Most pointedly, Wyatt ( 13), discussing the use of anthrax bombs as biological weapons, points out that the doses necessary to cause peracute infections would be adequate only at the point source. Germination outside of a suitable animal host, the basis of the incubator theory, is used to explain why spores do not just accumulate endlessly, or are even eliminated in an environment ( 11, 12). The dosages required for a peracute infection can rarely be demonstrated in the field in fact it is often not possible to find any spores even where they should logically be found ( 7– 10). There are several problems with the dose-dependent model. In Etosha, Namibia, as waterholes dried up the dose of spores would increase and, the incubator theory speculated that certain seasons and conditions could incubate the spores in the soil, vegetating exponentially and then re-sporulating ( 6). In Kruger National Park, South Africa, vegetation near carcasses was found to be highly contaminated with spores from blowfly activity. Most theories on what causes anthrax outbreaks, especially on a regular basis in nature, have been based on the role the external environment plays in providing an oral, point source form of an enormous quantity of spores.īased on their studies in Wood Buffalo National Park and the McKenzie Bison Sanctuary, Dragon and Rennie ( 5) concluded that low-lying areas would have spores drained into them and concentrated. Infection through the bites of tabanids caused only a mild, subclinical cutaneous infection ( 4).īacillus anthracis exists outside its animal host primarily in its spore state, and food and water contamination have been demonstrated to be sources of infection. Peracute disease and sudden death, the form normally associated with the disease in the field, requires a large oral dose of spores at lower doses the animal may recover.
But the current model for anthrax is based on only one cause that was derived from experiments that demonstrated a dose-dependent relationship between the severity of the disease and the oral dose of spores ( 2, 3).
It is believed that many years ago, this biome was completely covered by glaciers.
The soil is very thin due to the cold weather and because of this these trees are more likely to have shallow roots.These plants can only grow for about three months during summers when the temperatures are favorable.They also have needles for leaves and never drop their leaves. These trees produce their seeds in cones.This category includes spruce, pine and fir trees. The dominant plant in the taiga is the coniferous evergreen tree.The average annual rainfall in the boreal forest biome is approximately 33 inches.They are necessary to get rid of old and sick trees. In Taiga Biome, wildfires are very common.During winters, temperature can reach as low as -60☏. The spring and fall are too short to notice. The temperature changes in this biome are extreme. It is also found at cool high elevations in the more temperate latitudes. It is located right below the Tundra biome. It represents 29% of the world’s forest cover. It is named after Boreas the Greek god of the North Wind. It is also known as the Coniferous or Boreal Forest. The Taiga Biome is the largest land-based biome and extends across Europe, Asia and North America.