The Australian Red Cross Blood Service has announced it will not take blood from those who have been diagnosed with Chronic Fatigue Syndrome (CFS).
This follows recent research, describing a possible link between chronic fatigue, and a retrovirus called Xenotropic Murine leukaemia virus-related Virus (XMRV).
As the Blood Service currently defers donors who have CFS, this change will delay their return to donating until there is more scientific literature on the possible viral link.
The society said that its priority was the safety of Australia's blood supply.
Blood Service specialist, Dr Tony Keller, said eligibility to donate is always a balance between risk and benefit.
"There is at present no test available for CFS or XMRV, but our donor questionnaire alerts us when someone has CFS. Very few donors will be affected by this decision," Dr Keller said.
"The science on this internationally is unclear. The recent North American research findings haven't been supported by research undertaken in Europe, and there is currently no Australian research on XMRV.
"We will review our decision in two years time, when further studies into the virus have been done."
The Blood Service currently has 570,000 donors a year. Dr Keller said the Red Cross would write to their "very few" active donors who had recovered from CFS to explain the changes.
Before the moratorium, Australians with a history of CFS were able to donate blood as long as they had recovered and they had a letter from their GP confirming this.
Only those with active CFS were turned away. Dr Keller said this accounted for about 70 intending donors in the past two years.
Earlier this month, Canadian authorities placed a total ban on taking blood donations from people with a history of CFS.
XMRV (Xenotropic murine leukaemia virus-related virus) was first detected in prostate tumours in 2006, and a US study late last year found it was commonly detected in blood taken from people with CFS.
The study took in blood samples from 101 people with CFS and 95 per cent showed evidence of XMRV infection, though subsequent studies have not produced the same results, AAP reported.