The Zika virus has been in the headlines lately for its apparent association of microcephaly in the children of mothers infected when they were pregnant. While there is a strong correlation, a true causation has not been completely verified, and is still being investigated. In most people the virus causes only very mild illness that resolves on its own (such as fever, rash, muscle aches, and headache), and in many individuals is completely asymptomatic. Occasionally, its effects can be more severe, such as leading to reported cases of Guillain-Barre syndrome (a severe neuromuscular illness causing paralysis). It is still not known exactly why some people may develop severe complications while the majority do not. Zika virus has been covered previously on the ZME website.
It is also known that while the Zika virus typically spreads by an insect vector (the mosquito Aedes aegypti in most cases), it is now thought to also spread by sexual contact. It is uncertain if transmission could occur thorough organ donation, but if virus is present in the blood or other body fluids, then this mode of transmission would be possible in principle. Due to concern that this unusual mode of transmission could affect a vulnerable population, the Organ Procurement and Transplantation Network (OPTN) and United Network for Organ Sharing (UNOS) has set up an Ad Hoc Disease Transmission Advisory Committee (DTAC) to provide information and recommendations to transplant physicians, and this month came out with the first guidelines. As a transplant physician myself ( I’m a pediatric nephrologist, caring for children with End-Stage Kidney Disease who will need or have received a kidney transplant), I recognize the need to be certain that our supply of donor organs are safe for our patients, and to be able to advise our current transplant patients about travel to areas where Zika is known to be endemic.
Organ transplant recipients (such as heart, liver, kidney, lung, etc) represent a vulnerable population. In order to prevent rejection of the donor organ, the patient must be immunosuppressed with medications, making it difficult to fight off infections that most of us wouldn’t be very bothered by. It is completely unknown, at the present time, how Zika virus would affect an immunosuppressed individual. It’s affects could remain mild, as it is in most people with a normal immune system, or it could have serious unforeseen consequences.
The DTAC advises caution for people who have already received a transplant, or those who are on the transplant list, if they will be traveling to a Zika endemic area. Those areas would include Mexico, Central America, and South America. They also recommend that when a donor is being considered (and that could include either a living donor or deceased donor), that the transplant center should take into account the donor’s recent travel history, and if they had recent symptoms of viral infection. Again, many people (around 20%) will not have any symptoms at all, making symptomatology an unreliable marker of infection. The committee does not feel that even these factors should result in absolute exclusion of that organ being used, but should be decided on an individual basis for each patient. Some patients may be in more urgent need of an organ, and may not survive if they have to wait too much longer for the next matching organ to come up. In other cases, a person may have already been on the transplant list for a very long time due to having built up a lot of antibodies to other potential donors, and may not get another matching offer for years. It may be a decision that the patient, their family, and their transplant physicians need to make together if the organ in question is felt to be at a higher than average risk for Zika virus.
Unfortunately, routine screening methods are not yet available for use by clinical laboratories. Screening can be achieved by the CDC in suspected cases of Zika related illness, and therefore it is not yet recommended or possible for organ donor’s to be screened for Zika virus as part of a donor evaluation. With time we will likely have a better understanding of the risk that Zika poses to individuals immunosuppressed for organ transplant. We will also likely have better screening methods that will be more readily available. For now, I think it is prudent to take precautions until more is known, but feel that there is no reason to panic, since there is no evidence at this time that donor organs have been compromised in any way.
References and further reading:
“Guidances for organ donation and transplantation professionals regarding the Zika virus”. Feb. 4 2016. UNOS Newsroom.
Interim Guidelines for Pregnant Women During a Zika virus outbreak – United States 2016. CDC Morbidity and Mortality Weekly Report. Jan. 22. 2016.
Possible Association Between Zika virus infection and Microcephaly – Brazil 2015. CDC Morbidity and Mortality Weekly Report. Jan. 29, 2016.