A third plague struck large parts of the world, including Johannesburg in 1904 where Lord Alfred Milner moved black inhabitants and burned down their residential area. Elmien Wood then discussed the Great Flu of 1918, which claimed millions of lives worldwide.
Indications are that the largest number of deaths in the concentration camps during the Anglo-Boer War were due to measles and not poor sanitation as claimed. As early as 1854, John Snow realised that cholera in London was due to poor sanitation. This reaffirms the value of human behaviour, especially non-pharmacological intervention, in preventing infection, as for the Covid-19 pandemic.