The diseases that most affect the inhabitants of Ibadan are malaria, pneumonia, tuberculosis, chickenpox, measles, malnutrition, anaemia, eye disease and hypertension. Viral-parasitic diseases occur widely in the modern section of the city, while in the older districts diseases which stem from ignorance and poverty predominate. The most vulnerable age-groups are 0–9 and 20–49 years, with the older districts recording the highest proportions of sick children. Those in the low-income groups and the muslims suffer most from the diseases which are associated with ignorance and poverty. Socio-economic factors such as age-group, occupation, religion, and population and accomodation densities are significant in determining intra-city variations in sickness levels. However, the precise role of these factors is difficult to establish since major variations in access to and use of modern medical facilities occur between the modern and older sections of the city.