Incidence of enteric adenoviruses among children in Thailand and the significance of these viruses in gastroenteritis

Prevalence of enteric adenovirus and co-infection with rotavirus in children under 15 years of age with gastroenteritis in Qom, Iran

AIM

The current study is the first performed in Qom to determine the prevalence of adenovirus and co-infections with rotavirus in children aged <15 years with gastroenteritis symptoms.

BACKGROUND

Gastroenteritis-associated viral infections are a cause of death among young children worldwide, especially in developing countries. The Adenovirus species F (40 and 41) are responsible for a range of acute diarrhea cases among infants and children.

METHODS

Over a period of 9 months, a total of 130 children suffering from intestinal problems who referred to the infectious ward of Children's Hospital were enrolled in the current study. After clinical examination and collection of demographic information, fecal samples were obtained from the patients. Viral genomes were extracted with a commercial kit and amplified and typed by adenovirus-specific PCR assay. Adenovirus-positive samples were also evaluated for co-infection with rotavirus.

RESULTS

Patients had a mean±SD age of 2.66±2.72 years; 63.1% of patients were male and 36.9% were female. Adenovirus infection was identified in 23 cases (17.7%), 21 (91.0%) and 2 (9.0%) of which were type 41 and type 40, respectively. Fever was the most common clinical manifestation among adenovirus-positive patients. No significant difference was observed between adenovirus infection and clinical symptoms, seasonal pattern, or serum laboratory results. Co-infection was found in only 5 cases (21.7%).

CONCLUSION

This study was the first to demonstrate adenovirus infection with a relatively high prevalence among children, especially infants, in Qom. The findings further revealed co-infection with rotavirus, indicating a health problem in this region.

A review of 65 years of human adenovirus seroprevalence

Introduction: Human adenovirus (HAdV)-derived vectors have been used in numerous pre-clinical and clinical trials during the last 40 years. Current research in HAdV-based vaccines focuses on improving transgene immunogenicity and safety. Because pre-existing humoral immunity against HAdV types correlate with reduced vaccine efficacy and safety, many groups are exploring the development of HAdV types vectors with lower seroprevalence. However, global seroepidemiological data are incomplete. Areas covered: The goal of this review is to centralize 65 years of research on (primarily) HAdV epidemiology. After briefly addressing adenovirus biology, we chronical HAdV seroprevalence studies and highlight major milestones. Finally, we analyze data from about 50 studies with respect to HAdVs types that are currently used in the clinic, or are in the developmental pipeline. Expert opinion: Vaccination is among the most efficient tools to prevent infectious disease. HAdV-based vaccines have undeniable potential, but optimization is needed and antivector immunity remains a challenge if the same vectors are to be administrated to different populations. Here, we identify gaps in our knowledge and the need for updated worldwide epidemiological data.

Prevalence of Nosocomial Diarrhea Due to Adenoviruses 40 and 41 in a Paediatric Ward in Iran

BACKGROUND

Enteric adenoviruses 40 (Ad40) and adenovirus 41 (Ad41) have been shown to be a significant cause of paediatric gastroenteritis worldwide, but no data are available for nosocomial diarrhea due to adenovirus in Iran.

AIM

The present study was performed to determine the incidence of Ad40 and Ad41 in children less than five years with nosocomial diarrhea in Shahrekord, southwest Iran.

MATERIALS AND METHODS

Adenovirus was detected by polymerase chain reaction (PCR) in stool samples collected during one year (2010-2011) from children less than five years with nosocomial diarrhea admitted to a paediatric center in Shahrekord, Iran. Nosocomial diarrhea was defined as those occurring more than 72 hours after admission to hospital for non-diarrheal causes. PCR technique was used for investigation of Ad40 and Ad41.

RESULTS

In total of 100 samples, Ad40 and Ad41 DNA was found to be positive in 14/100 (14%), and 8/100 (8%) of diarrheic patients less than five years, respectively.

CONCLUSION

Ad40 and Ad41 are important causes of nosocomial diarrhea in less than five-year, hospitalized Iranian children.

Molecular Epidemiology of Adenovirus Infection among Pediatric Population with Diarrhea in Asia

A total of 3,577 fecal specimens from infants and children with acute gastroenteritis in Japan, Korea and Vietnam during 1998 and 2001 were tested for adenovirus by the ELISA method. Of these, adenovirus was detected in 158 (4.4%). The detection rate of adenovirus was highest in Korea (8.7%, 20/231) followed by 5.0% (100/1,991) in Japan and 2.8% (38/1,355) in Vietnam. All adenoviruses were further serotyped by PCR-RFLP. The diversity of adenovirus serotypes including Ad2, 3, 5, 8, 31, 40 and 41 was demonstrated. Worth of note was a decrease in the rate of isolation of Ad40 (7.6%, 12/158) and a concomitant increase of Ad41 (63.9%, 101/158) to become the predominant serotype. Another interesting feature of the study was the presence of Ad3 (4.0% and 30%) and Ad8 (8.0% and 20%) in Japan and Korea, respectively, which is mainly associated with keratoconjunctivitis worldwide. Our result underscored the importance of adenovirus in association with acute gastroenteritis in Asian countries.

Multiplex real-time PCR assays for the detection of group C rotavirus, astrovirus, and Subgenus F adenovirus in stool specimens

Group C rotavirus (GCRV), astrovirus (AstV), and adenovirus (subgenus F AdenoV) are etiologic agents of acute nonbacterial gastroenteritis, which often represents community outbreaks. For the efficient detection of GCRV, AstV, and subgenus F AdenoV in stool specimens, a multiplex real-time PCR assay was developed to detect these three viruses simultaneously, with high sensitivity and specificity. In total, 8404 clinical specimens were collected between April 2008 and March 2011 and tested for GCRV, AstV, and subgenus F AdenoV by the multiplex real-time PCR, as well as for norovirus (NoV), sapovirus (SaV), and group A rotavirus (GARV) by non-multiplex real-time PCR. Forty-one specimens were positive for GCRV, AstV, or subgenus F AdenoV, including 15 specimens that were also positive for NoV, SaV, or GARV. Multiple viruses were detected simultaneously in 29 out of 4596 (0.63%) specimens infected with at least one virus. The association rates of AstV and subgenus F AdenoV with other viruses were significantly higher than those of NoV, SaV, GARV, or GCRV.

Acute infectious diarrhea

Infectious diarrhea is both a local and a global concern. Illnesses can range from mild inconveniences to life-threatening epidemics. Although diarrhea can be caused by a vast array of pathogens, the cornerstone of prevention is provision of a safe food and water supply, application of basic hygiene principles, and the development and administration of vaccines. The cornerstone of treatment is rehydration. Selection of specific antimicrobial therapy should be based on disease presentation and epidemiologic factors.

Molecular epidemiology of human astrovirus and adenovirus serotypes 40/41 strains related to acute diarrhea in Tunisian children

Human astrovirus (AstV) and adenovirus types 40 and 41 (AdV 40/41) are responsible for epidemic and endemic acute gastroenteritis in children and adults. The present study was designed to evaluate the prevalence and genetic diversity of enteric viruses in children in Tunisia. A total of 788 fecal samples were collected during a 4-year period in the region of Monastir, from children under 12 years old, hospitalized or presenting in dispensaries with symptoms of acute gastroenteritis. AstV and AdV40/41 were detected by immunoenzymatic methods and confirmed by PCR/RT-PCR and sequence analysis. Phylogenetic analyses were performed for nucleotide homology with reference strains. AstV and AdV40/41 were characterized as a causative agent in 28 (3.6%) and 18 (2.3%) of the fecal samples, respectively. Phylogenetic analysis showed that the AstVs belonged to the serotypes 3 (n = 4; 14.3%) and 1 (n = 24; 85.7%), and the enteric AdVs to the serotypes 40 (n = 1; 5.6%) and 41 (n = 17; 94.4%). This is the first report that describes the molecular epidemiology of AstV and AdV40/41 in Tunisian children. Their respective detection rate was very low, far below that of rotavirus and norovirus. The genetic diversity among these two viruses is relatively limited and varies depending on the area.

Molecular epidemiology of adenovirus infection among infants and children with acute gastroenteritis in Dhaka City, Bangladesh

A total of 917 fecal specimens collected from infants and children with acute gastroenteritis in Dhaka City, Bangladesh during 2004-2005 were examined for the presence of adenoviruses by PCR. Adenoviruses were identified in 17 of 917 (1.9%) specimens. Detected adenoviruses were subjected to molecular genetic analysis by sequencing method. Adenoviruses detected in this study were classified into three serotypes, namely Ad9, Ad10 and Ad40. Of these, Ad40 was predominant, followed by Ad9 and accounted for 42% (7 of 17) and 36% (6 of 17), respectively. This is the first report of acute gastroenteritis attributed to Ad9 and Ad10 in Dhaka City, Bangladesh. Another interesting feature of the study was absence of Ad41 serotype. Our results clearly indicated that adenovirus infections were most commonly observed in winter season (October 2004 through January 2005) and in rainy season (May 2005 through July 2005) in Dhaka City. The most common clinical symptoms of adenovirus-infected patients were dehydration (94%), abdominal pain (59%) and vomiting (30%). To our knowledge, this is the first 1-year molecular epidemiological research of adenovirus infection in Bangladesh.

Diversity of viruses associated with acute gastroenteritis in children hospitalized with diarrhea in Ho Chi Minh City, Vietnam

A molecular epidemiological study on common diarrheal viruses was conducted in Ho Chi Minh City, Vietnam between October 2002 and September 2003. Fecal samples were collected from 1,010 hospitalized children with acute gastroenteritis. Those samples were screened for groups A, B, and C rotavirus, adenovirus, genogroups I and II norovirus (NoV), sapovirus (SaV), and human astrovirus (HAstV) by RT-multiplex PCR, and the positive specimens were characterized further by ELISA, nested PCR, or sequencing. Among the diarrheal viruses detected, group A rotavirus was the most common, with a proportion of 67.4%, whereas NoV GII, adenovirus, SaV, and HAstV were also found in 5.5, 3.2, 0.8, and 0.6%, respectively. It is noteworthy that the group C rotavirus was first reported in Vietnam, with a proportion of 0.5% in this study. Fifty-six of 1,010 (5.5%) samples were found positive with more than one viral agent, in which 25 samples contained both group A rotavirus and NoV GII. Group A rotavirus could be identified throughout year with the peaks in both the dry and rainy season, whereas other viruses prevailed mainly in the rainy season. G-typing for the group A rotavirus showed that genotype 1 was still the most prevailing (33.0%), but interestingly, serotype 9 was emergent and became the third most common rotavirus G-type in these samples (13.7%). The four most common G-P combinations globally, G1P[8], G2P[4], G3P[8], and G4P[8] were found in 46.8% of rotavirus-positive samples, and it is of interest that one unusual rotavirus G9P[19] strain was first detected in Vietnam. The majority of NoV strains belonged to GII/4, and SaV strains mainly clustered with the Manchester strain (GI/1). Twenty-seven out of 32 adenovirus strains were identified as serotype 41. All HAstVs belonged to genotype 1. The results indicated clearly the impact of viral agents causing gastroenteritis and the importance of vaccination against diarrhea in Vietnam.

Adenoviruses associated with acute gastroenteritis in hospitalized and community children up to 5 years old in Rio de Janeiro and Salvador, Brazil

Acute gastroenteritis is a major source of morbidity and mortality among young children in developed and developing countries. Human adenoviruses (HAdVs), and in particular species F, are related to childhood diarrhoea worldwide. This study presents the results obtained during an investigation of HAdVs causing acute gastroenteritis in children hospitalized in Rio de Janeiro, RJ, Brazil, from April 1996 to September 2003, as well as in children with diarrhoea living in the slums of Salvador, BA, Brazil, from October 2001 to September 2003. A total of 3060 stool samples was analysed by an enzyme immunoassay for rotavirus and adenovirus (EIARA) and 61 (2%) were found to be positive. HAdV presented with low prevalence throughout the year, with a slight but not significant increase in incidence in late summer and early autumn. Children up to 2 years of age were the most frequently affected (79% of all positive samples). All positive samples were analysed further by generic and species-specific HAdV PCR protocols, confirming 100% specificity of this rapid and inexpensive EIARA. Species F was the most prevalent (65%), despite the occurrence of species A (12%), C, D and co-infection F/D (5% each) and species B and co-infections F/A, F/C and B/D (2% each). In order to type the species F strains as HAdV-40 or -41, generic PCR and a HinfI restriction digest were performed. HAdV-40 and -41 were found to represent 62% (23/37) and 38% (14/37), respectively. These results demonstrated that a combination of generic and species-specific PCRs is useful and reliable for HAdV species and type identification directly from faecal specimens. The results confirmed the endemism of human adenoviruses, mainly species F, in children as aetiological agents of diarrhoea, although the limited sensitivity of EIARA as a screening method may have underestimated their prevalence.

Prevalence and characterization of enteric adenoviruses in the South of Ireland

Enteric adenoviruses have been shown to be a substantial cause of pediatric gastroenteritis in various parts of the world, and are considered to be the second most common cause of viral gastroenteritis, next to rotavirus in young children. Genetic characterization of 95 adenovirus isolates obtained from patients with acute gastroenteritis between 2002 and 2007 from the southern regions of Ireland, were characterized by PCR analysis, restriction endonuclease (RE) analysis and sequencing analysis. All isolates were found to be of adenovirus type 41 origin. Genetic analysis of seven hypervariable regions (HVRs) located within the hexon gene has revealed a high level of amino acid sequence homology in samples over the course of this study, with a very close relationship to the D22 genome type. The D22 genome type has been detected in several other countries, thus suggesting Irish isolates have common genome types with other stains worldwide. This is the first such study undertaken in the south of Ireland, to type and genetically characterize adenoviral gastroenteritis isolates, and has revealed a high level of conservation within the isolated analyzed.

Molecular epidemiology of subgenus F adenoviruses associated with pediatric gastroenteritis during eight years in Hiroshima Prefecture as a limited area

We have studied the prevalence of the subgenus F adenoviruses and the molecular characteristics of adenovirus type 41 in Hiroshima Prefecture, Japan, as a limited area during the period of 1997-2004. Subgenus F adenoviruses were detected in 30 (3.4%) of 892 fecal specimens by enzyme immunoassay (EIA), and 80.0% (24 of 30) of positive patients were <36 months old. One (3.3%) and 29 (96.7%) of the 30 EIA-positive specimens were adenoviruses type 40 (Ad40) and 41 (Ad41), respectively. The genomes of Ad41 strains amplified by PCR were divided into two genomic type clusters (GTC1 and GTC2) based on the hexon gene as described by Li et al. (J Clin Microbiol 42: 4032-4039, 2004.). Twenty-one (95.5%) of 22 Ad41 strains detected between 2000 and 2004 belonged to GTC1, whereas all seven strains detected between 1997 and 1999 belonged to GTC2. These genomic typings were the same for the hexon and fiber genes except for one strain. This strain contained a hexon gene belonging to GTC1 and a fiber gene belonging to GTC2 and was considered to be a recombinant between adenoviruses of these types.

Characterizations of adenovirus type 41 isolates from children with acute gastroenteritis in Japan, Vietnam, and Korea

Genetic and antigenic characterizations of 70 strains of adenovirus type 41 (Ad41), isolated between 1998 and 2001 from children in Japan, Vietnam, and Korea, were done by DNA restriction enzyme (RE) analysis, sequencing analysis, and monoclonal antibody (MAb)-based enzyme-linked immunosorbent assay (ELISA). Eight genome types were observed in the present study, among which D25, D26, D27, and D28 were novel genome types. These eight genome types were divided into two genome-type clusters (GTCs) based on phylogenetic analysis of the hypervariable regions (HVRs) of the hexon. GTC1 includes D1, D25, D26, D27, and D28, and the GTC2 contains D4, D12, and D22. The amino acid homologies among the members within a GTC were 97 to 100%, whereas between the members of different GTCs the homologies were 92 to 94%. The specificity of the GTC classification was confirmed by ELISA with MAb 1F, which was selected by the Ad41 prototype Tak strain. It was found that only the isolates of GTC1 but not of GTC2 reacted with MAb 1F. These results suggest that Ad41 isolates from the three countries should be classified into two subtypes. The accumulation of amino acid mutations located in HVRs of hexon are indicative for the classification of Ad41 subtype.

First report from the Asian Rotavirus Surveillance Network

Rotavirus remains the most common cause of severe, dehydrating diarrhea among children worldwide. Several rotavirus vaccines are under development. Decisions about new vaccine introduction will require reliable data on disease impact. The Asian Rotavirus Surveillance Network, begun in 2000 to facilitate collection of these data, is a regional collaboration of 36 hospitals in nine countries or areas that conduct surveillance for rotavirus hospitalizations using a uniform World Health Organization protocol. We summarize the Network's organization and experience from August 2001 through July 2002. During this period, 45% of acute diarrheal hospitalizations among children 0–5 years were attributable to rotavirus, higher than previous estimates. Rotavirus was detected in all sites year-round. This network is a novel, regional approach to surveillance for vaccine-preventable diseases. Such a network should provide increased visibility and advocacy, enable more efficient data collection, facilitate training, and serve as the paradigm for rotavirus surveillance activities in other regions.

Prevalence of enteric adenoviruses among children with diarrhea in four Brazilian cities

BACKGROUND

Enteric adenoviruses are related to child diarrhea and appear to be spread worldwide.

OBJECTIVES

The aim of the present study was to determine the prevalence of enteric adenovirus infection among children in four Brazilian cities.

STUDY DESIGN

stool specimens were collected from children under 5 years of age with acute diarrhea.

RESULTS AND CONCLUSIONS

Enteric adenoviruses were detected in 1.55% (n=1420) of the samples analyzed indicating the circulation of these viruses among Brazilian children in association to diarrheal disease. These agents were isolated throughout the year demonstrating no specific seasonal distribution. Also, no pattern of serotype distribution between the cities was observed.

Human caliciviruses in acute gastroenteritis of young children in the community

Episodes of acute gastroenteritis in prospectively followed children between 2 months and 2 years of age were examined for rotaviruses, enteric adenoviruses, astroviruses, and human caliciviruses, including both Norwalk-like viruses (NLVs) and Sapporo-like viruses (SLVs), using PCR and reverse transcription (RT)-PCR assays. A virus was identified in 60% (502/832) of all episodes and in 85% of the moderately severe or severe episodes. Human caliciviruses were as common as rotaviruses, both being detected in 29% of the cases. NLVs accounted for a 20% etiologic share of all cases; the clinical picture was a moderately severe disease with vomiting as a predominant symptom. SLVs were detected in 9% of the cases, the clinical picture being a mild diarrheal disease. Astroviruses were found in 10% and enteric adenoviruses in 6% of the cases. Diagnosis with PCR and RT-PCR methods increases the detection of all gastroenteritis viruses, particularly human caliciviruses. As a group, human caliciviruses are common causative agents of gastroenteritis in children <2 years of age in Finland, and, of these, NLVs cause more severe disease than SLVs.

Previous enteric adenovirus infection does not protect against subsequent symptomatic infection: longitudinal follow-up of eight infants

Eight infants followed longitudinally were found to have enteric adenovirus (EAdv) infections: in 5 infants with diarrhea and in 3 with no accompanying diarrhea. Sequential stool samples prior to EAdv infections were tested for adenovirus antigen, anti-adenoviral IgA and neutralizing antibodies to serotypes 40, 41 and 2 in order to ascertain whether protection from symptoms was due to prior infection. No difference was found in the number of adenoviral infections among infants prior to their EAdv infections with or without accompanying diarrhea. However, in 3 of the 5 infants in whom EAdv infection was accompanied by diarrhea and 2 of 3 control infants, previous EAdv infections had occurred as detected by serotype-specific antibody rises.

Gastrointestinal adenovirus infections in a tertiary referral centre in Saudi Arabia

To determine the prevalence of adenovirus and its serotypes in diarrhoeal stools in Saudi Arabia, 3,000 stool specimens were collected prospectively from subjects of all ages over a 28-month period. A total of 220 positive isolates were obtained. Fifteen serotypes were found, serotypes 40 and 41 being the most prevalent. Underlying disorders were found in the majority of patients, leukaemia being the most common single underlying condition. This investigation represents the first detailed study of the epidemiology of gastrointestinal adenovirus infections in Saudi Arabia.

Adenovirus genome types isolated from stools of children with gastroenteritis in São Paulo, Brazil

In a prospective one-year study of acute gastroenteritis in hospitalized children less than 2 years of age, in São Paulo (Brazil), adenoviruses were detected by specific enzyme immunoassay (El-ARA) in 7 of 67 (10%) ill children and in 9 of 79 (11.4%) controls. They were the sole recognizable agent of diarrhea in 6 ill children. In another child these viruses were detected in a dual infection with astrovirus. Enteric adenoviruses (Ad40/41) were the most common serotypes detected in children with diarrhea (3/7) and Ad7 the serotype most detected in the controls (5/9), associated with lower respiratory tract infection. Thirteen adenovirus strains, isolated in HEp2 or HEK-293 cells, were characterized by seroneutralization and restriction enzyme analysis. The established adenoviruses were typed as AV-7-D5 (five associated to lower respiratory tract infection and one to diarrhea), AV-1-D10 (one diarrhea case), AV-31-D2 (two controls with respiratory infection), and two isolates as AV-12-D7, a new genome type. One subgenus D isolate, serotype 28, with restriction patterns different from those of the prototype, remained untyped. Only one enteric adenovirus could be typed. The restriction patterns of this isolated were similar to those of the prototype AV-41-D1. The genome type of the other three enteric adenoviruses could not be determined.

Patients with enteric adenovirus gastroenteritis admitted to an Australian pediatric teaching hospital from 1981 to 1992

During the period 1981 to 1992, 4,473 fecal specimens collected from children hospitalized with acute gastroenteritis at the Royal Children's Hospital, Melbourne, Australia, were examined by electron microscopy. A monoclonal antibody enzyme immunoassay for enteric adenovirus (EAd) types 40 (Ad40) and 41 (Ad41) was used when adenoviruses were visualized. Fecal samples were positive for adenovirus by both electron microscopy and enzyme immunoassay in 138 patients (3.1%). Ad40 was identified in 19 children (14%), and Ad41 was identified in 119 children (86%). These EAd were identified during each of the 12 years surveyed. EAd were present year-round, but the annual number of hospitalizations was not constant. Yearly prevalence varied from 0.7% (1981) to 6.5% (1985). This was associated with monthly fluctuations in Ad41 activity, with overall peak monthly prevalence in May (late autumn). By contrast, Ad40 numbers remained low and constant year-round. The frequency of Ad41 relative to Ad40 increased from 25% in 1981 to exceed 75% after 1983. Children admitted with EAd infection were more likely to have diarrhea for more than 5 days (P < 0.001) but less likely to be febrile or dehydrated (P < 0.05) than children with rotavirus infection. EAd are responsible for enteric symptoms of only a fraction of hospitalized children with infectious diarrhea but result in a more-protracted illness than rotavirus. Their relationship to persistent diarrhea requires further investigation.

Identification of adenoviruses in faeces from patients with diarrhoea at the Hospitals for Sick Children, London, 1989-1992

Faecal samples from 137 patients that had been shown to contain adenoviruses by electron microscopy were identified in a series of enzyme immunoassays (EIA) using a single monoclonal antibody (Mab) to adenovirus 40 and four different Mabs to adenovirus 41. Adenoviruses were partially characterised by restriction enzyme analysis (REA) of DNA extracts using SmaI. Samples were also run in a commercial EIA (Adenovirus IDEIA; Dako, Ltd.) which detects group antigen. The majority (84%) of adenoviruses were subgenus F: adenovirus type 41, 87 (64%) and adenovirus type 40, 28 (20.4%). Subgenus A viruses were identified in ten, (7%) patients, eight were type 31, and two type 12. The adeno IDEIA test was sensitive and specific, detecting 127 of 131 positives and giving no false-positive results with other enteric viruses. Use of monoclonal-based EIAs showed significant differences depending on which adeno 41 Mab was used, although the restriction patterns obtained using SmaI appeared to be identical for 66 of 69 samples that produced recognisable bands. The Mab that performed best, M 4.3.1, was raised against strains obtained from children in England and detected 83 of 84 (99%) of the adenovirus 41 samples tested. In contrast Mab JH/41 raised against the prototype strain of adenovirus 41 (Tak) detected only 69 of 87 (79%).

Aetiology of gastroenteritis at a major referral centre in Saudi Arabia

To determine the causes of gastroenteritis at a major referral centre in Saudi Arabia, retrospective study was carried out on 58,110 fresh stools from 42,035 patients. Examination of stool specimens for pathogens was based on the clinical judgement of the physician responsible, so that all specimens were not tested for the presence of all pathogen groups. Bacterial enteropathogens were found in 7.7% of patients; Salmonella species (51.7%) were found to be the most frequent pathogens followed by Campylobacter jejuni (28%) and Shigella species (14.9%). Protozoan or metazoan parasites were detected in 27.8% of patients examined, the most common being Giardia lamblia and Hymenolepsis nana. Of the patients tested for viruses in stool, 14.1% had rotavirus, 5.3% adenovirus, 1.2% small round viruses and 0.3% coronavirus. Clostridium difficile toxin was also found in 9.5% of patients examined.

Detection of viruses in environmental samples: suitability of commercial rotavirus and adenovirus test kits

Commercially marketed kits are now available for rapid viral assay of clinical specimens. This study was conducted to determine the suitability of these kits for use in environmental testing. Eight rotavirus kits and one enteric adenovirus kit were screened for sensitivity using simian rotavirus SA11, human rotavirus Wa, and adenovirus 41. The most sensitive rotavirus kit and the adenovirus kit were selected for further evaluation using virus-seeded and unseeded sewage samples. The selected rotavirus kit proved capable of detecting virus at the 10(1) PFU/ml level. The enteric adenovirus kit was similarly sensitive, detecting virus at the 10(1) TCID50/ml level. Neither kit was adversely affected by the presence of sewage. Kit assay revealed 3 of 30 unseeded sewage samples to be positive for rotavirus. Adenovirus positive samples were not detected among the 30 samples. These results were confirmed using electron microscopy. It was concluded that sensitive commercial kits could provide a reasonable alternative to cell culture for the presumptive testing of environmental samples.

Diarrhoeal disease: current concepts and future challenges. Molecular biological approaches to the epidemiology of diarrhoeal diseases in developing countries

Diarrhoea in developing countries is caused by an increasingly long list of bacterial, viral, and parasitic pathogens with rotavirus, enterotoxigenic Escherichia coli, Campylobacter, Shigella, and Salmonella heading the list. Using methods to detect most of the known enteropathogens, one or more enteropathogen(s) is isolated in two-thirds of diarrhoeal illnesses in the developing world. Many of these enteropathogens are also frequently isolated from children without diarrhoea. An aetiologic agent is more frequently isolated from cases of invasive diarrhoea than from those with secretory diarrhoea. Deoxyribonucleic acid probes have proved very useful in detecting pathogens such as enterotoxigenic (ETEC), enteroinvasive (EIEC), and enteropathogenic E. coli (EPEC), but have not yet proved to be particularly rapid or less expensive. Molecular biology has proved useful in epidemiological studies as a means of strain identification. Plasmids were initially used as convenient markers and proved useful in identifying epidemic strains of bacteria. Other molecular markers, such as ribotyping, are accurate enough to be used as taxonomic tools.

Detection, typing, and subtyping of enteric adenoviruses 40 and 41 from fecal samples and observation of changing incidences of infections with these types and subtypes

Monoclonal antibody (MAb) preparations specific for the enteric adenoviruses of subgenus F (AdF) were generated and evaluated as typing reagents in virus neutralization tests and enzyme-linked immunosorbent assays (ELISAs). A panel of 11 genome types of adenovirus 40 (Ad40), 24 genome types of Ad41, and 47 adenovirus prototype strains was used to determine the specificities of the MAbs in the two assays. In this way two MAbs, MAb 40-1 (anti-Ad40) and MAb 41-1 (anti-Ad41) were selected. These two MAbs showed strict type specificity in both assays. A third MAb reacted in an ELISA with all 47 human adenovirus types. With two other MAbs, three antigenic subtypes of Ad41 could be distinguished by their reactivities in virus neutralization tests and ELISAs. On the basis of the five selected MAbs, a sensitive ELISA system was developed for the direct detection and simultaneous typing and subtyping of Ad40 and Ad41 present in stool specimens. The five MAbs were also used to study the epidemiology of infections with Ad40 and Ad41 in The Netherlands in the period 1981 through 1989. It was shown that there were no significant fluctuations in the annual incidence of the cluster of enteric adenoviruses as a whole. This cluster should therefore be considered to belong to the "endemic" rather than the "epidemic" adenoviruses. The relative incidence of Ad40 infections compared with that of Ad41 infections changed considerably during the period studied; the proportion of Ad41 infections rose from about 30% in 1981 to about 95% in 1986, after which it stabilized at 90 to 95%. The proportion of one of the subtypes of Ad41 (Ad41 subtype M3) increased from about 40 to 80% in the same period.

Enteric adenovirus infection among infants with diarrhea in rural Bangladesh

A total of 4,409 stool specimens from infants less than 5 years of age seeking treatment for diarrhea in Matlab, Bangladesh, were tested for the presence of adenoviruses by using an enzyme immunoassay (EIA). EIA-positive stool samples were serotyped with monoclonal antibodies specific for adenovirus type 40 (Ad40) and Ad41 and group antigen, inoculated into Graham G293 cells, and retested by EIA. Of adenovirus-positive cultures, 125 (2.8%) specimens were confirmed as enteric adenoviruses (EAds), of which 51 (40.8%) were typed as Ad40 and 74 (59.2%) were typed as Ad41, and 12 of 4,409 (0.3%) were identified as nonenteric adenoviruses. A slight peak of incidence of EAd infection was observed in the cool, dry months, and an outbreak of Ad40 infections occurred in March 1988, when the detection rate of EAd reached 12.3%. Information on age, gender, and symptoms was available for 80 infants infected with adenovirus only. Age distribution was similar for types 40 and 41 and nonenteric adenovirus; the median ages were 11, 12, and 12 months, respectively. The ratio of males to females for the 80 infants varied according to serotype; Ad40 had the highest male/female ratio, 2.17. The symptoms experienced by the 80 children were similar for each adenovirus type. The most common clinical features of EAd infection were watery diarrhea (87.5%), more than eight loose bowel movements per day in the 24-h period prior to presentation (68.8%), with vomiting (80.0%), abdominal pain (76.3%), and low-grade fever (95.0%); these symptoms are significantly similar to symptoms of infants infected with group A rotavirus. EAd infection generally gave rise to mild to moderate dehydration, which is significantly similar to dehydration produced by infection with rotavirus.

Epidemiology of enteric adenovirus infection in prospectively monitored Argentine families

To examine the role of enteric adenoviruses (EAV) in an urban area of Buenos Aires (Argentina), we prospectively studied faecal samples from 49 families of newborns. These were monitored weekly for diarrhoea for 2 years. A total of 180 samples from cases of diarrhoea and 766 samples obtained during diarrhoea-free periods were studied by dot-blot hybridization with an EAV-specific DNA probe. EAV were found in 6/180 (3.3%) cases of diarrhoea and 6/766 (0.8%) asymptomatic samples (P < 0.015). Incidence of EAV was 3.9 cases per 100 person-years in children < 60 months old. EAV-related diarrhoeas were slight and of short duration. In addition, 129 faeces from hospital out-patients, 1-30 months old, were also studied. EAV was identified in 7/129 cases (5.4%). These cases were 9.5 +/- 3.5 months old and the diarrhoea was mild or severe, of 3 +/- 1.5 days of duration. We suggest that EAV are low-risk causes of diarrhoea under natural conditions, although a few children may develop more severe diarrhoea. The diagnosis of EAV needs to be considered in these patients.

Seroprevalence of enteric and nonenteric adenoviruses in Bangladesh

Single serum samples obtained from infants between 0 and 24 months of age admitted to a diarrheal disease hospital in Bangladesh were tested for the presence of adenovirus-specific immunoglobulin G (IgG) and IgA antibodies by using enzyme immunoassay and neutralizing antibodies to adenovirus types 2, 40, and 41. IgG antibodies were more prevalent than IgA antibodies, and neutralizing activity to enteric adenovirus was found in serum samples from 50% of infants who had reached 2 years of age.

Outbreaks of human enteric adenovirus types 40 and 41 in Houston day care centers

OBJECTIVE

Human enteric adenovirus (EAd) types 40 and 41 cause diarrhea in young children, but little is known about their association with outbreaks of diarrhea in the child care setting. This study evaluated EAd as a cause of outbreaks of diarrhea among infants and toddlers in day care centers.

DESIGN

Stool specimens were collected weekly regardless of symptoms during four periods from January 1986 to April 1991, from children 6 to 24 months of age enrolled in prospective studies of diarrhea in day care centers. All diarrhea stool specimens were tested for bacterial enteropathogens, rotavirus, and Giardia lamblia. A total of 131 outbreaks occurred during the study. No etiologic agent was identified in 77 outbreaks. Stool specimens from 75 of these 77 outbreaks and from another 21 outbreaks of diarrhea with a known cause were evaluated for EAd with a monoclonal antibody-based enzyme immunoassay.

RESULTS

A total of 4402 stool specimens from 613 children from these 96 outbreaks was tested for EAd. The virus was detected in specimens collected during 10 outbreaks, 3 of which occurred in 1986, 3 in 1988, 1 in 1989, 1 in 1990, and 2 in 1991. Of 249 children, 94 (38%) in these 10 EAd outbreaks were infected with EAd. In 51 children (54%) the infection was symptomatic and in 43 (46%) it was asymptomatic. Outbreaks lasted 7 to 44 days (mean 24.5 days). Duration of EAd excretion ranged from 1 to 14 days (mean 3.9 days), with excretion occurring from 7 days (mean 2.6) before diarrhea began to 11 days (mean 5.3 days) after diarrhea stopped.

CONCLUSION

Enteric adenovirus types 40 and 41 are an important cause of outbreaks of diarrhea among children attending day care centers, often involve children in more than one room, and frequently produce asymptomatic infection.

Adenovirus colitis in the acquired immunodeficiency syndrome

Adenovirus was identified in colonic tissue by transmission electron microscopy or culture in 5 of 67 (7.4%) homosexual men seropositive for human immunodeficiency virus (51 with the acquired immunodeficiency syndrome) with diarrhea. Colonoscopy showed the mucosa to be normal in 3 cases and mildly inflamed in 2. Light microscopy showed foci of mucosal necrosis that contained chronic inflammatory cells and degenerating and necrotic epithelial cells with amphophilic nuclear inclusions. By transmission electron microscopy, hexagonal viral particles characteristic of adenovirus were identified within the inclusions. Only 1 patient was concomitantly infected by a second potential enteric pathogen. It was concluded that adenovirus, an uncommon enteric pathogen in immunocompetent adults, causes intestinal pathology and may be associated with diarrheal illness in persons with the acquired immunodeficiency syndrome.

Importance of rotavirus and adenovirus types 40 and 41 in acute gastroenteritis in Korean children

To examine the role of rotavirus (Rv) and adenovirus types 40 and 41 (Ad40/41) in Korean children with acute gastroenteritis, we evaluated 345 children with acute gastroenteritis and 90 children without acute gastroenteritis in Seoul, Korea, during a 29-month period. Stools were tested for group A Rv antigen and for Ad40/41 by using monoclonal antibody (MAb)-based assays. Rv was found in 68% of the ill children and 19% of the controls (P less than 0.001), whereas Ad40/41 was detected in 9% of the ill children and 2% of the controls (P less than 0.05). Also, 6% of the ill children and 0.01% of the controls excreted Rv and Ad40/41 simultaneously. Among the ill children, 96% of children with Rv and 94% of those with Ad40/41 were younger than 24 months. Although a peak of Rv infection was detected in early winter in both years of the study, there was no apparent seasonal trend with Ad40/41. Diarrhea with more than 10 stools per day, vomiting, or fever was most strongly associated with Rv shedding, whereas the first two manifestations were associated with coinfection of Rv and Ad40/41. To investigate the genetic and serotypic diversity of Rv strains, we tested 195 and 144 fecal Rv specimens isolated from the gastroenteritis cases, respectively, by polyacrylamide gel electrophoresis of the segmented RNA genome and by an enzyme-linked immunosorbent assay with serotype-specific MAbs. Of the 195 specimens, 154 yielded RNA patterns characteristic of group A Rv: 18% had short electrophoretic migration patterns, 81% had long patterns, and 1% had a mixture of short and long patterns. Of the 144 specimens, serotype specificity was determined in 51%: 89% were serotype 1, 10% were serotype 2, and 1% were serotype 3. Analysis of the specimens for which electropherotypes and serotypes were available indicated that a given RNA pattern corresponded to a particular serotype, except in one strain that showed short patterns but serotype 1. We suggest that Rv and Ad40/41 in stools be accepted critically as an important cause of diarrhea among young children in Korea.

Enteric adenoviruses

Human adenoviruses are classified into 47 serotypes and six subgenera (A-F) with different tropisms. In recent years adenovirus type 40 (Ad40) and 41 (Ad41) of subgenus F have been shown to be causative agents in enteric infections, which is second in importance only to rotaviruses as a cause of infantile gastroenteritis. Infection with EAds occurs worldwide and has been associated with 4-17% of cases of diarrhoea in children. AD40 and Ad41 primarily affect young children less than 2 years of age and occur throughout the year. The clinical characteristics include watery diarrhoea accompanied by vomiting, low grade fever and mild dehydration. A distinct feature of EAds infection is the protracted diarrhoea (mean 8.6 and 12.2 days for Ad40 and Ad41, respectively). Respiratory symptoms are infrequent. Serotypes Ad40 and Ad41 differ from all other (established) adenoviruses by being unable to replicate in conventional cell cultures. These fastidious viruses only grow in selected cell lines, 293 cells being the most commonly used. In spite of the difficulty of isolating Ad40 and Ad41, they can be directly identified and typed by ELISA and solid-phase immune electron microscopy. The amount of viral DNA in stool specimens is sufficient for identification by DNA restriction and dot-blot assays. The recent development of highly sensitive and specific monoclonal antibody-based ELISAs enable accurate diagnosis of adenovirus gastroenteritis in routine work and make possible the evaluation of the role of the enteric adenoviruses in diarrhoeal disease in the developing countries.

Adenovirus types 40 and 41 and rotaviruses associated with diarrhea in children from Guatemala

From March 1987 to February 1988, fecal excretion of adenovirus types 40 and 41 and rotavirus serotypes in 194 children (age, 0 to 3 years) from a rural community of Guatemala was monitored. In total, 458 samples taken during 385 episodes of diarrhea and 191 specimens obtained during symptom-free periods were examined by enzyme-linked immunosorbent assay. Fifty-seven children hospitalized because of diarrhea were also studied. Among the rural children, 43 (22.2%) excreted adenovirus types 40 and 41 and 20 (10.3%) shed rotaviruses. Adenovirus types 40 and 41 were associated with 54 (14.0%) illnesses, and rotaviruses were associated with 18 (4.7%) illnesses. Asymptomatic infections with adenovirus types 40 and 41 were documented in nine children and with rotaviruses in two children. Fifteen typeable rotaviruses were identified as serotype 2. In the hospital population, 36 (63.2%) children had viral infections. Rotaviruses were identified in 29 (50.9%) and adenovirus types 40 and 41 were identified in 15 (31.2%) of 48 subjects tested. Dual infections by these viruses were found in eight children. Of 22 typeable strains of rotaviruses, 9 (34.6%) were serotype 1, 12 (46.1%) were serotype 2, and 1 (3.8%) was serotype 3. All the children infected with serotype 2 rotavirus were coinfected with other enteric pathogens, while only three (37.5%) of those infected with rotavirus serotype 1 excreted another pathogen. Adenovirus types 40 and 41 are an important cause of gastroenteritis in both ambulatory and hospitalized Guatemalan children. There seems to be a difference in the pathogenicity among rotavirus serotypes.