Some woolly thinking
While I agree with the core of the argument in Dr. Hanson’s ‘Bioterrorist Attack: Fact or Fiction?’ That the $50 billion dollars has largely been wasted it brings up a few questions. Firstly what are these potential bio-weapons. He starts off by discussing Ricin which is not a bio-weapon it is a chemical weapon, and he mentions the film Outbreak which was not about bio-terrorism but about a zoonotics re-emergence event (the only malice was on the part of the US military which had a cure but would not give it to its citizens because of national security considerations and not wanting to admit what it had been up to) and the fact that a Maginot line across the Mexican boarder will not stop much but it will cause a fair bit of re-routing. These may seem minor quibbles but the first two are symptoms of a poor understanding of the bio-weapons threat - the good Dr. should have known better – but the general public do not have the background to understand and are so easily led – or misled. I would class the threat into three groups Major, Minor & Engineered.
I will start with Engineered as this is the nightmare scenario used to scare up funding and is generally useful for getting your agenda through. As a threat it is a non starter as the required technology is all science fiction. What we can do – given a well equipped level 3 or 4 bio lab and access to an existing deadly pathogen – is tinker with its genetic sequence and test the results to see if they make it any more of a super bug. As nature does this all the time and on a much larger scale it is unlikely you will get anything significantly more dangerous that you started with and I can not imagine anyone would bother, if you have the pathogen and were of a mind to use it you would just release it as it is.
Major. This is where you have a highly dangerous communicable disease (1918 H1N1, smallpox) the release is relatively simple (bio-suicide ‘bomber’ spends the day coughing and sneezing at Heathrow) the problem is it is totally untargeted the newly infected could just as easily be on there way to Mecca as Washington. This is more of an extortionist’s weapon (think Bond films).
The Minor has a disproportionate scare effect but is like the anthrax release. This type of weapon has a low CAR (see the quote box for an explanation of terms) so spreads little or not at all, it needs a dispersal mechanism and will normally only infect those directly targeted or those in close contact with this group.
A couple of other misconceptions re testing. I suspect most of the public think when a blood sample is tested it enters some black box procedure which then reports the pathogens found, the reality is you have to guess, based on symptoms, what you are dealing with and test for it if you do not find it you guess again and repeat. If the pathogen is new, or very rare, or only endemic in poor countries (where it is not worth manufacturing a test because they can not afford to use it) you may never find an answer.
If what I have written is true then the key to preventing Major (or Engineered attacks) is to keep the terrorists from getting hold of any of the really dangerous bugs in the first place, so shutting down as many of the new biolabs that are working with these pathogens as possible is the first step. I still think they are a far greater danger as a source of release by accident, mental instability in a lab worker or natural catastrophe – fire, flood, hurricane, tornado and earthquake. (I am glad the Sichuan quake has been burying nuclear-labs not bio-labs).
If you want a low cost bio-terror attack send a bunch of XDR-TB sufferers on a group holiday to Disneyland.
When considering the epidemiology of infectious disease there are a few terms that are useful
CAR (Clinical Attack Rate) The proportion of those exposed that become clinically ill.
CFR (Case Fatality Rate) The proportion of those clinically ill that die.
Ro (The Reproductive Number) This is the number of people one ill person infects.
If the Ro is less than 1 then the infection will die out, if greater than one you have an epidemic – the higher the number the faster the spread. Each disease has a typical Ro but it is not fixed (the same disease would have a higher Ro in a city than a sparsely populated region).
If you multiply CAR by CFR by population you get total fatalities. For the 1918 flu pandemic CAR was ~30%, CFR was ~2.5%, Ro was ~2.
Ebola & H5N1 have a CFR of > 60%.
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