Molecular characterization of enteric adenovirus genotypes 40 and 41 identified in children with acute gastroenteritis in Kolkata, India during 2013-2014

Clinical characteristics and phylogenetic analysis of human enteric adenovirus type 41 (HAdV-F41) from children with gastroenteritis during SARS-CoV-2 pandemic

Human adenovirus type 41 (HAdV-F41) usually causes pediatrics gastroenteritis. However, it was reported to be associated with the outbreaks of severe acute hepatitis of unknown aetiology (SAHUA) in pediatrics during COVID-19 pandemic. In this study, we investigated the prevalence of enteric HAdV-F41 in 37,920 paediatric gastroenteritis cases from 2017 to 2022 in Guangzhou, China. All children presented were tested negative for SARS-CoV-2 during the "zero-COVID" period. The main clinical symptom of the children was diarrhea (96.5%). No fatalities nor liver abnormal symptoms was found. In 2021, one year since the pandemic of COVID-19, the prevalence of HAdV-F41 abruptly increased from 3.71% to 8.64% (P < 0.001). All of HAdV-F41 circulating worldwide were classified into eight different subtypes (G1-G8) based on the phylogenetic clustering permutation of the four capsid genes of HAdV-F41. G3 was the predominant subtype (56.2%; 77/137). CRV5 isolates from SAHUA cases belong to this subtype, in which N312D and H335D mutations in the short fiber knob were identified in both Guangzhou and CRV5 isolates, presumably changing the virus tropism by directly interacting with the heparin sulfate (HS) receptor. Additionally, a novel recombinant G6 subtype, which is unique and only circulating in China was first identified in this study. This is the first study highlighting the prevalence of HAdV-F41 in paediatric cases of gastroenteritis during COVID-19 pandemic in China. The clinical and viral evolution finding of HAdV-F41 provide insight into the clinical characteristics of children with HAdV-F41 infections as well as the uncertain role of HAdV-F41 in the cause of SAHUA.

The short fiber knobs of human adenovirus in species F elicit cross-neutralizing antibody responses

Human adenovirus (HAdV) type 40 in species F (HAdV-F40) and HAdV-F41 represent the third most prevalent causative agents of non-bacterial acute gastroenteritis in infants and young children, following norovirus and rotavirus. Despite their significant contribution to global child morbidity, vaccines to preemptively combat these viruses remain elusive. In this study, we investigate the potential for cross-neutralization between HAdV-F40 and HAdV-F41 using immune sera with the short fiber knob (SFK). We implemented a series of assays to evaluate the responses, including enzyme-linked immunosorbent, micro-neutralization, immunofluorescence, and quantitative polymerase chain reaction. Our results demonstrate that immune sera with HAdV-F40 SFK or HAdV-F41 SFK could effectively neutralize both HAdV-F40 and HAdV-F41, indicating a mutual cross-neutralizing effect. Notably, the immune sera with HAdV-F40 SFK demonstrated a stronger neutralization effect, suggesting the potential to develop a subunit vaccine that can simultaneously counteract both viruses. These findings underscore the potential of SFK immunization in evoking a cross-neutralizing antibody response between HAdV-F40 and HAdV-F41. This suggests a promising avenue for developing subunit vaccines against HAdV-F40 and HAdV-F41 and provides a novel perspective on the potential of neutralizing antibodies to protect against these two types of HAdV.

Detection and complete genome sequence analysis of human adenovirus in children with acute diarrhea in Yunnan, China, 2015-2021

The aims of this study were to determine the distribution and prevalence of gastroenteritis caused by human adenovirus (HAdV) in children in Yunnan province, China, in 2015-2021 and to identify preventive measures that can be taken to reduce morbidity and mortality in children.HAdV is a significant agent of diarrhea in children, but limited data are available regarding the epidemiology and genetic diversity of HAdV in children with diarrhea in Yunnan province, China. A total of 1754 fecal samples were subjected to real-time RT-PCR to detect and quantify HAdV. Positive samples were further analyzed using next-generation sequencing (NGS), and epidemiological data were analyzed as well.1754 patients with diarrhea were enrolled, of which 1041 were male and 713 were female (M:F ratio: 1.46). Seventy-two stool samples out of 1754 (4.10%) were positive for HAdV. The detection rates of all age groups varied from 2.50-4.78%. The highest incidence of HAdV was observed in children under 2 years of age, especially in children 12-24 months-old. From 2015-2021, the annual detection rate ranged from 1.62-12.26%. HAdV was detected throughout the year, but with marked seasonality. Children were most likely to be positive for HAdV in June and November. We detected HAdV in 15.53% (16/103) of samples collected in June and in 8.19% (14/171) of those collected in November. The entire viral genome was successfully sequenced for 13 of the 72 HAdV-positive samples, and 76.92% (10/13) of these were classified as genotype F41 and 23.08% (3/13) were classified as genotype C2.ConclusionsIn Yunnan province, children of all ages are susceptible to HAdV infection, but there has been marked variation in the yearly prevalence. The highest rate of HAdV detection was in June, followed by November. Priority should be given to disease prevention over the development of targeted antiviral therapies, and effective vaccines for preventing HAdV diarrhea are needed. It is also important to establish a surveillance system to collect relevant clinical and epidemiological data quickly in order to assess the potential risk of HAdV infection in children and to identify epidemic strains for the development of effective vaccines.

Dissemination and genome characterization of a human adenovirus F41 in a patient with B-Cell lymphoma

Adenovirus (HAdV) F41 is a common cause of gastroenteritis and has rarely been reported associated with disseminated disease. In this report, an adult patient with a history of ulcerative colitis, cryptogenic cirrhosis, stage III adenocarcinoma, high-grade diffuse large B-cell lymphoma on chemotherapy was diagnosed with disseminated adenovirus infection. HAdV DNA was quantified in stool, plasma, and urine with viral loads of 7, 4, and 3 log10 copies/mL, respectively. The patient's course was rapidly progressive and he passed away 2 days after initiation of antiviral therapy. The patient's infecting virus was characterized as HAdV-F41 by whole genome sequencing.

Surveillance and epidemiological characterization of human adenovirus infections among outpatient children with acute gastroenteritis during the COVID-19 epidemic in Shanghai, China

BACKGROUND

Human adenovirus (HAdV) has been recognized as one of the common enteric viruses associated with acute gastroenteritis (AGE) in children. The aim of this study was carried out to illustrate the epidemiological characterization of HAdV Infections among children younger than 15 years in Shanghai during COVID-19.

METHODS

During May 2020 and April 2022, 1048 fecal samples were collected from children ≤ 15 years diagnosed with AGE in the Children's Hospital of Fudan University. HAdV was identified by PCR and sequenced with specific primers. All the obtained sequences were analyzed by MEGA (version 6.0). Demographic information and clinical features data were also collected and analyzed.

RESULTS

In total, 97 (9.3%, 97/1048) samples were detected to be HAdV during May 2020 and April 2022. We found an atypical upsurge in HAdV infection in the year 2021 after a major suppression in the year 2020. Approximately 84.5% (82/97) of HAdV-infected children were aged 0-60 months. Among the 97 HAdV-positive samples, only two species and five genotypes were detected. HAdV-F (88.7%, 86/97) was the most prevalent species and HAdV-F41 (87.6%, 85/97) was the most common genotype. Diarrhea, vomiting, and fever were the main clinical manifestations in children infected with HAdV. The children aged from 0 to 12 months showed simpler patterns of clinical presentation than those of children older than 13 months.

CONCLUSIONS

Our findings described the epidemiological changes of HAdV infection in children with AGE during the COVID-19, which further underscored the importance of continuous surveillance of HAdV at both local and global scales.

Enteric and non-enteric adenoviruses in children with acute gastroenteritis in Western India

Human adenoviruses (HAdVs) are the viral agents responsible for a wide spectrum of acute and chronic diseases. HAdVs are the most important etiological agents of acute gastroenteritis (AGE) and are identified as the major contributor to the deaths of diarrheal children globally. The significant rise in HAdV infections in rotavirus-vaccinated children documented in multiple studies demands continuous monitoring of HAdV strains. After the inclusion of rotavirus vaccines in the immunization schedule of India, public health research regarding prevalence, etiology, and risk factors is highly necessary for evidence-based policies and their implementation to sustain diarrhea prevention programs. In the present study, children admitted for AGE between 2013 and 2016 in seven different hospitals in Maharashtra and Gujrat states of Western India were subjected for investigation. HAdVs were found in 5.2% of the fecal specimens with the dominance of species-F (52.4%) strains, followed by the occurrence of non-enteric adenoviruses of species A (17.4%), C (11.4%), B (8.2%), and D (3.2%). The species-F strains were predominant in Ahmadabad (78.5%), Mumbai (61.5%), and Surat (57.1%) cities, followed by species-A strains. In Pune city, species B strains were detected in all HAdV patients, with none of the species A strains. Clinically, patients infected with enteric and non-enteric HAdV strains were indistinguishable. However, a high viral load was observed in species-F specimens as compared to non-species-F. The present study on fecal specimens collected in the pre-rotavirus vaccination era from hospitalized AGE patients will be important for future comparative analysis to know the exact impact of vaccination in children of Western India.

Genomic epidemiology of human adenovirus F40 and F41 in coastal Kenya: A retrospective hospital-based surveillance study (2013-2022)

Human enteric adenovirus species F (HAdV-F) is a leading cause of childhood diarrhoeal deaths. The genomic analysis would be key to understanding transmission dynamics, potential drivers of disease severity, and vaccine development. However, currently, there are limited HAdV-F genomic data globally. Here, we sequenced and analysed HAdV-F from stool samples collected in coastal Kenya between 2013 and 2022. The samples were collected at Kilifi County Hospital in coastal Kenya from children <13 years of age who reported a history of three or more loose stools in the previous 24 hours. The genomes were analysed together with the data from the rest of the world by phylogenetic analysis and mutational profiling. Types and lineages were assigned based on phylogenetic clustering consistent with the previously described criteria and nomenclature. Participant clinical and demographic data were linked to genotypic data. Of ninety-one cases identified using real-time Polymerase Chain Reaction, eighty-eight near-complete genomes were assembled, and these were classified into HAdV-F40 (n = 41) and HAdV-F41 (n = 47). These types co-circulated throughout the study period. Three and four distinct lineages were observed for HAdV-F40 (Lineages 1-3) and HAdV-F41 (Lineages 1, 2A, 3A, 3C, and 3D). Types F40 and F41 coinfections were observed in five samples and F41 and B7 in one sample. Two children with F40 and 41 coinfections were also infected with rotavirus and had moderate and severe diseases as defined using the Vesikari Scoring System, respectively. Intratypic recombination was found in four HAdV-F40 sequences occurring between Lineages 1 and 3. None of the HAdV-F41 cases had jaundice. This study provides evidence of extensive genetic diversity, coinfections, and recombination within HAdV-F40 in a rural coastal Kenya that will inform public health policy, vaccine development that includes the locally circulating lineages, and molecular diagnostic assay development. We recommend future comprehensive studies elucidating on HAdV-F genetic diversity and immunity for rational vaccine development.

Epidemiological investigations of diarrhea in children in Praia city, Cape Verde

Introduction

Diarrheal disease is a major cause of infant mortality and morbidity in Africa and results primarily from contaminated food and water sources, but its prevalence predictors in Cape Verde are not completely known. For this reason, this study aimed to identify the etiological agents of diarrhea in Cape Verdean children and assess its associated risk factors.

Methods

A survey questionnaire was used, and a total of 105 stool samples from children with diarrhea aged 0-12 years at the Central Hospital of Praia (Santiago, Cape Verde) were analyzed. The analyses were carried out using Biofire FilmArray Gastrointestinal Panels. Possible risk factors for these pathogens were analyzed using logistic regression, chi-square tests, or Fisher's exact test.

Results

Among the bacteria, enteroaggregative Escherichia coli (45.71%; 95% CI: 36.71-56.70), enteropathogenic E. coli (40%; 95% CI: 30.56-50.02), Shigella/enteroinvasive E. coli (29.52%; 95% CI: 21.02-39.22), E. coli enterotoxigenic (12.38%; 95% CI: 6.76-20.24), Campylobacter sp. (10.48%; 95% CI: 5.35-1.97), Vibrio sp. (4.76%; 95% CI: 1.56-10.76), Clostridioides difficile (3.81%; 95% CI: 1.05-9.47), Vibrio cholerae (2.86%; 0.59-8.12), Shiga-like toxin-producing E. coli (2.86%; 0.59-8.12) and Salmonella sp. (0.95%; 0.02-5.19) were identified; four viruses, Rotavirus A (28.57%; 95% CI: 20.18-38.21), Sapovirus I. II. IV and V (11.43%; 95% CI: 6.05-19.11), Norovirus GI.GII (6.67%; 95% CI: 2.72-13.25) and Adenovirus F 40.41 (6.67%; 95% CI: 2.72-13.25) were also observed. All the pathogens detected in this study were found in coinfections. Significant associations with risk factors were found; specifically, having a bathroom at home reduced the risk of Campylobacter sp., having animals at home increased the risk of Shigella/EIEC infection, and drinking bottled water reduced the risk of Sapovirus infection.

Discussion

From the findings of this study, it can be concluded that, in Cape Verde, there is a high prevalence and diversity of pathogens among children. Our results could help to establish an adequate diagnosis and effective treatments for diarrheal disease.

Comparative Analysis of Enzyme-Linked Immunosorbent Assay and Immunochromatography for Rotavirus and Adenovirus Detection in Children below Five Years with Acute Gastroenteritis

Introduction The most frequent etiologies of viral gastroenteritis among young children are rotavirus and enteric adenovirus. The clinical signs and symptoms of viral gastroenteritis are not distinct enough to allow for diagnosis. For the diagnosis and treatment of acute gastroenteritis, it is preferable to use quick, simple, and low-cost procedures. This study was undertaken to determine efficacy of immune-chromatography test (ICT) in comparison with enzyme-linked immunosorbent assay (ELISA) to detect rotavirus and adenovirus antigen in fecal specimen among children less than 5 years of age with acute gastroenteritis.

Materials and Methods In a cross-sectional observational study, 314 fecal samples were collected from children aged less than 5 years with acute gastroenteritis attending or admitted to a tertiary care hospital during the 1 year study period. Samples were tested for rotavirus and adenovirus antigen using ICT and ELISA.

Results Among the 314 children evaluated, 112 (35.66%) had rotavirus infection, nine (2.86%) had adenovirus infection, and three (0.95%) had both rotavirus and adenovirus infection. This study found that ICT is 98.20% sensitive and 100% specific for the diagnosis of rotaviral diarrhea and 100% sensitive and 99.7% specific for adenovirus diarrhea, compared to ELISA.

Conclusion Immunochromatography tests used for the detection of rotavirus and adenovirus in the fecal sample showed a high degree of sensitivity and specificity. The ICT is easy to perform and rapid, and it does not require any special equipment. Hence, the ICT could be used as an alternative method for detecting viral pathogens in clinical practice.

Isolation and Genotyping of Adenoviruses from Wastewater and Diarrheal Samples in Egypt from 2016 to 2020

Human adenoviruses (HAdV) are a prevalent cause of diarrhea in children all over the world. Adenoviral infections are responsible for 2% to 10% of diarrheic cases. A long-term investigation was required to gain better knowledge about the incidence of HAdV in Egypt. Herein, we conducted 5 years of detection, isolation, and genotyping of HAdV in fecal and sewage samples from 2016 to 2020, in Cairo, Egypt using molecular and cell culture assays. Human adenoviruses were identified in 35 of 447 fecal samples (7.8%), but only 53.3% (64/120) of the sewage samples. Children under the age of two had the highest positive rate for HAdV infection (77.1%). Species F of HAdV was the most common prevalent genotype in fecal and sewage samples, at 88.5% and 85.9%, respectively. The most prevalent genotypes detected in fecal samples were HAdV-41 (71.2%), HAdV-40 (17.2%), HAdV-6 (5.7%), and HAdV-1 (5.7%). In contrast, the most common genotypes in sewage samples were HAdV-41 (64%), HAdVs-40 (21.8%), HAdV-6 (7.8%), HAdV-1 (4.7%), and HAdV-2 (1.6%). HAdV was detected in all months of the year, with a peak period for clinical samples from December to February (p < 0.001), which matched Egypt’s rainy season, while the monthly distribution of HAdV in sewage samples remained consistent throughout the year, with no statistically significant peak period. Interestingly, the HAdV-type 41 genotype was the most common genotype during all of the years of this study. Throughout a 5-year period, our work revealed the infection rate, seasonal distribution, virus isolates, and genetic diversity of HAdV infections in environmental and clinical samples in Cairo, Egypt. Non-enteric adenovirus types (1, 2 and 6), as well as enteric adenovirus (41 and 40), may play a key role in gastroenteritis in Egypt.

Infection with adenovirus, rotavirus, and coinfection among hospitalized children with gastroenteritis in an Egyptian university hospital

Acute gastroenteritis is the main cause of mortality and morbidity in children worldwide. Studies stated that rotavirus and human adenovirus (HAdV) are common causes of nonbacterial gastroenteritis in children aged 0-5 years. The aim of this study was to determine the prevalence and the distribution of rotavirus, HAdV, and coinfections among hospitalized children with gastroenteritis below 7 years old and determine the prevalence of enteric HAdV among all HAdV gastroenteritis. The study was conducted on 150 children below 7 years old. Antigen detection for rotavirus and HAdV by ELISA and determination of enteric HAdV (serotype 40 and 41) by nested PCR and restriction endonucleases study were performed. Detection of rotavirus and HAdV antigens in 150 stool specimens from patients with gastroenteritis were 58% (87), 6.7% (10), and 8% (12) positive for rotavirus, HAdV, and coinfection, respectively. Out of 22 HAdV antigen-positive cases, 15 cases were positive by PCR for enteric HAdV, with the prevalence rate of enteric HAdV gastroenteritis among all HAdV gastroenteritis cases of 68%, a serotyping study by PCR detected serotype 40 in 46.7% of cases (7/15) and serotype 41 in 53.3% of cases (8/15) with no statistically significant difference between them. The study confirmed that rotavirus and HAdV are prevalent etiological agents of diarrhea in children below the school-age group, highlighting the necessity of the rotavirus vaccine in addition to the obligatory schedule of vaccines in Egypt. Also, it determined that the enteric HAdV gastroenteritis prevalence rate was 68% among all HAdV gastroenteritis.

Adenovirus is prevalent in juvenile polyps and correlates with low vitamin D receptor expression

BACKGROUND

The objective of this study was to assess human adenovirus (HAdV) infection in juvenile polyps (JPs) and to preliminarily establish a correlation to vitamin D receptor (VDR) expression.

METHODS

The study includes 76 patients of 5.2 ± 2.8 years old. Seventy-eight JP specimens and 24 parapolyp tissues from polypectomy were used. PCR was used to detect HAdV DNA and quantitative reverse transcription-PCR for viral and host gene expression. The PCR products were sequenced for virus typing. The correlation between VDR expression and HAdV infection was established using nonparametric Spearman's analysis.

RESULTS

Seventy-four children (97.4%) had a single polyp and two had two polyps. The histopathological characteristics of the polyps were in line with JP. Thirty-three samples had HAdV DNA (43.4%), including 32 subgroup C and 1 subgroup B HAdV; no enteric HAdV was detected. HAdV messenger RNA was detected in 5 of the 33 samples (15.2%). The samples had increased interleukin-1β (IL-1β), IL-6, and calprotectin expression, and reduced E-cadherin and VDR expression. JP samples with low VDR expression were more prevalent of HAdV DNA (r = 1.261, 95% confidence interval, 1.017-1.563), while VDR expression positively correlated with E-cadherin and negatively with inflammation gene expression.

CONCLUSIONS

HAdV latent infection was prevalent among JP tissues. The presence of HAdV correlated positively to low VDR expression.

IMPACT

The HAdVs infect the upper airways and gastrointestinal system and is found to persist in lymphoid tissues. The prevalence of HAdV and the status of the infection is unknown. The study investigated the prevalence of HAdV from polypectomy specimens of JP patients and found that HAdV was prevalent and was in a persistent state. HAdV infection was more prevalent in samples with low VDR expression. Whether HAdV infection and reactivation is a contributing factor to JPs is unknown. Factors such as proinflammation and bacterial metabolites that are known to promote HAdV reactivation warrant further investigation.

Molecular Epidemiology of Human Adenovirus, Astrovirus, and Sapovirus Among Outpatient Children With Acute Diarrhea in Chongqing, China, 2017-2019

OBJECTIVE

To investigate the epidemiology of human adenovirus (HAdV), human astrovirus (HAstV), and sapovirus (SaV), children with acute diarrhea in Chongqing, China from 2017 to 2019 were enrolled. Improved surveillance could provide better guidance for diarrhea prevention.

METHODS

Between 2017 and 2019, fecal specimens were collected from children <14 years of age presenting with acute diarrhea for treatment at the outpatient department of the Children's Hospital, Chongqing Medical University. Human HAdV in the fecal specimens was detected by PCR, while RT-PCR was adopted for the detection of HAstV and SaV.

RESULTS

A total of 1,352 fecal specimens were screened in this study. The detection rate of HAdV was 4.44% (60/1352), HAstV was 2.81% (38/1352), and SaV was 1.04% (14/1352). The prevalence of enteric viruses in males was not significantly different to females (p > 0.05). We found 96.67% (58/60) of the HAdV-positive cases, 92.11% (35/38) of the HAstV-positive cases, and 100% (14/14) of the SaV-positive cases among the children under 4 years old. HAdV cases were identified throughout the year, while the infection of HAstV peaked from March to May every year. By contrast, SaV was detected in May, July, and from September to December. In total, 41 strains of HAdV-F were identified, including F41 (39/60) and F40 (2/60). Furthermore, A31, B3, B7, C1, C2, C5, and C6 were also detected in the study. In addition, we detected two genotypes of HAstV, HAstV-1 (34/38) and HAstV-5 (4/38), and two genotypes of SaV, GI0.1 (13/14), GI0.2 (1/14).

CONCLUSION

The enteric viruses HAdV, HAstV, and SaV contribute to the overall burden of diarrhea in Chongqing, especially in children <4 years of age. Two genotypes were identified for HAstV (HAstV-1 and HAstV-5) and SaV (GI.1 and GI.2) with an additional nine genotypes detected in HAdV cases. While the F41 HAdV strain was predominant, HAdV-A31 was also detected in 10% of cases. The study results along with continuous surveillance of enteric viruses will aid in the design and implementation of future enteric vaccines and diarrhea mitigation strategies.

Molecular and epidemiological characterization of human adenoviruses infection among children with acute diarrhea in Shandong Province, China

Background

Human adenovirus (HAdV) had been recognized as one of the most common enteric viruses associated with acute diarrhea in children. The present study was carried out to demonstrate the molecular and epidemiological characterization of HAdV Infections among children in Shandong province in China between July 2017 and June 2018.

Methods

Fecal specimens were collected from children under 5 years old with acute diarrhea. DNA was extracted from the stool specimens and adenovirus DNA was detected by PCR amplification with specific primers. The amplification products were subjected to electrophoresis and visualized on a UV transilluminator. All positive RT-PCR amplification products were sequenced and the obtained sequences analyzed by MEGA (version 7.0). Demographic information and clinical manifestation data were also analyzed.

Results

In total, 656 fecal specimens were collected and the overall positive rate of HAdV was 7.47%. HAdV infections were detected in all age groups, in which children aged 13–24 months presented the highest positive rate. Seasonal pattern could be observed with a peak in December, January and February. Diarrhea, vomiting, dehydration and fever were the main clinical manifestations, in which vomiting was the most common accompanied symptom. By phylogenetic analysis, four species (A, B, C, and F) were detected and seven different serotypes were identified. HAdV-41 (48.98%, 24/49) was the most common serotype followed by HAdV-3 (18.37%, 9/49), HAdV-31 (14.29%, 7/49), HAdV-7 (8.16%, 4/49), HAdV-40 (4.08%, 2/49), HAdV-1 (4.08%, 2/49) and HAdV-2 (2.04%, 1/49).

Conclusion

This study indicated that HAdV infection was an important cause of acute diarrhea among children under 5 years old in Shandong province. The results will contribute to (a) increase understanding of the role of HAdV in diarrheal children and enhance identification of the predominant diarrhea pathogen for diagnosis; (b) avoid abuse of antibiotics; (c) monitor the change of prevalent HAdV serotypes and promote vaccine development and vaccination.

The Burden of Respiratory Viruses and Their Prevalence in Different Geographical Regions of India: 1970-2020

As per the 2019 report of the National Health Portal of India, 41,996,260 cases and 3,740 deaths from respiratory infections were recorded across India in 2018. India contributes to 18% of the global population, with severe acute respiratory infection (SARI) as one of the prominent causes of mortality in children >5 years of age. Measures in terms of the diagnosis and surveillance of respiratory infections are taken up globally to discover their circulating types, detect outbreaks, and estimate the disease burden. Similarly, the purpose of this review was to determine the prevalence of respiratory infections in various regions of India through published reports. Understanding the pattern and prevalence of various viral entities responsible for infections and outbreaks can help in designing better strategies to combat the problem. The associated pathogens comprise respiratory syncytial virus (RSV), rhinovirus, influenza virus, parainfluenza virus, adenovirus, etc. Identification of these respiratory viruses was not given high priority until now, but the pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has sensitized our system to be alert about the burden of existing infections and to have proper checks for emerging ones. Most of the studies reported to date have worked on the influenza virus as a priority. However, the data describing the prevalence of other respiratory viruses with their seasonal pattern have significant epidemiological value. A comprehensive literature search was done to gather data from all geographical regions of India comprising all states of India from 1970 to 2020. The same has been compared with the global scenario and is being presented here.

Evaluation of the Ridaquick Rotavirus/Adenovirus Immuno-Chromatographic Assay in Real-Life Situation

Immunochromatographic tests (ICT) are diagnostics tools providing rapid results without the need for specialized equipment. Our aim was to evaluate retrospectively the rotavirus and adenovirus ICT routinely used in the virology laboratory serving the University Hospital of Marseille, France. From January 2017 to March 2020, 715 stool specimens from patients were screened using the Ridaquick Rotavirus/Adenovirus Combi ICT (RR/AC ICT) and a commercially available multiplex PCR detection kit. Rotavirus was detected in 9.2% of specimens by PCR and 7.7% of specimens by RR/AC ICT while adenovirus was detected in 8.5% of specimens by PCR and 2.4% of specimens by RR/AC ICT. The RR/AC ICT parameters for rotavirus were 75.8% sensitivity, 99.2% specificity, 90.9% positive predictive value (PPV) and 97.6% negative predictive value (NPV). The RR/AC ICT parameters for adenovirus were 6.6% sensitivity, 98.0% specificity, 23.5% PPV and 91.8% NPV. While the ICT test may be suitable for rotavirus detection, a PCR–based assay is better adapted for adenovirus detection in stools.

Genetic diversity and molecular evolution of human adenovirus serotype 41 strains circulating in Beijing, China, during 2010-2019

Human adenovirus serotype 41 (HAdV-F41) is an important pathogen that causes diarrhea in children. However, the data on its molecular genetic characteristics and evolutionary history are still neither comprehensive nor sufficient. Four capsid protein genes from 58 HAdV-F41-positive specimens taken from diarrheal children in Beijing during 2010-2019 were amplified and analyzed. Variant amino acids in the hexon gene (18 sites) and short fiber gene (4 sites) clustered these strains into two clades and four subclades. The deletion of 15 amino acids found in the gene seemed to have little effect on the genomic strain cluster same as to penton gene. The HAdV-F41 strains had high diversity, as assessed from the intraspecific recombination of hexon, short fiber and long fiber. The molecular evolutionary rate of HAdV-F41's concatenated genes was 4.07 × 10^-5 substitutions/site/year, and it diverged from the most recent common ancestor in 1720. Apart from in the penton gene, positive selection codons were predicted in the other three genes, which may play a synergistic role in the evolution of HAdV-F41. These results provide new insights for understanding the characteristics of infectivity and developing vectors and vaccine vehicles for HAdV-F41.

Nonenteric Adenoviruses Associated with Gastroenteritis in Hospitalized Children

The object of this study was to investigate the frequency of human adenovirus (HAdV) infections in hospitalized pediatric patients. Stool samples were collected during a 1-year period (February 2018 to January 2019). HAdV was detected by a broad-range PCR and genotyped by sequencing and phylogenetic analysis. Demographic characteristics and detailed clinical information were analyzed for each patient. HAdV was detected in 7.1% of stool samples (34/476). Among these patients, 23.5% were coinfected with other enteric viral or bacterial pathogens. The majority (85.2%) of HAdV positives were detected in children of <5 years of age. Two HAdV species (B and C) with three types were identified in this study population. HAdV species F was not detected. Genetic analysis shows that the isolates circulating in our region present high diversity and do not exhibit clonal expansion. The presence of nonenteric HAdV in subjects with gastrointestinal symptoms and in immunocompromised patients has already been reported by different studies and underlines the need to develop routine molecular assays that have wide reactivity for most types of adenovirus in order to obtain an optimal tool for their rapid and accurate diagnosis. IMPORTANCE Gastroenteritis is the second leading cause of death among infants and children worldwide. Our study shows that adenovirus types other than 40 and 41 might be related to acute gastroenteritis. Therefore, a novel approach using diagnostic methods able to detect all adenovirus types is desirable in order to overcome the limitations of the current techniques.

Molecular and epidemiological characterization of human adenovirus and classic human astrovirus in children with acute diarrhea in Shanghai, 2017-2018

BACKGROUND

In addition to rotavirus and norovirus, human adenovirus (HAdV) and classic human astrovirus (classic HAstV) are important pathogens of acute diarrhea in infants and young children. Here, we present the molecular epidemiology of HAdV and classic HAstV in children with acute diarrhea in Shanghai.

METHODS

Fecal specimens were collected from 804 outpatient infants and young children diagnosed with acute diarrhea in Shanghai from January 2017 to December 2018. All of the samples were screened for the presence of HAdV and classic HAstV. HAdV and classic HAstV were detected using traditional PCR and reverse-transcription PCR, respectively. All of the HAdV and classic HAstV positive samples were genotyped by phylogenetic analysis.

RESULTS

Among the 804 fecal samples, 8.58% (69/804) of samples were infected with either HAdV or classic HAstV, and five were co-infected with two diarrhea viruses. The overall detection rates of HAdV and classic HAstV were 3.47% (28/804) and 5.22% (42/804), respectively. Four subgroups (A, B, C, and F) and seven genotypes (HAdV-C1, -C2, -B3, -C5, -A31, -F40, and -F41) of HAdV were detected. Subgroup F had the highest constituent ratio at 64.29% (18/28), followed by non-enteric HAdV of subgroup C (21.43%, 6/28) and subgroup B 10.71% (3/28). HAdV-F41 (60.71%, 17/28) was the dominant genotype, followed by HAdV-C2 (14.29%, 4/28) and HAdV-B3 (10.71%, 3/28). Two genotypes of classic HAstV (HAstV-1 and HAstV-5) were identified in 42 samples during the study period; HAstV-1 (95.24%, 40/42) was the predominant genotype, and the other two strains were genotyped as HAstV-5. No significant differences were found between boys and girls in the detection rates of HAdV (P = 0.604) and classic HAstV (P = 0.275). Over half of the HAdV infections (82.14%, 23/28) and classic HAstV infections (66.67%, 28/42) occurred in children less than 36 months. Seasonal preferences of HAdV and classic HAstV infections were summer and winter, respectively. In this study, the common clinical symptoms of children with acute diarrhea were diarrhea, vomiting, fever and abdominal pain.

CONCLUSIONS

Our findings indicate that HAdV and classic HAstV play important roles in the pathogenesis of acute diarrhea in children in Shanghai. Systematic and long-term surveillance of HAdV and classic HAstV are needed to monitor their prevalence in children and prevent major outbreak.

Enteric adenovirus epidemiology from historical fecal samples in Brazil (1998-2005): Pre-rotavirus vaccine era

Human adenovirus (HAdV) is recognized as frequent cause of acute gastroenteritis and enteric viruses can be preserved in frozen stored feces for long periods of times. The purpose of the present study was to investigate enteric HAdV genotypic diversity in archival fecal specimens stored from 1998 to 2005 in order to understand the natural history of HAdV in diarrheal patients in Brazil before rotavirus vaccine introduction. A total of 3346 specimens were tested for HAdV using conventional PCR. Genotypes were identified by sequencing. HAdV was detected in 6.8% (228/3346). Positivity was higher in children ≤ 5 years and males (p < 0.05). HAdV was most frequently observed during winter and spring seasons (p < 0.05). HAdV-F41 was the most prevalent genotype (59.2%;135/228), followed by HAdV-F40 (16.2%;37/228), HAdV-C1 (5.2%;12/228), HAdV-C2 (5.2%;12/228), HAdV-C5 (3.1%;7/228), HAdV-A12 (1.3%;3/228), HAdV-E4 (0.9%;2/228), HAdV-B3 (0.9%;2/228) and HAdV-B21 (0.4%;1/228). In 7.6% (17/228) only species D could be defined. HAdV-E4 strains were phylogenetic analyzed and classified as lineage (a)-like PG II. HAdV prevalence remained stable in Brazilian population, regardless rotavirus vaccine introduction. The predominant HAdV genotypes detected did not change over time, highlighting a high diversity of circulating strains in the country throughout decades. Due to the historical lack of HAdV genotyping surveillance in Brazil, HAdV-E4 epidemiology is virtually unknown in the country. The present study contributed significantly to the understanding of the natural history of HAdV in diarrheal patients in Brazil. The acquired data are important for clinical diagnosis, particularly for studies investigating enteric viruses' prevalence and molecular epidemiology of archival clinical specimens.

Genetic characterization and phylogenetic variations of human adenovirus-F strains circulating in eastern India during 2017-2020

Human adenovirus-F (HAdV-F) (genotype 40/41) is the second-most leading cause of pediatric gastroenteritis after rotavirus, worldwide, accounting for 2.8%-11.8% of infantile diarrheal cases. Earlier studies across eastern India revealed a shift in the predominance of genotypes from HAdV41 in 2007-09 to HAdV40 in 2013-14. Thus, the surveillance for HAdV-F genotypes in this geographical setting was undertaken over 2017-2020 to analyze the viral evolutionary dynamics. A total of 3882 stool samples collected from children (≤5 years) were screened for HAdV-F positivity by conventional PCR. The hypervariable regions of the hexon and the partial shaft region of long fiber genes were amplified, sequenced, and phylogenetically analyzed with respect to the prototype strains. A marginal decrease in enteric HAdV prevalence was observed (9.04%, n = 351/3882) compared to the previous report (11.8%) in this endemic setting. Children <2 years were found most vulnerable to enteric HAdV infection. Reduction in adenovirus-rotavirus co-infection was evident compared to the sole adenovirus infection. HAdV-F genotypes 40 and 41 were found to co-circulate, but HAdV41 was predominant. HAdV40 strains were genetically conserved, whereas HAdV41 strains accumulated new mutations. On the basis of a different set of mutations in their genome, HAdV41 strains segregated into 2 genome type clusters (GTCs). Circulating HAdV41 strains clustered with GTC1 of the fiber gene, for the first time during this study period. This study will provide much-needed baseline data on the emergence and circulation of HAdV40/41 strains for future vaccine development.

Pediatric acute gastroenteritis associated with adenovirus 40/41 in low-income and middle-income countries

PURPOSE OF REVIEW

To review the roles of enteric adenovirus types 40 and 41 and nonenteric adenoviruses in the global burden of pediatric diarrhea.

RECENT FINDINGS

Large studies using highly sensitive, type-specific molecular diagnostics have demonstrated a substantial and previously under-estimated burden of pediatric diarrheal disease because of enteric infections with adenovirus types 40/41. However, the true epidemiology of adenovirus 40/41 remains incompletely understood. Similarly, additional adenovirus types may also be implicated as agents of community-acquired pediatric gastroenteritis but current data are too limited to elucidate their epidemiological role(s), if any.

SUMMARY

Efforts at global diarrhea control in low-income and middle-income countries will require combating pediatric gastroenteritis because of enteric adenovirus infections. Future research in these settings using type-specific molecular diagnostics or strain genotyping to fully characterize the epidemiology of adenovirus 40/41 infections, identify non-40/41 adenoviruses significantly associated with gastroenteritis, and develop vaccines effective at preventing adenovirus diarrhea is warranted.

Diversity of enteric and non-enteric human adenovirus strains in Brazil, 2006-2011

During 2006-2011, 5035 fecal samples were tested by PCR for human adenovirus (HAdV) and sequenced. HAdV was detected in 198 cases (3.9%), with the highest rate in children ≤ 5 years. Enteric HAdVs were the most prevalent genotypes (78%; 146/187): HAdV-F41 (63.6%; 119/187), HAdV-F40 (12.3%; 23/187), HAdV-A12 (1.6%; 3/187) and HAdV-A31 (0.5%; 1/187). Non-enteric HAdVs were detected in 22% (41/187): HAdV-C1 (8.0%; 15/187), HAdV-C2 (6.9%; 13/187), HAdV-C5 (4.3%; 8/187), HAdV-D8 (1.3%; 2/187), HAdV-B21 (0.5%; 1/187), HAdV-B3 (0.5%; 1/187) and HAdV-C6 (0.5%; 1/187). This 6-year retrospective study points out a high diversity of HAdV types circulating in Brazil and highlights the need to carry out molecular epidemiological studies of HAdV among patients with acute diarrheal infection on a regular basis.

Foodborne Viruses and Innovative Non-Thermal Food-Processing Technologies

In recent years, several foodborne viruses' outbreaks have been recorded worldwide. Μost of the foodborne viruses have a low infection dose, are stable and can persist and survive in foods for a long time without loss of infectivity. The most important foodborne viruses are: human norovirus (HuNoV), human rotavirus (HRV), hepatitis A virus (HAV), hepatitis E virus (HEV), human astrovirus (HAstV), Aichi virus (AiV), sapovirus (SaV), human adenovirus (HAdV) and enterovirus (EV). In recent years, innovative non-thermal food-processing technologies including high-pressure processing (HPP), cold plasma (CP), ultraviolet light (UV), irradiation and pulsed electric field (PEF) for improving the quality and safety of foods, including foods of animal origin, have been under research. This review presents the recent data on foodborne viruses and reviews the innovative non-thermal technologies for the control of the foodborne viruses in foods.

Viral gastroenteritis in Tocantins, Brazil: characterizing the diversity of human adenovirus F through next-generation sequencing and bioinformatics

Human enteric adenovirus species F (HAdV-F) is one of the most common pathogens responsible for acute gastroenteritis worldwide. Brazil is a country with continental dimensions where continuous multiregional surveillance is vital to establish a more complete picture of the epidemiology of HAdV-F. The aim of the current study was to investigate the molecular epidemiology of HAdV-F using full-genome data in rural and low-income urban areas in northern Brazil. This will allow a genetic comparison between Brazilian and global HAdV-F strains. The frequency of HAdV-F infections in patients with gastroenteritis and molecular typing of positive samples within this period was also analysed. A total of 251 stool samples collected between 2010 and 2016 from patients with acute gastroenteritis were screened for HAdV-F using next-generation sequencing techniques. HAdV-F infection was detected in 57.8 % (145/251) of samples. A total of 137 positive samples belonged to HAdV-F41 and 7 to HAdV-F40. HAdV-F40/41 dual infection was found in one sample. Detection rates did not vary significantly according to the year. Single HAdV-F infections were detected in 21.9 % (55/251) of samples and mixed infections in 37.4 % (94/251), with RVA/HAdV-F being the most frequent association (21.5 %; 54/251). Genetic analysis indicated that the HAdV-F strains circulating in Brazil were closely related to worldwide strains, and the existence of some temporal order was not observed. This is the first large-scale HAdV-F study in Brazil in which whole-genome data and DNA sequence analyses were used to characterize HAdV-F strains. Expanding the viral genome database could improve overall genotyping success and assist the National Center for Biotechnology Information (NCBI)/GenBank in standardizing the HAdV genome records by providing a large set of annotated HAdV-F genomes.

Enteric Viral Co-Infections: Pathogenesis and Perspective

Enteric viral co-infections, infections involving more than one virus, have been reported for a diverse group of etiological agents, including rotavirus, norovirus, astrovirus, adenovirus, and enteroviruses. These pathogens are causative agents for acute gastroenteritis and diarrheal disease in immunocompetent and immunocompromised individuals of all ages globally. Despite virus–virus co-infection events in the intestine being increasingly detected, little is known about their impact on disease outcomes or human health. Here, we review what is currently known about the clinical prevalence of virus–virus co-infections and how co-infections may influence vaccine responses. While experimental investigations into enteric virus co-infections have been limited, we highlight in vivo and in vitro models with exciting potential to investigate viral co-infections. Many features of virus–virus co-infection mechanisms in the intestine remain unclear, and further research will be critical.

Validation of a Laboratory-Developed Triplex Molecular Assay for Simultaneous Detection of Gastrointestinal Adenovirus and Rotavirus in Stool Specimens

Enteric viral pathogens causing gastroenteritis include adenovirus and rotavirus, among others. Rotavirus is the leading cause of severe diarrhea in infants and young children worldwide. Among the adenoviruses known to cause gastroenteritis are those of species F (serotypes 40, 41). Here, we describe the development and validation of a laboratory-developed gastrointestinal triplex rRT-PCR (triplex) assay that targets adenovirus and rotavirus. Stool specimens were tested from patients across Ontario. Specimens were previously tested for adenovirus and/or rotavirus by electron microscopy (EM) or immunochromatographic test (ICT). Triplex sensitivity, specificity, positive and negative predictive values compared to Seegene assay (a commercial assay used here as the standard reference method) were 100%, 97.8%, 86.0%, 100% for adenovirus, and 99.1%, 98.4%, 96.3%. 99.6% for rotavirus, respectively. The triplex assay had a 95.2% and 97.3% overall percent agreements (OPAs) when compared to EM for adenovirus or rotavirus detection, respectively, and an OPA of 90.9% when compared to rotavirus ICT for rotavirus detection. Triplex assay exhibited similar performance to the Seegene assay for both adenovirus and rotavirus and detected more adenovirus and rotavirus than traditional testing methods. The high performance along with lower cost and reduced turnaround time makes the triplex assay a desirable testing method for a clinical microbiology laboratory.

Development and evaluation of a multiplex conventional reverse-transcription polymerase chain reaction assay for detection of common viral pathogens causing acute gastroenteritis

Timely identification of etiological agents of enteric infections is necessary to reduce the burden of infantile diarrheal mortality. Nucleic acid amplification-based detection methods offer a quick, reliable way for diagnosis of microbes in clinical specimens. This study was undertaken to evaluate an easy-to-use, cost-effective multiplex conventional reverse-transcription polymerase chain reaction (RT-PCR) assay developed at the Indian Council of Medical Research-National Institute of Cholera and Enteric Diseases virology laboratory to identify 4 common enteric viruses (rotavirus, norovirus, adenovirus, astrovirus) in stool samples from patients who were being evaluated for acute diarrhea. On comparison with a commercially available real-time PCR method, significant agreement in sensitivity and specificity was observed. Though the turnaround time for RT-PCR was 6-8 h compared to 5-6 h for real-time PCR, the real-time PCR has high test cost (approximately 28 USD/2000 INR) for Fast-Track Diagnostics kit-based quantitative RT-PCR versus 6 USD or 400 INR for conventional multiplex RT-PCR/sample. Thus, the conventional RT-PCR method is expected to be adaptable at local hospitals and health cares in resource-poor settings.

Molecular epidemiology of rotavirus A and adenovirus among children with acute diarrhea in Hangzhou, China

Background

Rotavirus A (RVA) and adenovirus (Adv) are important causes of acute diarrhea in children. RVAs are classified into G and P genotypes based on viral proteins (VP)7 and VP4 gene and Adv contains over 70 genotypes based on hexon and fiber gene. This study aimed to characterize the molecular epidemiology of RVA and Adv in children with acute diarrhea during 2017-2018 in Hangzhou.

Methods

The stool samples were collected and tested for RVA and Adv by reverse transcription-quantitative PCR (RT-qPCR) assay. The RVA positive samples were detected by RT-PCR for VP7(G) and VP4([P]) genotypes, and the Adv positive samples were detected by PCR for genotyping by the target to hexon gene.

Results

Among 228 RVA-positive samples, G9 was detected as the most frequent genotype (195/228, 85.5%), followed by G3 (20/228, 8.8%), G2 (7/228, 3.1%) and G1 (6/228, 2.6%). G9 strains were closely related to strains from China and neighboring countries, as well as the USA. On the other hand, P[8] strains were detected in 219 (96.1%) samples with most closely related to one strain from Malawi, and P[4] in 9 (3.9%) samples. G9P[8] (84.6%, 193/228) was the most prevalent rotavirus A strains, followed by G3P[8] (8.8%, 20/228), G2P[4] (3.1%, 7/228), G1P[8] (2.6%, 6/228) and G9P[4] (0.9%, 2/228). Of 167 Adv-positive cases, 2 different genotypes were identified with 152 (91.0%) of Adv-41and 15 (9%) of Adv-40. All Adv strains were closely related to prototype strains of Adv types 40 and 41 in India.

Conclusions

G9P[8] of RVA and Adv-41 were the most common genotypes that caused children's acute diarrhea in Hangzhou, 2017-2018.

Enteric and non-enteric adenoviruses associated with acute gastroenteritis in pediatric patients in Thailand, 2011 to 2017

Human adenovirus (HAdV) is known to be a common cause of diarrhea in children worldwide. Infection with adenovirus is responsible for 2–10% of diarrheic cases. To increase a better understanding of the prevalence and epidemiology of HAdV infection, a large scale and long-term study was needed. We implemented a multi-year molecular detection and characterization study of HAdV in association with acute gastroenteritis in Chiang Mai, Thailand from 2011 to 2017. Out of 2,312 patients, HAdV was detected in 165 cases (7.2%). The positive rate for HAdV infection was highest in children of 1 and 2 years of age compared to other age groups. HAdV subgroup C (40.6%) was the most prevalent, followed by subgroups F (28.5%), B (20.6%), A and D (4.8% each), and E (0.6%). Of these, HAdV-F41 (22.4%), HAdV-C2 (18.2%), HAdV-B3 (15.2%), and HAdV-C1 (13.3%) were the most common genotypes detected. HAdV infection occurred throughout the year with a higher detection rate between May and July. In conclusion, our study demonstrated the infection rate, seasonal distribution and genotype diversity of HAdV infection in children with diarrhea in Chiang Mai, Thailand over a period of 7 year. Not only enteric adenovirus (F40 and F41) but also non-enteric adenovirus (B3, C1, C2) may play an important role in gastroenteritis in this area. The information will be beneficial for the prevention and control of HAdV outbreaks in the future.

Genetic diversity and quantification of human mastadenoviruses in wastewater from Sydney and Melbourne, Australia

Human mastadenoviruses (HAdVs) are DNA viruses that can cause a wide range of clinical diseases, including gastroenteritis, respiratory illnesses, conjunctivitis, and in more severe cases hepatitis, pancreatitis and disseminated diseases. HAdV infections are generally asymptomatic or self-limiting, but can cause adverse outcomes within vulnerable populations. Since most HAdV serotypes replicate within the human gastrointestinal tract, high levels of HAdV DNA are excreted into wastewater systems. In this study, we identified the genetic diversity of HAdV at a population level using wastewater samples collected from Sydney and Melbourne from 2016 to 2017, with the use of next generation sequencing (NGS) technologies. In addition, HAdV DNA levels were quantified using quantitative polymerase chain reaction (qPCR) based methods to better understand the health risks involved if wastewater contamination occurs. An average of 1.8 × 10⁷ genome copies of HAdV DNA was detected in one litre of wastewater collected in Sydney and Melbourne, over the two-year study period. A total of six major groups of HAdV were identified in wastewater samples using MiSeq, which included 19 different serotypes. Of those, the most prevalent was F41 (83.5%), followed by F40 (11.0%) and A31 (3.7%). In contrast, five groups of HAdV were identified in clinical samples with F41 as the most dominant serotype, (52.5% of gastroenteritis cases), followed by C1 and C2 (each responsible for 15.0%), and B3 was the fourth most common serotype (7.5%). This study demonstrated the practicability of using amplicon based NGS to identify HAdV diversity and quantify HAdV genome levels in environmental water samples, as well as broadening our current understanding of circulating HAdV in the Australian population.

Molecular analysis of human adenoviruses in hospitalized children <5 years old with acute gastroenteritis in Tehran, Iran

Human adenoviruses (HAdVs), especially AdV-40 and 41, are common causes of nonbacterial sporadic and outbreak gastroenteritis in children. The present study aimed to describe the frequency and genetic analysis of HAdVs in hospitalized children <5 years old with acute gastroenteritis. A total of 376 stool samples obtained from June 2015 to December 2017 were investigated for the presence of HAdVs by polymerase chain reaction. The HAdV DNA was detected in 16 (4.3%) out of 376 stool samples. Based on the hexon hypervariable region (HVR), B, C, and F HADV species including five types HAdV-1, 2, 3, 6, and 41 were identified, among which enteric AdV species F (EAdV-41) was the most dominant. Moreover, our findings showed the presence of genomic type cluster 1 (GTC1) pattern in Iranian type 41 strains, which was closely similar to the D1 prototype strain (Tak) and D28. In this regard, a recombination was found in AdV-41 strains presenting the hexon sequence that belonged to GTC1, while fiber sequence clustered with GTC2.

Molecular epidemiology of human adenovirus infections in Denmark, 2011-2016

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We developed new primers to improve genotyping of HAdV D.

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Six out of seven HAdV species from at least 13 HAdV types were identified.

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Young children (<5 years old) were more likely to be positive for HAdV.

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Co-infections with other gastrointestinal or respiratory viruses were common.

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A HAdV surveillance system is required to monitor circulating species and types.

Background

Human adenoviruses (HAdVs) can cause respiratory tract infections, conjunctivitis, diarrhoea and outbreaks have been reported. However, little is known about the disease burden and the molecular epidemiology of HAdV.

Objectives

To retrospectively perform a molecular characterization of HAdV positive samples received at Statens Serum Institut during the period 2011–2016 and to compare this with demographic information, geographic location, sample collection date and type and co-infection with other viral pathogens.

Study design

152 HAdV positive samples were genotyped by Sanger sequencing of a fragment of the hexon gene using published primers along with a newly developed primer set for enhanced genotyping of HAdV D. Phylogenetic analysis was used for genotyping and genotypes were compared with epidemiological information. In addition, HAdV burden and co-infection was evaluated for samples tested in laboratory analysis packages.

Results

Six out of seven HAdV species were identified and represented by 13 types. Young children (<5 years old) were more likely to be positive for HAdV and co-infections with other gastrointestinal or respiratory viruses were common. Possible outbreaks of ocular infections due to HAdV D could not be confirmed.

Conclusion

A diverse set of HAdV species were circulating in Denmark in the study period and although possible transmission clusters were identified, this could not be verified with current genotyping methods Young children were commonly affected by HAdV infection and co-infections with other viral pathogens were frequent suggesting a possible underestimation of the real HAdV burden.

Detection and Molecular Characterization of Human Adenovirus Infections among Hospitalized Children with Acute Diarrhea in Shanghai, China, 2006-2011

Background: Human adenovirus (HAdV) is considered a significant enteropathogen associated with sporadic diarrhea in children. However, limited data are available regarding the epidemiology of HAdV in hospitalized children with viral diarrhea in Shanghai. The aim of this study was to characterize the epidemiology of HAdVs and describe their association with acute diarrhea in hospitalized children. Methods: A total of 674 fecal samples were subjected to PCR or RT-PCR to detect RVA, HuCV, HAstV, and HAdV. Results: HAdV infections were detected in 4.7% (32/674) of specimens, with detection rates of 13.4% (11/82), 4.6% (8/174), 3.2% (4/124), 4.1% (3/74), 2.0% (2/100), and 3.3% (4/120) from 2006 to 2011, respectively. Comprehensive detection of the four viruses revealed the presence of a high percentage (90.6%) of coinfections among HAdV-positive samples, where HAdV+RVA was the most prevalent coinfection. Of the 32 HAdV-positive samples, 50.0% (16/32) were classified as HAdV-41, and 18.8% (6/32) were classified as HAdV-3. Almost 94.0% of children infected with HAdV were less than 24 months of age. Conclusions: These results clearly indicated diversity across the HAdV genotypes detected in inpatient children with acute diarrhea in Shanghai and suggested that HAdVs play a role in children with acute diarrhea.

Diagnosis of Viral Infections

Accurate diagnosis of viral infections enhances the ability of the clinician to make decisions on appropriate treatment of patients, evaluate disease progression and prevent misuse of antibiotics. Knowledge of the pathogen involved also allow implementation of infection control and monitoring of success of antiviral treatments that may affect the prognosis of patients. Epidemiological data collected through accurate diagnostics play an important role in public health through identification and control of outbreaks, implementation of appropriate diagnostic tests, vaccination programs and treatment but also to recognize common and emerging pathogens in a community. It is key that the clinician have an understanding of appropriate specimens to send to the laboratory and the value of specific nucleic acid and serological testing for different viral pathogens. Molecular techniques have revolutionized viral diagnoses over the past decade and enhanced both the sensitivity and specificity of tests and the speed by which a diagnosis can be made and new tests be developed. The continued use of serology for viruses with a short viremia, or for chronic infections should however complement these tests. This chapter aims to provide an overview of the available tests, the principles of testing and appropriate tests to select for different viruses and syndromes. Also provided is a glimpse of new developments in diagnostics that may further enhance the capacity to make a conclusive diagnosis in the near future.