Use the official spelling for the names of organisations and programs. It is best to check directly with the organisation itself or its website; check for both spelling and use of a possessive apostrophe. The spelling the organisation uses takes precedence over the entry in the Macquarie dictionary:
World Health Organization [the official spelling used by WHO] not World Health Organisation [given in the Macquarie dictionary]
World Trade Organization Food and Agriculture Organization of the United Nations
All United Nations organisations use this spelling, and also ‘programme’ (eg United Nations Development Programme). But other international organisations may not; always check!
World Organisation for Animal Health (WOAH; previously OIE – Office Internationale des Epizooties)
Centers for Disease Control and Prevention (United States)
National Farmers’ Federation but Victorian Farmers Federation
