Zika Virus Infection and Solid Organ Transplantation: A New Challenge

Introduction

The detection of Zika virus (ZIKV) infection in the Federated States of Micronesia (Yap Island) in 2007 marked its emergence outside Africa and Asia, and documented the first large-scale ZIKV outbreak among humans. Since then, ZIKV has been reported in French Polynesia, New Caledonia, Cook Islands, Easter Island (Chile), Samoa, Brazil, and nearly every country in the Americas and the Caribbean. Its association with increased numbers of microcephaly and Guillain-Barré syndrome has led the World Health Organization to declare a Public Health Emergency of International Concern on February 1, 2016 1, 2. On May 2016, 48 countries and territories were found to have active ZIKV transmission 3. Recently, autochthonous ZIKV transmission has also been described in Cape Verde 4 and in the southern state of Florida, United States 5.

In urban and periurban environments, ZIKV is transmitted in a human–mosquito–human transmission cycle by mainly two species of Aedes mosquitoes—Ae. aegypti and, to a lesser extent, Ae. albopictus 6, 7. Epidemiological evidence suggests that ZIKV may be also transmitted from the mother to the fetus during pregnancy 8, sexual intercourse 9, and blood transfusion 10. The usual clinical presentation of ZIKV infection, in the general population, is usually nonspecific (mild fever, rash, arthralgia, and conjunctivitis) and might be misdiagnosed as several other arboviral diseases, most commonly dengue and chikungunya fever 11. ZIKV infection has also been associated with newborn microcephaly 12 and neurological complications, such as meningoencephalitis 13 and Guillain-Barré syndrome 14.

Thus far, no cases of ZIKV infection have been reported in solid organ transplant recipients (SOTr). As for other novel pathogens, the risk of development of severe disease due to ZIKV in these patients is unknown. Given the rapid growth of transplantation in developing countries, including endemic zones of active arbovirus transmission (e.g. Brazil), as well as travel to such regions by potential organ donors and recipients, it is important to describe the clinical characteristics of ZIKV infection in immunocompromised hosts. Here, we describe four SOT patients who presented in 2015 with a positive ZIKA reverse-transcriptase polymerase chain reaction (RT-PCR) and negative assays for other arbovirus infections, such as dengue virus (DENV) and chikungunya virus (CHIKV).

Methods

Patients were identified at a single center (Hospital de Base) located in São José do Rio Preto, northwest of São Paulo State, Brazil. This region is endemic for the circulation of DENV, and other arboviruses and co-infections with more than one arbovirus are observed 15, 16. All Zika cases were confirmed by PCR and were observed during the recent epidemic between June 2015 and January 2016.

All dengue-suspected SOT patients seen at our center were screened by PCR for exposure to the following arboviruses: DENV1–4, CHIKV, ZIKV, Saint Louis encephalitis (SLEV), Rocio virus (ROCV), Ilhéus virus, Bussaquara virus, Iguape virus, and West Nile virus (WNV). The screening period for these samples was within the onset of symptoms and the viremia phase (up to 7 days). DENV diagnosis was made according to Brazilian Ministry of Health guidelines in suspected patients living in or coming from areas with reported dengue or with the Ae. aegypti mosquito and who presented with fever usually between 2 and 7 days and with two or more of the following manifestations: nausea, vomiting, rash, myalgia, arthralgia, headache, retro-orbital pain, petechiae, positive tourniquet test, and leukopenia 17. Blood samples were collected and the patients were initially screened for DENV by NS1 and/or IgM (Alere S.A.).

PCR/quantitative PCR assays were applied to the isolated virus RNA to determine a diagnosis of DENV 1–4 18, ZIKV 19, or CHIKV 20. First, flavivirus genus–specific primers, targeting conserved NS5 regions, were used in a RT-PCR assay. Second, DENV 1–4, yellow fever virus (YFV), and SLEV species-specific primers were used, because these viruses are known to circulate in our region. In this way, multiplex nested PCR was used to identify DENV 1–4 and YFV. Different N-PCRs were used to detect SLEV, ROCV, Ilhéus virus, Bussaquara virus, Iguape virus, and WNV 18. To detect ZIKV and CHIKV, a one-step quantitative, real-time, fluorescent probed–based RT-PCR assay was performed using primers targeting the envelop (E) and NSP1 regions, respectively 19, 20. The ZIKV assay presents a sensitivity limit of 100 and 25 copies according to the set of primers/probes used 19. To CHIKV, the assay showed an analytical sensitivity <1 plaque-forming unit to both sets of primers/probes used 20. This study is part of an ongoing arbovirus surveillance program approved by the Ethical Review Board (CEP no 02078812.8.0000.5415).

Results

Between January 2015 and April 2016, 187 SOT (129 kidney transplants [KTx] and 58 liver transplants [LTx]) were performed in our service and 40 patients were suspected and were screened for DENV (KTx: 72.5% [29/40] and LTx: 27.5% [11/40]). Serology anti-dengue IgM and NS1 enzyme-linked immunosorbent assay tests were performed based only in the beginning of symptoms and thus they were not used for every patient. PCR was performed in 51.72% (15/29) of KTx and in 72.72% (8/11) of LTx. Four (10%; 4/40) of the dengue-suspected patients were confirmed by RT-PCR as ZIKV infections. All were male, two of these were liver recipients (LTx), and two of them were kidney recipients (KTx). The laboratory and clinical profile of these patients is described in Table 1.

The average time between the onset of symptoms and patient hospital admission was 7.25 ± 2.06 days (range of 5–10 days). All ZIKV-infected SOTr presented with complications, notably bacterial infections, and required hospitalization related to their transplant status or to ZIKV infection until resolution of their symptoms. One LTx was re-hospitalized and required re-transplantation due to hepatic artery thrombosis and biliary stenosis 91 days after ZIKV detection. Two patients reported fever, myalgia, and adynamia, while no patient exhibited conjunctivitis, exanthema, or neurological symptoms when admitted to the hospital. Three out of four SOT patients presented with anemia, and all of them had thrombocytopenia, with levels lower than 100 000/mm³ (platelet count mean 94 750/mm³ ± 29 600). Previous hematological parameters about 1 month before ZIKV infection detection are presented in Table 1. Signs of acute liver or renal damage were observed in all patients. Both KTx recipients had their immunosuppression regimen altered. No donor had available data about Zika fever suggested–symptoms, travel history, and/or previous ZIKV infection. They were followed up upon discharge as required due to their transplant follow-up care. Up to April 2016, no patient had died or presented neurological symptoms of any kind of clinical sequelae in follow-up visits.

Discussion

This is the first series of reports of ZIKV infection in organ transplant recipients. Based on this small series, it is not possible to ascertain the potential impact of ZIKV in the immunosuppressed SOTr, including infectious complications and graft rejection. Case reports describing ZIKV infection in patients with conditions associated with compromised immune systems are limited. Recently in Colombia, two fatal cases were reported in patients with leukemia, but the role of ZIKV infection in these cases was unclear 21. Because of scarcity of data on this subject, management of ZIKV infection has been based on past experience with other flavivirus infections in immunocompromised hosts, including DENV infection in SOT 22.

In the absence of data, some recommendations have been published regarding arbovirus infection in SOT 23. These recommendations suggest that transplant recipients and their physicians should familiarize themselves with the main clinical signs and complications of ZIKV infection, including meningoencephalitis and Guillain–Barré syndrome. The overlap between the symptoms of ZIKV infection and those caused by DENV, especially in areas where these arboviruses circulate concurrently, makes a differential diagnosis challenging 11.

In this series, the mean period from the beginning of symptoms until hospitalization was longer, at approximately 7.25 days, than for normal individuals with symptoms compatible with dengue or ZIKV for whom the observed mean period was shorter at 2.76 days (±1.42; range of 1–6 days) 24. Worsening liver or renal function was observed in almost all SOT ZIKV-infected patients, but given that they were also hospitalized due to complications, it is impossible to define, based on only these descriptions, the potential impact of ZIKV on clinical presentation severity and outcomes of these infections in an immunosuppressed individual.

The impact of immunosuppression on ZIKV infection in SOT is unclear as is the impact of ZIKV on allograft function. ZIKV must be compared with other arbovirus infections that may co-exist in the same regions. The laboratory and clinical profiles of DENV infection in SOT have been described previously 25, 26, and often include rash, fever, and conjunctivitis, which were absent in most of the present series. Thrombocytopenia is a very common manifestation in dengue 27, but as shown in this series, it is not exclusive to DENV infection as it was also observed in ZIKV infection. Data regarding severe dengue (SD) in SOT are conflicting 25, and early diagnosis and treatment are essential; in areas where ZIKV and DENV are circulating concurrently, it is essential that diagnostic assays be utilized for effective therapeutic management. Until recently, ZIKV was believed to cause only mild disease, which it still does in the majority of cases, with treatment focused on symptoms, except for a growing body of evidence that ZIKV infection results in severe congenital 14 and neurologic complications 7. On the other hand, patients with dengue exposure may present with severe disease, often in secondary heterologous infections, a condition attributed to antibody-mediated immune enhancement and activation of cross-reactive memory CD4+ and CD8+ T cells 26. In the absence of available antiviral drugs against DENV infection, treatment for these patients consists primarily of supportive care, including bed rest, antipyretics, analgesics, and urgent resuscitation with intravenous fluids to replace lost intravascular volume in cases of SD 28, a critical measure to reduce mortality of disease. Patients with clinical signs and epidemiological history compatible with viral disease and in regions where other arboviruses, such as dengue, are endemic should be tested for ZIKV and DENV infections.

The diagnosis of ZIKV must be determined by molecular testing generally within the first week of onset of symptoms but might be considered in any SOTr with a compatible syndrome and potential exposures, given the limited knowledge of the course and duration of ZIKV viremia in immunosuppressed patients, which might be prolonged. Such assays are not available in all areas; newer assays are under investigation. Cross-reactivity between flavivirus antibodies and/or antigens may lead to the erroneous diagnoses. Positive serology by detection of NS1 and anti-dengue IgM in nonrecipient of SOT dengue-suspected patients but with detected ZIKV infection by RT-PCR have already been reported 24. It is also essential to consider other modes of ZIKV infection, such as blood transfusion 10, donor-derived infection, or postoperative infection. A review of the donor epidemiological data is essential to prevent donor-derived infections, including travel history, presence of signs/symptoms of ZIKV infection, and place of residence regarding areas of arbovirus transmission. Such data are not routinely available in our area. Laboratory screening for ZIKV in transplant donors is challenging as ZIKV viremia detection by RT-PCR demands a qualified reference laboratory, while serologic screening may not reflect the true risk of transmission 29. After these preliminary retrospective results, our protocols to screen potential transplant recipients and donors have been reviewed. For transplant recipients, we suggest performing PCR for DENV, CHIKV, and ZIKV in serum to detect asymptomatic or mild infection. Donor screening is dependent on the government organ allocation system and availability of serum from them. PCR for DENV, CHIKV, and ZIKV in serum may be performed, as well as PCR for ZIKV in urine, especially in kidney donors, to detect potential kidney impairment.

This study describes clinical and laboratory data observed in four cases of SOTr infected by ZIKV and highlights the need to better understand the ZIKV clinical spectrum in immunocompromised hosts, including SOTr, the factors that may affect the clinical presentation, molecular and serologic diagnostic testing, and the differential diagnosis of disease.

Disclosure

The authors of this manuscript have no conflicts of interest to disclose as described by the American Journal of Transplantation.