Measles infections are not localised to particular risk groups or geographical areas - and occur anywhere in South Africa. Cases can be found in communities or in institutions like crèches or day care centres. 

Adult travellers who have not been vaccinated in childhood are also at risk of measles when visiting areas where measles cases have been reported, or where measles is relatively common. 

When many measles cases occur in a specified area over a short period of time (three or more cases in a health district within four weeks), this is called an outbreak and public health interventions are required to control the spread of the disease.