A fourth case of measles in Northland has health officials urging people to ensure their immunisation against the disease is up to date.
Measles is spreading around the North Island, after an outbreak in the Waikato from people attending the national kapa haka competition in Hamilton on April 16.
The first case in Northland was reported at the start of the month in Kaeo, in a person who had attended the kapa haka competition.
Northland DHB Medical Officer of Health Clair Mills said the three siblings of that first Northland case had now contracted measles and there was one case still being investigated. "And further cases are expected."
Dr Mills said the fact it was the siblings infected showed just how contagious measles is and advised Northlanders to ensure their families were protected.
"Given these cases and the bigger outbreak in the Waikato region occurring now, it is very possible that we will see this outbreak extend across Northland."
Measles is spread by tiny droplets in the air and is very infectious. The first symptoms, fever, cough, runny nose and red eyes, can be mistaken for a cold, with the rash appearing on the face and neck and spreading over the body three to five days later.
"Measles can be a very serious illness, with one in three sufferers experiencing complications such as ear infections, pneumonia, bronchitis or diarrhoea," said Dr Mills.
"While one in 10 on average requires hospitalisation, admission rates in recent New Zealand outbreaks have been even higher. This is an avoidable disease where there is an effective vaccine. Immunisation protects not only the individual, but also stops the spread of this disease."
Dr Mills said vaccination rates were around 90 per cent in Northland for children under 2, but coverage in the past was significantly lower, and many older children would be at risk as they were not vaccinated as infants.