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West Nile Virus & Organ Transplants #2
Date:
Wed, 4 Sept 2002
Posted by:
Lois Levitan (lcl3@cornell.edu)
1) Latest information re: organ transplants and WNV
2) Correction to estimate in Sept 3 WESTNILEVIRUS-L posting re: estimating WNV cases due to organ transplant/blood transfusion
(1)
Additional evidence is firming up the case that WNV can be transmitted via organ transplant: Three of the 4 people who received organs from a single donor with asymptomatic WNV are now WNV-positive. The possibility that all 3 became infected from mosquito bites is very small, especially since one of the patients had been hospitalized for longer than the typical 3-14 day WNV incubation period. It is still not known if the organ donor became infected via a mosquito bite or as result of blood transfusion from an infected person. For details see the following article from the NY Times, September 4, 2002:
TRANSPLANTS SEEM SOURCE of WEST NILE VIRUS CASES Lawrence K. Altman
Three of the four recipients of organs from a single donor who had West Nile virus also developed West Nile encephalitis, strengthening the possibility that the virus can be transmitted through organ transplants or blood, federal health officials said last night.
Test findings from the fourth recipient, a 71-year-old woman in Florida, are not ready, the officials said in a news conference. The woman is recovering at home from a fever and mild illness that she developed after the transplant.
Tests performed over the weekend and yesterday provide "clear evidence that the organ transplant appears to be the source" of the West Nile encephalitis in the three recipients, said Dr. James M. Hughes, a top official of the Centers for Disease Control and Prevention in Atlanta.
But the new tests do not necessarily prove that the three patients acquired West Nile encephalitis from the organ transplants. Because the three recipients lived in Georgia and Florida, where infected mosquitoes have transmitted the virus to humans and birds, a remote possibility exists that all three acquired the West Nile virus through insect bites.
It is also unknown how the organ donor, a woman who died of complications from an automobile crash in Georgia, acquired the West Nile virus. She was not known to be ill before the crash, Dr. Hughes said.
The possibilities are that she acquired the virus either from a mosquito bite or from the many blood transfusions she received after the accident, Dr. Hughes said.
Detection last week of West Nile virus in one of the transplant recipients, a 63-year-old resident of Miami-Dade County, Fla., set off an intensive epidemiologic and laboratory investigation involving several dozen health officials in Florida, Georgia and the federal government.
Health officials said they were being aggressive in their investigation because of concern that the virus, which was first detected in this hemisphere in New York City in 1999, could be transmitted through a new route - organ transplants or blood. Because transplanted organs also contain some of the donor's blood, health officials said it may be impossible to determine whether the virus was present in only the organ or only the blood, or both.
Federal health officials are preparing to notify organ procurement agencies of the new developments and to maintain awareness of the possibility of West Nile virus transmission. But they said they were not prepared to recommend any new procedures at this time.
Dr. Jesse Goodman, an official of the Food and Drug Administration, the federal agency that regulates tests performed in blood banks and organ transplant centers, said that the government would not stop transfusions because of the theoretical possibility of transmission of West Nile virus.
Doing so, Dr. Goodman said, "would create a humongous shortage of blood in this country," and could hurt more people than it would help. The investigation is focusing on the blood that the organ donor received and other patients who received blood from the blood donors.
The organ donor was critically injured in an automobile accident and received blood and blood products donated by more than 60 people, Dr. Hughes said. Epidemiologists are trying to detect West Nile virus in the small portion of blood that is routinely kept after each blood transfusion.
Blood from the more than 60 donors has been given to about a dozen patients, Dr. Hughes said.
As a precaution, health officials said they have ordered a hold on any blood from the donors that has not been given to recipients.
In addition, epidemiologists are seeking to interview the blood donors and recipients of their blood. Health officials would also like to test them for the West Nile virus.
Detection of West Nile virus in anyone who donated blood to the organ donor would provide epidemiologic evidence that the virus was transmitted to the organ donor from a transfusion.
If no West Nile virus is found in tests of every blood donor and recipient, then scientists might presume that the organ donor was infected from a mosquito bite.
But if one or more blood donors are not tested, the source of the organ donor's West Nile virus might remain a puzzle.
Dr. Hughes said he expected that it would take two weeks or so to complete all the tests and interviews and to analyze the pertinent data.
Publicity and alerts to health departments over the weekend have not turned up any new suspect or confirmed cases of West Nile virus from organ transplants or blood transfusions, Dr. Hughes said.
Meanwhile, health officials moved to reassure the public about the relative safety of the blood supply. But they repeated their concern about the lack of a rapid test to screen donated blood for the West Nile virus.
It will take months at least to conduct the research to develop a reliable screening test, they said.
Because the government has been concerned about the theoretical risk of transmitting West Nile virus through blood transfusions, about two weeks ago health officials reminded blood banks to adhere to their usual standards to reject would-be donors who had a fever or an infection.
Dr. Goodman said he was not aware that blood centers had conducted research to randomly test donated blood for the West Nile virus. A concern is that most people infected with West Nile virus have no symptoms but could have the virus in their blood when they donate. But unlike H.I.V. and hepatitis, West Nile virus is an acute infectious disease and chronic carriers have not been detected, Dr. Goodman said.
Copyright 2002 The New York Times Company
(2)
Correction to estimate in Sept 3 WESTNILEVIRUS-L posting re: estimating WNV
cases due to organ transplant/blood transfusion:
The term "additional cases" was used, but in actuality these would not be "additional cases" of infection or disease, but would be cases now attributable to organ transplant/blood transfusion rather than to mosquito bites as the source of infection. Revised text follows:
Labor Day Weekend 1999 brought first news of West Nile Virus in the Americas.
Labor Day Weekend 2002 brings news of another risk related to WNV, with the as-yet-unconfirmed evidence that the virus can be transmitted via organ transplant or possibly by blood transfusion from an infected person. While this speculation adds a wrinkle to the set of assumptions about disease transmission, it should be noted that even if confirmed, the general population is at no greater risk of contracting WNV than previously thought.
The news about the potential for transmitting WNV via organ transplant does make us aware that a sub-population of people about to undergo high risk organ transplants and/or receive blood transfusions may be at still greater health risk because (a) it is difficult to know whether a donor has WNV circulating in their blood system and (b) transplant patients are given immune suppressing drugs to prevent rejection of the donated organ. The immune-suppressed are more vulnerable to WNV infection and serious illness. However CDC health officials point out that the additional risk of contracting WNV is quite small in comparison with the much larger risks from these medical procedures.
In the Sept 2 NYTimes article on this subject, CDC and FDA officials are said to have calculated the risk of transmitting WNV through blood transfusions in the range of 1 to 2 cases per 10,000 transfusions. With about 13 million units of blood collected each year in the US, this implies that 1300 - 2600 infections per year could be transmitted via blood transfusions, if this is shown to be a viable means of transmission. Although rates of serious illness and death would likely be higher in this subpopulation than among the general public, we can perhaps calculate a ballpark estimate of the number of serious illnesses and fatalities attributable to receipt of infected blood by looking at data from previous years when about 1 infected person in 150 developed serious illness, and about 12% of those died: Thus one might expect at least 9 - 17 cases of WNV encephalitis per year in the US could be attributed to blood transfusion from a donor infected with WNV.
-- Lois Levitan, PhD Program Leader Environmental Risk Analysis Program Center for the Environment 213 Rice Hall, Cornell University Ithaca, New York USA 14853-5601 Phone: (607) 255-4765 Fax: (607) 255-0238 Email: LCL3@cornell.edu Program Email: envrisk@cornell.edu Web:http://www.cfe.cornell.edu/ERAP
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