EXPERIMENTAL AND CLINICAL TRANSPLANTATION

West Nile virus (WNV) was first described in 1937, and since then it has periodically appeared in various parts of the world with infection of people and horses. It has been most often identified in the Czech Republic and Romania in overwintering mosquitoes.¹ The WNV is an enveloped virion containing a positive-sense single-stranded RNA genome.² The first appearance of WNV in the Western hemisphere was in New York state, when infected individuals were diagnosed during the late summer of 1999. In the period from 1999 to 2010, more than a 2.5 million people were infected. More than 12?000 reported cases had severe complications such as encephalitis or meningitis, and more than 1300 of these cases resulted in fatal outcomes.³ West Nile virus infection is predominantly subclinical. Reported infection symptoms and signs may be highly variable and may range from fever and myalgias to meningoencephalitis.⁴ One of the most severe complications is encephalitis. Progression of neurological complications can occur, eg, acute flaccid paralysis with quickly advancing symptoms that may potentially involve all 4 limbs. These complications can lead to severe poliomyelitis-like syndrome and result in a poor long-term outcome.⁵ As many as 50% of older individuals may die, and significant morbidity occurs in the year after infection. Additionally, these patients have an increased risk of death for up to 3 years after acute infection.⁶ Patients over 70 years of age are the most sensitive population, for whom the case-fatality rate ranges from 15% to 29%. Infected infants and immunocom-promised patients also have a higher risk of fatality.⁷ The diagnosis of WNV infection is based on clinical criteria and testing for antibody responses. The incubation period for WNV infection varies from about 2 days to 2 weeks. The most common method for diagnosis of WNV is the presence of anti-WNV immunoglobulin M, particularly from cerebrospinal fluid (CSF).⁸

A 59-year-old patient was admitted to the University Clinical Center of Serbia, Belgrade, in September 2018, where liver transplant was performed to treat cirrhosis of ethyl etiology. Immunological analysis (antinuclear, anti-smooth muscle, antimitochondrial, anti-neutrophil cytoplasmic, and anti-liver-kidney microsomal type 1 antibodies), viral etiology (hepatitis B surface antigen, hepatitis C virus, hepatitis A virus, HIV, cytomegalovirus, Epstein-Barr virus, herpes simplex virus type 1, herpes simplex virus type 2, and varicella-zoster virus), the test for Toxoplasma gondii, and the Quantiferon Gold Plus test all produced negative results. The patient had decreased synthetic liver function, according to a Model for End-Stage Liver Disease score of 16, with occasional episodes of encephalopathy, according to West Haven criteria up to stage 3. The patient was in stable alcohol abstinence for 1 year, without comorbidities and contraindications for surgery. Immunosuppressive therapy was started imme-diately after successful transplant, which consisted of methylprednisolone (successive dose reduction every 24 hours as 250 mg, 125 mg, and 80 mg and then switched to 40 mg prednisolone), tacrolimus (gradual dose increase to a concentration of about 10 ng/mL), and mycophenolate mofetil (1 g per 12 hours). Mycophenolate mofetil was excluded from therapy on postoperative day 3 because of the progressive decrease in white blood cells (WBC) (from initial 12.1 × 10⁹ cells/L to 1.3 × 10⁹ cells/L). Except for pancytopenia (WBC, 1.3 × 10⁹ cells/L; red blood cells, 3.35 × 10¹² cells/L; and platelets, 37 × 10⁹ cells/L), reduced concentrations of total proteins (52 g/L) and albumin (33 g/L) were verified, with significant decreases in transaminase values (aspartate aminotransferase, 32 IU/L; alanine aminotransferase, 63 IU/L), cholestasis enzymes (alkaline phosphatase, 75 IU/L; ?-glutamyl transpeptidase, 150 IU/L), total bilirubin (11 ?mol/L), and parameters of inflammation (C-reactive protein, 11 mg/L; procalcitonin, 0.94 ng/mL). A good synthetic graft function was established (international normalized ratio, 1.36; antithrombin III, 70%). Tacrolimus concentration was monitored daily and was approximately 9 ng/mL. After filgrastim administration (48 MU per 0.5 mL), WBC recovery occurred. The patient reported feeling well, and the function of the graft was adequate. On postoperative day 8, WBC decreased again (2.8 × 10⁹ cells/L), and total proteins (39 g/L) and albumin (24 g/L) also decreased, but all other laboratory parameters showed improvement. Sternal puncture confirmed reactive bone marrow. The patient became febrile on postoperative day 11 (39.6 °C), and arm tremor, nausea, vomiting, and frequent fluid stools occurred. He complained of pain in the muscles and joints of the lower extremities. The next day he experienced occasional disorientation. The dose of tacrolimus was adjusted so that the concentrations were about 6 ng/mL. Neurological findings revealed no signs of acute focal neurological deficit, as confirmed by multi-slice computed tomography of the head. We performed culture tests to isolate pathological microorganisms, and results were negative in cultures of the blood (anaerobes, aerobes, and fungi), urine, feces, ascites, and a smear of the wound and tip of the central venous catheter. Test results were negative for viral markers (hepatitis B surface antigen, hepatitis C virus, HIV, cytomegalovirus, Epstein-Barr virus, herpes simplex virus type 1, herpes simplex virus type 2, varicella-zoster virus, and polymerase chain reaction cytomegalovirus DNA). Chest radiography showed no infiltrative changes in the lung parenchyma. Abdominal ultrasonography and Doppler ultrasonography findings were appropriate. The laboratory analyses showed stationary findings with an increase in the level of C-reactive protein to 29.2 mg/mL and a good graft function. Lumbar puncture revealed a clear CSF that was sent for analysis. The results from the CSF showed significant increases in WBC count (94 × 10⁶ cells/L), total proteins (1.61 g/L), and microalbumin (504.5 mg/L), with a reduction of immunoglobulin G (1.4 g/L). Serum protein electrophoresis confirmed that total protein was reduced by a deficit of immunoglobulin G (4.37 g/L). On postoperative day 15, positive serology of WNV immunoglobulin M in CSF was verified. The intensive monitoring and symptomatic and supportive therapy resulted in clinical and laboratory improvement, and the patient was discharged in good general condition on postoperative day ².

The usage of modern immunosuppressive therapy after orthotopic liver transplant (OLT) has led to significantly better graft and recipient survival. At the same time, those immunosuppressive agents are associated with a higher incidence of opportunistic infections, which are the leading cause of morbidity and mortality. It has been shown that more than 50% of patients after OLT will develop some type of infection.⁹ There are many other factors in addition to immunosuppressive therapy that could increase the risk of infection after OLT, including a pretransplant Model for End-Stage Liver Disease score greater than 30, the need for a second operation after OLT, posttransplant renal replacement therapy, and an intensive care unit stay longer than 48 hours.¹⁰ However, these risk factors were not observed for our patient, and immunosuppressive therapy was corrected immediately after the first signs of infection. Several factors may affect the timing of a specific post-OLT infection, including the net state of immunosuppressive therapy, environmental exposure to a specific organism, and the development of surgical complications (eg, bile leak, hepatic artery stenosis, or biliary strictures).¹¹ We performed screening for all the essential infectious agents before transplant (listed above), according to the Clinical Practice Guidelines of the European Association for the Study of the Liver.¹² The donor was also tested for the same viral markers as the recipient, and urine and blood culture tests were performed. A specific screening program should be performed on a subgroup of patients according to clinical history, comorbidities, and endemic diseases and local epidemiology. Recipients living in WNV-endemic areas require special follow-up with WNV serology and polymerase chain reaction.¹² Multiple organ transplant was performed from the same donor, albeit recipients of 2 kidneys and heart did not have any signs of infection. We concluded that our patient was infected in the incubation period at the moment of transplant. However, because WNV infection may be asymptomatic, we performed WNV serological testing of 3 other recipients, and the findings were negative. Also, the donor did not have any signs of infection. We searched the available literature, and all previously published reports of posttransplant WNV infections have described donor-derived infections or de novo infections. In a study by Shingde and colleagues, the results of 119 papers were reviewed, involving 139 donors and 207 kidney recipients. Donor-derived viral infections were most prevalent (n = 116; 56.0%), followed by bacterial (n = 32; 15.5%), fungal (n = 32; 15.5%), and parasitic (n = 27; 13.0%) infections. West Nile virus was represented by 6.3% (n = 13).¹³ Winston and colleagues presented results of a case series in which 23 transplant recipients had received organs from donors infected with WNV. Twenty of these transplant recipients (87%) became infected with WNV. The median time from transplant to the onset of symptoms was 13 days. Fourteen of the 20 transplant recipients (70%) developed encephalitis, 1 developed WNV fever, and 5 remained asymptomatic.¹⁴ The present therapeutic options against WNV are mainly supportive. Research studies directed toward identification of individual susceptibility markers, recombinant antibodies, peptides, RNA interference, and small molecules with the ability to directly or indirectly neutralize WNV have been published; nonetheless, an effective drug has not yet been discovered. The temporary reduction of immunosup-pression to allow the restoration of natural immunity (if present) to WNV has been suggested.¹⁵ We reduced the immunosuppressive therapy with the first signs of infection and applied robust supportive pharmacotherapy, and our patient responded with improvement of his general condition. Therefore, treatment with specific immunoglobulins was not used.

We presented a rare case of WNV infection after liver transplant that was neither a de novo infection nor a donor-derived infection. Considering the high risk of posttransplant complications, the question of whether all donors and recipients should be tested for WNV at the onset of transplant remains to be answered. It would be reasonable to consider WNV testing during specific parts of the year (May to September) in areas where WNV is endemic. Additionally, choosing a specific test to detect subclinical infections should also be considered.

Volume: 21 Issue: 1 January 2023

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