South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde
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A summary of the literature shows that there are well-marked seasonal variations in mortality for total deaths, for respiratory and cardiovascular diseases and for diabetes, the mortality rate being higher in winter than in summer. These seasonal variations in mortality are seen in infants under 1 year of age and in older people but not in youths and young adults. The amplitude of the seasonal variation in mortality increases with increasing age because of the higher incidence of cardiovascular and respiratory mortality in older people. ⋯ Comparison was made of the seasonal variations in mortality rates for all causes of death and for respiratory and ischaemic heart disease (IHD) deaths of Whites over 40 years of age in Durban and Johannesburg. This showed that the seasonal variation for all causes of death is greater in Johannesburg than in Durban, i.e. proportionately more older Whites die during winter in Johannesburg than in Durban. The reason for this difference is that the seasonal variation in respiratory disease mortality is much greater in Johannesburg than it is in Durban, but the seasonal variation in IHD mortality is the same in the two cities.