Smallpox Derivatives and Bioterror
Reader's Question Answered

In response to our article,
Biological Weapons and Terrorism, a reader, Sergio, has asked a question about the effectiveness of ebolapox and veepox. The following answer is provided by the author of the previous article, PWHCE administrator Trevor Stanley.
The QuestionHello,
I am currently doing a research project on the potency of biological weapons. I have a question. If something like veepox or ebolapox were released how would it be done? And if released how long would it take to wipe out countries?
Thank you for your time.
DisclaimerThis response to reader e-mail is based on information which is readily available in public libraries, combined with extrapolations of events which have already happened. The author makes this information publicly available in the belief that any would-be terrorist organisation which exercises enough initiative and influence to obtain ex-Soviet, military grade viral weaponry has probably had ample time to think through the possibilities and limitations of the weapon, and that therefore only the most uninformed or unimaginative terrorist could possibly benefit from the following information.
Sources of InformationRelevant information on smallpox, ebolapox and veepox can be hard to come by. Because smallpox was eliminated as an endemic disease in the late 1970s, modern microbiology text books refer to smallpox only in passing, as the classic case study of the elimination of a disease by vaccination, or in the section on viral taxonomy. The development of smallpox and the hybrid breeds ebolapox and veepox by Soviet Russia as weapons during the 1980s remains a closely guarded Russian (or Commonwealth of Independent States) state secret. Outside intelligence circles, expatriate scientists such as Ken Alibek are the only primary sources of such information in the West. For this reason, most useful information found whilst researching this answer came from Ken Alibek's book "Biohazard" and a medical handbook published in 1949.11 Ken Alibek with Stephen Handelman, Biohazard, Hutchinson Publishers, London, 1999.
H. Stanley Banks, The Common Infectious Diseases; A Handbook for Students and Postgraduates, Edward Arnold & Co., London, 1949.
The answer depends on many variablesThe time it would take for smallpox or ebolapox to 'wipe out' or at least cripple a whole country, or whether an outbreak would even achieve epidemic or pandemic scale, depends on a number of factors, including the method of delivery.
The method of delivery depends also upon the resources available to the aggressor, and the availability of resources would therefore set the parameters of any attack.
The likelihood or otherwise, of epidemic distribution of contagious outbreaksIt is important to distinguish between an outbreak of smallpox effecting a small number of people which may be controlled by quarantine, an epidemic, in which a significant number of people are infected and the spread of the disease is not yet under control, and a pandemic, where the epidemic spreads to new sites, covering a continent or the whole globe. In any case of smallpox or similar outbreaks, the authorities would quickly move to identify and isolate all infected individuals. To cause an uncontrolled epidemic, the pathogen must infect people faster than the authorities can keep up. 2Alibek and Handelman, op cit p114.
"Today there are 12 million doses of smallpox vaccine on hand in the United States - of which only seven million are fully reliable, according to the Centers for Disease Control in Atlanta - a portion of the roughly two hundred million doses available in the world." Similar figures have appeared in more recent news reports, and the number of doses currently available in the US and other western countries is likely to be larger today than it was in 1999, given the heightened priority now given to the threat of bioterrorism. Previously much of the vaccine was probably located in third world countries where a 'natural' outbreak would more probable.
3 Banks, op cit, p221.
4 Alibek, op cit, p112.
Bioterrorists have recently demonstrated their ability to infect precisely targeted victims by mailing a weaponised pathogen, anthrax, to particular individuals or organisations. Given that anthrax is not contagious, obviously such outbreaks do not lead to epidemics - widespread infection would require the delivery of much larger quantities of pathogen. On the other hand, viruses such as smallpox and ebola are readily infectious. However, delivering them through the mail would obviously announce their presence, allowing the authorities to quarantine effected individuals. The creation of an epidemic or pandemic by this method would therefore be unlikely, though not impossible - for example, postal workers could transfer the virus from their place of work to public places and their own families before the letter was opened, leading to several uncontained cases of the disease cropping up at the same time. The likelihood of an out-of-control epidemic increases in proportion to the duration and number of such cases. By their very nature, estimates of the likelihood and extent of such epidemic outbreaks are chaotic and difficult to quantify, although epidemiologists have devised formulæ to approximate the extent and speed of an epidemic given certain parameters.
Sergio's question seems to presuppose that any introduction of smallpox or genetic hybrids of smallpox would inevitably 'wipe out' the populations of whole countries. On closer examination, this expectation is, thankfully, not warranted. In previous centuries, smallpox remained unchecked by vaccines, and yet did not wipe out whole countries or continents - it was confined to outbreaks every couple of decades. While the mortality rate of smallpox may be relatively high, not all those who come into contact with a victim contract the disease.
Many speculations have been advanced about the likely spread of smallpox amongst today's unvaccinated communities. Some appear to think that without the natural defences conferred by the endemic presence of various poxes, modern populations are defenceless against smallpox. These speculations rest on the false premise that outbreaks in a vulnerable population are entirely without historical precedent. We must remember that, of the six populated continents of the earth, only half suffered from smallpox before Europeans began the colonisation of North America, South America and Australia. Smallpox, along with the common cold and other such diseases, did take a terrible toll on the native communities of all three 'new' continents, however it is a matter of record that on no continent was the entire native population eliminated.
Modern societies have both advantages and disadvantages when compared to the indigines of the three aforementioned continents. Densely concentrated and highly mobile modern populations obviously present opportunities for the acceleration of an epidemic. On the other hand, the greater concentration of resources and health, transport and communications infrastructure, informed by a modern understanding of diseases and their prevention and control, tend to offset these disadvantages. Furthermore, there are hundreds of millions of doses of smallpox vaccine in existence,2 and the vaccine is effective to some extent after infection has already taken place but before symptoms have emerged. An entire suburb or several city blocks could be readily vaccinated in response to an outbreak, with a reasonable chance of success. To achieve an uncontrollable epidemic or pandemic, a large number of simultaneous infections would be required - if the rate of emergence of new cases was allowed to overwhelm the defensive capabilities of a city or country, widespread devastation would follow.
Emphasising the slow spread and methods of control of smallpox is the following excerpt from Banks' book:
past history confirms that the evolution of an epidemic of smallpox is relatively slow. In the early stages, surveillance and vaccination of all contacts, rigorous search for new cases, utilising both clinical and bacteriological means of diagnosis, and prompt isolation and disinfection of all cases discovered, are measures which have been successful in rapidly stamping out any importations of smallpox into this country.3
An informative case study of smallpox containment is found in Alibek's book.4 In 1959, long after smallpox had been eliminated in Russia, an Indian traveller in Moscow who had been previously immunised but was carrying a form of smallpox "so virulent that an epidemic was only narrowly averted", "infected forty-six Muscovites with smallpox before authorities realised what had happened." The Soviets isolated this strain and used it as their "primary battle strain" after 1967. This demonstrates that a significant outbreak of highly virulent smallpox can be contained even in Russia in the 1960s, with an infrastructure far less advanced than the western world's today.
The nature of smallpox and ebolapoxSmallpox, ebola and VEE are all viruses, and viruses are notoriously difficult to culture and maintain. Ebola degrades rapidly in contact with air for example, however smallpox is an unusually hardy virus, with scabs remaining infectious for more than two years.5 Smallpox is caught primarily through inhalation but also from contact with victims, corpses or personal effects of a patient. Ebola is also caught through contact with patients.5 Banks, op cit, p211.
There are several strains of smallpox, which differ considerably in their symptoms. The most common strains of naturally-occurring smallpox had a mortality rate of 30-50%. On the other hand, the mortality rate of ebola is 70-90%. Ebolapox is a hybrid form of smallpox engineered by inserting ebola genes into the smallpox genome, whereas veepox results from the insertion of Venezuelan Equine Encephalitis (VEE) genes into the smallpox genome. I am not certain from what I have read exactly what the result is. From one recent reading, it appears that the point of the ebolapox hybrid is to turn a more common strain of smallpox (with 30-50% mortality) into one which always causes purpuric smallpox or 'black smallpox', a hæmorrhagic form which Banks describes as "invariably fatal from grave toxæmia before the seventh day" after infection. Black smallpox involves hæmorrhaging in place of pustules. By combining the virulence of ebola (70-90% mortality) with that of smallpox, it is obvious that a much more powerful weapon is produced. It is also likely that in ebolapox the two earlier phases of smallpox infection are shortened, particularly given that the Russian post-1967 weapons strain, when aerosolised, caused smallpox in exposed monkeys within one to five days.
Smallpox infection consists of three stages. The first stage is incubation, which lasts from 5-12 days (depending on the strain and prior vaccination) and is not very contagious. The second stage is called the prodromal, toxæmic or fever phase, and is contagious, though not so much as the third, 'eruptive' stage, in which the characteristic rashes (pustules and/or hæmorrhaging) occur.
I have insufficient information to comment specifically on veepox, except to say that as a smallpox virus into which VEE genes have been inserted, apparently at a point where they do not diminish any properties of smallpox, this hybrid virus is likely to be epidemiologically identical to smallpox. That is, it will spread in the same rate and in the same way, however the mortality rate and symptoms may differ.
Limitations on the production of viral weaponsAs viruses cannot reproduce outside living host cells, viral weapons are much harder to manufacture than bacterial weapons. The Russians originally cultured smallpox in hundreds of thousands of chicken eggs, before eventually moving on to technologically advanced reactors. The methods of fixing the resultant substance so that the virus does not lose virulence, and treating it so that it can be aerosolised without being destroyed are, naturally, kept secret. It would be highly impractical, if not impossible, to manufacture viral weapons in a Western country without detection, so any significant quantities would need to be smuggled in, and presumably bought on the ex-Soviet black market.
Consequences of the foregoing for the deployment of viral weaponsThere are no hard and fast rules for the deployment of smallpox-based viruses. The method of delivery depends on the objectives, resources and imagination of the aggressor. It should be remembered, however, that bioterrorists or aggressor States do not necessarily need to annihilate the entire population of a target country to achieve their political ends. For the purpose of answering the question "if something like veepox or ebolapox were released how would it be done?", six representative methods of delivery of ebolapox are considered here, in ascending order of scale. I do not by any means claim that these scenarios are likely to occur - these examples have each been concocted solely in order to demonstrate technical points.
1 Mailing letters containing powdered pox virus
A very cheap and anonymous way of deploying the disease, as the anthrax letters demonstrated. By targetting a particular individual, an individual terrorist can communicate a very succinct message. With a pathogen as contagious as ebolapox, the authorities would be less likely to take the gamble of keeping the postal system open during the quarantine period, as any exposure could lead to multiple new exposures. Furthermore, whereas the anthrax letter sent to Senator Daschle put potentially exposed staff out of action for a day, the quarantine requirements of ebolapox could put the entire Senate building into quarantine isolation for two weeks.
2 Vaccinated Smallpox/Ebolapox 'carriers'
The case of the Indian traveller in Moscow raises the possibility of using smallpox carriers to distribute the disease around a city. An individual could travel the city, being as sociable as possible, shaking strangers' hands, travelling in rush hour transport, and so on. Hundreds of unrelated victims could be infected before the culprit was identified.
3 Delivery into water supply, food supply, train networks or air conditioning
Large-scale distribution demands a higher quantity of pathogenic matter than most bioterrorists are likely to possess - a phial of fluid mixed into a reservoir would probably be too dilute to cause infection. Most drinking water is also treated with chlorine and/or flouride. On the other hand, an aggressor with access to, for example, the distribution network of a major fast-food chain or the air conditioning system of a large office building could definitely cause enough infections to cause an uncontrolled epidemic. Given Al-Quaida's demonstrated infiltration of certain airports, we must hope that either airport security has been tightened as much as is claimed, or that Al Quaida does not possess significant quantities of ebolapox, otherwise the consequences could obviously be dire. Failing access to the foregoing facilities, the aggressor could fall back on the much publicised method of dropping a lightbulb-full of pathogen onto a subway train track, and allowing the trains to sweep it throughout the city by suction power.
A large-scale outbreak within a city would lead to a shutdown of that city for months, equivalent to a siege. The probability of people 'escaping' from the city and spreading the disease to progressively larger areas would be significant.
4 Crop dusters or other sprayers
A much vaunted method for the deployment of pathogens, the limitations of this method have already been described in the press. Large quantities of pathogen and an especially modified light aeroplane would be required for 'crop dusting' a population centre, and the 'plane would most likely be shot down before it got anywhere near a city. Smaller spray-packs were shown to have limitations when used by the Aum Shinrikyo sect in Japan.
5 Rogue State Ballistic Missiles
North Korea, having proven its ability to launch a missile across Japan, could arm such a missile with smallpox (Alibek warns that several former Soviet researchers are now working for North Korea). A smallpox payload anywhere in the Osaka-Tokyo sprawl would lead to a huge number of infections and almost certainly an uncontrollable epidemic. Aside from the appalling loss of life, the resulting elimination of Japan from world trade would obviously have an impact on the global economy.
An Iraqi smallpox or ebolapox SCUD attack on Israel would also be devastating, though unlikely given the probable spread of the disease throughout the Middle East. If Saddam Hussein has access to such a quantity of pox virus, he has probably already calculated that such a use would be unwise, otherwise chemical and/or biological weapons would have been used during the Gulf War.
6 Russian cruise missiles
While the Soviet Union was developing ebolapox and veepox, it was also developing cruise missiles especially adapted to deliver biological bomblets in quantity. In the highly unlikely event of a major conflict between Russia and some non-European Western State (such as the USA), such cruise missiles could, theoretically, be fired at cities. Assuming a significant stockpile of biological agents is still being maintained by Russia,6 several cities could be targeted, leaving the target country battling multiple epidemics (possibly of different diseases) while also reeling from the loss of the productivity of those cities.6 Not entirely unthinkable based on Alibek's account (pp258-264).
ConclusionA major attack by a well-equipped state could knock out enough of the population of a country within a month, that the remaining population would not be sufficient to care for the victims. A smaller attack by terrorists would stand some chance of creating an epidemic which grew as a snowball effect, but that would probably take months to spread around a large country, and could still eventually be brought under control by special measures. Of course, if the aim was to terrify the target country, the mere chance of an epidemic would serve that aim to some extent.

Select Bibliography

  • Ken Alibek with Stephen Handelman, Biohazard, Hutchinson Publishers, London, 1999.

  • H. Stanley Banks, The Common Infectious Diseases; A Handbook for Students and Postgraduates, Edward Arnold & Co., London, 1949.

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