Press Release Details

Bioterrorism

Abstract

Bioterrorism is something that most of us hope we will never encounter outside of science fiction novels and movies. However, following the World Trade Center attacks, the postal anthrax scare in the United States and even the recent mail scare at the Indonesian embassy in Canberra, the possibility of it happening to â€˜usâ€™ seems suddenly possible.

Complete Article

15 Jul 2005

The use of biological weapons is not a new invention. In the 5th century BC the Scythians used arrows dipped in a mixture of blood, manure and snake intestines with lethal effect. Enemies who did not die from the arrow wound succumbed to tetanus and gangrene from the mix of Clostridium tetani and Clostridium perfringens.If Caffa (now Feodosiya) on the Black Sea in 1346 a Tartar warlord hurled the bodies of plague victims over the walls of the besieged Genoese merchants, precipitating their flight (and their return to Genoa with plague-carrying rats). The Russians used the same tactic in Estonia against the Swedes besieged in Reval in 1710. Again the panic that ensued led to the fall of the city. In both cases the corpses themselves would not have been infectious, although at the time that would not have been known. However, both attacks were devastatingly effective on those attacked due to the fear generated by the possibility of acquiring the infection not only the corpses, but from each other. An extremely detailed exercise called â€œDark Winterâ€ run by the US Homeland Security Department in 2002 modelled a bioterrorist incident in Oklahoma City with smallpox1. Amongst its conclusions was that the fear generated by such an attack would cause total disruption to normal society, far beyond any attack with conventional weapons including nuclear devices.Other major historical uses of bioterrorism include the use of smallpox infected blankets by British General Jeffery Amherst against American Indians in the 1760â€™s (killing tens of thousands), and failed Polish experiments in the 1600â€™s with hollow cannon balls filled with the saliva of rabid dogs. In World War I German agents in the US infected horses and mules destined for France with anthrax and glanders. In World War II the infamous Japanese Unit 731 experimented with anthrax on prisoners, killing over 3000, and then used ceramic bombs containing plague infected fleas in China and Manchuria in 1941 killing up to 20000 civilians and many thousands of invading Japanese troops.The Center for Diseases Control (CDC) in the US categorises potential bioterrorism agents into grades depending on their perceived likelihood of use2. The category A agents are anthrax, plague, smallpox, tularaemia, botulism, Ebola, Marburg, Lassa fever and the other South American haemorrhagic fevers. There are three important hurdles for a bioterrorist to overcome in order to be a threat. Firstly, they have to obtain enough of the pathogen, which hopefully will prove increasingly difficult. The Japanese AumShinrikyo death cult attempt to get viable anthrax from a property in the northwest of Australia but failed. They subsequently obtained a supply of anthrax and used it, but failed to realise they had obtained the non-toxic vaccine strain of B. anthraxis. Their attempt also failed because they were unable to overcome the second hurdle, â€˜weaponisingâ€™ the anthrax spores into an inhalable mixture. Unable to overcome these two hurdles AumShinrikyo moved on to sarin nerve gas and managed to overcome the last hurdle, gaining access to a vulnerable area, delivering their fatal attacks in Japanese subways.The important lesson from the AumShinrikyo attempts is that bioterrorism fortunately requires a much greater level of technical sophistication that than more traditional terrorist methods such as explosive devices.Despite this reassurance, there is no doubt that terrorists capable of funding and organising attacks like the World Trade Center one on September 11th 2001 could overcome these barriers. The release of between 4mg and 1g of anthrax from a military microbiological facility in Sverdlovsk (Russia) in 19793 killed up to 100 people as far as 70km downwind4. Around 100kg of anthrax is sufficient to kill 3-4 million people. At its peak the USSR was producing 5000kg of weapons grade anthrax per year, much of which is unaccounted for. In 1991 Iraq admitted to having 8500kg of Anthrax, some of which was loaded into Scud missiles.In the event of any major bioterrorist attack any health system in the world is likely to be rapidly overwhelmed. We have to rely on national and international security measures to prevent these. The key in limiting the mortality, morbidity and social damage from any bioterrorism incident is in early recognition and containment of secondary spread (and of course more incidents). All Australian states have emergency protocols and contact procedures that all medical practitioners should at least know how to access if the need arose4. The majority of the most likely (CDC category A) agents present with either severe respiratory symptoms or fever with purpura. Therefore several cases of unexplained severe pneumonia in a short time frame should trigger concern. It is then a matter for those treating the patients to try and establish a diagnosis as fast as possible as well trying to establish any potential common areas of exposure. As these agents, with the notable exceptions of anthrax and tularaemia, are highly contagious, strict isolation procedures to limit secondary spread is also critical.Finally, provided there is not massive exposure a degree of security is often provided by vaccination (in the case of smallpox and to a lesser extent with anthrax) or antibiotic prophylaxis. Again there are numerous protocols in the event of exposure. Despite this, it is important to realise that vaccine resistant strains of smallpox were developed by the USSR, as were antibiotic resistant strains of plague and anthrax. Furthermore, an Australia research group has also shown how relatively simple it is to make any virus (for example influenza) not only more lethal, but also remove any protection offered by vaccination5.In summary, the potential damage from a successful bioterrorist attack is enormous. However, thankfully technical difficulties in effectively using these agents will limit their use to groups who can muster sufficient expertise to use them. For the â€˜averageâ€™ terrorist chemical explosives are vastly easier to acquire and use. The major role for medical practitioners is in early recognition so that any outbreak can be contained as quickly as possible.References:1 www.upmc-biosecurity.org 2 www.bt.cdc.gov3 Meselson et al. The Sverdlovsk anthrax outbreak of 1979. Science 1994; 266(5188):1202-84 Brookmeyer et al. The statistical analysis of truncated data: application to the Sverdlovsk anthrax outbreak. Biostatistics. 2001; 2(2):233-475 Jackson RJ et al. Expression of mouse interleukin-4 by a recombinant ectromelia virus suppresses cytolytic lymphocyte responses and overcomes genetic resistance to mousepox. J Virol. 2001; 75(3):1205-10Dr Grant Waterer MBBS, PhD, FRACP, FCCPMedical DirectorVirtual Respiratory Centre