Many countries have reciprocal health arrangements with Britain under which British visitors may receive emergency treatment free or at reduced cost. Information about these arrangements is available from any local DSS office. General and specific advice for travellers on such matters as immunizations needed can be obtained from their general practitioner, through travel agents or one of the high street travel ‘health shops’. Travellers are advised to consult a doctor if they develop an illness after an overseas visit: some tropical disorders may take days or even weeks to produce symptoms.