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September 4, 2002
I've included a news report summarizing what is known about the probable cases of organ transplantation-associated mechanism for WNV transmission. This report is about the best I've seen. Statistically, the likelihood that transplantation was the mechanism of transmission is quite high (3 of 4 organ recipients with WNV encephalitis). However, this still doesn't change the fact that case attack rates, and case fatality rates are still very low in humans, and that human to human transmission (in absence of potentially massive doses of virus) in general does not occur. Blood and organ transfusions could potentially contain sufficient virus to effect transmission, while the typical viremic patient does not transfer sufficient virus to a mosquito to permit transmission to another person.
As of Sept 3, CDC reports a nationwide human clinical case total of 673, with 36 mortalities. Highest numbers (#cases - mortality) have been reported in Louisiana (205 - 8), Illinois (122 - 7), Mississippi (104 - 3), Ohio (40 - 4) and Texas (43 - 1). Note these are more inland and not coastal. If you compare numbers in states more widely affected in 2001 and 2000, you would note a significant difference between these newly affected states and previously affected states: New York (8 - 2), Florida (2 - 0), Connecticut (1 - 0), DC (1 - 0) and New Jersey (0 - 0) for 2002.
So far no further western spread reported. Here in Montana we have 15 equine cases (with 6 mortality/euthanasia (40%)), still all in the eastern half of the state. No cases yet reported in OR, WA, ID, CA, NV, or AZ.
Thomas J. Roffe, PhD, DVM
Northern Rocky Mountain Science Center
USGS-BRD
FWP Bldg, 1400 S. 19th Ave.
Bozeman, MT
T: 406-994-5789
F: 406-994-4090
Cell: 406-539-4955
Supporting Document:
Date: 1 Sep 2002
From: ProMED-mail <promed@promedmail.org>
Source: NY Times [edited]
<http://www.nytimes.com/2002/09/01/national/01FLOR.htmlHealth Officials Studying West Nile-Transplant
Federal health officials said on 31 Aug 2002 that 3 of 4 patients who received organs from one donor have apparently developed encephalitis, and tests show that one recipient is infected with the West Nile virus, raising suspicion that the virus can be transmitted through organ transplants.
One of the 4 recipients died about 4 weeks after the transplant. Standard pathology tests from an autopsy show that the recipient had encephalitis (inflammation of the brain and central nervous system). Tests are planned to determine whether the recipient was infected with West Nile virus, which causes encephalitis. Tests have shown that another recipient, a 63-year-old man who lives in Miami-Dade County, Florida, has West Nile fever.
Because the organ donor received a number of blood transfusions before dying in Georgia on 1 Aug 2002, health officials are also investigating the possibility that the virus can be transmitted through blood. Federal health officials said they were taking the situation seriously and were aggressively investigating the cluster of cases. The reason is that if additional tests confirm that the 3 recipients developed West Nile encephalitis, it would be a new route of transmission of the virus, which was first identified in this hemisphere in 1999, in New York City. No case of transmission of West Nile or closely related mosquito-borne virus through blood or organ transplants has been reported in this country, said Dr. James M. Hughes, a top official of the Centers for Disease Control and Prevention [CDC] in Atlanta.
On Friday night, Dr. Julie L. Gerberding, the director of the CDC, said that "transmission of the West Nile virus through blood and organs is biologically plausible" and that "a leading hypothesis that we are investigating is that it is related to the organ transplant." Dr. Gerberding's agency is responsible for protecting the public's health from infections like West Nile fever. Scientists have performed statistical analyses that show that transmission of West Nile virus could occur at a very low rate through blood transfusions, Dr. Gerberding said. The donor and the 4 recipients are from Georgia and Florida, where the virus is known to have infected mosquitoes, birds, and humans. Health officials said they were working to rule out a remote chance that all developed their illness from mosquito bites.
Dr. Hughes said in an interview that "several dozen" state and federal epidemiologists, laboratory scientists and other health workers had been thrust into the medical investigation. Some are working to obtain additional information about the donor's health before dying on 1 Aug 2002 from injuries suffered in a traffic accident. The transplants were performed on 2 and 3 Aug 2002, Dr. Hughes said. One patient received the donor's heart, a second patient received the liver, and 2 patients each received one kidney. One of the kidney transplant recipients died, Dr. Hughes said, and 2 of the organ recipients went home after surgery but returned when symptoms of encephalitis developed. The man in Florida did not leave the hospital.
Meanwhile, scientists at the CDC are conducting special laboratory tests on the brain of the kidney recipient who died for evidence of West Nile virus or a closely related virus. The medical investigators are about to begin tracing the individuals who gave the blood that the organ donor received before death.
Blood banks routinely keep a small amount of a donor's blood for testing in the event that infections or other complications develop among recipients of a donor's blood. Such tests have not been performed yet, Dr. Hughes said.
Also, the investigators are seeking any blood from the donor that may have been stored from before the time the donor received blood transfusions, to determine whether the recipient was infected with West Nile [previously]. West Nile virus usually produces its most serious illness among people older than 50 and those who immune system has been weakened by other diseases or treatment for them. As is standard for organ transplant recipients, all 4 recipients received immune-suppressing drugs to prevent rejection of the donated organ. The weakened immune status leaves such patients more vulnerable to infections and, in such cases, to more serious illness. One of the 4 organ transplant recipients developed a mild fever that resolved. Tests are planned to determine whether that recipient had a mild case of West Nile fever. Most people infected with the virus develop a mild flu-like illness or experience no symptoms.
If blood donations are confirmed as the source of the transmission, it would raise questions whether blood banks would need to test blood for the West Nile virus before it is transfused. Blood banks routinely test for viruses and bacteria that cause hepatitis, AIDS, and other infections. But, Dr. Gerberding said, "the problem is that we do not have a rapid test for West Nile virus," and other tests, like the PCR (for polymerase chain reaction), are not reliable for screening blood at this time. Dr. Gerberding expressed hope that the medical sleuths would be able to trace the source of infection quickly.
At least 556 cases of West Nile fever, including 28 deaths, have been reported to the CDC from 26 states and the District of Columbia this year.
U.S. Department of the Interior | U.S. Geological Survey
URL: http://biology.usgs.gov/cro/WNV9-04-02.htm
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