years ago when the land bridge between Asia and North America last closed at the end of the Younger Dryas [7,9,10]. Genetic analyses of WNA clade isolates show evidence of a north to south distribution pattern that is rooted in northern Canada [7].…”