EXPERIMENTAL AND CLINICAL TRANSPLANTATION

Key words : Deceased donor liver transplantation,Donor-derived infections, Immunosuppression, Infectious disease

Dengue is a mosquito-borne, single-stranded, positive-sense RNA virus within the genus Flavivirus (family Flaviviridae), first isolated by Ren Kimura and Susan Hotta in Japan in 1943. Antigenically, dengue virus can be classified into 4 serotypes (DENV1-4) that comprise phylogenetically distinct subtypes or genotypes. The global burden of dengue has reached epidemic proportions with approximately 390 million infections per year (96% credible interval 24 million to 528 million) of which only about 96 million infections manifest clinically.¹ Dengue is endemic in India, demonstrating a seroprevalence of almost 57% among the general population.² Although exact figures of the true burden of dengue are unavailable, publicly available data from the National Vector Borne Disease Control Program, India (https://www.nvbdcp.gov.in) database estimated 100 000 or more laboratory-confirmed infections with a case fatality rate of 0.07% in 2021. The major route of transmission of dengue is vector transmission by Aedes aegypti mosquito. Transmission via blood transfusions, vertical transfusion from mother to fetus, and organ transplant-related transmission are among the possible routes of nonvector transmission, and such cases are rare.³ There are a total of 5 previously reported cases, worldwide, of dengue transmission via donor liver transplant, and our case is the sixth case overall but is also the second case of transmission by deceased donor liver transplant (DDLT) ((Table1)). Herein, we report a case of probable deceased donor-to-recipient transmission of dengue virus with severe dengue symptoms that was managed conservatively.

Our patient, a 19-year-old woman, had a history of glucose-6-phosphate dehydrogenase enzyme deficiency with decompensated chronic liver disease secondary to Wilson disease (biopsy proven) with Model for End-Stage Liver Disease score of 16 and Child B cirrhosis treated with azathioprine and methylprednisolone. Preoperative ultrasonography revealed mild ascites, and blood investigations were suggestive of thrombocytopenia (platelet count, 23 000 cells/mL) and leukopenia (total leukocyte count, 2100 cells/mL). Possibility of azathioprine-induced myelosuppression was present. She underwent DDLT, and the surgery itself was uneventful and no blood products were transfused intraoperatively. Postoperatively, the patient was hemodynamically stable and extubated on the first postoperative day (POD1). Methylprednisolone and tacrolimus were started, per protocol. The immediate graft function was excellent, and liver function tests normalized rapidly within a week. Regular meals were started on POD3, which was well tolerated. Clear ascites (500 mL/d) drained for the first week after surgery, then gradually decreased but was persistent. On POD8, a high-grade fever of 103 °F developed, intermittent in nature, and was associated with chills, rigors, tachycardia, and tachypnoea. The patient was extensively evaluated to rule out sepsis. In South Asia, the months of October and November are known as a period of high risk for exposure to endemic vector-related diseases, and so we tested for dengue nonstructural protein 1 (NS1) antigen and IgM antibody, the results of which were positive. However, we deemed the possibility of community exposure to be a highly unlikely source of transmission for this patient, because the conditions of care did not favor this scenario (she was treated in the strict sterile environment typical of any intensive care unit [ICU]). Acute viremia was evident from positive test results for both NS1 antigen and IgM antibody, with a negative result for IgG antibody. A viral nucleic acid amplification test (NAT) for dengue was not unavailable. With a total leukocyte count of 6100 cells/mL, a platelet count of 44 000 cells/mL, C-reactive protein of 51 mg/L, and procalcitonin of 5 ng/mL, the possibility of sepsis was also considered; however, all cultured samples were negative for infectious agents. Test results from the other recipients of organs from the deceased donor (2 different recipients of kidney transplant) were also positive for both NS1 antigen and IgM antibody; however, donor serum samples were not available for testing. It is important to note that there are multiple wings of the hospital that host an ICU, and the transplant recipients were dispersed among these various ICU locations within the hospital; therefore, we excluded the possibility of cross-infection as the source of dengue exposure. In the second week after surgery, there were continuous episodes of high-grade fever, multiple episodes of loose stools with drainage of a large volume of clear ascites (1.5 L/d), reductions in hemoglobin and platelet counts, and higher levels of liver enzymes and bilirubin. Bedside liver Doppler sonography results showed no features of concern. The patient deteriorated further after the second week. On POD16, our patient had tachycardia, respiratory distress, and hypotension. Chest radiography results suggested acute respiratory distress syndrome. Bedside echocardiography results revealed a 30% ejection fraction suggestive of cardiomyopathy. Platelet counts continued to decline, and so platelet transfusions were performed; however, severe dengue symptoms with shock (severe plasma leakage with cardiomyopathy) and acute respiratory distress syndrome remained evident. The patient was treated in the ICU with sedation and ventilation, intravenous fluids, inotropic support, intravenous hydrocortisone, and cessation of tacrolimus treatment. Thereafter, the patient improved rapidly over a period of 5 days and was extubated on POD21. After week 3, the patient had been restored to a standard diet and the immunosup-pression regimen was restarted. However, the ascites fluid had changed to a milky appearance and output increased to more than 1.5 L/d. Results from biochemical analysis suggested chylous ascites with triglyceride content of 415.6 mg/dL (<110 mg/dL) and serum ascites albumin gradient of 2.27. The total leukocyte count in the drainage fluid was 100 cells/mL, and culture results were negative for infectious agents. Octreotide was started, and a low-fat, high-protein, medium-chain triglyceride-based diet was initiated. Within a week, the ascites resolved completely. Explant histopathology suggested Wilson disease. The patient was discharged subsequently on tacrolimus, prednisolone (Wysolone), and mycop-henolate mofetil. On follow-up at 3 months, her improvement was sustained.

Dengue fever is hyperendemic in northern India with frequent outbreaks characterized by ever-changing serotypes of dengue virus. Donor-derived disease transmission is reported to occur in less than 1% of transplant cases.⁴ In our case, the brain-dead donor had traumatic severe head injury with no history of fever, and the donor’s blood parameters on admission were within reference limits, with platelet count of 180 000 cells/mL. Preoperatively, the recipient had thrombocytopenia and leukopenia that were likely caused by azathioprine-induced myelosuppression.⁵ After transplant, platelets gradually improved over the first week, after which the patient became symptomatic with high-grade fever, loose stools with sudden and rapid reduction of platelets, higher liver enzyme levels, and higher bilirubin levels ((Figure 1) and (Figure 2)). Differentials involving sepsis, COVID-19 infection, cytomegalovirus infection, and acute cellular rejection were considered; however, tests for dengue virus and malaria were also performed in response to intermittent high-grade fever and the known endemicity of these to agents. Test results for dengue NS1 antigen and IgM antibody were positive on POD8, whereas the other workup test results were negative, including blood, drainage fluid, urine, and sputum cultures. The absence of retro-orbital pain, joint pain, and myalgia could be the result of an active regimen of immunosuppression, which can reduce such inflammatory symptoms.⁶ The recipients of the kidney allografts also developed symptoms during the same period, and their test results were also positive for both dengue NS1 antigen and IgM antibody. Because multiple recipients had developed posttransplant dengue infections, we strongly suspected that the donor common to all 3 recipients had subclinical infection on admission via mosquito bite prior to arrival to the hospital. Dengue testing is not a part of our institution’s routine evaluation of donors for solid-organ transplant; also, even if there were knowledge of postoperative dengue-positive status of a recipient, no pretransplant serum samples were retained. The incubation period of dengue virus ranges between 4 and 10 days, and most cases become symptomatic in 2 to 4 days.⁶ Thus, given the clinical timelines of symptom presentation in the liver and kidney transplant recipients, the possibility of dengue transmission from donor to recipient is highly plausible. The possibility of mosquito-borne virus transmission to recipients within the hospital or from the community was also explored; however, the recipients had been immediately transferred to one of several ICU facilities after transplant, so it was highly unlikely that mosquito-borne transmission to each recipient was the common cause of dengue virus infection. However, we could not prove the transmission of dengue from deceased donor to recipients, because neither donor nor recipient pretransplant serum samples were available. The epidemiological exposure to dengue infection of the donor can only be attributed to the endemic nature of dengue fever during the months of October and November in northern India, particularly Chandigarh, which was the location of clinic. The deceased donor did not have thrombocytopenia or any other symptomatic history suggestive of dengue fever. Retrospectively, it was possible that the donor was exposed to dengue virus during a period that predated the viremia phase. A total of only 5 cases of dengue transmission via liver transplant have been previously reported worldwide (4 from living donors and 1 from a deceased donor); our patient is the sixth case overall and the second case of a DDLT recipient. It is notable that our patient and the previous DDLT recipient have both survived. The clinical course of dengue infection in immunocompromised patients is not well understood.⁷ There have been additional reports of severe cases of dengue fever in renal transplant recipients.⁷ In the case reports summarized in (Table1), clinical symptoms of dengue infection developed within 1 week after transplant, and the likely cause was active viral replication in blood, with fever and thrombocytopenia as the most common presentation. Coexisting immunosuppression may contribute to higher viremia and altered immune response in transplant recipients, which may lead to greater severity of dengue infection. In our case, clinical deterioration of the patient, expressed as high-grade fever, diarrhea, respiratory distress, hypotension, and ascites, began at the end of week 2, with lower platelet counts, diminished hemoglobin, and rising levels of bilirubin. The ICU care with organ support and cessation of immunosuppression during the critical phase of severe dengue infection were factors that facilitated rapid recovery. A high index of suspicion is essential to ensure a proper diagnosis of dengue infection, and a misdiagnosis of acute rejection in a case such as ours would likely prove detrimental and lead to further aggravated dysfunction of the allograft; therefore, suspension of immunosuppression during the critical phase is essential for successful treatment of this condition. The published case reports summarized in (Table1) are characterized by severe symptoms of dengue infection and associated high levels of liver enzymes. There were no rejections reported among these cases, but 2 of the living donor transplant recipients died due to severe dengue with multiorgan failure. Among the reported DDLT recipients, one from Columbia and another reported by us, both have survived and are recovering well. With regard to living donor liver transplant, which is a planned elective procedure, it is not time bound, so transplant can be delayed if the donor or recipient are symptomatic for any infection.¹⁴ However, in cases of explant from a deceased donor, especially in endemic regions, there may not be sufficient time to perform extensive evaluation of the donor to assess details such as dengue infection.. The decision to continue with organ transplant from a dengue-positive donor remains controversial, and there are no established guidelines for these cases. However, there are reports that recommend organ use according to individual case analysis¹⁵ with exclusion of patients with positive results for NS1 antigen and proceeding with transplant for only those patients whose test results are positive for IgG antibodies and negative for NS1 antigen.¹² Dengue infection and transmission can be monitored with antibody serology tests, NS1 antigen tests, and NAT, and the sensitivity and specificity of these tests are variable according to the phase of the disease. The NS1 antigen is highly preserved through various dengue serotypes and is detectable in acute viremia, and there is a rapid test for the NS1 antigen that can produce useful test results at early stages of disease, perhaps before clinical symptoms develop. Anti-dengue IgM and IgG tests can differentiate between primary and secondary infection in the acute phase of disease, with an IgM-to-IgG ratio of 1.2 to 1.4 as the cutoff for variations between different laboratories. A major limitation of antibody serology tests in dengue-endemic areas is the tendency of antibodies to persist in a population as a result of previous infections or vaccinations, which may diminish the specificity of serology-based tests. Also, cross-reactivity with related flaviviruses (eg, yellow fever, Zika virus) can cause false-positive results with serology-based tests, which therefore may be best reserved for use in nonendemic areas for dengue. Combined IgM and NS1 antigen detection has high sensitivity during both the early phase and the late phase of dengue infection. The kits for these tests have a low financial cost, an overall accuracy of nearly 80%, and proven stability during prolonged storage at high temperature, which is a crucial attribute in a resource-limited setting.¹⁶ These tests for NS1 antigen and IgG/IgM produce results within 15 to 20 minutes with very high sensitivity and specificity with regard to primary infections (NS1, sensitivity 92% and specificity 98%; IgG/IgM, sensitivity 94% and specificity 96%). However, in secondary infections, the sensitivity of these tests maybe closer to 80%.² Most tropical countries do not have viral NAT confirmation on regular basis,¹ because there are significant barriers to its use as a diagnostic test, including a short window of opportunity during the viremic period, high risk of contamination, and reliance on expensive laboratory equipment. With variable sensitivity of 50% to 99% and high specificity of 99% to 100%, serotype analysis is a useful tool that may play an important role to predict future outbreaks, establish the periodicity of dengue outbreaks, and promote vaccine development.¹⁶

In dengue-endemic areas like India, tests for NS1 antigen during dengue outbreaks and annual periods of high transmission should be a part of the donor evaluation protocol in solid-organ transpla-ntation. The NS1 antigen test may allow detection of asymptomatic carriers and prevent late recipient infections and thereby reduce morbidity and associated mortality. This case highlights the importance of a high index of suspicion for dengue infection in the presence of graft dysfunction in dengue-endemic areas.

Volume: 20 Issue: 10 October 2022

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