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Bioterrorism: Getting the Big Picture. Texas Society of Infection Control Practitioners. This program has been created and made possible through a grant from the Texas Department of Health. Goal.
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Bioterrorism: Getting the Big Picture Texas Society of Infection Control Practitioners
This program has been created and made possible through a grant from the Texas Department of Health.
Goal • At the end of this workshop Infection Control Practitioners will be able to describe various components necessary to develop and implement a successful bioterrorism preparedness program
Objectives • Name the 6 Category A Biological Agents, treatment and prophylaxis • Discuss appropriate laboratory support systems for dealing with bioterrorism events • Describe key concepts of Mental Health in Disasters/Bioterrorism
Objectives • List appropriate infection control precautions for Category A biological agents • Identify security, transportation and communication needs in your facility • Identify roles of external agencies in a disaster event
Definition of Bioterrorism • The unlawful use, or threatened use, of microorganisms or toxins derived from living organisms to produce death or disease in humans, animals, or plants. The act is intended to create fear and/or intimidate governments or societies in the pursuit of political,religious, or ideological goals. Saint Louis Unversity School of Public Health
Bioterrorism Agents • Potentially hundreds • Features of most likely agents • Availability • Ease of production • Lethality • Stability • Infectivity Saint Louis Unversity School of Public Health
Bioterrorism: A Legitimate Threat • Most agents relatively easy to produce • Availability of information on the Internet • Access to dual use equipment • Relatively inexpensive • 1970 study–cost of 50% casualty rate per km2 • conventional - $2,000 • nuclear - $800 • anthrax - $1 Saint Louis Unversity School of Public Health
Bioterrorism: A Legitimate Threat • Dissemination may cover large area • Difficult to detect release • Symptoms occur days or weeks later • Some have secondary spread Saint Louis Unversity School of Public Health
Bioterrorism: A Legitimate Threat • Use can cause panic • Users able to protect selves • Users can escape before effect Saint Louis Unversity School of Public Health
Bioterrorism: A Legitimate Threat • Former Soviet scientists successfully weaponized many agents • Active research was undertaken to engineer more virulent strains Saint Louis Unversity School of Public Health
Bioterrorism: A Legitimate Threat • With the collapse of the Soviet Union, microbe stock & technology has possibly landed in hands of terrorists • State sponsorship of terrorism • At least 17 nations are known to have offensive biological weapons programs Saint Louis Unversity School of Public Health
Delivery Mechanisms • Aerosol likely route for most agents • Easiest to disperse • Highest number of people exposed • Most contagious route of infection • Food / Waterborne less likely • Only effective for some agents Saint Louis Unversity School of Public Health
Epidemiology • Clues suggesting a bioweapon release • Large numbers present at once (epidemic) • Previously healthy persons affected • High morbidity and mortality • Unusual syndrome or pathogen for region • Recent terrorist claims or activity • Unexplained epizootic of dead, sick animals Saint Louis Unversity School of Public Health
Role of Primary Care Physician • Have a high level of suspicion • Keep BT agents in differential diagnosis • Recognize typical BT disease syndromes • Be aware of unusual epidemiologic trends • Know treatment/prophylaxis of BT agents • Know how to report suspected BT cases Saint Louis Unversity School of Public Health
Category A Biological Agents • Can be easily disseminated or transmitted from person to person • Result in high mortality rates and have the potential for major public health impact • Might cause public panic and social disruption • Require special action for public health preparedness Centers for Disease Control
Category A Biological Agents • Anthrax • Botulism • Plague • Smallpox • Tularemia • Viral Hemorrhagic Fever Centers for Disease Control
Category B Biological Agents • Are moderately easy to disseminate • Result in moderate morbidity rates and low mortality rates • Require specific enhancements of CDC's diagnostic capacity and enhanced disease surveillance Centers for Disease Control
Category B Biological Agents • Brucellosis • Epsilon toxin of Clostridium perfringens • Food safety threats • Salmonella • E. coli O157:h7 • Shigella Centers for Disease Control
Category B Biological Agents • Glanders • Melioidosis • Psittacosis • Q Fever • Ricin toxin • Staphylococcal enterotoxin B Centers for Disease Control
Category B Biological Agents • Typhus fever • Viral encephalitis • Water safety threats • Vibrio cholerae • Cryptosporidium Centers for Disease Control
Category C Biological Agents • Third highest priority agents include emerging pathogens that could be engineered for mass dissemination in the future because of: • availability • ease of production and dissemination and • potential for high morbidity and mortality rates and major health impact Centers for Disease Control
Category C Biological Agents • Emerging infectious diseases • Nipah virus • Hantavirus Centers for Disease Control
Common Clinical Manifestations of Bioterrorism Agents • Skin lesions w/fever • Acute respiratory distress w/fever • Influenza-like illness • Neurologic syndromes
Skin Lesions w/Fever • Smallpox • Cutaneous Anthrax
Acute Respiratory Distress w/Fever • Inhalation Anthrax • Pneumonic Plague
Flu-like Illnesses • Tularemia • Inhalational Anthrax • Viral Hemorrhagic Fever • Smallpox • (Pretty much everything except the kitchen sink!)
Neurologic Illnesses • Ricin • VX • Sarin gas • Mustard gas • Botulism
Smallpox: History • Caused by variola virus • Most deaths of any infectious disease • ~500 million deaths in 20th Century • ~2 million deaths in 1967 • Known in ancient times • Described by Ramses • Natural disease eradicated • Last U.S. case – 1949 (imported) • Last international case – 1978 • Declared eradicated in 1979 Photo: National Archives Saint Louis Unversity School of Public Health
Smallpox: Bioweapon Potential • Features making smallpox a likely agent • Can be produced in large quantities • Stable for storage and transportation • Known to produce stable aerosol • High mortality • Highly infectious • Person-to-person spread • Most of the world has little or no immunity Saint Louis Unversity School of Public Health
Smallpox: Bioweapon Potential • Current concerns • Former Soviet Union scientists have confirmed that smallpox was successfully weaponized for use in bombs and missiles • Active research was undertaken to engineer more virulent strains • Possibility of former Soviet Union virus stock in unauthorized hands Saint Louis Unversity School of Public Health
Smallpox: Bioweapon Potential • Nonimmune population • <20% of U.S. with substantial immunity • Availability of virus • Officially only 2 stocks (CDC and Russia) • Potential for more potent attack • Combined with other agent (e.g. VHF) • Engineered resistance to vaccine Saint Louis Unversity School of Public Health
Smallpox: Bioweapon Potential • Delivery mechanisms • Aerosol • Easiest to disperse • Highest number of people exposed • Most contagious route of infection • Most likely to be used in bioterrorist attack • Fomites • Theoretically possible but inefficient Saint Louis Unversity School of Public Health
Smallpox: Epidemiology • All ages and genders affected • Incubation period • From infection to onset of prodrome • Range 7-17 days • Typical 12-14 days Saint Louis Unversity School of Public Health
Smallpox: Epidemiology • Transmission • Airborne route known effective mode • Initially via aerosol in BT attack • Then person-to-person • Hospital outbreaks from coughing patients • Highly infectious • <10 virions sufficient to cause infection • Aerosol exposure <15 minutes sufficient Saint Louis Unversity School of Public Health
Smallpox: Epidemiology • Person-to-person transmission • Secondary Attack Rate (SAR) • 25-40% in unvaccinated contacts • Relatively slow spread in populations (compared to measles, etc.) • Higher during cool, dry conditions • Historically 3-4 contacts infected • May be 10-20 in unvaccinated population • Very high potential for nosocomial spread • Usually requires face-to-face contact Saint Louis Unversity School of Public Health
Smallpox: Epidemiology • Transmission via fomites • Contaminated hospital linens/laundry • May have been successfully used as weapon in French-Indian War Saint Louis Unversity School of Public Health
Smallpox: Epidemiology • Infectiousness – Rash is marker • Onset approx one day before rash • Peaks during first week of rash • ? Carrier state possible • Some data show virus detectable in saliva of contacts who never become infected • Unclear if they can transmit infection, but theoretically possible Saint Louis Unversity School of Public Health
Smallpox: Epidemiology • Infectious Materials • Saliva • Vesicular fluid • Scabs • Urine • Conjunctival fluid • Possibly blood Saint Louis Unversity School of Public Health
Smallpox: Epidemiology • Role of index case severity • Does not predict transmissibility • Does not predict severity of 2° cases • Role of prior vaccination • Immunity wanes with time • Maintain partial immunity for many years • Partial immunity reduces disease severity • Reduces transmissibility (less virus shed) Saint Louis Unversity School of Public Health
Smallpox: Epidemiology • Mortality • 25-30% overall in unvaccinated population • Infants, elderly greatest risk (>40%) • Higher in immunocompromised • May be dependent on ICU facilities • Dependent on virus strain • Dependent on disease variant Saint Louis Unversity School of Public Health
Smallpox: Epidemiology • Factors that allowed smallpox eradication • Slow spread • Effective, relatively safe vaccine • No animal/insect vectors • No sig. carrier state (infected die or recover) • Infectious only with symptoms • Prior infection gives lifelong immunity • International cooperation Saint Louis Unversity School of Public Health
Smallpox: Microbiology • Variola virus – the agent of smallpox • Orthopoxviridae family • 2 strains of variola • Variola major • Variola minor • Vaccinia • Used for current vaccine • Namesake of “vaccine” • Cowpox – used by Jenner in first vaccine • Monkeypox – rare but serious disease from monkeys in Africa Saint Louis Unversity School of Public Health
Smallpox: Microbiology • Variola major • Classic smallpox • Predominant form in Asian epidemics • Highest mortality (~30%) Saint Louis Unversity School of Public Health
Smallpox: Microbiology • Variola minor • Same incubation period, mode of transmission, clinical presentation • Causes milder disease • Less severe prodrome and rash • Mortality ~1% • Discovered in 20th century • Started in S. Africa • Was most predominant form in N. America Saint Louis Unversity School of Public Health
Smallpox: Microbiology • Environmental survival • Longest (>24hr) in low temp/low humidity • Inactive within few hours in high temp/humidity • Dispersed aerosol • completely inactivated within 2 days of release Saint Louis Unversity School of Public Health
Smallpox: Pathogenesis • Virus lands on respiratory/oral mucosa • Macrophages carry to regional nodes • Primary viremia on Day 3 • Invades reticuloendothelial organs • Secondary viremia on Day 8 Saint Louis Unversity School of Public Health
Smallpox: Pathogenesis • White Blood Cells infected • WBCs migrate capillaries, invade dermis • Infects dermal cells • Influx of WBCs, mediators cause vesicle • Systemic inflammatory response • Triggered by viremia • Sepsis, multiorgan failure, often DIC Saint Louis Unversity School of Public Health