Much of the collection is made up of diaries and notebooks relating to expeditions sent to Africa by the Liverpool School of Tropical Medicine to study diseases such as malaria and trypanosomiasis. From Todd's subsequent career there is also material on journeys to Western Canada to study Swamp Fever in horses and to Poland to study Typhus, some general notes on tropical diseases, a laboratory notebook on experiments with fever ticks and a paper on the Congo Free State as a political unit. The dates covered are 1901-1920. A final block of material consists of letters and loose papers including sketches, covering 1890-1949.