Adenovirus Hepatitis: Clinicopathologic Analysis of 12 Consecutive Cases From a Single Institution

Epidemiology of Adenovirus Infection in Hospitalized Children in the United States From 1997 to 2019

OBJECTIVE

The study aimed to explore the prevalence, clinical features, resource utilization, temporal trends and outcomes associated with adenoviral infections in hospitalized children.

METHODS

A retrospective analysis using the Healthcare Cost and Utilization Project's Kids' Inpatient Database from 1997 to 2019 was performed. Children aged 29 days to 17 years with adenoviral infection were selected. Chi-square, Kruskal-Wallis tests, linear trend analysis and multivariable analysis were used for data analysis.

RESULTS

A total of 40,135 children under 18 years of age with adenoviral infection were discharged in the United States with an overall prevalence of 18.9 per 10,000 discharges and 6.9 children per 100,000 population. By linear trend analysis, the hospitalization rate has significantly increased with the highest prevalence in 2019. Adenoviral infection was more prevalent in Black children, in winter months, in the Midwest region, in children with government insurance and in the lowest income quartile. The majority (85%) of adenovirus-related hospitalizations occurred under 6 years of age. Mechanical ventilation, extracorporeal membrane oxygenation support, acute kidney injury and liver failure were documented in 11.9%, 0.4%, 2.7% and 0.4%, respectively. The overall case fatality rate was 1.4%, which decreased from 1997 to 2019 (P < 0.05). By regression analysis, an increased mortality rate was associated with the need for mechanical ventilation, the presence of complex chronic conditions, immune deficiency, central nervous system infection and pneumonia/bronchiolitis.

CONCLUSIONS

Most human adenovirus infections occur in children under 6 years of age and cause mild illness. Human adenovirus can lead to serious illness in children with complex chronic conditions and immune deficiency conditions.

Viral meningoencephalitis in pediatric solid organ or hematopoietic cell transplant recipients: a diagnostic and therapeutic approach

Neurologic complications, both infectious and non-infectious, are frequent among hematopoietic cell transplant (HCT) and solid organ transplant (SOT) recipients. Up to 46% of HCT and 50% of SOT recipients experience a neurological complication, including cerebrovascular accidents, drug toxicities, as well as infections. Defects in innate, adaptive, and humoral immune function among transplant recipients predispose to opportunistic infections, including central nervous system (CNS) disease. CNS infections remain uncommon overall amongst HCT and SOT recipients, compromising approximately 1% of total cases among adult patients. Given the relatively lower number of pediatric transplant recipients, the incidence of CNS disease amongst in this population remains unknown. Although infections comprise a small percentage of the neurological complications that occur post-transplant, the associated morbidity and mortality in an immunosuppressed state makes it imperative to promptly evaluate and aggressively treat a pediatric transplant patient with suspicion for viral meningoencephalitis. This manuscript guides the reader through a broad infectious and non-infectious diagnostic differential in a transplant recipient presenting with altered mentation and fever and thereafter, elaborates on diagnostics and management of viral meningoencephalitis. Hypothetical SOT and HCT patient cases have also been constructed to illustrate the diagnostic and management process in select viral etiologies. Given the unique risk for various opportunistic viral infections resulting in CNS disease among transplant recipients, the manuscript will provide a contemporary review of the epidemiology, risk factors, diagnosis, and management of viral meningoencephalitis in these patients.

The Role of Adenovirus in Hepatitis of Unknown Etiology Among Children in Turkey, July 2022 to January 2023

BACKGROUND

In the first half of 2022, the increase in cases of severe acute hepatitis in children with no epidemiological link and unknown cause has aroused concern worldwide. In this study, we aimed to determine the frequency of adenovirus in children with hepatitis of unknown origin in Turkey.

METHODS

In this study, which was conducted with the participation of 16 centers from Turkey, between July 2022 and January 2023, 36 pediatric patients under the age of 18 who met the definition of acute hepatitis were included.

RESULTS

Twenty (55,6%) of patients were female and 16 (44,4%) were male, with a mean age of 41.55 ± 39.22 (3-192) months. The most common symptoms were fever (66.7%), weakness (66.7%), loss of appetite (66.7%), fatigue (61.1%), vomiting (61.1%), and diarrhea (47.2%). Six (16 %) children had acute hepatic failure. Eight of the 15 children (46%) had respiratory viral infections (rhinovirus/enterovirus, n = 4; rhinovirus + parainfluenza, n = 1; parainfluenza, n = 1, SARS-CoV-2 n = 2). Adenovirus was detected in 16 (44%) patients. Adenovirus and coinfections were detected in 7 patients. History of diarrhea and fatigue in the last month was significantly higher in the adenovirus group ( P = 0.023 and 0.018). One child who had both adenovirus and rhinovirus infection required liver transplantation; all others recovered with supportive care.

CONCLUSION

There were no deaths in our series; however, the number of cases, etiology, and severity of the clinical course may have differed between countries owing to differences in case definitions, laboratory facilities, or regional genetic differences.

Clinicopathological characteristics of 3 probable pediatric cases with acute severe hepatitis of unknown aetiology

Background

Acute severe hepatitis with unknown aetiology in children (ASHep-UA) has become a global health alert. This article reported clinicopathological characteristics of 3 probable ASHep-UA cases.

Methods

We respectively collected serological data and liver biopsies of 3 suspected cases of ASHep-UA. Neutralizing antibodies titer for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variants were determined by virus neutralization test (VNT). Histological assessment, immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) for cytomegalovirus (CMV), Epstein-Barr virus (EBV), human adenoviruses (HAdV), adeno-associated virus (AAV2), human herpes virus type 6 (HHV-6) were performed to identify possible aetiologies.

Results

Remarkable elevation of transaminase (median ALT level, 1100 IU/liter; median AST level, 500 IU/liter) were revealed with undetectable hepatitis A-E and non-hepatotropic virus in both sera and tissues. Weakness, jaundice, pale stools and splenomegaly were observed. Interestingly, two individuals had SARS-CoV-2 Omicron variants infection. Histologically, moderate or severe lobular necroinflammation, active interface hepatitis and portal inflammatory infiltrate with lymphocytic, plasma cells, neutrophils and eosinophilic cells were noted.

Conclusions

The exact aetiology of ASHep-UA was still unknown. By reporting the 3 probable cases, we expect to enrich the clinical experience in diagnosis and treatment of ASHep-UA as well as the pathological characteristics.

A Report on a Nationwide Surveillance System for Pediatric Acute Hepatitis of Unknown Etiology in Korea

BACKGROUND

Several cases of pediatric acute hepatitis of unknown etiology related to adenoviral infections have been reported in Europe since January 2022. The aim of this study was to compare the incidence, severity, possible etiology, and prognosis of the disease with those in the past in Korea.

METHODS

The surveillance group collected data between May and November 2022 using a surveillance system. Acute hepatitis of unknown etiology was defined in patients aged < 16 years with a serum transaminase level > 500 IU/L, not due to hepatitis A-E or other underlying causes. For comparison, data from 18 university hospitals were retrospectively collected as a control group between January 2021 and April 2022.

RESULTS

We enrolled 270 patients (mean age, 5 years). The most common symptom was fever. However, the incidence was similar between 2021 and 2022. Liver function test results, number of patients with acute liver failure (ALF), liver transplantation (LT), death, and adenovirus detection rates did not differ between the two groups. None of the adenovirus-positive patients in either group experienced ALF, LT, or death. In the surveillance group, adenovirus-associated virus-2 was detected in four patients, one of whom underwent LT. Patients with an unknown etiology showed significantly higher bilirubin levels, a lower platelet count, and a higher LT rate than patients with a possible etiology.

CONCLUSION

The incidence of pediatric acute hepatitis of unknown etiology and adenovirus detection rate have not increased in Korea.

Multi-omic analysis characterizes molecular susceptibility of receptors to SARS-CoV-2 spike protein

In the post COVID-19 era, new SARS-CoV-2 variant strains may continue emerging and long COVID is poised to be another public health challenge. Deciphering the molecular susceptibility of receptors to SARS-CoV-2 spike protein is critical for understanding the immune responses in COVID-19 and the rationale of multi-organ injuries. Currently, such systematic exploration remains limited. Here, we conduct multi-omic analysis of protein binding affinities, transcriptomic expressions, and single-cell atlases to characterize the molecular susceptibility of receptors to SARS-CoV-2 spike protein. Initial affinity analysis explains the domination of delta and omicron variants and demonstrates the strongest affinities between BSG (CD147) receptor and most variants. Further transcriptomic data analysis on 4100 experimental samples and single-cell atlases of 1.4 million cells suggest the potential involvement of BSG in multi-organ injuries and long COVID, and explain the high prevalence of COVID-19 in elders as well as the different risks for patients with underlying diseases. Correlation analysis validated moderate associations between BSG and viral RNA abundance in multiple cell types. Moreover, similar patterns were observed in primates and validated in proteomic expressions. Overall, our findings implicate important therapeutic targets for the development of receptor-specific vaccines and drugs for COVID-19.

Solved the enigma of pediatric severe acute hepatitis of unknown origin?

Hepatitis is an inflammation of the liver whose etiology is very heterogeneous. The most common cause of hepatitis is viral infections from hepatotropic viruses, including hepatitis A, B, C, D and E. However, other factors such as infections from other agents, metabolic disorders, or autoimmune reactions can also contribute to hepatitis, albeit to a lesser extent. On April 5, 2022, the United Kingdom Health Security Agency alerted the World Health Organization (WHO) on the increased incidence of severe acute hepatitis of unknown causes (not A-E) in previously healthy young children, with symptoms of liver failure that in some cases required liver transplantation. By July 2022, 1,296 cases were reported in 37 countries. Acute hepatitis of unknown causes is not an exceptional phenomenon: in fact, it represents more than 30% of cases of acute hepatitis in children, however in the present instance the large proportion of severe cases was surprising and alarming (6% of liver transplants and almost 3% mortality). Multiple hypotheses have been proposed to explain the etiology of such higher proportion of acute hepatitis, including their co-occurrence in the context of COVID-19 pandemic. This is a review of the history of a clinical threat that has put in check a world health care system highly sensitized by the current COVID-19 pandemics, and that it looks like has ended with the arguments that the severe acute pediatric hepatitis is caused by Adeno-associated virus 2 (AAV2) infection associated with a coinfection with a helper virus (human Adenovirus HAdV or human herpesvirus 6) in susceptible children carrying HLA-class II antigen HLA-DRB1*04:01.

Liver Pathology After Hematopoietic Stem Cell Transplantation

Hematopoietic stem cell transplantation is used to treat a variety of hematologic malignancies and autoimmune conditions. The immunosuppressive medications as well as other therapies used both before and after transplantation leave patients susceptible to a wide spectrum of complications, including liver injury. Causes for liver damage associated with stem cell transplantation include sinusoidal obstruction syndrome, graft-versus-host disease, iron overload, and opportunistic infection. Here, the authors review the clinical and pathological findings of these etiologies of liver injury and provide a framework for diagnosis.

Signatures of AAV-2 immunity are enriched in children with severe acute hepatitis of unknown etiology

Severe acute hepatitis of unknown etiology in children is under investigation in 35 countries. Although several potential etiologic agents have been investigated, a clear cause for the liver damage observed in these cases remains to be identified. Using VirScan, a high-throughput antibody profiling technology, we probed the antibody repertoires of nine cases of severe acute hepatitis of unknown etiology treated at Children's of Alabama and compared their antibody responses with 38 pediatric and 470 adult controls. We report increased adeno-associated dependoparvovirus A (AAV-A) breadth in cases relative to controls and adeno-associated virus 2 (AAV-2) peptide responses that were conserved in seven of nine cases but rarely observed in pediatric and adult controls. These findings suggest that AAV-2 is a likely etiologic agent of severe acute hepatitis of unknown etiology.

Lipid nanoparticle-encapsulated, chemically modified anti-adenoviral siRNAs inhibit hepatic adenovirus infection in immunosuppressed Syrian hamsters

RNA interference has demonstrated its potential as an antiviral therapy for treatment of human adenovirus (hAd) infections. The only existing viral vector-based system for delivery of anti-adenoviral artificial microRNAs available for in vivo use, however, has proven to be inefficient in therapeutic applications. In this study, we investigated the potential of stabilized small interfering RNA (siRNA) encapsulated in lipid nanoparticles (LNPs) for treatment of hepatic hAd serotype 5 (hAd5) infection in an hAd infection model using immunosuppressed Syrian hamsters. The siRNA sipTP_mod directed against the adenoviral pre-terminal protein (pTP) and containing 2'-O-methyl modifications as well as phosphorothioate linkages effectively inhibited hAd5 infection in vitro. In light of this success, sipTP_mod was encapsulated in LNPs containing the cationic lipid XL-10, which enables hepatocyte-specific siRNA transfer, and injected intravenously into hAd5-infected immunosuppressed Syrian hamsters. This resulted in a significant reduction of liver hAd5 titers, a trend toward reduced liver injury and inflammation, and reduction of viral titers in the blood and spleen compared with hAd5-infected animals that received a non-silencing siRNA. These effects were demonstrated in animals infected with low and moderate doses of hAd5. These data demonstrate that hepatic hAd5 infection can be successfully treated with anti-adenoviral sipTP_mod encapsulated in LNPs.

Liver Transaminases in Pediatric Adenovirus Infection-A Five-Year Study in Two Major Reference Centers from Romania

Human adenovirus causes infections with a very heterogeneous clinical picture, and children are often the most frequently affected group. Interest in adenovirus has increased with the 2022 outbreak of severe acute hepatitis of unknown etiology as human adenovirus was considered as one of the possible etiological agents. We conducted a retrospective study over a 5-year period in two major tertiary hospitals in the Romanian capital with the aim to characterize the clinical picture and the dynamics of liver function tests in children with confirmed adenovirus infection. The study included 1416 children with a median age of 1.1 years (IQR: 0.3, 2.3 years). Digestive symptoms were predominant in 95.2% of children, mainly diarrhea (90.5%) and vomiting (50.5%), and 38.0% had respiratory symptoms. Increased transaminases were identified in 21.5% of patients. Age over 1 year, lethargy, vomiting and dehydration significantly increased the odds of liver cytolysis independent of other risk factors such as chronic conditions or co-infections. Aspartate aminotransferase (AST) was more commonly increased compared to alanine aminotransferase (ALT). Only six children had transaminase increases above 500 U/L, three of which had co-infections with rotavirus, Epstein-Barr virus (EBV), or respiratory syncytial virus (RSV). Liver function tests should be part of routine monitoring for pediatric patients with adenovirus infection. The current study fills a gap in current knowledge related to the frequency and the extent of liver involvement in human adenovirus infection among pediatric patients.

Adenoviruses in medicine: innocuous pathogen, predator, or partner

The consequences of human adenovirus (HAdV) infections are generally mild. However, despite the perception that HAdVs are harmless, infections can cause severe disease in certain individuals, including newborns, the immunocompromised, and those with pre-existing conditions, including respiratory or cardiac disease. In addition, HAdV outbreaks remain relatively common events and the recent emergence of more pathogenic genomic variants of various genotypes has been well documented. Coupled with evidence of zoonotic transmission, interspecies recombination, and the lack of approved AdV antivirals or widely available vaccines, HAdVs remain a threat to public health. At the same time, the detailed understanding of AdV biology garnered over nearly 7 decades of study has made this group of viruses a molecular workhorse for vaccine and gene therapy applications.

[(Rare) infectious hepatitis as an important differential diagnosis of unclear hepatopathy]

BACKGROUND

Liver biopsies to determine the cause of unclear hepatopathy and acute liver failure represent a diagnostic hallmark and require close cooperation between clinicians and pathologists. The commonly acute presentation of hepatic dysfunction warrants a rapid diagnosis. Infectious causes of hepatitis may be identified by the pathologist, supporting further diagnostic and therapeutic steps.

OBJECTIVES

Rare infectious causes of hepatic dysfunction with distinct histomorphological features are presented.

MATERIALS AND METHODS

Retrospective cases of liver biopsies for evaluation of hepatic dysfunction with infection confirmed by laboratory tests were selected from the archive of the institute of pathology of TUM and evaluated for morphologic diagnostic criteria.

RESULTS AND CONCLUSIONS

Infections with adenovirus, Herpes simplex virus, Hepatitis A virus, and coxiella burnettii are rare findings in liver core biopsies but able to cause hepatic dysfunction that present with distinct histomorphologic alterations that can contribute to the identification of the causative agent. Rare infectious causes should be considered in any patient presenting with hepatic dysfunction of unknown etiology. Knowledge of the histomorphologic criteria by the pathologist is crucial to initiate further diagnostic testing and treatment.

Acute severe non-A-E-hepatitis of unknown origin in children - A 30-year retrospective observational study from north-west Germany

BACKGROUND & AIMS

The etiology of the current acute severe non-A-E hepatitis epidemic in children remains unclear. We aimed to describe the occurrence and outcomes of acute severe hepatitis in pediatric patients in North-West Germany over a period of more than 30 years and in the context of the current epidemic.

METHODS

We analyzed all cases of acute severe hepatitis in childhood, as defined by the World Health Organization, at Hannover Medical School from 1990 and at the University Hospital of Essen from 2009 to 16 May 2022. We separated cases into a historic cohort (1990-2018) and a COVID-19 era cohort (2019-2022).

RESULTS

After application of exclusion criteria, 107 patients with acute severe hepatitis were identified (2.32 cases/center/year). Annual incidence per center rose significantly from 2.2 (historic cohort until 2018) to 4.25/center/year (from 2019, p = 0.002). Of all cases, 75.7% presented with jaundice, while 53.3% had clinical signs of infection. Two cases of adenovirus were proven (2004/2016), other pathogens detected were HHV-6 (4), CMV, HSV, EBV(3). Sixty-nine patients (64.5%) met the criteria of pediatric acute liver failure, with 44 requiring liver transplantation. In the current cohort, patients with infection, gastrointestinal symptoms and higher alanine aminotransferase had a better chance of transplant-free survival, whereas hepatic encephalopathy, higher international normalized ratio and bilirubin predicted a poor outcome. Twenty-five patients developed hepatitis-associated aplastic anemia and 19 patients (17.8%) died.

CONCLUSIONS

Acute non-A-E-hepatitis in children is a rare but severe entity, often leading to acute liver failure. Clinical presentation in our current cohort resembles 2022 NAEH cases, with improved outcomes compared to historic controls. The rising incidence of NAEH in our centers since 2019, in the absence of adenoviral infection, indicates other potential triggers of similar NAEH cases.

IMPACT AND IMPLICATIONS

As the current epidemic of severe acute non-A-E-hepatitis cases in children highlights our limited understanding in the field, we aim to describe current cases, characterizing the presentation over time, and defining similarities and discrepancies before and during the COVID-19 pandemic. Our data show a rising incidence of non-A-E-hepatitis cases since the beginning of the COVID-19 pandemic. These cases were not associated with adenoviral infections, suggesting that the recently described accumulation of adenovirus infections in relationship to hepatitis is a new trigger for a known phenomenon, rather than a new disease entity. Therefore, the role of protective isolation and subsequent lack of contact with trivial infections in children during the pandemic should be the subject of further examinations. We expect our data to contribute to a better understanding of severe acute hepatitis in childhood, increased vigilance for this potentially lethal disease beyond the current epidemic, and ultimately improved clinical diagnosis and care.

A link between severe hepatitis in children and adenovirus 41 and adeno-associated virus 2 infections

Over the past few months there have been reports of severe acute hepatitis in several hundred, otherwise healthy, immunocompetent young children. Several deaths have been recorded and a relatively large proportion of the patients have needed liver transplants. Most of the cases, so far, have been seen in the UK and in North America, but it has also been reported in many other European countries, the Middle East and Asia. Most common viruses have been ruled out as a causative agent; hepatitis A virus (HAV), hepatitis B virus (HBV) and hepatitis C virus (HCV) were not detected, nor were Epstein–Barr virus (EBV), cytomegalovirus (CMV) and human immunodeficiency virus (HIV) in many cases. A small proportion of the children had been infected with SARS-CoV-2 but these seem to be in a minority; similarly, almost none of the children had been vaccinated against COVID-19. Significantly, many of the patients were infected with adenovirus 41 (HAdV-F41). Previously, HAdV-41 had not been linked to hepatitis and is usually considered to cause gastroenteritis in both immunocompetent and immunocompromised patients. In two most recent studies, adeno-associated virus 2 (AAV2) was detected in almost all patients, together with species C and F HAdVs and human herpesvirus 6B (HHV6B). Here, I discuss the possibility that a change in tropism of HAdV-41 and changes in AAV2 may be responsible for their links to acute hepatitis.

Hepatitis of unknown origin in children: Updated evidence and concise review

The rapid emergence of severe acute hepatitis across several European countries and several geographical regions in the United States has created panic among health institutions, local authorities, governmental organizations and regulatory bodies. Early reporting, stringent surveillance and supportive care can temporarily help tackle this crisis. However, definitive containment measures and management require characterization of the clinical spectrum, epidemiological assessment and extensive investigations. Furthermore, a sound management strategy requires randomized trials to explore the treatment options.

A Case Series of Children with Acute Hepatitis and Human Adenovirus Infection

BACKGROUND

Human adenoviruses typically cause self-limited respiratory, gastrointestinal, and conjunctival infections in healthy children. In late 2021 and early 2022, several previously healthy children were identified with acute hepatitis and human adenovirus viremia.

METHODS

We used International Classification of Diseases, 10th Revision, codes to identify all children (<18 years of age) with hepatitis who were admitted to Children's of Alabama hospital between October 1, 2021, and February 28, 2022; those with acute hepatitis who also tested positive for human adenovirus by whole-blood quantitative polymerase chain reaction (PCR) were included in our case series. Demographic, clinical, laboratory, and treatment data were obtained from medical records. Residual blood specimens were sent for diagnostic confirmation and human adenovirus typing.

RESULTS

A total of 15 children were identified with acute hepatitis - 6 (40%) who had hepatitis with an identified cause and 9 (60%) who had hepatitis without a known cause. Eight (89%) of the patients with hepatitis of unknown cause tested positive for human adenovirus. These 8 patients plus 1 additional patient referred to this facility for follow-up were included in this case series (median age, 2 years 11 months; age range, 1 year 1 month to 6 years 5 months). Liver biopsies indicated mild-to-moderate active hepatitis in 6 children, some with and some without cholestasis, but did not show evidence of human adenovirus on immunohistochemical examination or electron microscopy. PCR testing of liver tissue for human adenovirus was positive in 3 children (50%). Sequencing of specimens from 5 children showed three distinct human adenovirus type 41 hexon variants. Two children underwent liver transplantation; all the others recovered with supportive care.

CONCLUSIONS

Human adenovirus viremia was present in the majority of children with acute hepatitis of unknown cause admitted to Children's of Alabama from October 1, 2021, to February 28, 2022, but whether human adenovirus was causative remains unclear. Sequencing results suggest that if human adenovirus was causative, this was not an outbreak driven by a single strain. (Funded in part by the Centers for Disease Control and Prevention.).

Human adenoviruses: A suspect behind the outbreak of acute hepatitis in children amid the COVID-19 pandemic

As of 10 May 2022, at least 450 cases of pediatric patients with acute hepatitis of unknown cause have been reported worldwide. Human adenoviruses (HAdVs) have been detected in at least 74 cases, including the F type HAdV41 in 18 cases, which indicates that adenoviruses may be associated with this mysterious childhood hepatitis, although other infectious agents or environmental factors cannot be excluded. In this review, we provide a brief introduction of the basic features of HAdVs and describe diseases caused by different HAdVs in humans, aiming to help understand the biology and potential risk of HAdVs and cope with the outbreak of acute child hepatitis.

Acute hepatitis of unknown origin in children: Behind the statistics

Since April 2022, the world has been witnessing a rapidly spreading outbreak of acute hepatitis of unknown origin in children < 16 years old that has affected several countries around the world. Most of the cases have presented with the clinical picture of severe hepatitis that has led to resorting to liver transplantation in several cases. Despite the numerous theories that have been suggested on the possible underlying etiologies of the outbreak, an association with hepatitis A-E viruses and a link to COVID-19 vaccines have been excluded. Adenovirus serotype 41 has been detected in numerous cases, which makes it the most likely underlying cause of the disease. Nevertheless, other hypotheses are being investigated to justify the severity of the clinical picture, which is not typical of this type of virus. This review aims to summarize the current knowledge about the outbreak, highlight the suggested working hypotheses, and report the public health measures undertaken to tackle the outbreak.

Severe acute hepatitis in children with unknown aetiology, etiology analysis and the next action

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MIS-C and severe acute hepatitis might share the common pathogenic mechanism.

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SARS-CoV-2 persistence throughout multiorgan and tissues.

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Relationship between COVID-19 vaccines and severe acute hepatitis worth investigating.

Interim Analysis of Acute Hepatitis of Unknown Etiology in Children Aged <10 Years - United States, October 2021-June 2022

On April 21, 2022, CDC issued a health advisory^† encouraging U.S. clinicians to report all patients aged <10 years with hepatitis of unknown etiology to public health authorities, after identification of similar cases in both the United States (1) and Europe.^§ A high proportion of initially reported patients had adenovirus detected in whole blood specimens, thus the health advisory encouraged clinicians to consider requesting adenovirus testing, preferentially on whole blood specimens. For patients meeting the criteria in the health advisory (patients under investigation [PUIs]), jurisdictional public health authorities abstracted medical charts and interviewed patient caregivers. As of June 15, 2022, a total of 296 PUIs with hepatitis onset on or after October 1, 2021, were reported from 42 U.S. jurisdictions. The median age of PUIs was 2 years, 2 months. Most PUIs were hospitalized (89.9%); 18 (6.1%) required a liver transplant, and 11 (3.7%) died. Adenovirus was detected in a respiratory, blood, or stool specimen of 100 (44.6%) of 224 patients.^¶ Current or past infection with SARS-CoV-2 (the virus that causes COVID-19) was reported in 10 of 98 (10.2%) and 32 of 123 (26.0%) patients, respectively. No common exposures (e.g., travel, food, or toxicants) were identified. This nationwide investigation is ongoing. Further clinical data are needed to understand the cause of hepatitis in these patients and to assess the potential association with adenovirus.

Pediatric Acute Liver Failure: A Clinicopathological Perspective

Pediatric acute liver failure (PALF) is a life-threatening disorder characterized by acute hepatocellular injury occurring in children without recognized underlying liver disease. The clinicopathologic evaluation of PALF requires a different approach from that in adults. The diagnostic considerations differ depending on the age, personal and family history, geographical region, and clinical presentation. Distinct entities such as gestational alloimmune liver disease, herpes simplex virus infection, and metabolic disorders should be considered in neonates with acute liver failure, while acetaminophen toxicity and autoimmune hepatitis are more frequently seen in older children and adolescents. An identified cause for PALF despite a negative complete evaluation (indeterminate) is lacking in 30 to 50% of cases. Although not routinely performed in the setting of PALF, liver biopsy may be helpful in assessing the etiology, potential mechanisms of injury, determining the appropriateness of liver transplantation, and prognostication of the patients. In this article, we review the clinicopathologic characteristics of PALF with an emphasis on general approach of pathologic evaluation and histopathologic characteristic of selected entities.

Fulminant Adenoviral-Induced Hepatitis in Immunosuppressed Patients

Human adenovirus (HAdV) can often lead to fulminant hepatitis in immunocompromised patients, mostly after reactivation of HAdV. Different risk factors, e.g., transplantation and chemotherapy, increase the risk of developing a HAdV hepatitis. We retrospectively analyzed three patients who showed the characteristics of a HAdV hepatitis observed in disseminated disease. In addition to PCR, diagnosis could be proven by pathology, CT scan, and markedly elevated transaminases. All patients had a hemato-oncologic underlying disease. Two had received a stem-cell transplant, and one was under chemotherapy including rituximab. Despite therapy with cidofovir, all patients died. As the incidence of HAdV hepatitis is low, diagnosis may be easily overlooked. No treatment approaches have yet been established. HAdV hepatitis should be considered as a differential diagnosis, especially when risk factors are present. To avoid dissemination, treatment should be initiated as soon as possible.

Pediatric Acute Severe Hepatitis of Unknown Origin: What is New?

Globally, there are emerging cases of acute severe hepatitis of unknown origin in children. These cases have gathered increasing attention, owing to the development of acute liver failure in some cases that resulted in liver transplantation. This review briefly summarizes the outbreak and diagnostic criteria of the disease. We further discuss the possible causes and related mechanisms underlying its occurrence and progression, and analyze the challenges in management. Finally, this review emphasizes patient management in clinical settings and a combination of efforts to unmask the disease.

Severe Acute Hepatitis of Unknown Etiology in Children: Is It Caused by Pathogens or Non-infectious Factors?

Recently, an outbreak of severe acute hepatitis of unknown etiology in children has been reported in more than 27 countries worldwide. However, information on its prevalence in different countries and regions is still lacking. The evidence is suggestive of a potential viral infection, but this has not been fully confirmed. Cases of this disease have been reported in children, mainly in those younger than 5 years old. The reason for the age range of the disease requires further investigation.

Suspected Adenovirus Causing an Emerging HEPATITIS among Children below 10 Years: A Review

In October 2021, a case of acute hepatic failure without any known cause was identified in the United States of America. Upon further investigation, other children aged 1–6 years were reported to have the same liver failure, and some of them were positive for adenovirus 41 type F. On 21 April 2022, the Centers for Disease Control and Prevention (CDC) released an alert after 74 cases were identified in United Kingdom (UK) between 5 and 8 April in children below 10 years of age, some of whom were also found to be positive for SARS-CoV-2. All the patients showed symptoms such as vomiting, diarrhea, jaundice, and abdominal pain. The patients’ liver enzymes were remarkably increased. A total of 650 cases had been reported from 33 countries as of 27 May 2022, among which 222 cases were reported in the UK alone. No connection with SARS-CoV-2 or its vaccine has been found so far. However, the suspected cause is adenovirus, including its genomic variations, because its pathogenesis and laboratory investigations have been positively linked. Until further evidence emerges, hygiene precautions could be helpful to prevent its spread.

Human Adenovirus Associated Hepatic Injury

Human adenovirus (HAdV) is a common virus, but the infections it causes are relatively uncommon. At the same time, the methods for the detection of HAdV are varied, among which viral culture is still the gold standard. HAdV infection is usually self-limited but can also cause clinically symptomatic in lots of organs and tissues, of which human adenovirus pneumonia is the most common. In contrast, human adenovirus hepatitis is rarely reported. However, HAdV hepatitis has a high fatality rate once it occurs, especially in immunocompromised patients. Although human adenovirus hepatitis has some pathological and imaging features, its clinical symptoms are not typical. Therefore, HAdV hepatitis is not easy to be found in the clinic. There are kinds of treatments to treat this disease, but few are absolutely effective. In view of the above reasons, HAdV hepatitis is a disease that is difficult to be found in time. We reviewed and summarized the previously reported cases, hoping to bring some relatively common characteristics to clinicians, so as to facilitate early detection, early diagnosis, and early treatment of patients.

Current status of human adenovirus infection in China

BACKGROUND

Outbreaks of severe, acute hepatitis among children have recently attracted global attention. The pathogen causing the outbreak remains unknown, but there is growing evidence that it may be associated with human adenovirus (HAdV).

DATA SOURCES

A review of adenovirus-related clinical studies, epidemiological studies, etiological studies, and case reports was conducted by reviewers independently.

RESULTS

HAdV can cause a wide variety of clinical symptoms. In the Mainland of China, HAdV infection accounts for 5.8%-13% of patients with acute respiratory infections, and these infections are mainly caused by species B, C, and E of HAdV. For acute conjunctivitis, 39.8%-74.9% of sporadic cases were infected by B and D species of HAdV. Outbreaks of keratoconjunctivitis and pharyngoconjunctival fever related to HAdV infection could be found throughout the country. In pediatric patients with acute gastroenteritis, HAdV-41 was the predominant HAdV type, followed by HAdV species B and C. Several types of HAdV, including HAdV-5, HAdV-7, HAdV-1, and HAdV-2, have previously been reported as potential pathogens associated with HAdV hepatitis in immunocompromised patients. However, few HAdV-related hepatitis cases have been reported in China to date.

CONCLUSIONS

There are no systematic surveillance and clinical studies on HAdV hepatitis in China. Therefore, it is imperative to establish a nationwide HAdV virological surveillance system to collect relevant clinical, epidemiological and virological surveillance data and risk factor information as soon as possible to assess the potential risk of HAdV hepatitis among children.

Acute severe hepatitis outbreak in children: A perfect storm. What do we know, and what questions remain?

During the first half of 2022, the World Health Organization reported an outbreak of acute severe hepatitis of unknown aetiology (AS-Hep-UA) in children, following initial alerts from the United Kingdom (UK) where a cluster of cases was first observed in previously well children aged <6 years. Sporadic cases were then reported across Europe and worldwide, although in most countries incidence did not increase above the expected baseline. There were no consistent epidemiological links between cases, and microbiological investigations ruled out known infectious causes of hepatitis. In this review, we explore the evidence for the role of viral infection, superimposed on a specific host genetic background, as a trigger for liver pathology. This hypothesis is based on a high prevalence of Human Adenovirus (HAdV) 41F in affected children, together with metagenomic evidence of adeno-associated virus (Adeno-associated viruses)-2, which is a putative trigger for an immune-mediated liver injury. Roles for superantigen-mediated pathology have also been explored, with a focus on the potential contribution of SARS-CoV-2 infection. Affected children also had a high frequency of the MHC allele HLA-DRB1*04:01, supporting an immunological predisposition, and may have been vulnerable to viral coinfections due to disruption in normal patterns of exposure and immunity as a result of population lockdowns during the COVID-19 pandemic. We discuss areas of ongoing uncertainty, and highlight the need for ongoing scrutiny to inform clinical and public health interventions for this outbreak and for others that may evolve in future.

Adenovirus: Epidemiology, Global Spread of Novel Types, and Approach to Treatment

Adenoviruses (AdVs) are DNA viruses that typically cause mild infections involving the upper or lower respiratory tract, gastrointestinal tract, or conjunctiva. Rare manifestations of AdV infections include hemorrhagic cystitis, hepatitis, hemorrhagic colitis, pancreatitis, nephritis, or meningoencephalitis. AdV infections are more common in young children, due to lack of humoral immunity. Epidemics of AdV infection may occur in healthy children or adults in closed or crowded settings (particularly military recruits). The vast majority of cases are self-limited. However, the clinical spectrum is broad and fatalities may occur. Dissemination is more likely in patients with impaired immunity (e.g., organ transplant recipients, human immunodeficiency virus infection). Fatality rates for untreated severe AdV pneumonia or disseminated disease may exceed 50%. More than 100 genotypes and 52 serotypes of AdV have been identified and classified into seven species designated HAdV-A through -G. Different types display different tissue tropisms that correlate with clinical manifestations of infection. The predominant types circulating at a given time differ among countries or regions, and change over time. Transmission of novel strains between countries or across continents and replacement of dominant viruses by new strains may occur. Treatment of AdV infections is controversial, as prospective, randomized therapeutic trials have not been done. Cidofovir has been the drug of choice for severe AdV infections, but not all patients require treatment. Live oral vaccines are highly efficacious in reducing the risk of respiratory AdV infection and are in routine use in the military in the United States but currently are not available to civilians.

Adenovirus vector-attributed hepatotoxicity blocks clinical application in gene therapy

Adenoviruses (Ads), common self-limiting pathogens in humans and animals, usually cause conjunctivitis, mild upper respiratory tract infection or gastroenteritis in humans and hepatotoxicity syndrome in chickens and dogs, posing great threats to public health and livestock husbandry. Artificially modified Ads, which wipe out virulence-determining genes, are the most frequently used viral vectors in gene therapy, and some Ad vector (AdV)-related medicines and vaccines have been licensed and applied. Inherent liver tropism enables AdVs to specifically deliver drugs/genes to the liver; however, AdVs are closely associated with acute hepatotoxicity in immunocompromised individuals, and the side effects of AdVs, which stimulate a strong inflammatory reaction in the liver and cause acute hepatotoxicity, have largely limited clinical application. Therefore, this review systematically elucidates the intimate relationship between AdVs and hepatotoxicity in terms of virus and host and precisely illustrates the accumulated understanding in this field over the past decades. This review demonstrates the liver tropism of AdVs and molecular mechanism of AdV-induced hepatotoxicity and looks at the studies on AdV-mediated animal hepatotoxicity, which will undoubtedly deepen the understanding of AdV-caused liver injury and be of benefit in the further safe development of AdVs.

Hepatic Manifestations of Nonhepatotropic Infectious Agents Including Severe Acute Respiratory Syndrome Coronavirus-2, Adenovirus, Herpes Simplex Virus, and Coxiella burnetii

Nonhepatotropic viruses such as adenovirus, herpes simplex virus, flaviviruses, filoviruses, and human herpes virus, and bacteria such as Coxiella burnetii, can cause liver injury mimicking acute hepatitis. Most of these organisms cause a self-limited infection. However, in immunocompromised patients, they can cause severe hepatitis or in some cases fulminant hepatic failure requiring an urgent liver transplant. Hepatic dysfunction is also commonly seen in patients with severe acute respiratory syndrome coronavirus-2 infection. Patients with preexisting liver diseases are likely at risk for severe coronavirus disease 2019 (COVID-19) and may be associated with poor outcomes.

Detection of adenovirus hepatitis and acute liver failure in allogeneic hematopoietic stem cell transplant patients

Human adenovirus (HAdV) is an important cause of the common cold and epidemic keratoconjunctivitis in immunocompetent individuals. In immunocompromised patients, HAdV can sometimes cause severe infection such as cystitis, gastroenteritis, pneumonia, encephalitis, hepatitis, or disseminated disease, resulting in significant morbidity and also mortality. In particular, severe cases have been reported in patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Indeed HAdV has been recognized as a pathogen that requires careful monitoring in allo-HSCT patients. While HAdV hepatitis leading to severe acute liver failure is rare, such liver failure progresses rapidly and is often fatal. Unfortunately, HAdV hepatitis has few characteristic symptoms and physical findings, which makes it difficult to promptly confirm and start treatment. We report here four cases of HAdV hepatitis after allo-HSCT and their autopsy findings.

The grim reaper evading modern medicine: aspergillosis, adenovirus, and Hodgkin lymphoma

Illustrative cases of diseases that are difficult to suspect and diagnose can serve as useful reminders. Invasive pulmonary aspergillosis and adenovirus hepatitis are two such diseases, both revealed by autopsy in this case of Hodgkin lymphoma refractory to chemotherapy treated with allogeneic hematopoietic stem cell transplantation complicated by these two fatal infections. This patient was cured of Hodgkin lymphoma, Clostridioides difficile colitis and thrombotic thrombocytopenic purpura using the marvels of modern medicine. This case illustrates many features of aspergillosis and adenovirus hepatitis, shows the value of autopsy in revealing diagnoses, and illustrates the limits of modern medicine, which should serve as a mental spur in our efforts to advance medical science, to try to defeat the numerous demons of disease, who seem to keep outwitting us.

Approach to infection and disease due to adenoviruses in solid organ transplantation

PURPOSE OF REVIEW

Adenoviruses are an important cause of morbidity and mortality of solid organ transplant patients and remain a clinical challenge with regard to diagnosis and treatment. In this review, we provide an approach to identification and classification of adenovirus infection and disease, highlight risk factors, and outline management options for adenovirus disease in solid organ transplant patients.

RECENT FINDINGS

Additional clinical data and pathologic findings of adenovirus disease in different organs and transplant recipients are known. Unlike hematopoietic cell transplant recipients, adenovirus blood PCR surveillance and preemptive therapy is not supported in solid organ transplantation. Strategies for management of adenovirus disease continue to evolve with newer antivirals, such as brincidofovir and adjunctive immunotherapies, but more studies are needed to support their use.

SUMMARY

Distinguishing between adenovirus infection and disease is an important aspect in adenovirus management as treatment is warranted only in symptomatic solid organ transplant patients. Supportive care and decreasing immunosuppression remain the mainstays of management. Cidofovir remains the antiviral of choice for severe or disseminated disease. Given its significant nephrotoxic effect, administration of probenecid and isotonic saline precidofovir and postcidofovir infusion is recommended.

The Adenovirus Death Protein - a small membrane protein controls cell lysis and disease

Human adenoviruses (HAdVs) cause widespread acute and persistent infections. Infections are usually mild and controlled by humoral and cell-based immunity. Reactivation of persistently infected immune cells can lead to a life-threatening disease in immunocompromised individuals, especially children and transplant recipients. To date, no effective therapy or vaccine against HAdV disease is available to the public. HAdV-C2 and C5 are the best-studied of more than 100 HAdV types. They persist in infected cells and release their progeny by host cell lysis to neighbouring cells and fluids, a process facilitated by the adenovirus death protein (ADP). ADP consists of about 100 amino acids and harbours a single membrane-spanning domain. It undergoes post-translational processing in endoplasmic reticulum and Golgi compartments, before localizing to the inner nuclear membrane. Here, we discuss the current knowledge on how ADP induces membrane rupture. Membrane rupture is essential for both progression of disease and efficacy of therapeutic viruses in clinical applications, in particular oncolytic therapy.

The Role of Emerging and Neglected Viruses in the Etiology of Hepatitis

PURPOSE OF REVIEW

In this review, we present the overview of emerging and neglected viruses associated with liver involvement.

RECENT FINDINGS

Hepatitis E virus (HEV) emerged in the last two decades, causing hepatitis in many parts of the world. Moreover, liver involvement was also described in some emerging arboviral infections. Many reports showed dengue-associated liver injury; however, chikungunya, West Nile, tick-borne encephalitis, and Zika virus are rarely associated with clinically manifest liver disease. In addition, some neglected highly prevalent viruses such as adenoviruses and parvovirus B19 are capable of causing hepatitis in specific population groups. Anelloviruses (torque teno virus/torque teno mini virus/torque teno midi virus, SEN virus), human bocavirus, pegiviruses, and lymphocytic choriomeningitis virus have shown a little potential for causing hepatitis, but their role in the etiology of liver disease remains to be determined. In addition to the well-known hepatotropic viruses, many emerging and neglected viruses have been associated with liver diseases. The number of emerging zoonotic viruses has been increasingly recognized. While zoonotic potential of HEV is well documented, the recent identification of new hepatitis-related animal viruses such as HEV strains from rabbits and camels, non-primate hepaciviruses in domestic dogs and horses, as well as equine and porcine pegivirus highlights the possible zoonotic transmission in the context of "One Health." However, zoonotic potential and hepatotropism of animal hepatitis viruses remain to be determined.

Protracted course of disseminated adenovirus disease with necrotizing granulomas in the liver

A 52- year-old male with chronic lymphocytic leukemia was hospitalized with disseminated adenovirus disease. More than a month following recovery, hepatic necrotizing granulomas secondary to adenovirus were found. This case illustrates the protracted course that adenovirus disease may take and emphasizes an unusual presentation with hepatic necrotizing granulomas.

Acute Liver Failure: An Update

Pediatric acute liver failure (PALF) is a dynamic, life-threatening condition of disparate etiology. Management of PALF is dependent on intensive collaborative clinical care and support. Proper recognition and treatment of common complications of liver failure are critical to optimizing outcomes. In parallel, investigations to identify underlying cause and the implementation of timely, appropriate treatment can be life-saving. Predicting patient outcome in the era of liver transplantation has been unfulfilling and better predictive models must be developed for proper stewardship of the limited resource of organ availability.

The Pathology of Acute Liver Failure

Varied injuries may manifest clinically as acute liver failure. The pathologic features include variable amounts of necrosis and regeneration. This article reviews pathologic classification of patterns of necrosis and associated inflammatory and regenerative responses in specimens from patients with acute liver failure. Detailed pathologic examination of these specimens with clinical pathologic correlation can give the multidisciplinary team vital information regarding etiology and timing as well as extent of injury, and regenerative response. Pathologists are a vital component of the health care team for patients with acute liver failure.