A national outbreak of whooping cough has been declared by the Ministry of Health, with 1315 cases reported since the beginning of the year.

The Ministry is encouraging people to be extra vigilant as they gather for Christmas and New Year celebrations, in order to protect young babies from the highly contagious illness.

Director of Public Health Dr Caroline McElnay says anyone with coughs should be especially careful if they are likely to come in to contact with babies.

She says most adults don't realise they have whooping cough, but it is incredibly contagious.