Summary to Section 2
In Session 2 you have been introduced to the concept of the scientific method and should now appreciate how useful it has been in combating infectious disease. The power of using systematic observation to identify correlations and develop testable hypotheses is well illustrated by the story of John Snow and the 1854 cholera outbreak in London. This example also underlines the terrible effect of pollution on human health – in particular as a cause of water-borne infectious diseases – and the utility of concerted public health campaigns.
Through a second historical tale, the example of Edward Jenner and smallpox, you have also learned about vaccination and its capacity to fight infectious disease. As we have described, the success of vaccination against smallpox has been absolute and the WHO have declared smallpox to be globally eradicated.
However, the war against infectious disease is far from over. Although effective vaccines now exist against diphtheria, measles, polio and several other infectious diseases, current vaccines against some others, including cholera, are only weakly effective or short-lasting. In 2015, there were still no effective vaccines against several life-threatening infections, including HIV/AIDS, but a vaccine against malaria was looking promising and the first Ebola vaccine proved highly effective in initial trials (Henao-Restrepo et al., 2015). Another problem is illustrated by influenza viruses, which change their structural features so rapidly that this year’s flu vaccine may not give protection against the viruses in circulation next year. And as you have learned, although entirely preventable, pollution remains a major source of water-borne infectious diseases in much of the developing world today. Thus, effective strategies to combat infectious disease remain as relevant today as in Jenner’s era.
You can now go to Session 3.