Strict infection control has been put in place at the Hawke's Bay Hospital after a norovirus outbreak.
Seven patients and 30 hospital staff are thought to have the highly contagious vomiting and diarrhoea bug.
Control measures were in place in some of the hospital wards to prevent the spread of the bug.
Chief Medical and Dental Officer John Gommans said norovirus was circulating in the community and infected patients had been admitted to hospital, affecting some hospital staff.
Dr Gommans said hospital visitors were reminded that they should stay away from visiting family or friends in hospital if they are sick.
"If you are unwell with vomiting and diarrhoea or have been around people who have been unwell - please do not visit the hospital for at least 48 hours."
Visitors would also find that some wards were closed to new admissions, and visiting would be restricted and only allowed in exceptional circumstances to some areas of the hospital.
"The infection control measure we have put in place should contain any spread through the hospital, but as it is highly contagious we are being very vigilant, and will isolate other areas of the hospital to visitors if we have to," Dr Gommans said.
Medical Officer of Health Nick Jones said it was likely the bug was circulating in the community.
"To help prevent the spread of the virus it was very important for anyone with nausea, vomiting, diarrhoea, stomach cramps to stay away from work for 48 hours after symptoms disappear.
He said sick children should also be kept away from school for the same period of time, he said.
It was advised if symptoms didn't get better, or if people were becoming dehydrated, that they seek medical attention and phone ahead to your general practice clinic for advice if you become concerned.
Dr Jones said anyone attending the Hawke's Bay show this week, should also be mindful norovirus was circulating and wash hands thoroughly before eating food, and be very thorough with hand washing after using public toilets.
Good hand cleaning is washing hands often with soap and warm water for at least 20 seconds before drying thoroughly.