Bioterrorism/poxviruses Flashcards
key features that make a microbiological agent a potential bioweapon
- High morbidity and/or mortality
- Potential for person-to-person spread
- Low infectious dose, and ability to be spread by aerosol
- Lack of widespread rapid diagnostic tests
- Lack of stockpiles of effective drugs
- Lack of an effective and available vaccine
- Lack of widespread immunity in target population
- Ability to obtain pathogen and cultivate it in large amounts
- Stability of infectious organism in the environment
- Potential to be weaponized
- Mass casualties that could overwhelm the health care system
Specific bugs that could be used potential bioweapons
- Poxviruses: have 2 known stockpiles, CDC and Russia.
- Clandestine supplies may be located in other countries.
- Routine immunization stopped in 1972, so could be a potential target
- Ebola: Difficult to work with, need a space suit. Less likely to be utilized.
- Plague could be used but has effective treatment with gentamycin or doxycycline. Very virulent. Spread by fleas or person to person (pneumonic).
- Francisella is also very virulent, hardy. Spread by arthropods.
Characteristics of CDC Category A
Highly lethal
Easily transmissible
High mortality rates and major public health impact
Might cause public panic and social disruption
Require special action for public health preparedness
Bugs in CDC category A
- Bacillus antracis (anthrax)
- Clostridium botulinum toxin (botulism)
- Yersinia pestis (plague)
- Variola major (smallpox) and other related pox viruses
- Francisella tularensis (tularemia)
- Viral hemorrhagic fevers:
- Arenaviruses (LCMV, Junin, Machupo, Lassa Fever)
- Bunyaviruses (Rift Valley fever virus)
- Flaviviruses (Dengue)
- Filoviruses (Ebola, Marburg)
Anthrax: danger, prevention, dx, tx
Can be spread by inhalation.
Vaccine exists and new vaccine in trials.
Culture of organism, ID of 2 virulence plasmids by PCR. Wrights stain of peripheral blood.
Antibiotics effective after symptoms occur, and prevent disease.
Botulism: danger, prevention, dx, tx
- One gram of botulinum toxin can kill 1 million people if efficiently delivered. by aerosol or in food. Has been made on a large scale and weaponized by several governments and terror groups.
- 60-100% fatality rate.
- Prevention
- Military vaccine against all 7 serotypes is being developed. Botulism toxoid is used to immunize people that work with C. botulinum or the toxin, but is not available in large amounts.
- Dx = Flaccid paralysis.
- 4Ds: diplopia, dysarthria, dysphonia, dysphagia
- Tx = Equine anti-toxins vs types A, B and E are available in limited quantities to bind any circulating toxin that has not yet reached the nerves. Use of horse serum can cause serum sickness, and human monoclonal antibodies are being developed against the toxin as a substitute.
Yersinia pestis: danger, prevention, dx, tx
Can be spread by inhalation. Highly infectious.
New vaccine is needed, containing V and F1 antigens.
Pneumonic
Antibiotics before and after exposure for a week.
Pox viruses: danger, prevention, dx, tx
- Vaccination worldwide was ended in 1980 so most people in the world today never got smallpox vaccine.
- Prevention
- Military and first responders are vaccinated.
- Vaccination with a live attenuated antigenically related virus called vaccinia propagated in cow skin was used to prevent smallpox.
- Dx = Fever, prostration and characteristic pustular rash. Extensive scarring results from smallpox.
- Tx = Because of the long incubation period of smallpox, people exposed to a case of smallpox could be protected from disease by vaccination after exposure.
- There is no antiviral drug proven to be effective against smallpox.
Tularemia: danger, prevention, dx, tx
Waterborne outbreaks and has been used as aerosol for bioterrorism. Infectious dose is 10 organisms.
No vaccine.
Systemic illness with fever, lymphadenopathy. Skin test similar to PPD and measurement of titers of antibodies.
Antibiotics before and after exposure.
Viral hemorrhagic fevers: danger, prevention, dx, tx
Several have been weaponized for aerosol transmission. Fatality rates can be very high. Many are readily transmitted from human to human or infected animal to humans, and many are spread in hospital settings to medical staff.
Vaccines in development. Live attenuated yellow fever vaccine has been available for years but not made in large quantities.
Febrile illness with hemorrhagic manifestations in many tissues.
No drugs proven to be effective.
Mechanisms for manipulation of pathogenic mechanisms, virulence, antigenicity and antibiotic resistance of existing microbiological pathogens for use as biothreat agents.
Enhancing virulence of a known pathogen.
Genes of a known pathogen can be manipulated or naturally occurring variants of the organism can be selected to enhance virulence.
Could include adding antibiotic resistance genes, changing antigenicity so that no one has protective antibody, changing immune responses to increase pathogenicity, altering tissue tropism, increasing the yield of organisms, and changing host range.
Describe how new or chimeric pathogens could be created as bioweapons
Construction of chimeric microbes by recombinant DNA technology.
Using genetic engineering techniques, genes from one organism such as a toxin or other virulence factor can be recombined into the genome of an unrelated organism.
Construction of pathogens de novo from oligonucleotides.
The entire genome of a virulent virus could be constructed in a few weeks from oligonucleotides purchased from the internet! The publication of full genome sequences can facilitate construction of a virulent pathogen.
Describe how clinicians can rapidly recognize a bioweapons incident, and how the health care network can respond.
- communication and education
- btwn physicians/hospitals w/single case
- physician education programs
- unusual presentation, cases of rare dz
- surveillance netowrks
- public health agencies
- network of diagnostic labs
- isolation and quarantine
- stockpiles of response equipment and reagents
- med equipment/drugs/vaccines
- epidemiologist-led responses
- public information
- accurate info to new media
- distinguishing bioweapons events from emerging disease outbreaks
