Questions related to West Nile Virus Infections in Organ Transplant
Recipients --- New York and Pennsylvania, August--September,
2005. MMWR Dispatch, October 5, 2005
Q. How were these cases identified?
A.After unexplained neurological illnesses occurred in two organ recipients from one donor, serum and plasma collected from the donor were retrieved and tested. The samples tested positive for WNV IgM and IgG antibodies, but were negative for WNV RNA by PCR.
Q: How was the organ donor infected?
A. It is likely that the organ
donor was infected by the bite of an infected mosquito, as he
was reported to have spent time outdoors and infected
mosquitoes were collected from a site near the person’s home
approximately 10 days before he died.
Q.What is the current protocol for testing donors or organs before a transplant is conducted?
A. Organ donors are screened to identify infectious risks on the basis of national organ-procurement standards. Screening of all organ donors with WNV NAT is not currently required or routinely performed due to:
(1) the length of turnaround time to obtain WNV NAT testing, and
the unproven test performance in the organ-donation setting. National guidelines for organ-donor screening are continuously reevaluated by the Health Resources and Services Administration in consultation with FDA, CDC, and organ-procurement organizations.
agencies regulate transplant and blood issues?
A. The US Health Resources and Services Administration (HRSA) and
Centers for Medicare and Medicaid Services (CMS) have
oversight over organ procurement and transplantation, while
the Food and Drug Administration (FDA) regulates tissue and
Q. You have stated that the system of
testing donated blood for WNV by nucleic acid-amplification
test (NAT) has markedly reduced the risk of transfusion
transmission. How is the testing of organs before
A. There are several
issues to consider: (a) time, (b) type of test and (c)
potential biological differences.
(a) Time is a critical factor in organ donation; one
analysis suggested that WNV NAT screening might result in a
net loss of years of life among certain types of potential
transplant recipients because screening might exclude healthy
donors from an already limited donor pool. The time pressure
to test and process donated blood is not as extreme.
(b) Additionally, NAT has not yet been proven as an
effective test in the organ-donation setting—it is not known
at this time that it would prove as useful as it has in
identifying blood donations that pose a risk.
has been learned through limited retrospective studies that
transfused viremic donations did not transmit WNV infection if
IgM antibody was present, and investigation of all 30 cases of
WNV transmitted by blood transfusion documented to date
indicated that the donors’ viremias can be of low titer and
that all resulted from IgM antibody-negative donations. This
instance of organ-transplant-associated WNV transmission
suggests that transmission through solid organ transplantation
can occur from donors with IgM and IgG antibodies and without
detectable nucleic acid by PCR in their serum. Experimental
evidence in humans and animals suggests that WNV might persist
in organs after clearance of viremia (e.g.., when virus is no
longer circulating in the bloodstream.) This would present a
different scenario, requiring different testing, than the case
of NAT testing of donated blood.
Q. Is there
testing available that would have been able to identify the
risk of WNV infection before the organs were transplanted?
A. It is currently unknown whether NAT would have
detected West Nile virus in this donor.
What will be done to follow up these cases, and to reduce
the risk of WNV infection through transplanted organs
in the future?
A. Clinicians should be aware that transplant-associated
infectious disease transmission can occur and should be
vigilant for unexpected outcomes in transplant recipients,
particularly when they occur in clusters.
Cases of suspected WNV infection through organ transplant
should be reported promptly to local and state health
departments and CDC.
We will continue the evaluation of the blood donor to
the organ donor to look for evidence of WNV infection,
and the evaluation of the organ donor serum. When done
with our investigation, HRSA, CMS, FDA, CDC, state and
city authorities and organ procurement organizations will
be working together closely to see if evidence in these
cases might be used to develop protocols to reduce risks
of WNV infection associated with transplanted organs.
Q. What type of treatment is being given to the
organ recipients? Is that treatment available to other
people with WNV disease?
A. The organ recipients were treated with Omr-IgG-am,
an intravenous immunoglobulin product with high-titered
neutralizing antibody to WNV available through a Food
and Drug Administration (FDA)-approved IND compassionate
release protocol. No proven effective treatment or prophylaxis
for WNV infection exists; a randomized placebo-controlled,
double-blind trial of Omr-IgG-am is underway, and more
information on participation can be obtained at http://www.clinicaltrials.gov/show/NCT00068055
Information on other randomized placebo-controlled, double-blind
trials for WNV infection is also available at http://www.cdc.gov/ncidod/dvbid/westnile/clinicalTrials.htm
If I recently had a transfusion or transplant, should
I be concerned about getting West Nile virus?
A. You should be aware of the potential
risk for West Nile virus infection and the need to monitor
your health. If you have symptoms of West Nile virus or
other concerns you should contact your physician. If a
patient who recently received a blood transfusion or organ
transplantation develops a West Nile virus infection,
that does not necessarily mean that the transfusion/transplantation
was the source of infection.
to donated organs, and the use of screening and diagnostic
tests for West Nile virus was issued January 9, 2004 and
is posted on the website of the Organ Procurement and Transplantation Network.