An Auckland hospital affected by an increase in the number of norovirus cases is confident the situation is under control.
Middlemore Hospital in south Auckland has isolated 18 patients and a number of staff have been affected.
At Tauranga Hospital, four wards are being closely monitored and 22 patients have taken ill from the virus.
Middlemore Central manager Dorothy McKeen said norovirus is very contagious.
She said people need to wash their hands to make sure they are not picking up or passing on the virus.
McKeen said anyone who has suffered from recent diarrhoea or vomiting should not be visiting the hospital.
Norovirus causes nausea, abdominal pain, vomiting and diarrhoea.