Plague Research Paper

The plague, which is caused by Yersinia pestis, a gram-negative rod-shaped, non-motile, non-sporulating bacterium has a great historical significance. Plague is a zoonotic disease transmitted to humans by rodents (e.g., rats, mice, ground squirrels). Fleas that live on the rodents can transmit the bacteria to humans, who then suffer from the bubonic form of plague. The bubonic form may progress to the septicemic and pneumonic forms. Pneumonic plague would be the predominant form having potential to be used as a BW, due to its ease of aerosol dissemination (Heat et al, 1998).

This is the only weapon besides smallpox, which can cause devastation beyond those persons who are initially infected. With modern air travel, containing an outbreak of
plague could be challenging. The lethality and contagiousness of plague makes the plague it a life threatening biological agent. Although its capability is limited by the presence of effective antibiotic treatment and the difficulties in its weaponization, plague remains to be an advantage for BW’s development (Perry et al., 1997).
Early in the history plague was called as a black death, which remained to be a form of bubonic-flea-borne variety of plague.
Now we see the evolution of far more contagious pneumonic variety as a cause of human epidem¬ics. Direct human exposure to aerosolized plague bacilli was the most effective way to cause human illness and death as reported previously. The biological weapons programs of the USA and the former Soviet Union have pursued aerosol transmission capabilities for plague (First, 2002). Although Soviets had intercontinental ballistic missile warheads containing plague bacilli available for launch before 1985, yet, virtually insurmountable problems arose in the production and aerosol dispersal of substantial quantities of plague organisms by modern weapon systems (Davis, 1999). Despite these difficulties, plague is viewed as a high-risk disease for bio-weapons production (Henderson,
1999).

Clostridium botulinum
C.botulinum is a spore forming and obligate anaerobe, etiological agent of botulism, which can be isolated from the soil, its natural habitat. Four species of C.botulinum are known, characterized by different genomes and their common botulinum toxin. In addition, seven distinct antigenic types of botulinum toxin (A-G) are defined by the absence of cross-neutralization. The toxin is responsible for the disease and is a dichain polypeptide: a heavy chain of 100 KDa is joined by a single disulfide bond to a 50 KDa light chain, which is zinc containing endopeptidase that blocks acetylcholine-containing vesicles from fusing with the terminal membrane of the motor neuron, resulting in flaccid muscle paralysis (Arnon et al, 2001). Botulinum toxin is the most lethal toxin known and all seven types act in similar ways.
Death often occurs as a result of paralysis of pharyngeal and diaphragmatic muscles, followed by respiratory arrest (Bhalla and Warheit, 2004).Botulinum toxin poses a major bio-weapon threat because of its extreme potency and lethality; its ease of production, transport, and misuse; and the need for prolonged intensive care among affected persons (Biological and chemical terrorism, 2000).An outbreak of botulism constitutes a medical emergency that requires prompt provision of botulinum antitoxin and, often, mechanical ventilation, and it constitutesa public health emergency that requires immediate intervention to prevent additional cases. Timely recognition of a botulism outbreak begins with an astute clinician who quickly notifies public health officials. Botulinum toxin is the most poisonous substance known (National institute of occupational safety and health,
1996).