There is no greater proximate factor in susceptibility to infectious disease than nutritional status. Thus, in relapsing fever, his example, mortality increases by 12-fold, ceteris paribus, in a situation of famine (The Cambridge World History of Human Disease, ed K Kiple, Cambridge University Press, 1993).
Byron avers that action by health workers during the famine was futile because the disease vector had not been discovered. I draw his attention to the Austrian cordons sanitaires of the 18th century, which prevented the incursion of the third plague cycle into Europe. Closer to home, look no further than the famous Broad Street pump in London, which John Snow had removed in 1855 to halt a cholera epidemic - 30 years before the cholera bacillus was identified.
Dr NANU GREWAL
Oriel College, Oxford