The fourth confirmed case and the probable case were confirmed on April 2 after two people returned from the Philippines on March 19 and flew to Whanganui the following day.
On April 3, two more confirmed cases were found in the region, a couple in the Ruapehu District.
The couple arrived in Auckland from the UK on March 24 and drove to the Ruapehu District the next day.
But by April 16, all confirmed seven cases had recovered.
A day later on April 17, the Ministry of Health confirmed another case of Covid-19 in the Whanganui region to be a person aged 20-29.
This person, who lives in the Whanganui District, had not travelled overseas and had no known link to the seven other cases in the region.
The source for this infection is still under investigation.
On April 22, the Ministry of Health confirmed another probable case of Covid-19 in the Whanganui region, bringing the total to nine confirmed and probable cases.
The latest case lives in the Whanganui district and is a family member of the confirmed case reported on Friday, April 17.
O'Connor said the latest case is classed as probable because the swab result was inconclusive and there has been close household contact with a confirmed case but further tests are awaited.
None of the nine cases have needed to be hospitalised and the Whanganui DHB have confirmed all cases have been following the self-isolation restrictions.