Presentation on theme: "A Historical Look at Bioterrorism Christine Chung Aaron Little Angela Serrano Laurie Wallis."— Presentation transcript:
A Historical Look at Bioterrorism Christine Chung Aaron Little Angela Serrano Laurie Wallis
Introduction Bioterrorism is a growing concern in social, political, and scientific communities globally Historically, Category A Select Agents, as identified by the CDC, have been used or acquired with intent to disseminate Category A Select Agents are those with high morbidity or mortality combined with high transmission rates including Anthrax, Botulism, Plague, Smallpox. Also included is Category B Agent, Salmonella because of the relative ease of acquisition and historical use. Note: Follow hyperlinked buttons in the timeline to view Select Agent information.
Biological Weapons Timeline 1346: Plague victims are catapulted over city walls during the Tarter siege of Kaffa. 1746: British army distributes smallpox infected blankets to Native Americans during the “French and Indian War” 1925: The Geneva Protocol is signed, banning the use of BW in warfare 1932 – 1945: Japan uses BW against China and POWs 1942: British test weaponized anthrax on sheep on Gruinard Island, Scotland leaving the island under quarantine for 48 years.
Biological Weapons Timeline 1969: US President Richard Nixon announces that the US will never use BW under any circumstances 1972: The Biological Weapons Convention is signed. There are currently 163 signatories to the BWC. 1975: US signs the Geneva Protocol 1979: Anthrax is accidentally released from BW production facility in Sverdlovsk, USSR. 1984: The Rajneeshees deliberately contaminate salad bars in Oregon with salmonella bacteria. 1992: Russian President Boris Yeltsin reaffirms Russia’s commitment to the BWC after disclosing the existence of Biopreparat, a major clandestine BW program
Biological Weapons Timeline 1995: Larry Wayne Harris obtains vials of plague from ATCC. 1995: Aum Shinrikyo develops and attempts to disseminated botulinum toxin and anthrax. 1998: All US Armed Service personnel must be vaccinated against anthrax. 2001: Genetic manipulation significantly increases virulence of mousepox virus (similar to smallpox) 2001: Letters containing weaponized anthrax are sent through the US postal system. 2002: Polio virus is artificially synthesized within laboratory 2009 and beyond: Advances in biotechnology create countless benefits, but introduce new proliferation threats…
Bacillus anthracis Toxin Disease Caused: −Anthrax Produced by Bacillus anthracis −Related to B. Cereus and B. thuringiensis which do not produce capsules and not infectious to humans Large gram-positive rod Capable of endosporulation, particularly in high CO 2 (>5%) concentration −Spores can survive in soil and harsh conditions for decades Zoonotic disease primarily infects cattle, horses, goats, sheep −Natural transmission is extremely rare −No human to human transmission
Bacillus anthracis Toxin 89 known strains, including –Ames strain of 2001 attacks –Vollum strain of 1935 WWII Gruinard bioweapon trials –Sterne strain for vaccines Pathogenicity is via poly-D-glutamyl capsule and 3 factors –Edema Factor (EF) –Protective Antigen (PA) –Lethal Factor (LF) LD 50 : varies greatly within species –Rat: 1,590 colony-forming units/kg –Monkey 7.5 million units/kg –Human estimated 8,000 units/kg
Anthrax Pathogenic B. anthracis requires a capsule to mediate the invasive stage and a multicomponent toxin to mediate the toxigenic stage –poly-D-glutamate polypeptite coating nontoxic, protects against complement, and phagocytosis and bactericidal components of macrophages –construction requires pX02 plasmid, obtained from conjugation –Protective Antigen (PA) acts as the binding (B) domain –Edema Factor (EF) acts as an active (A) domain, homologous to the alpha domain of adenylate cyclase –Lethal Factor (LF) acts as an active (A) domain, a Zn++ dependent protease and member of the MAPKK family
Anthrax Mechanism –PA, EF, and LF combine to form an A-B enzymatic binding structure –cause edema, attracting leucocytes to the area –impair macrophage and neutrophil phagocytosis PA+EF elevates cAMP levels, reducing permeability also depletes ATP, required for engulfment process –PA+LF act to disrupt cell signaling pathway; not entirely understood –septicemia causes death from oxygen depletion, secondary shock, increased vascular permeability, respiratory failure, cardiac failure; sudden and unexpected after 3-10 days
Anthrax Routes of infection –Cutaneous: boil, then eschar, then necrotic ulcer; painless; minor lethality –Gastrointestinal: severe gastrointestinal irritability; highly lethal route –Pulmonary: induces flu-like symptoms; most lethal route Treatment –Vaccination for potential contact, given yearly and at least 4 weeks prior to exposure –Antibiotics (eg penicillin) for inhalation victims, given within 24 hours –Cutaneous inoculation has minor lethality, usually none with antibiotics Cleanup –Spores are hardy, resistant to dessication, heat, extreme chemicals, and natural decay –CDC and BW protocol recommend steam sterilization or burning for at least 30 minutes –other approved chemicals may not destroy them all
Anthrax in Bioterrorism Location: More than 60 sites in the US Perpetrator: Bruce Ivins, suspect Objective: Unknown Organism: –Bacillus anthracis spores Dissemination –4-7 letters sent through postal system –22 confirmed cases of anthrax 11 Cutaneous 11 Inhalational (5 Deaths) Outcome: FBI Named Bruce Ivins of USAMRIID as suspect. Ivins committed suicide before he could be tried. “Amerithrax” Back to Timeline
Plague Organism: –Yersinia pestis (formerly known as Pasteurella pestis) Location: Africa, former Soviet Union, the Americas, Asia, and the Middle East Types of Plague: –Sylvatic plague: in wild rodent populations –Urban plague: involves rats and is the major source for human endemics The WHO (World Health Organization) reports 1,000-3,000 cases of plague worldwide each year, with an average of 5-15 in the western U.S. – probably an underestimate –Highest incidence in Africa (>90% of cases worldwide) –90% of U.S. cases in New Mexico, Arizona, Colorado, and California
Urban Plague Bubonic Plague –Infection of lymphatic system –Occurs within a week of infected flea bite –Known as “Black Death” as multiplication of bacteria produces “buboes” (swollen, painful lymph nodes) –75% mortality rate –Up to 15% of bubonic plague victims develop secondary pneumonic plague Pneumonic Plague –Infection of respiratory system –Occurs in crowded conditions when contaminated respiratory droplets are expelled by infected humans and directly inhaled by others –Characterized by shorter incubation period and greater mortality (90%) Septicemic Plague –“blood-poisoning” form –Can result from bubonic and pneumonic plague when bacteria enters the bloodstream from the lymphatic and respiratory systems –Least common form of plague, characterized by high fevers, purple skin patches and vomiting –Can cause DIC (disseminated intravascular coagulation) –Almost always fatal (near 100%)
Yersinia pestis Gram-negative coccobacillus (an Enterobacteriaceae), non-motile Facultative anaerobe “Safety pin” appearance in bipolar staining Colonial Morphology: grey-white, “fried-egg”, irregularity, hemolytic, grows faster and larger at 28°C Produces a thick anti-phagocytic slime layer Produces two antiphagocytic components necessary for virulence: –F1 antigen and VW antigens –Both produced at 37°, not lower, thus not virulent in fleas that have body temp. of 25°) Expresses vadBC gene, allowing for adherence and invasion of epithelium Type III secretion system: allows bacteria to inject six different substances into macrophages and immune cells for cytolysis, apoptosis, platelet aggregation, actin microfilament disruption (limits phagocytosis by targeting actin) –Necessary for virulence
Yersinia pestis (cont.) Bacteria can survive for weeks outside of a host –Viable in blood for 100 days –Dried blood for three weeks –In flea feces for five weeks –In infected human bodies for up to 270 days –Can survive in soil for some time Fleas act as vectors Mainly rodents are the reservoirs, but hundreds of animals can be potential hosts, including cats, dogs, rabbits, and squirrels (most prevalent vector in the U.S.)
Mechanisms of Action (Pneumonic plague) Can spread between humans through sneezing, coughing, and/or direct contact of infected tissue –Estimated that only 50kg of Y. pestis released as an aersol in a city of 5 million would infect 150,000, of which 36,000 would die Most carnivores, except cats, are resistant to plague infection Epidemiology –Occurs in urban and/or wild rodent populations –Humans acquire primarily via infected fleas –Y. pestis multiplies in flea intestinal tract Known mechanisms –Sites of Entry and ExitSites of Entry and Exit –Incubation period: 1-3 days (pneumonic); 2-6 days (bubonic) –Infection spreads from lymph nodes near the bite site where swelling occurs, then spreads to other organs such as the spleen, liver, lungs, skin, mucous membranes, and the brain (but usually not the kidney)
Current Research on Mechanisms, etc. The CDC considers an average of one flea per rodent as the maximum threshold to reduce the risk of Y. pestis transmission to humans. –A reduction of rodent and/or flea populations is optimal –Chitin synthesis inhibitors used to reduce flea populations effectively on certain species of rodents Type III secretion of Y. pestis targeted for new therapeutics Interleukin-10-deficient mice are resistant to Y. pestis –Heterozygotes also able to survive high doses of IV infections –Two substrains of 129 mice resistant to high-dose KIM5 –Resistance is not recessive –129-derived genomic DNA near IL-10 confers resistant to Y. pestis KIM5 Ail (Attachment and Invasion locus) protein found to be crucial in binding and cytotoxic Yop protein delivery into the host cell (type III secretion) –Single deletion in ail locus severely hindered Yop delivery –Mice with KIM5 ∆ail mutant: >3,000-fold increased LD 50 1,000-fold less bacteria in spleens, livers, and lungs
Effects Symptoms –General malaise; pain or tenderness at regional lymph nodes; septicemia; DIC; convulsions; shock; headache; prostration; bacteria in blood “Signs” –High fever (hyperpyrexia); diffuse, hemorraghic changes in the skin; dark skin at extremities that led to the name “black death”; coughing and sneezing in the case of pneumonic plague Secondary Illnesses –Complications: DIC, pneumonia, meningitis –Bubonic plague victims may develop pneumonic plague, which is contagious through coughing and considered the most severe form of the disease
Plague in Bioterrorism Location: Ningbo, China and Changde, China Perpetrator: Japanese secret biological warfare research facility (Unit 731) Objective: Infect civilian populations Organism: –Yersinia pestis Dissemination –Ceramic bombs full of bubonic plague-carrying fleas dropped over Ningbo by the Imperial Japanese Army Air Force –80% of fleas survived the bombing to infect civilians –Changde: plague-contaminated foods were distributed to civilians and water supplies contaminated Outcome: Largely ineffective in comparison to distribution as aerosols; caused epidemic plague outbreaks; 400,000 Chinese killed in Ningbo Back to Timeline
Plague Events (as Biological weapon) Earliest reference to bubonic plague (approx BC) in book of I Samuel 6 th Century: Plague of Justinian (First Pandemic) through Byzantine Empire, greatly weakening the Roman empire by reducing the population by one-third 1346: Mongol warriors of the Golden Horde threw infected corpses over the walls of the besieged Crimean city of Kaffa (in present day Ukraine) : “Black Death” (Second Pandemic), possibly originated in Gobi Desert 1710: Russian forces attacked the Swedes by fling plague-infected corpses over the city walls of Reval in Estonia (Tallinn) s: The Third Pandemic, originated in China, spread worldwide via ships WWI: the German Army allegedly spread plague in St. Petersburg, Russia 1940: Imperial Japanese Army Air Force bomb Ningbo with plague-carrying flea ceramic bombs 1941: Unit 731 air-drop plague-carrying fleas on Changde 1944: the Japanese planned on dropping porcelain plague-flea bombs on invading Gis to defend their airstrip on Saipan, but failed when carrier submarine sank before reaching the island Biological warfare generally not used after WWII, but challenged by China and North Korea, who accuse the U.S. of using disease-carrying insects against them during the Korean War. 1953: U.S. initiated disease vector weaponization efforts with focus on plague-fleas, etc. Vietnam War: plague was endemic among natives; U.S. soldiers well-protected with vaccines 1995: Discovery of multi-drug resistant (MDR) strain of plague in Madagascar 1996: an Ohio man attempted to obtain bubonic plague cultures through the mail
Pathogenesis Y. pestis primarily a rodent pathogen; humans are accidental hosts when bitten by infected rat fleas Y. pestis grows and multiplies in flea’s intestinal tract, blocking the flea’s proventriculus, and loses its capsular layer. Several proteins including hemin storage (Hms) system and Yersinia murine toxin (Ymt) contribute to maintenance of bacteria in flea’s digestive tract. Hms genetic loci aggregate in esophagus and proventriculus of flea, which ruptures blood cells, which inhibits feeding causing the flea to feel hungry. Ingested blood is pumped into the esophagus, dislodging the bacteria cultivating there and is regurgitated and transferred into a new host (i.e. humans) when fleas feed Most get phagocytosed and killed by leukocytes in human.
Pathogenesis (cont.) Few are taken up by tissue macrophages, which are unable to kill the bacteria and instead provide a protected environment. Y. pestis kills the macrophage in order to enter the extracellular environment, resisting phagocytosis by the polymorphs. Quickly spread to the draining lymph nodes, which are inflamed, giving rise to black buboes. Within hours of the flea bite, the infection enters the bloodstream, reaching the liver, spleen, and lungs. Human host develops severe bacterial pneumonia, releasing large numbers of Y. pestis into the air with coughing fits.
Present uses and/or Possible future uses Present treatments/therapy –Rapid diagnosis essential Rapid disease progression High mortality rate –Bubonic plague: 75% mortality in few days –Pneumonic plague: >90% mortality within 24 hours –Without treatment, fatality rates increase up to 90% for bubonic plague, 100% for septicemic or pneumonic plague –With treatment, fatality rate = 5-20% Rapid treatment crucial to survival rates –Antibiotics: Streptomycin, chloramphenicol, tetracycline, fluoroquinolones, sulfonamides, ciprofloxacin, and potentially doxycycline or gentamicin, etc. –Multi-drug resistant strains have been isolated –Best laboratory diagnosis is made by PCR, etc.
Present uses and/or Possible future uses Weaponized plague development and Other Current Events –On the list of potential terrorist agents –Transmission by aerosols is potentially deadly and can spread from person to person –Institute of Ultra Pure Biochemical Preparations, Leningrad: a weaponized plague center –Al Qaeda Roughly 40 al-Qaeda terrorists reportedly died from bubonic plague in their Algerian training camp Late 1990s: Osama bin Laden set up 19 chemical and biological weapons laboratories in Afghanistan, which were stocked with anthrax, plague, and botulinum toxins. Possible threats: could spread in public by a lone suicidal bioterrorist (i.e. in subways), or could contaminate self with the plague first to conduct a bioterrorist attack –Could take up to a week for symptoms to appear –2002: two NYC residents acquired plague from New Mexico
Present uses and/or Possible future uses Present research being conducted in the maintenance of plague –Experiments with genetic engineering of vaccines based on F1 and V antigens are underway Bacteria lacking F1 antigen are still virulent These vaccines may not fully protect potential hosts –Research suggests that descendants of medieval European plague survivors are less likely to catch plague –Recent research indicates that ongoing outbreaks of plague can be caused by viral hemorrhagic disease, similar to Ebola –A handful of Western laboratories are actively conducting research on MDR Y. pestis (resistant to at least eight drugs traditionally used to treat plague) Should conduct additional research to effectively fight MDR strain
Present uses and/or Possible future uses Prevention and vaccination –By law, pneumonic plague patients must be isolated –Sanitation measures Control of rat populations and elimination of fleas; etc. –Formalin-inactivated vaccine for adults (age 18-61) at high risk, and continuous booster shots Not very effective May lead to severe inflammation –As of the mid-1990s, the vaccine is no longer available in the U.S. –Research being conducted currently for more effective vaccines –Scientists hypothesize that a mutation in the CCR5 gene, which gives rise to a natural immunity to the HIV virus, may also confer immunity to Y. pestis –Currently, hospitals are poorly equipped/prepared to deal with patients in the case bioterrorism may occur. Back to Timeline
Salmonella Disease Caused: −Salmonellosis/Gastroenteritis/Enteric Fevers (including Typhoid Fever) Gram-negative Bacterium Characterized by O, H, and Vi antigens Ingested in contaminated food and water Zoonotic-worldwide human and animal disease Resilient and capable of survival for several years Sensitive to moist and dry heat and many disinfectants
Salmonella Mechanism –Bacteria pass through gastric acid barrier and invades mucosa of small and large intestines and produce toxins –Irritation of the small and large intestines Results of Exposure –Profuse vomiting and diarrhea –Leads to dehydration –Can result in death with severe dehydration. Treatment –Antibiotics –Hydration
Salmonella in Bioterrorism Location: The Dalles, Oregon Perpetrator: Rajneesh Cult Objective: Gain control of the Wasco County Court by affecting the election Organism: Salmonella typhimurium –Purchased from commercial supplier Dissemination –Restaurant salad bars –751 illnesses Early investigation by CDC suggested the event was a naturally occurring outbreak Cult member arrested on unrelated charge confessed involvement with the event Bhagwan Shree Rajneesh Back to Timeline
Smallpox Disease caused by Variola major virus. Humans are the only natural reservoir for variola virus −Originated in Egypt or India over 3000 years ago −Eradicated in nature by vaccination programs in s. Only known stocks of virus at CDC in Atlanta, and a Russian repository. Mortality rate of 30% −Up to 90% mortality for flat and hemorrhagic forms of virus.
Smallpox Mechanism −Entry through the respiratory mucosa −virus migrates rapidly to regional lymph nodes, then to spleen, bone marrow, kidneys, and liver −virus localizes in small blood vessels of the dermis and oropharyngeal mucosa, and evolves into skin lesions. Results of Exposure −Incubation period 7-14 days −Flu-like symptoms −Development of pustules Treatment −None
Smallpox in Bioterrorism Location: North America during French and Indian War Perpetrator: British Forces in North America Objective: Infect Native Americans with Smallpox disease Organism −Variola Major Dissemination: −Blankets used by smallpox patients given to Native Americans as “gifts” during war −50% Native American mortality rate Outcome: Smallpox outbreak claimed lives of many Native Americans, British leader Jeffrey Amherst claimed parts of Canada and the United States in war victory Back to Timeline
Botulinum Toxin Disease caused: Botulism Produced by Clostridium botulinum, C. baratii, and C. butyricum –Multiple types of toxin: A, B, C, D, E, F, G –Only A, B, E, and F produce human disease Spore forming bacteria is highly stable Toxic protein is degraded by heat and humidity – relatively stable for a protein LD 50 : 0.001µg/kg –The lowest known LD 50 of all toxins Found in soil, water, and contaminated food Therapeutic use as a paralyzing agent when highly diluted
Botulinum Toxin Mechanism –Neurotoxin degrades the SNARE complex in the synaptic bulb. –Permanently interferes with the release of acetylcholine, preventing nerve stimulation for muscle contraction. Results of Exposure –Paralysis –Respiratory failure Treatment –Antitoxin (limited supplies) –Supportive care Ventilator machine Extensive rehab
Botulinum Toxin in Bioterrorism Location: Tokyo, Japan Perpetrator: Aum Shinrikyo Cult Objective: Over throw government via targeted assassination and pubic dissemination. Organisms: –Bacillus anthracis Vaccine strain –Clostridium botulinum Environmental isolate Avirulent strain –Ebola virus Attempted to acquire from Zaire outbreak under guise of an “Humanitarian mission” Dissemination –Aerosolization in Tokyo B. anthracis Botulinum toxin Outcome: –Use of non-virulent strains and ineffective dissemination methods resulted in no casualties from biological weapons –Successful sarin nerve gas attack in subway –Leader Asahara was convicted of criminal activity Aerosolization of Bacillus anthracis and botulinum toxin by Aum Shinrikyo Back to Timeline
Summary The future threat of bioterrorism is increasing with the advances in biotechnology. –Increasing ease of acquisition and production Sequencing technology advances and publications Small-scale operations sufficient to incite fear –Historical failures decreasing many past attempts failed because of bad science Terrorists gaining required knowledge and skills –Political treaties / federal restrictions reducing ability of research –Biodefense difficulties Vaccines are expensive, and preventative only antibiotics are best line of defense, but select agents increasingly resistant Slow spreading awareness of complex topics Back to Timeline
References Aceto, D., Astuto-Gribble, L., and Gaudioso, J The Acquisition of Dangerous Biological Materials: Technical Facts Sheets to Assist Risk Assessments of 46 Potential BW Agents. Sandia National Laboratories Report. Ackerman, G., and Tamsett, J., Editors Jihadists and Weapons of Mass Destruction. Chapter Six “Jihadists and Biological and Toxin Weapons” by Loeb, C. Pg CRC Press. Ajayi, T Smallpox and Bioterrorism. Stanford Journal of International Relations. [Internet] Vol. 3 Issue 2. [cited 2009 April 4] Available from: htmlhttp://www.stanford.edu/group/sjir/3.2.02_ajayi. html Biological Warfare. In: Wikipedia the Free Encyclopedia. [Internet]: Wikipedia; [cited 2009 Mar 1]. Available from: Black Death. In: Wikipedia the Free Encyclopedia. [Internet]: Wikipedia; [cited 2009 Mar 28]. Available from: Bubonic Plague. In: Wikipedia the Free Encyclopedia. [Internet]: Wikipedia; [cited 2009 Mar 1]. Available from: Center for Infectious Disease Research and Policy [Internet]. Smallpox page. [cited 2009 April 4] Available from: Chamberlain, Neal R. [Internet]. [updated 2004 Aug 3]. Kirksville (MO): Kirksville College of Osteophathic Medicine, A.T. Still University; [cited 2009 Mar 3]. Available from: du/faculty/chamberlain/website/lectures/lecture/plague.htmhttp://www.kcom.e du/faculty/chamberlain/website/lectures/lecture/plague.htm
References Cunha CB, Cunha BA Impact of Plague on Human History. Infect Dis Clin N Am 20(2006): Davis RM, Cleugh E, Smith RT, Fritz CL Use of a chitin synthesis inhibitor to control fleas on wiild rodents important in the maintenance of plague, Yersinia pestis, in California. Journal of Vector Ecology 33(2): Deadly Diseases: Plague. In: RX for Survival, a Global Health Challenge. [Internet]: PBS; [cited 2009 Apr 10]. Available from: Dire DJ Biological Warefare. In: eMedicineHealth Practical Guide to Health. [Internet]: eMedicineHealth; [cited 2009 Mar 13]. Available from: warfare/article_em.htmhttp://www.emedicinehealth.com/biological_ warfare/article_em.htm Drysdale M, Heninger S, Hutt J, Chen Y, Lyons CR, et al. (2005) Capsule synthesis by Bacillus anthracis is required for dissemination in murine inhalation anthrax. Embo J 24: 221–227. Felek S, Krukonis ES The Yersinia pestis Ail Protein Mediates Binding and Yop Delivery to Host Cells Required for Plague Virulence. Infection and Immunity 77(2): Fix, Douglas F. [Internet]. Carbondale (IL): Southern Illinois University Carbondale; [cited 2009 Mar 3]. Available from: Inglesby TV, Dennis DT, et. al Plague as a Biological Weapon: Medical and Public Health Management. JAMA 283(17): Kare, John Plague and Anthrax: Ancient Diseases, Modern Warfare. Top Emerg Med 24(3):77-87.
References List of Historical Plagues. In: Wikipedia the Free Encyclopedia. [Internet]: Wikipedia; [cited 2009 Mar 1]. Available from: McGovern TW, Friedlander, AM Chapter 23: Plague. Medial Aspects of Chemical and Biological Warfare. [Internet]: Borden Institute the Textbooks of Military Medicine; [cited 2009 Apr 14]. Available from: Mangold T, Goldberg J Plague Wars: The Terrifying Reality of Biological Warfare. New York: St. Martin’s Griffin. Maginnis, Robert Al-Qaeda and The Plague. In: Human Events. [Internet]: Human Events; [cited 2009 Mar 24]. Available from: Marik PE, Bowles S Management of Patients Exposed to Biological and Chemical Warfare Agents. Journal of Intensive Care Medicine 17(4): Pan NJ, Brady MJ, Leong JM, Goguen JD Targeting Type III Secretion in Yersinia pestis. Antimicrobial Agents and Chemotherapy 53(2): Plague Attributes – Biological Weapons. In: GlobalSecurity.org. [Internet]: GlobalSecurity; [cited 2009 Mar 13]. Available from: Relman, D. A Bioterrorism — Preparing to Fight the Next War. The New England Journal of Medicine. Vol. 354: Septicemic plague. In: Wikipedia the Free Encyclopedia. [Internet]: Wikipedia; [cited 2009 Apr 3]. Available from:
References Todar, K [Internet] "Bacillus anthracis and anthrax." Todar's Online Textbook of Bacteriology. University of Wisconsin-Madison Department of Bacteriology. [cited 2009 April 12] Available from: Turner JK, Xu JL, Tapping RI Substrains of 129 Mice Are Resistant to Yersinia pestis KIM5: Implications for Interleukin-10-Deficient Mice. Infection and Immunity 77(1): University of Texas Medical Branch. [Internet] Epidemiology Corner: Infectious Disease Page: Salmonella. [cited 2009 April 4] Available from: gy/InfectiousDiseases/Salmonellahttp://www.utmb.edu/mchd/Information/Epidemiolo gy/InfectiousDiseases/Salmonella Weyant, R. S., J. W. Ezzelland, Jr., and T. Popovic [Internet] Basic laboratory protocols for the presumptive identification of Bacillus anthracis. Centers for Diseases Control and Prevention, Atlanta, Ga. [cited 2009 April 12] Available from: pdfhttp://www.bt.cdc.gov/Agent/Anthrax/Anthracis pdf West, Alex Al-Qaeda terrorists killed by Black Death after the killer bug also known as the plague sweeps. In: The Sun. [Internet]: The Sun; [cited 2009 Mar 24]. Available from: hesun.co.uk/sol/homepage/news/article ecehttp://www.t hesun.co.uk/sol/homepage/news/article ece Willey JM, Sherwood LM, Woolverton CJ The Epidemiology of Infectious Disease. Prescott, Harley, and Klein’s Microbiology. 7 th ed. Boston: McGraw-Hill. p Yersinia pestis. In: Wikipedia the Free Encyclopedia. [Internet]: Wikipedia; [cited 2009 Mar 10]. Available from: