Figure 7:

Relapsing fever. A standard reference was Otto Frentzel, ‘Zur Kenntnis des Fieberganges bei Influenza’, Centralblatt fur klinische Medicin (11 January 1890), who characterised three types of fever epidemic in the Municipal General Hospital at Friedrichshain. Type II, shown here, was a relapsing fever that could last for a week, with significant temperature fluctuations, in which the patient might appear to recover, only for the fever to return. Source: J.W.S. Moore, ‘Influenza’, in J.W. Ballantyne (ed.), Encyclopaedia Medica (Edinburgh: Green & Son, 1919), 517