An outbreak of typhoid in Auckland has seen 10 people hospitalised.
The Auckland Regional Public Health Service (ARPHS) is tracing people who have been in contact with the confirmed cases.
In a statement it said it is following usual protocols to control the spread of the disease.
Medical Officer of Health Dr David Sinclair said typhoid is spread primarily through water and food but can be spread person to person.
He added good basic hand-washing is one of the best means of protection.
Symptoms include a high fever developing over several days, headaches, general weakness and muscle aches.
Stomach pain and constipation are also common but some people get diarrhoea.
It can be a serious illness and is potentially fatal but it can be treated with antibiotics.
ARPHS has alerted the health sector to the outbreak. Dr Sinclair urges anyone with those symptoms feeling very unwell to see their doctor or an after-hours clinic.