It has already claimed a number of lives in Ireland and is said to be the worst outbreak in 50 years.
The MMA champ said on Instagram that he had been ‘shaking in bed for the next last few days’ and that half his family had been struck down by the virus, medically known as strain H3N2.
Conor, 29, added: ‘Well that was a wild New Year’s Eve. Half the family hit with the Australian flu virus and some even left in hospital with it. I’ve never even been to Australia wtf.’
‘Big New Year’s Eve party cancelled at the last minute and I am left shaking in bed the past two days.
‘I’ll leave that with the rest of the bad behind me in 2017 and take with me the many great experiences I’ve had this year!
‘None greater than the birth of my son Conor Jr and the continued support of my family, my friends and my dedicated staff through thick and thin.’
On Christmas Eve, Conor, who is based in Dublin, shared a cute picture of his partner Dee and his baby son, Conor Jr. in matching festive onesies.
The virus has claimed the lives of ‘under 10’ people in Ireland so far, though doctors have refused to reveal an exact figure.
Dr Kevin Kelleher, from the Irish Health Protection department, said: ‘There have been a few deaths already, under 10 people have died so far this year.
‘I don’t give specific numbers when it’s less than 10 because people could be identified.’
Meanwhile, figures released by Public Health England show a sharp rise in cases, triggered by a surge in two aggressive subtypes attacking the population simultaneously.
Experts fear the virulent flu strain, which has now reached the UK, could prove as deadly as the Hong Kong flu in 1968, which killed one million people.