Holiday companies cancel trips to Tunisia after 17 foreign tourists killed . Raises possibility terrorists spread to other countries popular with tourists . Brits questioning which destinations are infected by barbaric Islamic State . Travel watchdog ABTA advises consulting Foreign Office before travelling .
Holiday companies cancel trips to Tunisia after 20 foreign tourists killed . Raises possibility terrorists spread to other countries popular with tourists . Brits questioning which destinations are infected by barbaric Islamic State . Travel watchdog ABTA advises consulting Foreign Office before travelling .