"For the most part I don't think they should be overly worried but they should be cautious about travelling to countries that have got Ebola.
"If they do travel to countries that have got Ebola, or for whatever reason they seriously believe they have been in contact with someone that has got that disease, then they should report to authorities straight away."
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Mr Key said health authorities would continue to monitor the situation, which he said had become a "more significant issue" given recent developments.
"We have facilities on stand-by around the country, and if the situation worsens, or we are more likely to be affected by it, then we will take further steps."
Director of Public Health Dr Darren Hunt earlier said an expert advisory group had been set up to ensure New Zealand was as prepared for the virus as possible, but the Ministry of Health assessed the risk of Ebola arriving in the country remained very low.
The Ebola virus. Image / CDC/AP
A hazmat team arrives at the infected nurse's apartment. Photo / AP
On average, less than one person a day arrived in the country after having been in an Ebola-affected country, compared with more than 30 per day entering the UK, he said.
There were also no direct flights between the affected countries and New Zealand.
The Ministry of Foreign Affairs and Trade confirmed 47 New Zealanders were registered as being in Ebola-affected countries - 35 in Nigeria, six in Sierra Leone, three in Senegal, two in Liberia and one in Guinea.
Dr Hunt had described Ebola as "not easy to catch", with infection requiring direct contact with infected body fluids such as blood or heavily contaminated objects.
The ministry was closely monitoring advice from the World Health Organisation, and existing isolation facilities and infection control protocols in New Zealand hospitals were suitable for managing a suspected or confirmed case.
Middlemore, Wellington and Christchurch Hospitals have all been designated as receiving hospitals for any patient suspected to be carrying the virus.
Healthcare workers wear protective gear before entering into an Ebola treatment centre in Sierra Leone. Photo / AP
- AP