lecture 19: forebsics of biological terrorism

what is microbial forensics

encompasses three(ish) areas involving analysis of microorganisms related to:

• person on person crime

• post-modern interval estimation

• geolocation, trace evidence comparisons

what is a bioterrorism agent?

any intentionally released microorganism or virus that can cause harm (direct or indirect) to human beings:

disease agents

agents that affect plants and livestock

bioterrorism

• forensic analyses of biothreat agents fall into one of two categories

1. detection: what is the threat?

2. attribution: who made it?

bioterrorism agents

typically two factors involved in determining ‘threat level’ of each agent:

virulence/lethality: how deadly is it

ease of access/cultivation: can anyone acquire it? can anyone grow it

relative threat level determines the type of forensic tests that are developed and implemented in local crime labs

yersinia pestis

• agent of bubonic (black) plague

• historically important pathogen, est 200 million people have died

• antibiotic strains, natural hotspots

francisella tularensis

• agent of tularemia, “rabit fever”

• found in small mammals (rodents, rabbits, voles), transmitted by tick bites, inhalation (lawn mowers disease)

• approx. 200 cases each year in southern and western US

Bacillus anthratics

• agent of anthrax, forms spores that are highly resistant to environmental stress, survive for long periods of time

• natural life cycle in the environment, resides in soil and infects livestock

• infects through contact with spores in the environment

• breathe in spores after contact with infected animal hides (inhalation), drinking contaminated water (gastrointestinal)

• B. anthracis also infects humans through direct contact with open wounds, cuts, lesions

• hiking, other outdoor activity (cutaneous form)

salmonella spp and E.coli

• responsible for many cases of food poisoning, improperly preserved meat and poultry

• easy to grow in lab, incapacitating but not lethal

• environmental forensics and fecal contamination

clostridium botulinum

• agent of ‘botulism’

• releases botulinum toxin. deadly nerve agent (1g enough to kill entire city)

• ubiquitous in the environment, especially in soil

• 85% cases occur around construction zones, mining

viruses

• smallpox, ebola. flu…

• deadliest non-chemical agents

  • no direct countermeasures, treatments

  • easy to transmit person to person

• natural reservoirs if they exist, remote

• difficult to cultivate in the lab, skilled personnel and biosafety equipment needed

pathogen monitoring

• development and optimization of PCR-based methods to characterize bacterial DNA

• rapid (results<hour)

• assays can be species/strains specific

• instruments can be portable

Biowatch program

• autonomous filters that collect bacteria, toxins in air samples

• deployed in select cities

• genetic identification: PCR-based amplification of microbial DNA

covert surveillance

• distinguishing between natural and laboratory derived source also critical for virus epidemiology