CDC Telebriefing Transcript

West Nile Virus Update

September 3, 2002

MS. SWENARSKI: Thank you very much, everyone, for joining us. I apologize for this late notice, but I'm glad you were able to get the advisory and to join us.

We're here to give you an update on CDC's investigation of a West Nile virus case and possible transmission through organ transplantation. Dr. James Hughes will be our main spokesperson, and will make some brief remarks. He's the director of CDC's National Center for Infectious Diseases.

Afterwards, we'll have a Q&A opportunity, and we have several people on the line available to answer questions. Those are Dr. Jesse Goodman of the FDA; William Hobson, from the Health Resources and Services Administration, also part of HHS; Dr. Steven Wiersma, of the Florida Department of Health; and Dr. Susan Lance-Parker, from the Georgia Department of Human Resources.

Dr. Hughes.

DR. HUGHES: Thank you very much, Lisa, and thank all of you for joining us here for this update this evening.

The Centers for Disease Control and Prevention, the Food and Drug Administration, the Health Resources and Services Administration, the Georgia State Department of Health, and the Florida Department of Health continue to investigate possible West Nile virus transmission through organ transplantation. CDC and the Florida Department of Health laboratory have confirmed that three of four persons who received organs from a single donor were infected with the West Nile virus. Those three had encephalitis. One has died, and the other two are recovering in the hospital.

The Florida Department of Health is obtaining samples from the fourth organ recipient
for West Nile virus testing. This person developed a febrile illness after transplantation, and is now recovering at home.

Testing of the organ donor demonstrated evidence of West Nile virus infection from samples taken shortly before death. The means of the donor's infection remains under investigation. It is most likely that the donor became infected with the West Nile virus either through a mosquito bite or via a blood transfusion shortly before organ donation.

As a precaution, remaining blood products from donors of blood given to the organ donor as well as to the organ recipients are being recalled. Donors of blood given to the organ donor are being contacted so testing for West Nile virus can be done. Recipients of blood products from these donors are also being contacted and tested for the West Nile virus.

The CDC, Food and Drug Administration, Georgia and Florida state health departments, Health Resources and Services Administration, and blood collection agencies are working together to identify the source of the organ donor's infection.

Thank you very much. That completes my update. My colleagues and I will be happy to respond to your questions.

MS. SWENARSKI: Okay we're ready for the first question.

AT&T FACILITATOR: First we go to Miriam Falco of CNN.

QUESTION: Hi. Thanks for doing this again. I just want to clarify if I heard it right. Three out of the four people who received organs were indeed infected with West Nile; we've confirmed that?

DR. HUGHES: That's correct.

QUESTION: Okay, one has died, the other two are recovering in the hospital?

DR. HUGHES: That's correct.

QUESTION: And the patient with the fever after transplantation is at home. Did you say that you were sending the stuff to the Florida Department of Health, or where is that patient? That patient is in Florida, right?

DR. HUGHES: That patient is in Florida, and we may want Dr. Wiersma to comment on the specifics of what's being done to further investigate that patient.

QUESTION: Okay, and before we get to that, just one other point of clarification. You have also confirmed that the donor had West Nile?

DR. HUGHES: There is evidence, yes, today that the donor had evidence of West Nile infection that was apparent at the time of organ donation. The question is, of course, how did the donor acquire that infection.

QUESTION: Right. So if the gentleman from the Florida Health Department could answer the question, that would be great. Thank you.

DR. WIERSMA: Sure. The 71-year-old female patient in Florida is being tested by the Florida Department of Health laboratories, and those results are not yet available.

AT&T FACILITATOR: Next we go to Seth Ornstein [sp] with Knight-Ridder. Please go ahead.

QUESTION: Yes, and once again, thank you for doing this. On the how the organ donor got infected, you say it's either a mosquito bite, which is normal, or blood transfusion. I'm wondering how many--when did the donor receive blood, and how many units have you been able to track from there, where the West Nile might have been?

DR. HUGHES: Yes, that's the focus of the active, ongoing investigation. The organ donor was injured in an automobile accident on July 30th, and received a number of blood products over the next two days.

QUESTION: And so I guess the idea is--and then the person died, so do you think--what you're saying is that perhaps the person received donated blood early and then within two days after the person died, the donation was there so it would have been a very quick transmission? And why do you think that it's not--I guess, and why is it not the normal mosquito thing?

DR. HUGHES: Well, I'm not speculating this evening. I'm just giving you the facts as we currently know them. And again, I'll emphasize that this is an ongoing investigation, so the information will continue to accumulate over the next one to two weeks.

You know, again, in terms of how did the donor acquire this West Nile virus infection, the two possibilities are a mosquito bite before the time that the person was injured in the automobile accident, or receipt of a blood product immediately after the injury.

QUESTION: And I guess--okay, I was just trying to figure out why you would go to the blood product instead of the normal mosquito bite.

DR. HUGHES: Well, I think we have to aggressively pursue the possibility that a blood product is responsible for this. I mean, that's the focus of the investigation, to determine whether or not a blood product is involved.

MS. SWENARSKI: Next question, please.

AT&T FACILITATOR: That is from the line of Dierdre Henderson with the Denver Post.

QUESTION: I'm wondering why there's no quick test available for West Nile to screen it out of blood that goes into the blood system. Right now there's a test that, within 24 hours, can alert the blood centers for hepatitis or HIV in a sample, and then that sample isn't used. How long does it take to test for West Nile? Is it close to 24 hours, and how long will it take to get a test close to 24 hours for West Nile?

DR. HUGHES: Okay, let me make several comments on that. First of all, West Nile virus infection is an excellent example of an emerging infectious disease. It was just identified for the first time in the Western Hemisphere there years ago. To date, all confirmed cases of West Nile have been as a result of being bitten by a mosquito. Yes, today we do have tests to screen blood for HIV and for HCD and for a number of other blood-borne pathogens, but it took several years to develop those tests.

There are tests available for diagnosis of West Nile virus infection. They have been evaluated and used for the diagnosis of infection of people with symptoms. So we won't be starting from scratch in looking at tests that could be used to screen the blood supply. But the available tests have really not been evaluated in that context.

MS. SWENARSKI: Next question, please.

AT&T FACILITATOR: That is from the line of Rick Weiss with the Washington Post.

QUESTION: Hi. Two questions. One, is West Nile virus clonally diverse enough so that genotyping could tell you with some assuredness whether the strains in the recipients are, you know, probably came from this donor as opposed to themselves having been bitten by mosquitos; and are you doing those tests? And secondly, how many people are in this dragnet that you've now described with all the recipients of various blood products from all the various--I've heard as many as 37 units were put into this woman, so there's a lot of people potentially that you're looking for right now.

DR. HUGHES: Rick, this is Jim Hughes. Excellent question. First, in terms of the diversity of this virus, it's not diverse at all, unfortunately, so that the molecular typing that we will do, and will do that through sequencing of nucleic acid that we're able to amplify from specimens that we have, we will do that. But we do not anticipate that it will be very helpful in the context of the investigation, because to date all the strains of West Nile that have been looked at in the United States are virtually identical.

In terms of the number of people, that is the focus of the ongoing investigation. And I hesitate to give specific numbers because the other day we did say 37, and now further investigation has actually identified that blood the donor received actually came from as many as slightly over 60 people. So we're--I'm going to stay away from the numbers because they will change.

QUESTION: But each of those 60 people, on average, blood from one person goes to X number of people. Can you give me that average number?

DR. HUGHES: I can't off the top of my head give you that average number, but what I can do is tell that we're working with our partners to identify those blood components and to hold them so that no additional components are administered to patients.

MS. SWENARSKI: Next question, please?

AT&T FACILITATOR: That is from the line of Marilyn Marccion [sp] with the Milwaukee Journal-Sentinel.

QUESTION: Hi. Thank you for doing this. Dr. Hughes, is anything known about how long the virus circulates in blood, and can you say anything about the risk of transmitting through organs versus blood, or any precautions you could take for testing organs right away?

DR. HUGHES: In terms of duration of the virus circulating in blood, what we know is that by the time people who become symptomatic as a result of West Nile virus infection, by the time they're symptomatic, the virus is very, very, very difficult to demonstrate in their blood. So the virus presumably circulates during the incubation period, which is recorded to range anywhere from two to three days on the low end, up to 14 days on this high end.

QUESTION: Okay, a follow-up, then. Does that give you any optimism about a narrow window that you might be able to test for in terms of someone's being able to be a blood donor?

DR. HUGHES: Well, it's important to recognize this in contrast to some of the other viruses that we've talked about earlier--HIV and hepatitis C virus. This is not a chronic infection. This is an acute infection, so that the period of viremia, as we say, would be expected to be relatively brief.

MS. SWENARSKI: Next question, please.

AT&T FACILITATOR: We'll go to A.J. Hostetler with the Richmond Times Dispatch.

QUESTION: Hi, good evening. I understand that a couple of weeks ago the FDA alerted the country's blood banks to the issue of transmission. I also understand that the organ procurement organizations, however, have not heard anything from the FDA or the CDC. Do you have any plans to alert them? And also, if you're telling blood banks to be on the alert for people who are sick with West Nile, doesn't that then allow all those people who are infected but asymptomatic to still get through?

DR. HUGHES: Well, first, let me invite my colleagues from both the FDA and HRSA, who are on the line, the answer your questions. First, maybe, FDA, Dr. Goodman.

DR. GOODMAN: Yeah, I think your question is a very important one, which is can asymptomatic blood donors, during that brief period Dr. Hughes described, potentially transmit virus through the blood supply. And that is a lot of what the intensive investigation of this case is about, and we do have a concern. If that occurs and occurs to a significant degree, then disqualifying donors who are sick or have early signs of infection would not remove those patients from the blood supply. And applying screening, at least to people at potential risk of having --donors at potential risk of being exposed to West Nile would be the logical strategy.

So this is an evolving situation. If blood transmission is confirmed--and, in fact, irregardless--you know, we do want to move toward having the availability of screening if needed. So we can move in that direction if needed.

QUESTION: And my question about the organ procurement organizations, are they going to be alerted?

DR. HUGHES: Sure. Mr. Hobson is on the line. He may wish to speak to that.

MR. HOBSON: Yes, we're preparing a notification to go out to the organ procurement organizations basically asking them to maintain awareness of all of the CDC information, clinical information alerts, all of the FDA clinical information alerts, and what we will be doing is trying to focus their awareness on this problem. At this point in time, it's been outlined. There are no specific changes in procedures that we're ready at this point in time to really recommend with regard to the organ procurement organizations.

DR. GOODMAN: You know, Jim, just to amplify a little there on the testing issue. Again, Jim's point that this is a brief time window, I think does help keep some perspective on the risk; and also the point that in the United States each year there are approximately 4.5 million recipients of blood. And if this turns out to be indeed a case that was transmitted by blood--and we are very concerned about it--but if it turns out, it has to be kept in that perspective of the large number of transfusions that occur. That doesn't mean it's acceptable, but we need to keep the risk in that perspective.

The other point I think Jim partly got at that's important is that some of the technologies that could be brought to bear are technologies now in use in research and public health laboratories, including CDC, that share some elements with what the blood banks and the blood industry have been able to implement for other viruses where there has been a need to detect them in blood screening, so that we would anticipate at least that we have a head start, if needed, in transferring that kind of technology from the research or public health lab to the much larger, potentially more challenging clinical blood banking arena.

QUESTION: Dr. Goodman, are you talking about the nucleic acid testing?

DR. GOODMAN: That would be one example. That would be one example, absolutely.

QUESTION: Okay, thank you. I apologize for the excessive follow-ups.

DR. GOODMAN: No, that's fine.

MS. SWENARSKI: Thank you. Next question, please.

AT&T FACILITATOR: We'll go to Dr. Sean Kenniff with CBS-Miami.

Okay, we're not getting a response. We'll move on to Bob Serkin [sp] with CBS Radio.

QUESTION: Yes, thank you very much. Dr. Hughes, yesterday you said that no one should not seek blood if they need it, from various blood banks. Do you make the same statement today, and can you once again, perhaps in simpler terms, explain how much do you think at this point the nation's blood supply has been contaminated by this problem?

DR. HUGHES: Well, first of all, thank you for the question, but at the moment there's no evidence right now that the nation's blood supply has been contaminated at all. This is the focus of an ongoing investigation, and one of the possibilities is that the donor acquired infection as a result of receipt of a blood product; the other possibility is the donor acquired infection as a result of a mosquito bite, which is the common way, and so far the only way, that people in this country have acquired West Nile virus infection.

QUESTION: So, again, you're saying to people who need blood not to, in any case, hesitate to get it?

DR. HUGHES: Yes. I will say today what I said recently, which was that if I personally needed a blood transfusion, the last thing I'd be worried about is West Nile virus infection. If I needed an organ transplant because I was chronically ill, the last thing I would be worried about, I think, is West Nile virus infection. And finally, I think it's very important that we not, in translating this message, that we not do anything to discourage people from donating blood, because we experience blood shortages frequently and we must not discourage blood donors from donating.

QUESTION: And if I could just clarify one more point. You said earlier that some blood was being recalled. Am I right in saying that, and if so, what is it exactly being recalled?

DR. HUGHES: Yes, you are correct. Some of the blood is being recalled. The blood that I mentioned, that there are over 60 donors that provided blood components that the organ donor received, so all of the blood from those 60-plus donors that has not yet been administered is being recalled.

MS. SWENARSKI: Thank you. Next question, please.

AT&T FACILITATOR: We'll go to Tina Heffman with St. Louis Dispatch.

QUESTION: Hi. It's the Post-Dispatch.

I wanted to know if you are advising blood banks to take any other screening measures of their blood donors, if you're advising them to ask people about recent mosquito bites, given that people could be asymptomatic but still have virus circulating in their blood.

MS. SWENARSKI: Dr. Goodman, would you like to answer that?

DR. GOODMAN: Sure. I think that, again, just to reiterate, it's important to keep in perspective that this is under investigation, but we don't know at this point whether the transfusion, one of these multiple transfusions might have transmitted the virus.

Your question is a good one, which is short of having--if that is the case, and if there is a need for better screening for this disease, could a question such as mosquito bites improve that screening. I think most of the medical evidence would suggest that that wouldn't be very effective. Of course, the--you know, many, many people in the United States will report mosquito exposures in the summer months and we would then automatically create a humongous shortage of blood based on a risk that at present would appear extremely low.

So that's one point. The other point is that there will be other individuals who may not report or have noticed mosquito exposure who may themselves--in fact could be infected if that indeed was the source of the infection.

So unfortunately, I don't think that would be an efficient or effective way of screening at this time.

QUESTION: So you're reporting that they should do business as usual, their usual screening practices?

DR. GOODMAN: At the present time, what--first of all, I would say that for the Public Health Service and the agencies on this phone call, it's hardly business as usual. Everybody is working around the clock to try to figure out what the source of this is and in fact whether blood could have been the source. For the blood banks there are no new recommendations at this time. As stated before this even occurred, we did work to alert the blood community to this possibility and to do what we can with current screening to exclude people who might at least have early symptoms of West Nile disease. If the evidence warrants and we need to go beyond that, we will try to adapt whatever would be an effective strategy to deal with this, whether it's trying to rapidly implement new screening tests, as described, or whether we can come up with other identification of donors who might be at risk to transmit the disease.

AT&T FACILITATOR: Next we go to Ann Carrns with the Wall Street Journal.

QUESTION: Hi. Thank you. I have a couple of points to clarify. I'm still a little confused as to, of these 60-plus blood donors, how many have been tracked and identified, and if there is any estimate of the number of patients who may have received transfusions with that blood before this recall was implemented.

And if I could also ask Dr. Goodman to give his title, please.

DR. HUGHES: Okay, in terms of the number of people that may have received blood from these 63 people, it's a relatively low number. It's roughly--it appears to be roughly a dozen.

DR. GOODMAN: And my title is deputy director of the Center for Biologics, Evaluation, and Research at FDA.

QUESTION: Okay, thank you. And a quick follow-up. Of these dozen that appear to have received the blood, has any of them been contacted, any of them have symptoms of West Nile?

DR. HUGHES: That investigation is in progress. And remember now, I didn't say a dozen, I said roughly a dozen.

AT&T FACILITATOR: Next we go to Lynn Adreen [sp] with ABC News.

QUESTION: Is it possible--thank you for doing this conference call. I was just wondering, is it possible, in a way that the general public can understand--what will you do to determine how the donor--what methodology do you use to determine how the donor contracted West Nile, or is it just a shot in the dark?

DR. HUGHES: Well, it's not a shot in the dark. What we're doing is, as we do every day when we're dealing with infectious disease issues, is we work very closely with partners at the state and local level. And you will recall that I pointed out that the people in Georgia and people in Florida have been working very hard on this through the weekend. We work with our federal partners, FDA and HRSA, and the blood banking community to aggressively investigate this. We work in the field doing epidemiologic investigations assessing the clinical picture. And then we work very hard in the laboratory to apply modern laboratory techniques to identification of infected patients.

So that is what is going on. And it's going to continue to go on for at least a couple of more weeks.

MS. SWENARSKI: Next question, please.

AT&T FACILITATOR: That will be from the line of Bill Scanlon [sp] with Rocky Mountain News.

QUESTION: Yes, most people who get infected are asymptomatic. Is that also true, or somewhat less true, of people who might get infected by blood transfusions, given their sicknesses and diseases? If 10 people get infected with blood, should we expect maybe one or two or three, or all 10 of them, to because symptomatic with West Nile?

DR. HUGHES: Okay, well, we--I can't answer that question precisely, but let me tell you what we do know. What we know is that, as you said, the majority of people who are infected with West Nile virus remain totally asymptomatic. Of those who develop an illness, the vast majority develop a very mild illness, and only one of approximately 150 will develop the severe form of West Nile virus that we're discussing in these patients.

We know that risk factors for severe disease are primarily age. And so people over the age of 50 are at increased risk for having the severe manifestations of the disease. With many infections, people who are immuno-suppressed or immuno-compromised, such as these organ transplant patients are, are at increased risk for severe--more severe disease on average.

So that's what we do know.

MS. SWENARSKI: Thank you. Next question, please.

AT&T FACILITATOR: Next we go to Ben O. Schmidt [sp] with WTVJ-Miami.

QUESTION: I just wanted to simplify something. It's a little redundant, but I wanted to simplify again two points. Number one, are you able to find--I think you answered this, and this is to any of the doctors, are you able to find out when someone should not--in other words, when someone may be a hazard to a blood supply? Is there that test out there now which can determine at what stage of the virus they shouldn't give blood? And number two is, if you could simplify again the numbers of potential donors and the number of people being tested.

DR. HUGHES: Dr. Goodman, can you take that first question?

DR. GOODMAN: Yeah. I think that, in fairness, right now there is not a test refined to the point that it could be employed in blood banks all over the United States tomorrow to test everybody's blood and determine whether there is any risk of that individual transmitting the virus. You know, on the other hand, to reiterate, there is technology that's been applied to viruses, like the AIDS virus and hepatitis, where the risk is considerably higher because they are chronic infections, but some of those technologies--similar technologies have been used in research and public health labs and could be adapted and tested for use and probably scaled up and into use fairly rapidly.

We don't have enough information right now to know exactly, you know, what proportion of individuals might have what amount of virus, and what risk, if any, that might pose at all to people who receive the transfusion.

So it's an area where we're investigating, gaining new information rapidly, but if needed, do have tools to bring to bear on this and will work, all of us together, to do that.

And I guess--Jim, you've been handling the question on the numbers of blood donors, et cetera.

DR. HUGHES: Okay, yes, thank you, Jesse. Yes, I guess--one other point before we go to the numbers is simply to remind people that we have said that FDA has reminded the blood banking community of the need to exclude people with acute febrile illness from donation. That doesn't get at the asymptomatic infections, but it certainly would get at people with mild symptomatic West Nile virus infection.

Now, in terms of the quantitative aspects with respect to this organ donor, the person received blood from approximately 60 different people. What is being done there is several things. There is--as I've mentioned, we've put a hold on transfusion of any of those blood components that remain. We're working with our state and local partners and the blood banks to obtain remaining samples that they have held from those units so that those can be tested for evidence of West Nile infection.

But we're not stopping there. In addition, we're working with the blood banks and the transfusion services to notify those donors, and we'll be asking them some questions and be offering them the opportunity to be tested for evidence of recent West Nile virus infection.

So it's a multi-faceted investigation.

MS. SWENARSKI: Thank you, next question, please.

AT&T FACILITATOR: Next we go to Kristin Wyatt [sp], with the Associated Press.

QUESTION: All my questions have been answered, thank you.

AT&T FACILITATOR: Thank you, Ms. Wyatt. And next we'll go to Emilio Morero with WLTV.

QUESTION: I've already had mine answered as well. Thank you.

AT&T FACILITATOR: Next we'll go to Sharon Butterworth with WPLG-Miami.

QUESTION: Thank you. My question's for Dr. Wiersma. Is there any new information you can give me on the 71-year-old woman who you said you had taken samples of. Is she still hospitalized, and can you elaborate at all on the illness you said she had after the transplant?

DR. WIERSMA: Well, I think, as Dr. Hughes has already pointed out, we're limiting how much information we put out on all these patients while the investigation's ongoing. We can say that she is at home recuperating at this time. That's about as much detail as we can give.

MS. SWENARSKI: Is there a follow-up?

QUESTION: Nope, that's it.

MS. SWENARSKI: All right, thank you. Next question?

AT&T FACILITATOR: We will go to Larry Altman with the New York Times.

QUESTION: Yes, three questions here, quickly. One, has there been question of any new case or new cluster that has arisen as a result of the publicity over the one you're working on? Second, how much of the blood remaining the Georgia has not been recalled? And thirdly, have any of the blood banks begun testing blindly just on donors to see if they're picking up stray West Nile virus? Have they done that in the past?

DR. HUGHES: Okay, Larry, this is Jim Hughes. First of all, we're not aware of any additional clusters needing investigation at this time, but we have continued to urge people to heighten their surveillance efforts and to report promptly any cases of suspected West Nile virus infection occurring in a person who's received a recent transplant or a blood transfusion.

In terms of the recall in Georgia, all the blood that I mentioned has had a hold put on it.

QUESTION: Yes, but how much has been used and how much remains?

DR. HUGHES: I can't be quantitative there, but again, the approximately dozen people that have received, that we know have received this blood, that we're following up on.

Now, in terms of what blood banks are doing, maybe Jesse could comment on that better than I.

DR. GOODMAN: No, I'm not aware of the kind of testing that you're talking about. But we have been discussing the kind of public health and research agenda sections that would be helpful in further defining whether there's risk and the quantity of that risk.

MS. SWENARSKI: Next question, please.

AT&T FACILITATOR: We will go to Chuck Raven with the Miami Herald.

QUESTION: Hi, there. I just wanted to check on a date. The accident victim who was the organ donor, what day did that person pass on?

DR. HUGHES: For confidentiality reasons, we're trying to not be real specific when it comes to dates. But it was right at the end of July.

QUESTION: I believe earlier you guys said July 30th. But that's okay.

I also--how long typically, the organs that were donated, is it within a day, within two days, within a week that these organs have to be received by the receiver?

DR. HUGHES: They need to be transplanted quickly. Maybe Mr. Hobson could comment on the specifics. They wouldn't be held for a week.

QUESTION: Do you know what date the 63-year-old man in Miami had his heart transplant?

DR. HUGHES: That's for Dr. Wiersma.

DR. WIERSMA: I don't know that we've released that information in the past, but--

DR. HUGHES: Right, that gets to confidentiality concerns and we're reluctant to be that specific.

MS. SWENARSKI: Next question, please.

AT&T FACILITATOR: We'll go to Rick Weiss with the Washington Post. Please go ahead.

QUESTION: Hi. Thanks for the chance for one more follow-up. You've been very careful about making the point that you don't know how the organ donor may have become infected and that it may have been a mosquito bite. But can you be a little more up front with regard to the implications of your findings that at least three out of the four recipients of organs now have been found to have this same infection? I mean, if you get this by organ transplant, I take it it's by means of blood.

DR. HUGHES: The organ donor, again, if this resulted from organ transplantation--and it appears to have--then the organ donor was the source. So the question then, again, becomes did the organ donor get the infection as a result of a mosquito bite or as the result of the transfusions that were used to treat the acute severe injury that led to the person becoming the organ donor.

QUESTION: Right, but--

DR. HUGHES: And this person obviously received a lot of blood products following the injury before donation.

QUESTION: But even if it's uncertain how she became infected, isn't the evidence quite strong now that this disease can be transmitted by blood, either via an organ transplant or perhaps other means?

DR. HUGHES: Or, you know, the organ itself. You know, blood or the organ. The patients received the organ, which presumably had--may have had some blood components in it.

QUESTION: So is that a yes?

DR. HUGHES: I'm telling you what I know.

QUESTION: That the evidence is now fairly strong that this disease can be transmitted by blood or organs directly from person to person?

DR. HUGHES: Again, what I'm saying is that in this cluster of three confirmed cases of West Nile infection, with the possibility that there will be a fourth, that there's clear evidence that organ transplantation appears to have been the source.

Now, having said that, though, let me, you know, throw in one bit of additional information. These patients all lived in areas where mosquito-borne transmission of West Nile virus is occurring and is continuing to occur. So it--this is complicated. It's important that we not jump to conclusions and that we continue to follow this aggressive ongoing investigation. And we will share new results with you as they become available.

MS. SWENARSKI: Thank you, next question, please.

AT&T FACILITATOR: That is from the line of Paul Monise [sp] with WCBS-TV.

QUESTION: Thank you for taking my question. There's a lot of concern here at the New York blood center about shortages. The president and CEO said to me today that he is concerned that if the mosquito question made it on the list, it would dissuade many people from donating and cause even more of a shortage. So you mentioned that the risk is very low, perhaps 1 and 2 in 10,000. If 4.5 million transfusions are done every year, you're still talking about the potential for 900 people to become infected with West Nile. Would it be prudent to halt blood donations for a period of time until an accurate and quick test could be developed?

DR. HUGHES: Well, maybe--Dr. Goodman, would you like to take a first crack at that?

DR. GOODMAN: Well, I think that to halt blood donations, you know, in all areas where there is a possibility that a person could get West Nile, based on the current circumstance of a single incident where the possibility of transfusion transmission is being considered would probably hurt a lot more people than it would conceivably protect. I think we do need to proceed to have a test that can be used if this problem is such that there's that need. And I think we do need to take the measures that we're talking about. But I think that that would be premature and would probably hurt more individuals than it would conceivably help.

DR. HUGHES: Let me make one other comment. You know, West Nile virus is a member of a group of viruses called flavy viruses, and that includes dengue virus and St. Louis encephalitis virus and yellow fever virus, and others. In terms of what's known about blood-borne transmission of these agents or organ transplantation-associated transmission of these agents that are very common in many parts of the world, is that there is very little documentation of transmission.

With dengue, for example, there is one instance of transmission of dengue virus infection in a bone marrow transplant that was done between siblings. In addition, there is one case of dengue virus infection documented to have occurred as a result of a needle stick injury. And that's it.

DR. GOODMAN: I could add that to our knowledge, in countries where this has been around for a long time, including Israel, we are not aware of any transmission. You know, I think this is new. It's an emerging infection. We need to monitor it. But, you know, even your question, if this was--you know, first of all, it's important to realize that risk estimate that you cited was based on some of the best available data, but the data is very limited and that estimate was also based on the assumption that it would transmit to any individual exposed to the blood, which may not be correct either. But we certainly haven't seen 900 cases of West Nile virus from transfusion. We may possibly [inaudible] in the case of an organ transplant donor infected; we don't know yet.

So I think that, again, the current situation makes us concerned about a risk but does not suggest that that risk is widespread at this time. And to reiterate, that for people who need blood or an organ transplant, the benefit is going to far outweigh that risk. We need to continue to work on this and, if there is a need for additional intervention, to do that in a very timely manner.

QUESTION: A follow-up, if I could. Is there any better estimate today, and how long would it take to develop a quick test to detect West Nile either right before someone were to give blood or after the blood enters the system?

DR. HUGHES: Well, it's not going to happen tomorrow or next week. I mean, these things take time. It's months, at least.

MS. SWENARSKI: Thank you. Next question, please.

AT&T FACILITATOR: We'll go to Ira Dreyfus with AP Radio.

QUESTION: Hi, just two quick questions. One of them is exactly how much blood are we talking about from these 60-some-odd folks? And exactly when do you expect to get results back?

DR. HUGHES: Well, in terms of results, they're becoming available daily. But, you know, the testing that's involved in documenting West Nile virus infection is done in a sequential manner. So that's why we've been saying that this investigation is going to be continuing for at least a couple of weeks.

QUESTION: So then you don't expect final results for at least a couple of weeks? And exactly how much blood are we talking about?

DR. HUGHES: Well, how much total blood we're talking about is one of the subjects that we're focusing on in the investigation.

QUESTION: Can you give me a ballpark?

DR. HUGHES: No, I gave you the ballpark in terms of there being about a dozen--roughly a dozen people who have appeared to have received blood from these approximately 60 donors. But beyond that, in terms of how many units, I don't have that information. But it's being collected.

QUESTION: Okay. And do you have yet a date by which you expect to have enough results to make a determination?

DR. HUGHES: You can't predict in these ongoing investigations. We know more today than we knew yesterday; we'll know a little more tomorrow than we know today. But stay tuned.

MS. SWENARSKI: Thank you. Next question, please.

AT&T FACILITATOR: We will go to Miriam Falco with CNN.

QUESTION: Thank you. I have a couple of more questions. Number one, did the donor--I don't know if your investigation has gone this far, but did your donor show any symptoms of West Nile virus? Of course, that person, if they would have been bitten by a mosquito, could have been asymptomatic.

And then number two, what was the time between the organs being donated and received and the illness appearing in the four patients?

And then also, if the gentleman from the FDA could tell me exactly what it was that led to the alert two weeks ago. What specifically made the FDA say we've got to check the blood?

DR. HUGHES: Let me answer the first two, and then let Jesse speak to the third.

As far as we can tell, and this is--we're not finished with the information gathering, but as far as we know today, the donor was not ill prior to the injury that she received.

The incubation period, the time from receipt of organ to onset of symptoms was in the range of two to two and a half weeks.

DR. GOODMAN: On your question about the alert and why we issued it, I think there are several reasons that I can share with you. One is that it has been clear from the epidemiologic data being collected by CDC that the incidents and number of cases of West Nile virus and its geographic distribution in the United States was spreading. It was also clear from knowledge about this disease that--and the anecdotal information Dr. Hughes mentioned about rare cases where some of the other flavy viruses were transmitted through bone marrow or other mechanisms--but not, to our knowledge, blood transfusion--but it was clear that this biologically was plausible and can make sense.

In addition, our colleagues at the CDC did some mathematical modeling based on a New York epidemic of three years ago to try to determine, based on this short period in which virus could be in the blood, what would be the risk that that could be going on with a blood donor at the time they were donating blood.

And putting all this together with, really, the desire to be ahead of the curve, to always keep blood as safe as possible, to increase awareness so that if there were a problem we would hear about it, and to reduce the risk to the extent that we felt we easily could and appropriately could by being sure that these donor exclusion criteria were followed--thinking through all those things and working together with all our partners, we decided to issue the alert at that time.

QUESTION: If I may follow up, though, since the high incidence of cases started much earlier this summer, why didn't this happen, like, in July, instead of two weeks ago? Did it have something to do with the knowledge of these four cases, and--

DR. GOODMAN: Absolutely not. We were not, certainly, aware of that at all at FDA. You know, I can't speak for CDC, but certainly we were in intimate discussions with CDC and this didn't come up. In fact, we were discussing this at that point as a theoretical possibility and, you know, debated whether we should do this, and felt that, on balance, we should.

A proximate event occurring about that time was a publication of the modeling information, and we sort of felt that we needed to keep that in perspective but also address that. So in terms of the timing, that was a big part of that, to my knowledge.

MS. SWENARSKI: Next question, please.

AT&T FACILITATOR: We'll go to John Lauerman with Bloomberg News.

QUESTION: Hi. Thanks for taking my call. Just a little housekeeping. So there are three patients with confirmed West Nile virus who received transplants. Could you just go through them and tell me which state and what is the medical condition of each of the patients? I understand that two have died and one is still sick, but I want to make sure who is where and who is in what kind of condition.

DR. HUGHES: Well, let me offer Dr. Lance-Parker the opportunity to speak about the two in Georgia and then Dr. Wiersma to speak about the two in Florida.

DR. LANCE-PARKER: Hi. There were two patients who received organs in Georgia. One patient died; the other patient is hospitalized but improving.

QUESTION: That patient has encephalitis, is that right?

DR. LANCE-PARKER: That patient has encephalitis.

MS. SWENARSKI: Dr. Wiersma?

DR. WIERSMA: Yes. There were two patients in Florida that received organ transplants. One patient, who was a 62-year-old male who had encephalitis and is a confirmed case, and is recuperating in hospital. The second person received a transplant, we do not have any lab tests back on. That is a 71-year-old female. That patient is recuperating at home.

QUESTION: Okay. So one patient has died.

DR. HUGHES: Correct.

QUESTION: One patient has died, okay. All right, thanks very much.

MS. SWENARSKI: Thank you. Next question.

AT&T FACILITATOR: We'll go to Tom Maugh with the Los Angeles Times.

QUESTION: The number of 60 for donors, is that because you use pooled products? Is that why there are so many potential donors here?

DR. HUGHES: And it's approximately 60.

QUESTION: Well--yeah, approximately, okay.

DR. HUGHES: This individual was severely injured in a motor vehicle crash. In an effort to save the individual, multiple transfusions were provided.

QUESTION: Now, if you don't find West Nile in any of the people who donated to her, then is that presumptive evidence that she was infected by a mosquito?

DR. HUGHES: Well, that--if we're able to get specimens from everybody who was involved in donation of blood or blood products that the donor received, it may. If those specimens were all handled correctly and tested carefully, as they will be in our lab and other public health labs, then the evidence would, if that were to happen, then that probably would suggest the possibility of community-acquired infection.

But it's the reason that we need to move as rapidly as we can to collect those specimens that are available, identify and talk with the donors, and obtain additional specimens. That is how we will try in the end to determine the most likely route of transmission.

QUESTION: One thing I haven't heard here is anybody talk about the role of immuno-suppression in this. These are all transplant patients, so their immune systems are being battered down pretty strongly. Could that have played a major role in this?

DR. HUGHES: Well, I did mention it briefly in terms of what we know about risk of developing severe manifestations in West Nile infection. We know that the principal determinant of that is age, and that in general it's people over 50 who are at increased risk for severe disease. But for most infectious diseases, being immuno-suppressed puts you at risk for developing more severe disease, so we would think that that's probably true here as well.

MS. SWENARSKI: Thank you. We have time for one more question.

AT&T FACILITATOR: And that question will be from the line of Dierdre Henderson with the Denver Post.

QUESTION: I was curious if the testing that you have available right now will give you an indication of when the donors were infected. If I were a donor and I gave a month ago, would you be able to tell if I was infected a month ago, versus bitten by a mosquito a week ago?

DR. HUGHES: Well, in terms of the tests that we have available, there are--it's not going to be possible to precisely determine that. We look for different types of antibody, we look for evidence of viral nucleic acid, and we can look for evidence of virus. And when you get those results from any individual patient, you can make an informed judgment about--within a range of roughly when infection might have occurred. But it's not going to be very precise.

DR. GOODMAN: Jim, just to add--one of the things that CDC and the blood organizations are working on is obtaining samples from the actual donor material at the time of blood donation. And at least for a substantial number, or maybe Jim can comment, in the majority of these cases that material is available and will be tested by CDC. So that should really help if we find the virus itself or its nucleic acids at that time. If a patient just subsequently developed--a donor, excuse me--on follow-up was just found to have antibody, as Dr. Hughes said, it could be, you know, hard to known exactly when they acquired that infection, or where.

MS. SWENARSKI: Thank you. That concludes our telebriefing for this evening. We would like to add that we will continue to update you all as the investigation progresses and that this evening we will post a transcript of the telebriefing. Thank you very much.

[End of telebriefing.]

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