A police prosecutor from Christchurch has been diagnosed with measles, and is likely to have infected many other people.
A statement from New Zealand's law society confirmed on Tuesday that the prosecutor is likely to have infected others during the period in which they were contagious, but was unaware they had contracted the disease.
"Any non-immunised, or partially immunised person is at risk of catching the measles should they have had contact with either the prosecutor or any of their contacts," said the statement.
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"The latter will include all prosecutors in the Christchurch district. The extent of other contacts will be extensive and impossible to trace."
The Judiciary, all Ministry of Justice staff, all Police staff, representatives of the profession, and all ancillary agencies who work within the courts have been notified.
Measles is highly infectious - if someone goes within two metres of an infected person while unimmunised, or partially immunised, they have a 90 percent chance of contracting the disease.
The statement advises anyone who begins to experience the early symptoms of measles to isolate themselves pending diagnosis.
Christchurch is currently suffering a shortage of the vaccine for measles, so supplies are being allocated to those most at risk first, the statement said.
"If you are not immunised, or partially immunised, then your GP will have limited supplies of the MMR vaccine available this week but these will be allocated according to those most at risk first.
"It is unlikely there will be sufficient supplies to meet demand."