1.5 Summary of Section 1

• Smallpox, caused by the variola virus, was one of the great pandemic infectious diseases for more than 10,000 years, killing a high proportion of infected people and changing the course of history.

• Variolation in the seventeenth and eighteenth centuries used material from ‘mild’ smallpox cases to infect healthy people, most of whom developed protective immunity, but there was a 2–3 per cent death rate.

• In 1796 Edward Jenner began experiments that led to widespread vaccination with cowpox virus (vaccinia), which elicits antibodies that cross-react with variola and protect against smallpox. By 1980, vaccination had eradicated smallpox globally.

• Since 2001, the costs and benefits of reintroducing smallpox vaccination have been debated in response to the possible threat of bioterrorism.

Find out more about polio by reading the Case Study below, where we discuss the biology and epidemiology of polio and reflect on the global vaccination programme, which aimed to eradicate it from the world by 2005. You should allow around three hours for this, including some time for exploration of WHO and UNICEF websites, which publish regularly updated information on the progress of the polio eradication campaign. There is also an optional visit to a website on the social history of polio epidemics in the USA in the twentieth century.

Click to view the Polio Case Study [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] .