Smallpox could be the poster disease for exploration. It has crisscrossed continents and voyaged over oceans in company as varied as Islamic expansionists, Crusaders, and the explorers of the 16th-19th centuries.
In the age of exploration, smallpox was endemic to (regularly found in) Europe, and parts of Asia, the Middle East and northern Africa. When the people of these regions began to disperse around the globe, colonizing all the ice-free landmasses they could find, they brought with them an unsavory gift: smallpox. This distasteful offering was arguably the most important weapon in the arsenal of the colonial powers, particularly in their forays into southern Africa, Oceania, and the Americas, where the disease devastated the local, previously unexposed populations. Although it is extremely difficult to estimate the number of deaths related to smallpox alone, there are documented occurrences of smallpox epidemics in these “new” lands with mortality rates ranging from 33% to 100%2.
Thankfully this grisly legacy is not smallpox’s only connection to October’s theme. The pathogen has also served as humanity’s guinea pig, giving us the means to explore countermeasures, and indeed, an ultimate cure.
As early as 1000 CE, there were attempts to combat smallpox through exposure to the variola virus (its cause) or similar viruses. These and subsequent efforts eventually led to the discovery of the first vaccine by Edward Jenner in 1796. The practice of vaccination was rapidly adopted around the globe, paving the way for future innovations and the use of vaccines against other pathogens. The Smallpox Eradication Programme, led by the World Health Organization, marshaled the power of the smallpox vaccine and successfully eliminated the disease in 1980 (officially; the last naturally occurring case actually happened in 1977)1. This remains the only example of total disease eradication.
Cause: Smallpox is caused by infection by the variola virus. The disease is transmitted directly from person to person through prolonged face-to-face contact (I’m fairly certain that’s CDC code for macking it), contact with bodily fluids or contaminated items, such as clothing or bedding. On rare occasions, smallpox has been transmitted through the air in confined spaces. A person is contagious from the time spots appear until all the scabs have fallen off.
Consequence: After an incubation period of 7-17 days, a person with smallpox will get a high fever, and experience flu-like symptoms (fatigue, body aches, and vomiting). A few days later, red spots will appear in the mouth and throat and spread to the rest of the body. The spots will become raised, then fill with opaque liquid and turn into pustules that are hard to the touch. About two weeks after the spots appear, they will scab over and about a week later, the scabs will fall off, leaving pitted scars.
Cure: There is no cure for smallpox once it has been contracted. Prevention is the only treatment, and there is a highly effective vaccine. Let’s hope that things don’t get weird and we never have to use it again.
1. Fenner, F. (1993). Smallpox: Emergence, global spread, and eradication. History and Philosophy of the Life Sciences, 15(3): 397-420.
2. Fenner, F, DA Henderson, I Arita, Z Ježek, & ID Ladnyi. Smallpox and its Eradication. Geneva, World Health Organization, 1988.
3. Smallpox fact sheet: Smallpox disease overview. Centers for Disease Control and Prevention, 30 December 2004. Web. 8 September 2013. http://www.bt.cdc.gov/agent/smallpox/overview/disease-facts.asp
Image source: Creative Commons, https://en.wikipedia.org/wiki/Christian_Radich