By Kathy Dix
Organand tissue donors are screened more thoroughly than any other group. Blooddonors receive much the same treatment. But there are still pathogens that slipthrough the cracks. Of all the bugs that can be disseminated via organ or blooddonation, West Nile Virus (WNV) has received the most recent press. InSeptember, the Centers for Disease Control and Prevention (CDC) released casehistories of four patients, all believed to be infected with WNV from a singledonor.
The donor was the victim of a motor vehicle accident and received multipleblood transfusions before death. Physicians have not determined the source ofher infection; it may be from the blood transfusions, or it may be from the moretraditional mode of exposure: a mosquito bite.
Very little is known about WNV transmission through blood transfusions ororgan donations. Such transmission has not been previously reported; therefore,no one can quantify the risk of contracting WNV via this route. So far, however,there is not enough evidence to support a change in existing screening andtesting practices for organ or blood donors.
Because the aforementioned organ donor had been healthy before her injury, amosquito bite or a blood transfusion is the most likely source of infection.Four patients received organs from the donor; three of these met the casedefinition for WNV encephalitis; testing is still pending on the fourth.
Recipient 1, who received a kidney, developed symptoms of WNV 13 days aftertransplant and is now recovering. Recipient 2, who also received a kidney,became ill 17 days after transplant and eventually died of encephalitis.Recipient 3, who received a heart, developed ataxia eight days after transplantand eventually required mechanical ventilation; his condition has improved andhe no longer needs a ventilator. Recipient 4 developed fever, cough and malaiseseven days after transplant but did not develop encephalitis; his symptomsresolved and he was discharged from the hospital.
What is striking about these patients is that three -75 percent - developedencephalitis. Generally, one in 150 people with WNV develop encephalitis ormeningitis. CDC points out that "it is unknown whether immunosuppressedpersons, such as organ transplant recipients, are at increased risk for severeWNV-related disease following infection. Similarly, it is unknown if the routeof transmission increased the risk for encephalitis in these organ transplantrecipients."1
A separate case -- this time involving a blood transfusion -- also worriedhealth officials, who wondered if the patient acquired her infection via bloodtransfusion or a simple mosquito bite. She had received 18 pints of blood duringan obstetric procedure, but she also presented with multiple mosquito bites onadmission.2
Because the virus does not normally live long in the blood, it was previouslybelieved that WNV could not be transmitted via blood or organ donations. But theevents of 2002 have turned that theory on its head.
CDC stresses one item in particular: WNV infection is a possibility inpatients who receive organ transplants and blood transfusions. But CDC officialsnote the investigation is ongoing and that in the meantime, clinicians withpatients who are febrile following transplant bear in mind the possibility ofWNV infection, especially if the patient has developed encephalitis ormeningitis.
The panic of viral infection control in the 1980s is hardly forgotten. WhenHIV and AIDS first came to the attention of the general public, the disease wasfound in homosexual and heterosexual people alike -- including hemophiliacs andsurgery patients who had received blood transfusions. Since then, screeningprograms have become standard to detect HIV-infected blood. Blood donors areasked about at-risk behaviors every time they donate. Even the blood of those atlow risk is screened for HIV each and every time.
The families and friends of deceased organ donors are asked about at-riskbehaviors of the donor to determine if there is a high risk of HIV infection."Questions include sexual behavior (especially homosexual or promiscuousbehavior), intravenous drug abuse, blood transfusion history, etc. Thequestioning of the next of kin obviously is not the perfect history,since many do not know the details of their (loved ones' lives), but it is thebest information we can get ... and we do decline donations of patients who testnegative for HIV but have questionable social history," writes AndrewWheelock of the New England Organ Bank in response to a question about AIDSacquired from transplants.3
Wheelock refers to a highly publicized case of one donor infecting manyrecipients with the HIV virus, but emphasizes the sophisticated screeningprocess used now.
Of course, there are other transplant issues associated with HIV. Manypatients who are HIV positive but in need of transplants have difficulty evengetting on a list of prospective recipients. Although United National OrganSharing (UNOS) has guidelines allowing HIV-positive patients to be included inorgan transplants, some regional centers still frown upon transplanting organsin HIV patients. Some people believe that the immunosuppression necessary withorgan transplants will have a significant effect on the immune systems of HIVpatients.4
Even if they are considered for a transplant -- and willing to receive organsfrom HIV-positive donors -- those organs are hard to come by, what with thecustom of refusing HIV-positive donors and even people suspected of at-riskbehavior.
And if all these roadblocks were cleared, there are still the insurancecompanies to contend with. What insurer will pay for transplantation of anHIV-positive organ in an HIV-positive recipient?
In 2001, one woman with HIV and hepatitis C Virus (HCV) campaigned for herinsurer to pay for a liver transplant; when the insurer refused, Belynda Dunntook her appeal to the Massachusetts Office for Patient Protection. Although theoffice upheld the insurer's decision, the mayor of Boston spearheaded afundraising campaign to pay for the surgery. The insurer eventually agreed topay all costs above what had been raised. The transplant was performed in March2002, but the first liver was rejected and Dunn died of a blood clot in the lungafter the second transplant.5
Such stories highlight the ongoing controversy about HIV patients; are theyviable candidates for transplants? Should HIV-positive organs be used in thiscohort? Ethicists could dispute incessantly over the ramifications. Butultimately, the decision will be determined by the level of public support,insurers and Type-A surgeons willing to straddle the line between establishedprocedures and experimentation.
Hepatitis is ubiquitous in some pockets of the world. For Taiwan inparticular, hepatitis B virus (HBV) infection is hyperendemic. Because HBV is sowidespread, there is a severe shortage of organs from donors who do not carrythe virus. Thus, one group of physicians utilized hearts from HBV-positivedonors.6
Based on their experience, they conclude that although infection with HBV wascommon (but not universal), it generally responded well to lamivudine. Theypoint out heart transplantation is not contraindicated by HBV carrier status; itsimply necessitates close monitoring for potential hepatitis flare-up inpatients with HBV antibodies or infection.
Researchers at the Starzl Transplantation Institute had much the sameexperience; they discovered that a combination drug therapy prevented hepatitisinfection in patients who received HBV-infected livers. Twelve patients whoreceived a combination treatment of hepatitis B immune globulin (HBIG) andlamivudine are still HBV-free anywhere between five and 25 months aftertransplantation. A thirteenth patient -- to whom lamivudine was not yetavailable -- received only HBIG and developed HBV six months later. The authorsconcluded that the combination therapy might be able to prevent infection evenwhen the organ is from an HBV-positive donor.7
Other pathogens -- less common, perhaps, but just as damaging in scope -- arevaried. Trypanosoma cruzi, a parasite that causes Chagas disease, wasfound in three organ recipients in 2001. The donor was an immigrant from CentralAmerica; in Latin America, Chagas is endemic. All three patients were treatedwith nifurtimox. Two of the patients died (one of unrelated causes); the otherhas recovered and has had no recurrence of T. cruzi infection.8
Although there are between 25,000 and 100,000 Latin American immigrantsinfected with T. cruzi currently in the U.S., there is no policyregarding the screening of potential donors for T. cruzi. Serologic testsfor the infection do exist, but they differ in terms of sensitivity andspecificity. None of these tests have been licensed in the U.S. for testingorgan or blood donors. However, CDC has notified UNOS of the three cases andwill consider whether or not screening of potential donors should becomestandard operating procedure.
Other pathogens that can be transmitted via organ donation includecytomegalovirus, Epstein-Barr virus, toxoplasma and syphilis. 9Candida has even been a topic of discussion. In Transplantation magazine,one expert was asked if the presence of Candida in a donor's urine is acontraindication to donation. However, the answer is not a simple yes or no;typically, a positive culture for Candida is secondary to colonization, notsepsis or urinary tract infection. But Candida can be transmitted throughinfected urine. Thus, concludes the expert, it is crucial to verify the originof the culture, and to remember that there is the potential for a seriousCandida infection in the kidney.10