(Abandoned smallpox hospital. Photo credit: reivax)

This is a round one post in the ongoing tournament of pandemics.

Smallpox

Smallpox is eradicated, and has been for almost 30 years, so we can forget about it. Next!

Or can we?

Smallpox is a viral disease caused by the Variola virus, whose floral-sounding name covers a multitude of sins: ranging from a nasty body rash and high fever, to extensive internal bleeding. Case fatality rate is around 30%, and we still don't know for certain what is actually the mechanism causing death. Smallpox has been a historical pivot, at various times killing reigning monarchs (for an interesting view on smallpox' historical influence, read Hopkins (2002)).

Smallpox is the only example of an infectious disease that has been eradicated by human effort, and is often cited as an example for other, similar efforts (e.g. to eradicate polio), usually ignoring a host of important differences between the disease to be eradicated and its environment on the one hand, and those of smallpox in the 1960s and 1970s on the other. And in fact, one can wonder whether it really has been eradicated...

There are currently two known stocks of smallpox virus, one in the USA and one in Russia. Both are ostensibly kept (on recommendation of the WHO, after repeated changes of its position) as a safeguard so new vaccines can be made if an outbreak would ever again occur. However, there are concerns that these, and possibly other, unknown stockpiles, could also be used to develop weaponized versions of the virus. In fact, smallpox is the only human disease that has ever been successfully used as a biological weapon.

It might be telling that one of the very few countries in the world that offers (voluntary) routine smallpox vaccination, is also the only country that has been in a continuous state of war since its inception, 60 years ago: Israel. As almost nobody in the world now has any immunity against the disease, an intentional release would probably be disastrous and could lead to a pandemic that would be unprecedented in human history. That is a big ‘if', though: any country that would want to use smallpox as a weapon would first have to immunise its own population, something that would not go unnoticed.

This leaves the only possible source: terrorism. How likely is it for a terrorist group to get its hands on a viable batch of smallpox virus? Not very, but not totally impossible either. I think (and fervently hope and pray) that we have seen the last of smallpox, but sadly I cannot totally ignore the possibility.

High noon

So which will it be: move-at-a-snail's-pace (literally) schistosomiasis (or as one of my former colleagues endearingly calls it: schizosomiasis)? Or flashy-but-hopefully-eradicated smallpox?

Neither are very strong candidates, but because of its fatality, its infectiousness, and the potential for biological warfare, my money is on smallpox. However, I fully expect it to be knocked out in the next round. At least, I hope so.

Some further reading

Hopkins, D. R. (2002). The Greatest Killer: Smallpox in History, with a New Introduction. Chicago: University of Chicago Press.

Molyneux, D. H. (Ed.). (n.d.). Control of Human Parasitic Diseases. Advances in Parasitology. Amsterdam: Elsevier.

Razzell, P. E. (2003). The Conquest of Smallpox: The Impact of Inoculation on Smallpox Mortality in Eighteenth Century Britain (2nd ed.). Firle: Caliban Books.

Secor, W. E., & Colley, D. G. (Eds.). (2005). Schistosomiasis. World Class Parasites (Vols. 1-11, Vol. 10). Springer Science + Business Media.