Anthrax persistence

To conduct an epidemiologic assessment of anthrax in Azerbaijan, it is necessary to pay attention to the so-called hearths of disease, which are numerous and persistent. Presently, 115 stationary, nonsatisfactory foci of infection, encompassing all physical and geographical regions of Azerbaijan, are registered. 

For Fildes s successors at Porton Down, the problem is now beginning to look insoluble. As Rex Watson, the present Director of Porton Down, put it in an interview in 1981 The attraction of anthrax when it was used was that it was thought to be sufficiently resistant an organism to withstand being dispersed by a munition... I don t think at that time perhaps they understood as much as we do now about its persistence over very long periods. 7 Porton would expect there to be an area of contamination for the next tens, perhaps even hundreds of years. Until that area is clear, Gruinard will remain closed to the public. At the moment, to be sure of being safe, the Porton men who go back still have to wear protective suits and take a seven and a half month course of injections. I doubt, added Dr Watson, that we would do such an experiment now if we had to in those conditions. ... 

Schneidmiller C. Years after Anthrax Attacks, Hoaxes Persist. Global Security News-wire. Available http //www.nti.org/d newswire/issues/2005/7/19/9c68a408-b230-431e-9769-6805f6855b99.html. 

Anthrax spores are highly persistent and resist adverse enviromnental elements and remain viable for hundreds of years in soil and in dried or processed hides. Spores are resistant to drying, heat, and sunlight. They have been known to survive in milk for up to 10 years, on dried filter paper for 41 years, on dried silk threads for up to 71 years, and in pond water for 2 years. 

Anthrax occurs worldwide. The organism exists in the soil as a spore. The question remains unsettled as to whether its persistence in the soil is due to significant multiplication of the organism in the soil, or if it is due solely to cycles of bacterial amplification in infected animals whose carcasses then contaminate the soil.7,8 The form of the organism in infected animals is the bacillus. Only when the organism in the carcass is exposed to air does sporulation occur. 

In the twentieth century, 18 Americans have fatally inhaled anthrax spores. The victims include a San Francisco woman who played bongo drums made from infected skins. Others included gardeners who handled fertilizer made with ground bone from infected animals (Park, 2001). Goat and sheep skins from the Mideast are a small but persistent source of anthrax in the United States. Five more people died of anthrax in the United States in 2001 as a result of the anthrax-laden letters they handled. 

Spore formation also makes anthrax a difficult microbe to kill. Its persistence was demonstrated by British experiments carried out on Guinard Island in Scotland during World War II. Following the conclusion of tests conducted on Guinard between 1942 and 1943, viable anthrax spores remained for decades. So hardy were they that only disinfectants like formaldehyde were strong enough to adequately decontaminate the island s topsoil. 

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