Clinical characteristics of viral intestinal infection in preterm and term neonates

Human norovirus cultivation models, immune response and vaccine landscape

Norovirus infections are a leading cause of gastroenteritis worldwide. Despite the substantial global health burden and economic impact, there are currently no approved antiviral therapeutics or vaccines. Additionally, much of our knowledge of norovirus comes from experiments using surrogate viruses, such as murine norovirus and feline calicivirus. The challenge surrounding human norovirus research arises from a lack of robust cell culture systems and efficient animal models. In this review, we explore recent advances in the in vitro cultivation of human norovirus and reverse genetics systems and discuss commonly used in vivo models. We summarize the current understanding of both innate and adaptive immune responses to norovirus infection and provide an overview of vaccine strategies and the current clinical trial landscape, with a focus on the only vaccine candidate that has reached phase III clinical development stage.

Bile acid-sensitive human norovirus strains are susceptible to sphingosine-1-phosphate receptor 2 inhibition

Human noroviruses (HuNoVs) are a diverse group of RNA viruses that cause endemic and pandemic acute viral gastroenteritis. Previously, we reported that many HuNoV strains require bile or bile acid (BA) to infect human jejunal intestinal enteroid cultures. BA was not essential for the replication of a pandemic-causing GII.4 HuNoV strain. We found the hydrophobic BA glycochenodeoxycholic acid (GCDCA) promotes the replication of the BA-dependent strain GII.3 in jejunal enteroids. Furthermore, we found that inhibition of the G-protein-coupled BA receptor, sphingosine-1-phosphate receptor 2 (S1PR2), by JTE-013, reduced GII.3 infection dose-dependently and inhibited GII.3 cellular uptake in enteroids. Herein, we sought to determine whether S1PR2 is required for other BA-dependent HuNoV strains, the BA-independent GII.4, and whether S1PR2 is required for BA-dependent HuNoV infection in HIEs from other small intestinal segments. We found a second S1PR2 inhibitor, GLPG2938, reduces GII.3 infection dose-dependently, and an S1PR2 agonist (CYM-5520) enhances GII.3 replication in the absence of GCDCA. GII.3 replication also is abrogated in the presence of JTE-013 and CYM-5520. JTE-013 inhibition of S1PR2 in jejunal HIEs reduces GI.1, GII.3, and GII.17 (BA-dependent) but not GII.4 Sydney (BA-independent) infection, providing additional evidence of strain-specific differences in HuNoV infection. Finally, GII.3 infection of duodenal, jejunal, and ileal lines derived from the same individual is reduced with S1PR2 inhibition, indicating a common mechanism of BA-dependent infection among multiple segments of the small intestine. Our results support a model where BA-dependent HuNoVs exploit BA effects on S1PR2 to infect the entire small intestine.IMPORTANCEHuman noroviruses (HuNoVs) are important viral human pathogens that cause both outbreaks and sporadic gastroenteritis. These viruses are diverse, and many strains are capable of infecting humans. Our previous studies have identified strain-specific requirements for hydrophobic bile acids (BAs) to infect intestinal epithelial cells. Moreover, we identified a BA receptor, sphingosine-1-phosphate receptor 2 (S1PR2), required for infection by a BA-dependent strain. To better understand how various HuNoV strains enter and infect the small intestine and the role of S1PR2 in HuNoV infection, we evaluated infection by additional HuNoV strains using an expanded repertoire of intestinal enteroid cell lines. We found that multiple BA-dependent strains, but not a BA-independent strain, all require S1PR2 for infection. In addition, BA-dependent infection requires S1PR2 in multiple segments of the small intestine. Together, these results indicate that S1PR2 has value as a potential therapeutic target for BA-dependent HuNoV infection.

Bile acid-sensitive human norovirus strains are susceptible to sphingosine-1-phosphate receptor 2 inhibition

Human noroviruses (HuNoVs) are a diverse group of RNA viruses that cause both endemic and pandemic acute viral gastroenteritis. Previously we reported that many strains of HuNoV require bile or bile acid (BA) to infect human jejunal intestinal enteroid cultures. Of note, BA was not essential for replication of a pandemic-causing GII.4 HuNoV strain. Using the BA-requiring strain GII.3, we found that the hydrophobic BA GCDCA induces multiple cellular responses that promote replication in jejunal enteroids. Further, we found that chemical inhibition of the G-protein coupled receptor, sphingosine-1- phosphate receptor 2 (S1PR2), by JTE-013 reduced both GII.3 infection in a dose- dependent manner and cellular uptake in enteroids. Herein, we sought to determine if S1PR2 is required by other BA-dependent HuNoV strains and BA-independent GII.4, and if S1PR2 is required for BA-dependent HuNoV infection in other segments of the small intestine. We found JTE-013 inhibition of S1PR2 in jejunal HIEs reduces GI.1, GII.3, and GII.17 (BA-dependent) but not the GII.4 Sydney variant (BA-independent) infection, providing additional evidence of strain-specific differences in HuNoV infection. GII.3 infection of duodenal, jejunal and ileal lines derived from the same individual was also reduced with S1PR2 inhibition, indicating a common mechanism of BA-dependent infection among multiple segments of the small intestine. Our results support a model where BA-dependent HuNoV exploit the activation of S1PR2 by BA to infect the entire small intestine.

Importance

Human noroviruses (HuNoVs) are important viral human pathogens that cause both outbreaks and sporadic gastroenteritis. These viruses are diverse, and many strains are capable of infecting humans. Our previous studies have identified strain-specific requirements for hydrophobic bile acids (BAs) to infect intestinal epithelial cells. Moreover, we identified a BA receptor, sphingosine-1-phosphate receptor 2 (S1PR2), required for infection by a BA-dependent strain. To better understand how various HuNoV strains enter and infect the small intestine and the role of S1PR2 in HuNoV infection, we evaluated infection by additional HuNoV strains using an expanded repertoire of intestinal enteroid cell lines. We found that multiple BA-dependent strains, but not a BA- independent strain, all required S1PR2 for infection. Additionally, BA-dependent infection required S1PR2 in multiple segments of the small intestine. Together these results indicate S1PR2 has value as a potential therapeutic target for BA-dependent HuNoV infection.

Phenol Derivatives Obtained from Grape Seed Extract Show Virucidal Activity against Murine Norovirus

Human noroviruses are the most common pathogens known to cause acute gastroenteritis, a condition that can lead to severe illness among immunocompromised individuals such as organ transplant recipients and the elderly. To date, no safe and effective vaccines or therapeutic agents have been approved for treating norovirus infections. Therefore, we aimed to demonstrate the virucidal activity of grape seed extract (GSE), which contains >83% proanthocyanidins, against murine norovirus (MNV), a surrogate for human norovirus. GSE showed virucidal activity against MNV in a dose- and time-dependent manner. Atomic force microscopic analysis showed viral particle aggregates after treatment of MNV with GSE. MNV treated with 50 µg/mL of GSE for 10 min resulted in the absence of pathogenicity in an animal model of infection, indicating that GSE has irreversible virucidal activity against MNV particles. Thus, GSE may aid in the development of treatments for norovirus infections.

Epidemiology, Clinical Features, and Unusual Complications of Norovirus Infection in Taiwan: What We Know after Rotavirus Vaccines

Noroviruses (NoVs) are one of the emerging and rapidly spreading groups of pathogens threatening human health. A reduction in sporadic NoV infections was noted following the start of the COVID-19 pandemic, but the return of NoV gastroenteritis during the COVID-19 pandemic has been noted recently. Research in recent years has shown that different virus strains are associated with different clinical characteristics; moreover, there is a paucity of research into extraintestinal or unusual complications that may be associated with NoV. The genomic diversity of circulating NoVs is also complex and may vary significantly. Therefore, this short narrative review focuses on sharing the Taiwan experience of NoV infection including epidemiology, clinical features, and complications following suboptimal rotavirus immunization in Taiwan (after October 2006). We also highlight the unusual complications associated with NoV infections and the impacts of NoV infection during the COVID-19 pandemic in the literature for possible future research directions. To conclude, further research is needed to quantify the burden of NoV across the spectrum of disease severity in Taiwan. The evidence of the connection between NoV and the unusual complications is still lacking.

Virucidal and Immunostimulating Activities of Monogalactosyl Diacylglyceride from Coccomyxa sp. KJ, a Green Microalga, against Murine Norovirus and Feline Calicivirus

Human noroviruses are the most common pathogens causing acute gastroenteritis and may lead to more severe illnesses among immunosuppressed people, including elderly and organ transplant recipients. To date, there are no safe and effective vaccines or antiviral agents for norovirus infections. In the present study, we aimed to demonstrate the antiviral activity of monogalactosyl diacylglyceride (MGDG) isolated from a microalga, Coccomyxa sp. KJ, against murine norovirus (MNV) and feline calicivirus (FCV), the surrogates for human norovirus. MGDG showed virucidal activities against these viruses in a dose- and time-dependent manner—MGDG at 100 μg/mL reduced the infectivity of MNV and FCV to approximately 10% after 60 min incubation. In the animal experiments of MNV infection, intraoral administration of MGDG (1 mg/day) exerted a therapeutic effect by suppressing viral shedding in the feces and produced high neutralizing antibody titers in sera and feces. When MGDG was orally administered to immunocompromised mice treated with 5-fluorouracil, the compound exhibited earlier stopping of viral shedding and higher neutralizing antibody titers of sera than those in the control mice administered with distilled water. Thus, MGDG may offer a new therapeutic and prophylactic alternative against norovirus infections.

Glycan Recognition in Human Norovirus Infections

Recognition of cell-surface glycans is an important step in the attachment of several viruses to susceptible host cells. The molecular basis of glycan interactions and their functional consequences are well studied for human norovirus (HuNoV), an important gastrointestinal pathogen. Histo-blood group antigens (HBGAs), a family of fucosylated carbohydrate structures that are present on the cell surface, are utilized by HuNoVs to initially bind to cells. In this review, we describe the discovery of HBGAs as genetic susceptibility factors for HuNoV infection and review biochemical and structural studies investigating HuNoV binding to different HBGA glycans. Recently, human intestinal enteroids (HIEs) were developed as a laboratory cultivation system for HuNoV. We review how the use of this novel culture system has confirmed that fucosylated HBGAs are necessary and sufficient for infection by several HuNoV strains, describe mechanisms of antibody-mediated neutralization of infection that involve blocking of HuNoV binding to HBGAs, and discuss the potential for using the HIE model to answer unresolved questions on viral interactions with HBGAs and other glycans.

Viral Acute Gastroenteritis in Special Populations

Viral acute gastroenteritis (AGE) is common and afflicts people of all ages. Nonviral causes of AGE are less common. Norovirus is a leading cause of sporadic cases and outbreaks of AGE across all ages. Universal rotavirus vaccination of infants has reduced frequency and severity of rotavirus AGE cases in children and indirectly reduced cases in older adults. Severe illness is more likely in persons at age extremes or with immunocompromising conditions. Viral causes of AGE can lead to protracted diarrheal illness in immunocompromised persons. Nucleic acid amplification tests are changing diagnostic testing algorithms.

Temporal and seasonal variations in incidence of stage II and III NEC-a 28-year epidemiologic study from tertiary NICUs in Connecticut, USA

OBJECTIVE

To investigate seasonality and temporal trends in the incidence of NEC.

STUDY DESIGN

A retrospective cohort study from two tertiary NICUs in northern and central Connecticut involving 16,761 infants admitted over a 28-year period. Various perinatal and neonatal risk factors were evaluated by univariate, multivariate, and spectral density analyses.

RESULTS

Incidence of NEC was unchanged over the 28 years of study. Gestational age, birth weight, and birth-months (birth in April/May) were independently associated with stage II or III NEC even after adjusting for confounding factors (p < 0.05). Yearly NEC incidence showed a multi-modal distribution with spectral density spikes approximately every 10 years.

CONCLUSION(S)

Temporal and seasonal factors may play a role in NEC with a peak incidence in infants born in April/May and periodicity spikes approximately every 10 years. These trends suggest non-random and possibly environmental factors influencing NEC.

Necrotizing Enterocolitis in Neonates With Hyperinsulinemic Hypoglycemia Treated With Diazoxide

The most common cause of persistent hypoglycemia in the neonatal period is hyperinsulinism. Severe, refractory hypoglycemia resulting from hyperinsulinism can lead to significant brain injury and permanent cognitive disability. Diazoxide is the first-line and only US Food and Drug Administration-approved, pharmacologic treatment for refractory hyperinsulinism. In recent years, the use of diazoxide in neonates with persistent hyperinsulinemic hypoglycemia has increased in the United States. Known adverse effects of diazoxide include fluid retention, hypertrichosis, neutropenia, thrombocytopenia, and more recently, pulmonary hypertension. It is currently unknown if diazoxide exposure is associated with an increased risk of necrotizing enterocolitis (NEC) in neonates. We reviewed the cases of 24 patients in a level IV NICU at Massachusetts General Hospital who received diazoxide over 12 years (April 2006-April 2018). All 24 patients received enteral diazoxide for refractory hyperinsulinemic hypoglycemia. A total of 5 patients developed NEC after initiation of diazoxide based on clinical and radiographic findings, corresponding to 20% of infants exposed to diazoxide. This is above our baseline incidence of NEC (1% for all inborn infants and 6% for all inborn very low birth weight infants). More research and monitoring are necessary to characterize the potential risk of NEC associated with the use of diazoxide in the neonatal period.

Rotavirus vaccination in the neonatal intensive care units: where are we? A rapid review of recent evidence

PURPOSE OF REVIEW

Rotavirus is a leading cause of viral acute gastroenteritis in infants. Neonates hospitalized in neonatal intensive care units (NICUs) are at risk of rotavirus infections with severe outcomes. The administration of rotavirus vaccines is only recommended, in the United States and Canada, upon discharge from the NICU despite rotavirus vaccines being proven well tolerated and effective in these populations, because of risks of live-attenuated vaccine administration in immunocompromised patients and theoretical risks of rotavirus vaccine strains shedding and transmission.We aimed to summarize recent evidence regarding rotavirus vaccine administration in the NICU setting and safety of rotavirus vaccines in preterm infants.

METHODS

We conducted a rapid review of the literature from the past 10 years, searching Medline and Embase, including all study types except reviews, reporting on rotavirus vaccines 1 and 5; NICU setting; shedding or transmission; safety in preterm. One reviewer performed data extraction and quality assessment.

RECENT FINDINGS

Thirty-one articles were analyzed. Vaccine-derived virus shedding following rotavirus vaccines existed for nearly all infants, mostly during the first week after dose 1, but with rare transmission only described in the household setting. No case of transmission in the NICU was reported. Adverse events were mild to moderate, occurring in 10-60% of vaccinated infants. Extreme premature infants or those with underlying gastrointestinal failure requiring surgery presented with more severe adverse events.

SUMMARY

Recommendations regarding rotavirus vaccine administration in the NICU should be reassessed in light of the relative safety and absence of transmission of rotavirus vaccine strains in the NICU.

Norovirus encounters in the gut: multifaceted interactions and disease outcomes

Noroviruses are major causes of gastroenteritis, with epidemic outbreaks occurring frequently. They are an important global health concern, especially for pediatric and immunocompromised populations, and are challenging pathogens to target immunologically due to their rapid rates of genetic and antigenic evolution and failure to stimulate durable protective immunity. In this Review, we summarize our current understanding of norovirus pathogenesis, noting the prominent role of murine norovirus as a small animal model for norovirus research. We highlight intriguing data supporting the possible involvement of norovirus in sequelae including irritable bowel syndrome and inflammatory bowel diseases, and describe the innate and adaptive immune mechanisms involved in control of both human and murine norovirus infection. Furthermore, we discuss the potential implications of recent discoveries regarding norovirus interactions with the gut microbiota, and briefly detail current understanding of noroviral evolution and its influence on viral pathogenesis. Our mechanistic understanding of norovirus pathogenesis continues to improve with increasing availability of powerful model systems, which will ultimately facilitate development of effective preventive and therapeutic approaches for this pathogen.

In silico screening for human norovirus antivirals reveals a novel non-nucleoside inhibitor of the viral polymerase

Human norovirus causes approximately 219,000 deaths annually, yet there are currently no antivirals available. A virtual screening of commercially available drug-like compounds (~300,000) was performed on the suramin and PPNDS binding-sites of the norovirus RNA-dependent RNA polymerase (RdRp). Selected compounds (n = 62) were examined for inhibition of norovirus RdRp activity using an in vitro transcription assay. Eight candidates demonstrated RdRp inhibition (>25% inhibition at 10 µM), which was confirmed using a gel-shift RdRp assay for two of them. The two molecules were identified as initial hits and selected for structure-activity relationship studies, which resulted in the synthesis of novel compounds that were examined for inhibitory activity. Five compounds inhibited human norovirus RdRp activity (>50% at 10 µM), with the best candidate, 54, demonstrating an IC₅₀ of 5.6 µM against the RdRp and a CC₅₀ of 62.8 µM. Combinational treatment of 54 and the known RdRp site-B inhibitor PPNDS revealed antagonism, indicating that 54 binds in the same binding pocket. Two RdRps with mutations (Q414A and R419A) previously shown to be critical for the binding of site-B compounds had no effect on inhibition, suggesting 54 interacts with distinct site-B residues. This study revealed the novel scaffold 54 for further development as a norovirus antiviral.

Epidemiology of Classic and Novel Human Astrovirus: Gastroenteritis and Beyond

Since they were identified in 1975, human astroviruses have been considered one of the most important agents of viral acute gastroenteritis in children. However, highly divergent astroviruses infecting humans have been recently discovered and associated with extra-intestinal infections. The report of cases of fatal meningitis and encephalitis, especially in immunocompromised individuals, has broadened their disease spectrum. Although zoonotic transmission among animal and human astroviruses has not been clearly recognized, the genetic similarity between some human and animal viruses makes it likely to occur. This review provides an update on the epidemiology of both classic and novel human astroviruses, and a comprehensive view on confirmed or potential association between astrovirus and human disease.

The viral dsRNA analogue poly (I:C) induces necrotizing enterocolitis in neonatal mice

BACKGROUND

Necrotizing enterocolitis (NEC) is a life-threatening gastrointestinal disease in premature infants with high mortality and morbidity with uncertain pathogenesis. Recent research focused on the role of intraluminal bacteria and lipopolysaccharide (LPS). However, an additional role of viral agents in the pathogenesis of NEC has recently been postulated. We assessed the role of polyinosinic:polycytidylic acid (pIC) mimicking viral dsRNA in contributing to the development of NEC in neonatal mice.

METHODS

Four-d-old C57BL/6J pups were stressed by asphyxia and hypothermia twice daily. Animals were either fed by formula only (FO), formula containing LPS or pIC. After 72 h, mice were euthanized, intestines harvested, and the severity of NEC was assessed.

RESULTS

Breastfed mice showed no evidence of NEC. Very mild NEC-like lesions were observed in mice fed by FO. Supplementation of LPS or pIC to the formula led to increased intestinal tissue damage and inflammation compared with FO in a similar manner.

CONCLUSION

Our study demonstrates the ability of viral factors to induce NEC in neonatal mice even in the absence of LPS. Furthermore, we present a new mouse model of pIC-induced NEC which may be used to obtain further mechanistic insights in the pathogenesis of this disease.

Depth of bacterial invasion in resected intestinal tissue predicts mortality in surgical necrotizing enterocolitis

OBJECTIVE

Up to a third of all infants who develop necrotizing enterocolitis (NEC) require surgical resection of necrotic bowel. We hypothesized that the histopathological findings in surgically resected bowel can predict the clinical outcome of these infants.

STUDY DESIGN

We reviewed the medical records and archived pathology specimens from all patients who underwent bowel resection/autopsy for NEC at a regional referral center over a 10-year period. Pathology specimens were graded for the depth and severity of necrosis, inflammation, bacteria invasion and pneumatosis, and histopathological findings were correlated with clinical outcomes.

RESULT

We performed clinico-pathological analysis on 33 infants with confirmed NEC, of which 18 (54.5%) died. Depth of bacterial invasion in resected intestinal tissue predicted death from NEC (odds ratio 5.39 per unit change in the depth of bacterial invasion, 95% confidence interval 1.33 to 21.73). The presence of transmural necrosis and bacteria in the surgical margins of resected bowel was also associated with increased mortality.

CONCLUSION

Depth of bacterial invasion in resected intestinal tissue predicts mortality in surgical NEC.

Norovirus immunology: Of mice and mechanisms

Noroviruses (NoVs) are the most common cause of sporadic and epidemic gastroenteritis in the United States and Europe and are responsible for 20% of acute gastroenteritis worldwide. Over the past decade, the understanding of NoV immunology has grown immensely. Studies of the natural immune response to NoV in humans and animal models have laid the foundation for innovations in cell culture systems for NoV and development of new therapeutics. Evidence from animal models, NoV surrogates, observational human research, and human challenge studies suggest that the innate immune response is critical for limiting NoV infection but is insufficient for viral clearance. NoV may antagonize the innate immune response to establish or prolong infection. However, once a robust adaptive immune response is initiated, the immune system clears the infection through the action of T and B cells, simultaneously generating highly specific protective immunologic memory. We review here both the current knowledge on NoV immunity and exciting new developments, with a focus on ongoing vaccine development work, novel cell culture systems, and advances in understanding the role of the gut microbiome. These changes reinforce the need for a better understanding of the human immune response to NoV and suggest novel hypotheses.

Infectious causes of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency among premature infants. Although a large body of research has focused on understanding its pathogenesis, the exact mechanism has not been elucidated. Of particular interest is the potential causative role of infectious culprits in the development of NEC. A variety of reports describe bacterial, viral, and fungal infections occurring in association with NEC; however, no single organism has emerged as being definitively involved in NEC pathogenesis. In this review, the authors summarize the literature on infectious causes of NEC.

Norovirus

Norovirus, an RNA virus of the family Caliciviridae, is a human enteric pathogen that causes substantial morbidity across both health care and community settings. Several factors enhance the transmissibility of norovirus, including the small inoculum required to produce infection (<100 viral particles), prolonged viral shedding, and its ability to survive in the environment. In this review, we describe the basic virology and immunology of noroviruses, the clinical disease resulting from infection and its diagnosis and management, as well as host and pathogen factors that complicate vaccine development. Additionally, we discuss overall epidemiology, infection control strategies, and global reporting efforts aimed at controlling this worldwide cause of acute gastroenteritis. Prompt implementation of infection control measures remains the mainstay of norovirus outbreak management.

Acute gastroenteritis and enteric viruses in hospitalised children in southern Brazil: aetiology, seasonality and clinical outcomes

Viral acute gastroenteritis (AG) is a significant cause of hospitalisation in children younger than five years. Group A rotavirus (RVA) is responsible for 30% of these cases. Following the introduction of RVA immunisation in Brazil in 2006, a decreased circulation of this virus has been observed. However, AG remains an important cause of hospitalisation of paediatric patients and only limited data are available regarding the role of other enteric viruses in these cases. We conducted a prospective study of paediatric patients hospitalised for AG. Stool samples were collected to investigate human adenovirus (HAdV), RVA, norovirus (NoV) and astrovirus (AstV). NoV typing was performed by nucleotide sequencing and phylogenetic analysis. From the 225 samples tested, 60 (26%) were positive for at least one viral agent. HAdV, NoV, RVA and AstV were detected in 16%, 8%, 6% and 0% of the samples, respectively. Mixed infections were found in nine patients: HAdV/RVA (5), HAdV/NoV (3) and HAdV/NoV/RVA (1). The frequency of fever and lymphocytosis was significantly higher in virus-infected patients. Phylogenetic analysis of NoV indicated that all of these viruses belonged to genotype GII.4. The significant frequency of these pathogens in patients with AG highlights the need to routinely implement laboratory investigations.

Gross blood in stools of premature neonates, a clinical and microbiological follow-up study

AIM

To characterize the clinical course and the gut microecology of premature infants with macroscopic gross blood in stools.

METHODS

We studied 14 premature infants receiving breast milk supplemented with probiotics, according to our units practice, with macroscopic blood in stools without signs of ileus or systemic infection upon occurrence of the symptom and 14 days later. Controls were matched prospectively by gestational and postnatal age and type of feeding. Gut microbiota composition was analysed by quantitative real-time polymerase chain reaction (qPCR), and the presence of enteric viruses in the stools was assayed by PCR and by reverse transcription reaction followed by PCR (RT-PCR).

RESULTS

The symptom was transient, benign and self-limiting and none of the background factors explained it. No enteric viruses were detected, and the bacterial analyses showed no statistically significant differences between the infants with or without gross blood in stools. The characterization of the gut microbiota revealed low bacterial diversity.

CONCLUSION

Gross blood in the stools of premature infants without other clinical signs of infection can be an innocuous and self-limiting symptom. This cohort of preterm infants receiving breast milk supplemented with probiotics showed no alterations in gut microecology to be associated with the symptom.

Targeted rotavirus vaccination of high-risk infants; a low cost and highly cost-effective alternative to universal vaccination

BACKGROUND

The cost-effectiveness of universal rotavirus (RV) vaccination is controversial in developed countries. As a result, RV vaccination programs do not currently exist in most European countries. Hospitalization is the main driver of RV disease costs, and prematurity, low birth weight (LBW) and underlying medical conditions have been associated with RV hospitalization and complications. We investigated the cost-effectiveness of targeted RV vaccination of high-risk infants and universal RV vaccination versus no vaccination.

METHODS

Disease burden, mortality and healthcare costs of RV hospitalization for children with and without prematurity, LBW and congenital pathology were quantified in two hospital-based observational studies in the Netherlands. Cost-effectiveness analysis was based on an age-structured stochastic multi-cohort model of the Dutch population comparing universal RV vaccination and targeted vaccination of high-risk infants to no vaccination. The primary endpoint was the incremental cost-effectiveness ratio (ICER), with a threshold of €35,000/quality-adjusted life year (QALY) from the healthcare provider perspective. Sensitivity analyses included vaccine price and coverage, herd-immunity and QALY losses.

RESULTS

A total of 936 children with RV infection were included. Prematurity, LBW and congenital pathology were associated with increased risks of RV hospitalization (relative risks (RR) ranging from 1.6 to 4.4), ICU admission (RR ranging from 4.2 to 7.9), prolonged hospital stay (1.5 to 3.0 excess days) and higher healthcare costs (€648 to €1,533 excess costs). Seven children succumbed due to RV complications, all belonging to the high-risk population. Targeted RV vaccination was highly cost-effective and potentially cost-saving from the healthcare provider perspective with ICERs below €20,000/QALY in all scenarios with total (undiscounted) annual healthcare costs between -€0.1 and €0.5 million/year. Results were most sensitive to mortality rates, but targeted vaccination remained highly cost-effective up to reductions of 90% compared to observed mortality. Universal RV vaccination was not considered cost-effective (mean ICER: €60,200/QALY) unless herd-immunity and caretaker QALY losses were included and vaccine prices were €60 at most (mean ICER: €21,309/QALY).

CONCLUSION

We recommend targeted RV vaccination for high-risk infants in developed countries.

Isolated colon ischemia with norovirus infection in preterm babies: a case series

INTRODUCTION

Norovirus infection with necrotizing enterocolitis has so far been reported as a specific tropism of the small bowel in premature newborns.

CASE PRESENTATION

Three cases of premature newborns presenting with extensive isolated colonic ischemia due to norovirus infection are reported.Patient 1 was a Caucasian girl with a gestational age of 29+2 weeks. She had sudden onset of abdominal distension on the 30th day of life. Radiological signs of colonic pneumatosis were present 48 hours before perforation and stool analysis was positive for norovirus. On the 34th day, free air was detected on plain abdominal X-ray. At laparotomy, stenosis, necrosis and perforations involved the whole colon. The patient underwent ileostomy. A large colon resection and ileosigmoid anastomosis were done 3 months later.Patient 2 was a Caucasian boy with a gestational age of 28+3 weeks. On the 19th day, bloody stools with abdominal distension appeared. Stool analysis resulted positive for norovirus. A plain abdominal X-ray showed distended bowel loops. Antibiotic treatment was started. On the 32nd day due to the progressive deterioration of clinical conditions and the appearance of colic pneumatosis, a laparotomy was performed. Severe damage of the transverse colon and multiple areas of necrosis were found. Terminal ileostomy was performed. Six months later surgery consisted of mid-transverse colon resection as far as the splenic flexure, colocolic anastomosis and closure of ileostomy.Patient 3 was a Caucasian boy with a gestational age of 30 weeks. On the 44th day bloody-mucous stools appeared and stool analysis was positive for norovirus infection. Even with institution of antibiotic therapy clinical abdominal radiologic signs of colonic pneumatosis of the upper right quadrant were found. At the 70th day an explorative laparotomy showed dilated bowel loops and stenotic right colon and ileostomy was mandatory. Partial colectomy was later necessary and ileocolic anastomosis was performed.

CONCLUSION

We hypothesize that norovirus infection may be responsible for severe, distinctive colonic lesions, even in premature newborn infants.

A clinical perspective of necrotizing enterocolitis: past, present, and future

Necrotizing enterocolitis (NEC) primarily affects premature infants. It is less common in term and late preterm infants. The age of onset is inversely related to the postmenstrual age at birth. In term infants, NEC is commonly associated with congenital heart diseases. NEC has also been associated with other anomalies. More than 85% of all NEC cases occur in very low birth weight infants or in very premature infants. Despite incremental advances in our understanding of the clinical presentation and pathophysiology of NEC, universal prevention of this disease continues to elude us even in the twenty-first century.

Astrovirus and digestive disorders in neonatal units

AIM

To describe clinical signs associated with Human Astrovirus (HAstV) in stools in neonatal units.

METHODS

During 2005-2006, all stool virology performed for isolated digestive symptoms or suspicion of neonatal infection was tested for HAstV by an amplified enzyme-linked immunoassay (IDEIA™ Astrovirus test, Dako Cytomation). Each newborn with a positive result (HAstV+ group) was retrospectively matched with the first following symptomatic newborn in the same care unit having a negative stool virology (HAstV- group). Clinical data were collected during two 3-day periods (just after faecal samples collection and 1 week before) and compared within and between each group.

RESULTS

Human astrovirus was detected in faeces of 68 newborns [gestational age: 31.4(28.8-34) weeks] at a post-natal age of 23 (15-42) days without seasonal dominance. Human astrovirus+ and HAstV- groups were comparable. Bloody stool (54.4% versus 14.7%, p < 0.01) and stage II-III necrotizing enterocolitis (20.6% versus 4.4%, p < 0.05) were more frequently observed in HAstV+ than in HAstV- group; these associations were confirmed by logistic regression analysis.

CONCLUSION

This descriptive study argues for a possible association between HAstV and digestive symptoms in newborns specifically in preterm infants.

The coincidence of necrotizing enterocolitis and rotavirus infections and potential associations with cytokines

BACKGROUND

Necrotizing enterocolitis (NEC) is the most common gastrointestinal disease in neonatal intensive care units. Although the pathogenesis of NEC remains unclear, evidence suggests that infections, especially bacterial infections, may play an important role. Viral infections may also result in NEC. Several outbreaks of NEC associated with rotaviruses have been described previously.

OBJECTIVE

To investigate the association between rotavirus (RV) and serum interleukin (IL)-6 and IL-8 levels in infants with NEC.

METHODS

RV infections were prospectively studied using antigen detection in the stools of 31 infants with NEC. Additionally, serum levels of IL-6, IL-8 and tumour necrosis factor-alpha were tested using micro-ELISA at 0 h and 48 h after diagnosis of NEC.

RESULTS

Fecal specimens from 13 infants were positive, while fecal specimens from 18 infants were negative for RV according to antigen detection (RV+ and RV- groups, respectively). The mortality rate and the severity of NEC were not significantly different between the RV+ and RV- groups. IL-6 levels at 0 h and 48 h after diagnosis of NEC in RV+ infants were lower compared with RV- infants, while IL-8 levels were greater at 0 h and 48 h after diagnosis of NEC in RV+ infants compared with RV- infants.

CONCLUSION

A high prevalence of RV infection in neonates with NEC was found. Decreased IL-6 levels and increased IL-8 and tumour necrosis factor-alpha levels in RV+ neonates with NEC suggests a role for RV in NEC.

Pathogenesis and prevention of necrotizing enterocolitis

PURPOSE OF REVIEW

Necrotizing enterocolitis (NEC) remains the most common serious acquired gastrointestinal disorder affecting preterm infants. Here we review recent advances in our understanding of the pathogenesis of this multifactorial condition and consider the implications for practice and research.

RECENT FINDINGS

NEC is an important cause of mortality and serious morbidity in preterm infants. The risk is inversely proportional to gestational age and weight at birth. Fetal growth restriction and compromise may be additional specific risk factors. NEC, particularly severe NEC requiring surgical intervention and NEC with invasive infection, is associated with acute morbidity and mortality and adverse neurodevelopmental outcomes. The principal modifiable postnatal risk factors for NEC in preterm infants relate to enteral feeding practices including formula milk feeding, early and rapid advancement of enteral feed volumes, and exposure to H2-receptor antagonists.

SUMMARY

Our understanding of the pathogenesis of this condition remains incomplete. With the exception of feeding with human milk, only limited evidence is currently available to support interventions to prevent NEC. Promising strategies that merit further evaluation in randomized controlled trials include the use of prebiotics and probiotics and the avoidance of exposure to H2-receptor antagonists.

A 10-month-old with rotavirus gastroenteritis, seizures, anasarca and systemic inflammatory response syndrome and complete recovery

This report describes a 10-month-old infant who presented with generalised tonic clonic seizures following 2 days of vomiting, diarrhoea and a low-grade fever. The patient was moderately dehydrated and the blood investigations were remarkable for hyponatraemia (126 mEq/l), leukocytosis (19.4 × 10(3)/l (46% lymphocytes)), thrombocytosis (637 × 10(3)/l), hypoalbuminaemia (albumin 1.9 g/dl) and elevated C reactive protein (96 mg/l). Stool was positive for white and red blood cells but the cultures for bacteria were negative. Rotavirus antigen in stool was positive. There was microscopic haematuria without proteinuria and the nasogastric aspirate was coffee ground. Generalised oedema with pleural and peritoneal effusions ensued requiring drainage, correction of fluid and electrolytes imbalance and albumin infusions. Over the next 72 h, the patient descended into shock and disseminated intravascular coagulopathy which required packed red blood cells and fresh frozen plasma transfusions. By day 12 the patient was clinically and biochemically normal.

Necrotizing enterocolitis in a term neonate following intravenous immunoglobulin therapy

A term baby with severe BO isoimmunization was treated with intravenous immunoglobulin. Shortly after the completion of the infusion, the baby developed clinical and radiological signs of necrotizing enterocolitis, with intestinal perforation and massive hemorrhagic ascites, resulting in the death of the baby.