It may take a number of days to confirm whether a New Zealand health worker who has just returned from West Africa has Ebola.
The woman returned from helping Ebola patients in West Africa on Wednesday and fell ill yesterday.
She is now in isolation at Christchurch Hospital in a stable condition.
Canterbury's chief medical officer Nigel Miller said even if test results due tomorrow are negative, another test would need to be carried out because early negative results are no indication a person does not have the virus.
He said in the meantime, medical staff helping the woman are taking extra precautions including wearing protective clothing to prevent being touched by any body fluids, the main means of spreading the virus.
Dr Miller said there was always a level of risk working with suspected Ebola cases and he praised staff helping the woman.
The only other person she had been in regular contact with since arriving back in the country was her partner who was said to be self-monitoring his condition.
The illness only becomes contagious once a person shows symptoms.
A Canterbury District Health Board spokesperson said the isolation unit at Christchurch Hospital was the same one they use for people with other infectious diseases such as measles.