There is at least one case of tuberculosis, known as TB, in the Spring Hill prison in North Waikato, and a prison officers' union says it is unhappy at a lack of communications from Corrections.
Spring Hill Prison director Megan Tuhoro said the secure and controlled nature of the prison environment meant they were able to quickly isolate the unwell prisoner.
She said they were following the advice of Waikato District Health Board's Public Health Service, and there was no risk to any other prisoners or staff at this stage.
However, the union representing prison officers said it was unhappy with the lack of communication from the Corrections Department.
Corrections Association President Allan Whitley said the union only heard about the case at Spring Hill after it was contacted by RNZ.
He said it was important prison officers know straight away when an inmate was unwell, so all measures could be taken to avoid passing it on.
"Unfortunately, medical information is not readily given out to staff, and it's a concern of ours that somebody comes in with something transferrable via the atmosphere, and we don't know about it until we find out."
The prisoner arrived into prison on 31 August, during Covid-19 alert level 2 restrictions, and was admitted to Waikato Hospital 18 days after arriving at the prison.
He is now back in the prison in a stable condition and is receiving medical care while in isolation.
Tuhoro said all newly received prisoners were managed together in a separation unit for their first 14 days in custody, and all prison staff wore masks while working in this unit.
Tuberculosis is an infectious bacterial disease which can become serious. People can have the disease with no symptoms, and can carry it for some time before they become symptomatic. It generally affects the lungs, but can also affect other parts of the body.
The World Health Organisation said the level of TB in prisons has been reported to be up to 100 times higher than that of the civilian population.
It believes cases of TB in prisons may account for up to 25 percent of a country's burden of TB.
Corrections says the prisoner had an initial health assessment on 1 September with no respiratory symptoms raised or observed.
On 18 September he was seen by health services and raised concerns about symptoms he was experiencing, and was taken to hospital.
He returned on 28 September and is being cared for in a single cell in a separation unit, and all staff working with him are wearing PPE.
Tuhoro said a health and safety review is underway.
The case was initially announced by the Corrections Association. The Waikato DHB has been approached for comment.
The Corrections department have a joint management plan with the Ministry of Health to manage TB outbreaks in prisons.
The Ministry of Health's website says there are typically about 300 cases of TB diagnosed in the country each year, and New Zealand is classified as a low incidence country for the disease.