Nitazoxanide treatment for norovirus infection in solid organ transplant recipients

Norovirus Management and Outcomes in a Multicenter Pediatric Kidney Transplant Population

BACKGROUND

Norovirus is the most common cause of viral gastroenteritis. Studies in adult kidney recipients have documented significant morbidity associated with norovirus infection, but there are few studies in pediatric recipients.

METHODS

Multicenter retrospective cohort study of pediatric kidney transplant recipients with norovirus, confirmed by stool PCR, between January 1, 2008, and December 31, 2018. Outcomes of interest included duration of diarrhea, incidence of chronic diarrhea, management strategies, and graft function.

RESULTS

Forty pediatric kidney transplant recipients from four centers were identified for inclusion. Median age at transplant was 5.4 years (IQR 2.2-11.2 years), and median time post-transplant was 1.9 years (IQR 0.8-3.8 years). Median diarrheal duration was 16 days (IQR 6.0-41.5 days); 15 patients (43%) had acute diarrhea, 8 (23%) had persistent, and 12 (30%) had chronic diarrhea. Twenty-one (53%) patients developed acute kidney injury. Thirty-five (88%) patients required supplemental fluids, 8 (20%) patients underwent immunosuppression reduction for a median of 22 days, 5 (13%) were treated with nitazoxanide, and 5 (13%) received oral immunoglobulin. Acute rejection was diagnosed in 3 (8%) patients within 6 months of norovirus diagnosis. We observed no sustained decline in eGFR at 12 months after diarrhea resolution (median eGFR difference: 2.8 mL/min/1.73 m2 [IQR: -17.1, 7.4]). Of the patients in the cohort, two lost their graft at 6.8 and 30.0 months after the onset of diarrhea.

CONCLUSION

Norovirus is associated with significant morbidity in pediatric kidney transplant recipients. Various treatment interventions are being employed for norovirus infection. Larger studies, both observational and interventional, are needed to determine the optimal treatment.

Presentation, management, and outcomes of norovirus in adult and pediatric solid organ and hematopoietic stem cell transplant recipients: A multicenter, retrospective study

BACKGROUND

Norovirus (NoV) can cause chronic relapsing and remitting diarrhea in immunocompromised patients.  Few multicenter studies have described the clinical course, outcomes, and complications of chronic NoV in transplant recipients.

METHODS

A multicenter retrospective study of adult and pediatric SOT and HSCT recipients diagnosed with NoV between November 1, 2017, and February 28, 2021. Data were obtained from electronic medical records (EMR) and entered into a central REDCap database. Descriptive statistics were calculated.

RESULTS

A total of 280 NoV+ patients were identified across eight sites. The majority were adults (74.1%) and SOT recipients (91.4%). Initial diagnosis of NoV occurred a median of 36 months post-Tx (IQR [15.0, 90.0]). Most NoV cases had >3 diarrheal episodes daily (66.0%), nausea and vomiting (60.1%). Duration of diarrhea varied greatly (median = 10 days, mean = 85.9 days, range (1, 2100)). 71.3% were hospitalized. Adjustment of immunosuppression, including reduction and discontinuation of mToR inhibitor, CNI, and/or MMF, was the most common management intervention for NoV. Other therapies resulted only in temporary improvement. Four patients died within 30 days and three others died by 180 days postdiagnosis. Clinically significant renal dysfunction was observed in 12.5% by 30 days and 21.4% by 180 days post-NoV diagnosis.

CONCLUSION

In HSCT and SOT patients, NoV frequently resulted in severe symptoms, prolonged diarrhea (30% persistent with diarrhea for >30 days), and clinically significant renal dysfunction (up to 21% of patients). Utilized therapies did not reliably result in the resolution of infection demonstrating the need for more effective treatment.

Sapovirus: an emerging pathogen in kidney transplant recipients?

PURPOSE

Diarrhea is an important cause of morbidity and mortality in immunocompromised patients. After including sapovirus to the viral gastroenteritis screening of our institution's laboratory, we noticed an increase in sapovirus infections among kidney transplant recipients. Therefore, we assumed former gastrointestinal tract infections with unidentified pathogens could have been caused by sapovirus. To better understand the characteristics of a sapovirus infection in a high-risk group we initiated this study.

METHODS

Over a period of 6 months, all transplant recipients with diarrhea and later identified viral/unknown pathogens were included. Kidney function, levels of immunosuppressants and  c-reactive protein, acid-base balance, onset of symptoms and time of hospitalization were analyzed.

RESULTS

Among 13 hospitalized kidney transplant recipients sapovirus was detected in four patients, while in the remaining nine, three were diagnosed with norovirus, one with cytomegalovirus, one with inflammatory bowel disease and in four patients no pathogen was identified. Even though statistically not significant, creatinine levels at admission tended to be higher in sapovirus patients (median: sapovirus: 3.3 mg/dl (1.3; 5.0), non-sapovirus: 2.5 mg/dl (1.1; 4.9), p = 0.710). Also, Tacrolimus levels showed the same trend (sapovirus: 13.6 ng/ml (12.9; 13.6), non-sapovirus: 7.1 ng/ml (2.6; 22.6), p = 0.279). On discharge creatinine levels improved equally in both groups (sapovirus: 1.7 mg/dl (1.4; 3.2), non-sapovirus: 2 mg/dl (1.0; 3.6), p = 0.825).

CONCLUSION

In high-risk patients, early symptomatic treatment remains crucial to protect the transplant`s function. In our cohort all patients recovered well. Larger cohorts and longer follow-up times are needed to detect the long-term consequences and a potential need for further research regarding specific treatment.

TRIAL REGISTRATION

The study has been registered on DRKS (trialsearch.who.int), Reg. Nr. DRKS00033311 (December 28th 2023).

Molnupiravir inhibits human norovirus and rotavirus replication in 3D human intestinal enteroids

Human norovirus (HuNoV) and human rotavirus (HRV) are the leading causes of gastrointestinal diarrhea. There are no approved antivirals and rotavirus vaccines are insufficient to cease HRV associated mortality. Furthermore, treatment of chronically infected immunocompromised patients is limited to off-label compassionate use of repurposed antivirals with limited efficacy, highlighting the urgent need of potent and specific antivirals for HuNoV and HRV. Recently, a major breakthrough in the in vitro cultivation of HuNoV and HRV derived from the use of human intestinal enteroids (HIEs). The replication of multiple circulating HuNoV and HRV genotypes can finally be studied and both in the same non-transformed and physiologically relevant model. Activity of previously described anti-norovirus or anti-rotavirus drugs, such as 2'-C-methylcytidine (2CMC), 7-deaza-2'-C-methyladenosine (7DMA), nitazoxanide, favipiravir and dasabuvir, was assessed against clinically relevant human genotypes using 3D-HIEs. 2CMC showed the best activity against HuNoV GII.4, while 7DMA was the most potent antiviral against HRV. We identified the anti-norovirus and -rotavirus activity of molnupiravir and its active metabolite, N4-hydroxycytidine (NHC), a broad-spectrum antiviral used to treat coronavirus disease 2019 (COVID-19). Molnupiravir and NHC inhibit HuNoV GII.4, HRV G1P[8], G2P[4] and G4P[6] in 3D-HIEs with high selectivity and show a potency comparable to 2CMC against HuNoV. Moreover, molnupiravir and NHC block HRV viroplasm formation, but do not alter its size or subcellular localization. Taken together, molnupiravir inhibits both HuNoV and HRV replication, suggesting that the drug could be a candidate for the treatment of patients chronically infected with either one of these diarrhea causing viruses.

Sapovirus infection as another cause of persistent viral diarrhea: case series and review of the literature

Human sapovirus (HuSaV) is a common cause of gastroenteritis worldwide and is responsible for approximately 4% of acute gastroenteritis episodes in Europe. As reported with norovirus, patients with immunocompromised states are at increased risk of developing HuSaV infection, which can lead to persistent diarrhea and chronic viral shedding in some individuals. Chronic infections are incompletely investigated in these patients, and, due to the lack of specific treatment for HuSaV infection, different clinical approaches were carried out in order to provide further evidence on clinical evolution of these patients with different treatments. In this retrospective study, we report five immunocompromised pediatric patients with recurrent diarrhea caused by HuSaV and long-term viral shedding. Stool samples were analyzed by real-time PCR and tested for enteropathogenic viruses and bacteria and protozoa. Among transplant recipients, reduction of immunosuppressant therapy led to clinical improvement and relief of symptoms, maintaining a balance between managing the infection and preventing graft rejection. Nitazoxanide for 14 days was only used in one of these patients, showing to be an effective therapy to achieve reduction in time to resolution of symptoms. Neither nitazoxanide nor modification of immunosuppressant therapy could avoid recurrences. Further investigations are needed to develop new approaches that can both clear the infection and avoid persistent diarrhea in these patients.

How we treat diarrhea in pediatric transplant patients: a brief review

Diarrhea is a common problem faced by both hematopoietic and solid organ transplant recipients. The differential diagnosis is wide, ranging from infectious to non-infectious causes and from benign to emergent illness. Here we present two patients with diarrhea and discuss our approaches to the diagnostic evaluation and management of transplant recipients with diarrhea. We also include a review of the literature and discuss areas in need of further study.

Standardization of an antiviral pipeline for human norovirus in human intestinal enteroids demonstrates nitazoxanide has no to weak antiviral activity

Human noroviruses (HuNoVs) are the leading cause of acute gastroenteritis. In immunocompetent hosts, symptoms usually resolve within 3 days; however, in immunocompromised persons, HuNoV infection can become persistent, debilitating, and sometimes life-threatening. There are no licensed therapeutics for HuNoV due to a near half-century delay in its cultivation. Treatment for chronic HuNoV infection in immunosuppressed patients anecdotally includes nitazoxanide, a broad-spectrum antimicrobial licensed for treatment of parasite-induced gastroenteritis. Despite its off-label use for chronic HuNoV infection, nitazoxanide has not been clearly demonstrated to be an effective treatment. In this study, we standardized a pipeline for antiviral testing using multiple human small intestinal enteroid lines representing different intestinal segments and evaluated whether nitazoxanide inhibits replication of five HuNoV strains in vitro. Nitazoxanide did not exhibit high selective antiviral activity against any HuNoV strain tested, indicating it is not an effective antiviral for HuNoV infection. Human intestinal enteroids are further demonstrated as a model to serve as a preclinical platform to test antivirals against HuNoVs to treat gastrointestinal disease. Abstr.

Norovirus and sapovirus infections after allogeneic hematopoietic stem cell transplantation: is it worth it to look for them?

Norovirus (NoV) and Sapovirus (SaV) are potential causative agents of diarrhea after allogeneic HSCT but little is known in this population. We performed a retrospective analysis by RT-PCR of calicivirus (NoV and SaV), Human adenovirus (HAdV), rotavirus (RV), Aichi virus (AiV), enterovirus (EV), human parechovirus (HPeV) and Human bocavirus (HBoV) in the diarrheal stools of patients after allogeneic HSCT. 49/162 patients had positive viral assays: HAdV (17%), EV (7%), NoV (4.3%), RV and HBoV (3.1% each), SaV (1.9%), AiV (1.2%), HPeV (0.6%). Seven patients were positive for NoV and 3 for SaV. Among viruses-positive samples, the frequency of caliciviruses cases was 7% in the 6 months post-HSCT compared to 40% after (p < 0.0001). The median duration of symptom was 0.7 months but 2 cases, occurring more than one year after HSCT, were chronic, undiagnosed and strongly contributed to morbidity. Systematic testing of caliciviruses appears especially useful in late chronic diarrhea.

Noroviral diarrhea in solid organ transplant recipients: An analysis of interventions and outcomes

INTRODUCTION

Noroviral infection can lead to chronic diarrhea in solid organ transplant (SOT) recipients with significant morbidity and mortality. Existing literature has described a wide spectrum of illness and has not come to a consensus on the optimal management of this condition.

METHODS

We undertook a retrospective review of all adult SOT recipients between 1/1/2018 and 12/31/2020 who were diagnosed with their first episode of noroviral diarrhea (NVD). Demographic, clinical interventions, and outcomes within 6 months of diagnosis were recorded. Patients' outcomes were classified as either resolved, improved or persistent at 6 months.

RESULTS

Seventy-nine SOT recipients were included. Thirty-eight patients (48%) had chronic diarrhea at baseline (CDB). Thirty-two patients (40%) received nitazoxanide, 28 patients (35%) had their immunosuppression adjusted and seven patients (9%) received intravenous immunoglobulin. Diarrhea improved or resolved in 68 patients (85%). Improvement or resolution of diarrhea was observed in 98% of those who did not have history of chronic diarrhea versus 74% in those who did (p = .002). NVD improved in all 12 patients who had mycophenolate discontinued, although this was not statistically significant (p = .131).

CONCLUSION

CDB was associated with worse outcomes regardless of intervention. A low threshold to test for NVD in SOT recipients with chronic diarrhea is prudent to prevent delayed diagnosis.

Aspects of Antiviral Strategies Based on Different Phototherapy Approaches: Hit by the Light

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which caused the COVID-19 pandemic spreading around the world from late 2019, served as a ruthless reminder of the threat viruses pose to global public health. The synthesis of new antiviral drugs, as well as repurposing existing products, is a long-term ongoing process which has challenged the scientific community. One solution could be an effective, accessible, and rapidly available antiviral treatment based on phototherapy (PT). PT has been used to treat several diseases, and relies on the absorption of light by endogenous molecules or exogenous photosensitizers (PS). PT has often been used in cancer treatment and prophylaxis, and as a complement to established chemotherapy and immunotherapy in combined therapeutic strategy. Besides significant applications in anticancer treatment, studies have demonstrated the beneficial impact of PT on respiratory, systemic, emerging, and oncogenic viral infections. The aim of this review was to highlight the potential of PT to combat viral infections by summarizing current progress in photodynamic, photothermal, and photoacoustic approaches. Attention is drawn to the virucidal effect of PT on systemic viruses such as the human immunodeficiency virus and human herpes viruses, including the causative agent of Kaposi sarcoma, human herpes virus (HHV8). PT has good potential for disinfection in anti-norovirus research and against pandemic viruses like SARS-CoV-2.

Norovirus disease among older adults

Norovirus, a leading cause of gastroenteritis outbreaks worldwide, results in substantial direct and indirect healthcare costs. Adults older than 65 years of age bear a significant proportion of the disease burden, and the disease course in this population is often more severe and protracted. In this narrative review, we discuss the epidemiology of norovirus infection, mechanisms of pathogenesis, and transmission pertinent to outbreaks along with infection prevention and control efforts. We also describe the clinical manifestations of norovirus disease with a focus on individuals older than 65 years of age, diagnosis and available treatment options, and the challenges and progress within vaccine development.