Potential concerns for simian foamy virus (SFV) transmission by blood and blood products

1
Potential concerns for simian foamy virus (SFV)
transmission by blood and blood products

• Hira Nakhasi, Ph.D.
• DETTD/OBRR/CBER/FDA
• BPAC, December 13, 2001

2
Potential concerns for simian foamy virus (SFV)
transmission by blood and blood products

• Issue
• FDA seeks advice on its approach to assessing the
  possible transfusion risk from SFV

3
Background Information

• Infections in Primates
• Simian Foamy viruses (SFV) belong to retroviridae
  family.
• Prevalence of SFV infection in wild animals is
  high
• Seroprevalence higher in captive vs wild
  animals..
• Precise mode of transmission is not clear
  transmission by saliva is indicated in animals.
• Virus has been isolated from various organs of
  infected animals, but without evidence of
  pathology.

4
Background Information

• Infections in humans
• Some human populations in Africa harbor SFV
  infections
• Humans who are occupationally exposed to
  non-human primates can be infected by SFV.
• Association of several diseases in humans with
  SFV infection is tenuous
• Thorough analysis resulted in failure of such an
  association.

5
Current Concerns

• Unlinked CDC serosurvey of North American zoo
  workers identified positive workers
• 4/322 were identified as seropositive for SFV
  originating from chimpanzees all 4 individuals
  handled non-human primates.
• Seropositivity to SFV found in 1.8-3.0 of
  persons occupationally exposed to non-human
  primates
• Unlinked SFV surveillance of non-human primate
  handlers conducted by Health Canada found 2/46
  seroreactive
• 1/46 individual serum sample tested strongly
  positive in SFV western blot (WB) analysis.
• 1/46 serum sample reacted weakly in SFV WB test.

6
Current Concerns.

• SFV has been isolated from human peripheral blood
  lymphocytes of workers exposed to non-human
  primates.
• Look back study by CDC and ARC
• 4 transfused recipients who received blood
  components from one SFV positive donor tested
  negative for SFV 1.5 to 7 years post transfusion.
• Data appear insufficient to exclude risk from
  transfusion

7
Topics to be discussed

• A. Review of SFV biology and pathogenesis. (Arifa
  Khan, FDA)
• B. Review of investigation on human infections
  with SFV and proposed human studies (Louisa
  Chapman, CDC)
• C. Review of risk assessment (Paul Sandstrom,
  Health Canada)
• D. Proposed animal study on SFV transmission by
  blood (Arifa Khan, FDA)

8
Questions for the Committee

• 1. Does the committee agree that the currently
  available data are insufficient to determine
  whether SFV can cause adverse health effects in
  humans?

9
Questions for the Committee cont.....

• 2. Does the committee agree that currently
  available data are insufficient to determine
  whether SFV can be transmitted by blood
  transfusion?

10
Questions for the Committee cont......

• 3. Please comment on the adequacy of the proposed
  studies to evaluate SFV transmission by blood
  transfusion.