Simultaneous infections with different enteric and respiratory tract viruses

Simultaneous investigation of influenza and enteric viruses in the stools of adult patients consulting in general practice for acute diarrhea

BACKGROUND

Gastrointestinal symptoms are not an uncommon manifestation of an influenza virus infection. In the present study, we aimed to investigate the presence of influenza viruses in the stools of adult patients consulting their general practitioner for uncomplicated acute diarrhea (AD) and the proportion of concurrent infections by enteric and influenza viruses.

METHOD

A case-control study was conducted from December 2010 to April 2011. Stool specimens were collected and tested for influenza viruses A (seasonal A/H3N2 and pandemic A/H1N1) and B, and for four enteric viruses (astrovirus, group A rotavirus, human enteric adenovirus, norovirus of genogroups I - NoVGI - and genogroup II - NoVGII).

RESULTS

General practitioners enrolled 138 cases and 93 controls. Of the 138 stool specimens collected, 92 (66.7%) were positive for at least one of the four enteric viruses analysed and 10 (7.2%) tested positive for one influenza virus. None of these 10 influenza positive patients reported respiratory symptoms. In five influenza-positive patients (3.6%), we also detected one enteric virus, with 4 of them being positive for influenza B (2 had co-detection with NoVGI, 1 with NoVGII, and 1 with astrovirus). None of the 93 controls tested positive for one of the enteric and/or other influenza viruses we investigated.

CONCLUSIONS

In this study we showed that the simultaneous detection of influenza and enteric viruses is not a rare event. We have also reported, for the first time in general practice, the presence of seasonal and pandemic influenza viruses in the stools of adult patients consulting for uncomplicated AD. A simultaneous investigation of enteric and influenza viruses in patients complaining of gastrointestinal symptoms could be useful for future studies to better identify the agents responsible for AD.

Multiple simultaneous viral infections in infants with acute respiratory tract infections in Spain

Background

The clinical significance of the presence of more than one type of virus in the respiratory specimens of children with respiratory infections is not clear.

Objectives

To describe the clinical characteristics of multiple viral infections versus single infection by respiratory syncytial virus (RSV) in hospitalized infants.

Study design

This is a prospective study conducted in all infants under 2 years of age admitted for acute respiratory infection (September 2000–June 2003) in a secondary teaching hospital. Virological diagnosis was made by two different multiplex reverse transcription-nested polymerase chain reaction (RT-PCR) assays in nasopharyngeal aspirates. We describe the clinical characteristics of the patients with multiple viral infections and compare them to a group of 86 randomly selected patients infected only with RSV.

Results

749 specimens taken were analyzed. Respiratory viruses were detected in 65.9% of the samples. 86 children had multiple viral infections (17.4% of all positive specimens). The most frequent clinical diagnosis in this group was recurrent wheezing in 44% and bronchiolitis in 52%. Fever was significantly more frequent (p < 0.001), hospital stays were longer (p = 0.05), and antibiotic treatment was used more (p = 0.03) in infants with multiple viral infections than in the RSV-infected group.

Conclusions

Multiple viral infections are frequent in hospitalized children with respiratory tract disease (17.4%). Multiple viral infections are linked to higher fever, longer hospital stays and more frequent use of antibiotics than in the case of infants with single RSV infections.

A simple and rapid single-step multiplex RT-PCR to detect Norovirus, Astrovirus and Adenovirus in clinical stool samples

A single-step multiplex reverse transcription-polymerase chain reaction (RT-PCR) assay that detects and identifies Norovirus, Astrovirus and Adenovirus in clinical stool samples is described. Four hundred sixty stool samples were tested from patients with non-rotavirus acute gastroenteritis, that were either stored at -80 degrees C and tested retrospectively, or tested immediately after viral nucleic acid extraction in a prospective manner, including outbreaks of gastroenteritis that occurred in Germany during the winter of 2003. The multiplex RT-PCR was validated against simplex RT-PCR with published primers for Norovirus (JV12/JV13 and p289/p290) and Astrovirus (Mon340/348), and against simplex PCR for Adenovirus. In both retrospective and prospective settings, the multiplex RT-PCR was equally sensitive and specific in detecting non-rotavirus infections compared with simplex RT-PCR/PCR. The specificity of the multiplex RT-PCR was assessed by sequencing of the amplicons that showed high nucleotide identities to Norovirus genogroup I/1, I/4, II/2, or II/4 clades, as well as to Astrovirus serotypes 1, 2, 4, or 8. The multiplex RT-PCR was also more sensitive than Astrovirus and Norovirus antigen enzyme immunoassays (IDEIA, Dako), as well as Astrovirus isolation in cell culture. This novel multiplex RT-PCR is an attractive technique for the rapid, specific, and cost-effective laboratory diagnosis of non-rotavirus acute gastroenteritis.

Suivi prospectif des diarrhées nosocomiales dans 28 services de pédiatrie du quart Sud-Est de la France au cours d’un trimestre d’hiver

The aim of this study was to evaluate the risk of hospital-acquired diarrhoea during an epidemic period through a prospective multicentre observational study. A systemic investigation of the hospital-acquired diarrhoea (occurring at least 48 h after hospital admission) was conducted through a standardised questionnaire from January to March 1999 in patients of 5 years old or less hospitalised in 28 wards (620 beds) belonging to 20 hospitals located in the south-east part of France. Overall, 241 cases of hospital-acquired diarrhoea were collected, corresponding to a prevalence of 3.3% (3.6% after exclusion of patients admitted for diarrhoea) and a density of incidence of 0.81 per 100 days of hospitalisation. The mean stay duration of hospital-infected patients was greater than 10 days, versus 3.9 days for the other children (P < 0.001). A readmission was required in 27% of the infected children. Rotavirus was involved in 97.8% of microbiologically documented cases (88%). In 50% of the cases, the hospital-acquired diarrhoea was seen in patients with bronchiolitis. Contact isolation measures were prescribed in 88.4% of the cases. These results stress that hospital-acquired diarrhoea represent an important medical and economic load for paediatric units and could be used as reference data to evaluate the impact of preventive measures, especially to reduce readmission and mean stay duration.

Viral replication in the nasopharynx is associated with diarrhea in patients with severe acute respiratory syndrome

The role of severe acute respiratory syndrome (SARS) coronavirus as an enteric pathogen was investigated in a cohort of 142 patients with SARS who were treated with a standard treatment protocol. Data from daily hematological, biochemical, radiological, and microbiological investigations were prospectively collected, and the correlation of these findings with diarrhea was retrospectively analyzed. Sixty-nine patients (48.6%) developed diarrhea at a mean (± standard deviation [SD]) of 7.6 ± 2.6 days after the onset of symptoms. The diarrhea was most severe at a mean (±SD) of 8.8 ± 2.4 days after onset, with a maximum frequency of 24 episodes per day (median, 5 episodes; range, 3–24 episodes). A higher mean virus load in nasopharyngeal specimens obtained on day 10 after the onset of symptoms was significantly associated with the occurrence of diarrhea (3.1 log₁₀ vs. 1.8 log₁₀ copies/mL; P = .01) and mortality (6.2 vs. 1.7 log₁₀ copies/mL; P < .01). However, diarrhea was not associated with mortality. The lung and the gastrointestinal tract may react differently to SARS coronavirus infection. Additional investigation of the role of SARS coronavirus in the pathogenesis of diarrhea in patients with SARS should be conducted.

Identification of contaminating adenovirus type 1 in the ATCC reference strain of respiratory syncytial virus A2 (VR-1302)

ATCC reference strain of respiratory syncytial virus A-2 (VR-1302), which was originally isolated from the lower respiratory tract of an infant (Lewis et al., 'Med. J. Aust. 2 (1961) 932'), is contaminated with adenovirus type 1. The presence of adenovirus was deduced from microscopic observation of CPE in HEp-2 cells and confirmed by electron microscopy, PCR, serological typing and immunofluoresence. Since RSV A2 is used worldwide as a representative virus of RSV type A viruses, and because the ATCC is often cited as the source of the parent stock, we considered it important to bring these findings to the attention of the wider community.

Parainfluenza viruses

Human parainfluenza viruses (HPIV) were first discovered in the late 1950s. Over the last decade, considerable knowledge about their molecular structure and function has been accumulated. This has led to significant changes in both the nomenclature and taxonomic relationships of these viruses. HPIV is genetically and antigenically divided into types 1 to 4. Further major subtypes of HPIV-4 (A and B) and subgroups/genotypes of HPIV-1 and HPIV-3 have been described. HPIV-1 to HPIV-3 are major causes of lower respiratory infections in infants, young children, the immunocompromised, the chronically ill, and the elderly. Each subtype can cause somewhat unique clinical diseases in different hosts. HPIV are enveloped and of medium size (150 to 250 nm), and their RNA genome is in the negative sense. These viruses belong to the Paramyxoviridae family, one of the largest and most rapidly growing groups of viruses causing significant human and veterinary disease. HPIV are closely related to recently discovered megamyxoviruses (Hendra and Nipah viruses) and metapneumovirus.

Histologic distribution of fatal rotaviral pneumonitis: an immunohistochemical and RT in situ PCR analysis

Rotaviral infection is a common cause of gastroenteritis and pharyngitis; to our knowledge, infection has not been associated with severe pneumonia. We report on two cases of fatal pneumonitis in 49-and 54-year-old men; the latter was on long-term steroid treatment of multiple sclerosis. In the latter case, the histologic examination after a several week history of symptoms showed severe organizing interstitital pneumonitis and necrotizing bronchiolitis with extensive squamous metaplasia. The other case, which was fatal several days after the onset of symptoms, showed marked septal capillaritis with denudement of the alveolar pneumocytes, extravascated red blood cells, and intravascular thrombi formation. In each case, rotaviral RNA was localized by reverse transcription (RT) in situ PCR to the endothelial cells of the alveolar capillaries, macrophages, and pneumocytes as well as, in the second case, to the squamous metaplastic cells. Immunohistochemical analysis for the virus demonstrated an equivalent histologic distribution. It is concluded that rotaviral infection can lead to fatal pneumonitis and that the mechanism of this complication is centered on a diffuse septal endothelialitis with concomitant tissue damage.

[Viral co-infections in immunocompetent infants with bronchiolitis: prospective epidemiologic study]

The nature of viral infection was prospectively investigated in 202 immunocompetent infants with bronchiolitis. Nasal aspirates were evaluated by immunofluorescence assay, viral isolation technique and polymerase-chain-reaction-hybridization assay. In 55 infants (27%) more than one respiratory virus were detected. A Rotavirus was found in 40 infants (20%), without any relationship with the respiratory viral status, respiratory syncytial virus being the main virus (46/55), and the association of respiratory syncytial virus and adenovirus being the most frequent (21/55). No difference was found between monoviral infections on the one hand and simultaneous viral infections on the other hand according to age, weight, neonatal disease, past history of personal or familial atopy, central temperature, Silverman's index, oxygen dependency, length of hospitalization, microbiology data. There was no indication that simultaneous virus infections were associated with an increased severity of the bronchiolitis in immunocompetent infants.

Local succession of adenovirus strains in pediatric gastroenteritis

Assessment of the current incidence of different adenovirus types in local gastroenteritis involved the examination of over 1,000 stool specimens annually from 1988-1992. Adenoviruses were detected by electron microscopy and/or cell culture in 32% of the specimens in which a viral pathogen was detected. The identification of every adenovirus isolate to type by neutralization with specific antisera against the first 6 types and by restriction analysis of nonneutralized isolates was started in 1990. Samples from 1988 and 1989 were examined retrospectively. Adenovirus strains were compared to those isolated in a study between 1980-1983. Enumeration of individual adenovirus types revealed a number of trends, demonstrating that rapid changes in the local incidence of several strains were occurring in Manitoba. The incidence of adenovirus type 40 (Ad40) as a cause of gastroenteritis was found to have fallen dramatically in recent years. The predominant cause of gastroenteritis in Manitoba is a variant strain of Ad41, increasing in predominance each year and now responsible for over a third of the symptomatic cases examined since 1990. The majority of restriction site differences of the Ad41 variant strain from the prototype strain Tak were mapped to the hexon and fiber genes, both of which code for the neutralizable external viral epitopes. The probability of the observed pattern of mutations occurring by chance was calculated as P < 0.0005, indicating a strong pressure for selection of these immunologically significant alterations to the viral proteins responsible for cell attachment.(ABSTRACT TRUNCATED AT 250 WORDS)

Mixed viral infections: detection and management

An analysis was done of the incidence and nature of mixed virus infections diagnosed in the same clinical specimen from immunocompetent patients; respiratory viruses were emphasized. Few studies have addressed mixed viral infections in any systematic fashion. The relevant studies reviewed focused on clinical relationships or diagnostic methods. Data relating to multiple infections were usually derived incidentally to the purpose of the investigations. Sixty-three percent of the reports with data on mixed infections identified them in < 5% of the total number of viral infections. Respiratory syncytial virus was the most common coinfecting virus, and respiratory syncytial virus and influenza virus were the most common virus pair identified. In considering rapid diagnostic techniques, in 87% of the reports with available data a virus was diagnosed in > 10% of specimens that were negative for the virus targeted by one method. There was no indication that mixed infections were associated with increased disease in immunocompetent patients or in certain immunocompromised patients. Immunocompromised patients, however, appeared to have a greater incidence of multiple infections. Mixed infections of single cells also occur and may have important clinical implications relative to reactivation of latent viruses and enhanced disease. The requirement for a comprehensive strategy for viral diagnosis involving multiple techniques was indicated by these findings.

Detection of enteric adenoviruses with synthetic oligonucleotide probes

The abilities of hybridization probes to detect all human adenovirus types and to identify enteric adenovirus types were evaluated. The efficiency of hybridization was compared to other tests currently in routine laboratory use on clinical specimens from young children with gastroenteritis. Probes were derived from various regions of the adenovirus types 2 and 41 genomes, and were evaluated by hybridization with a series of DNA quantities from 1 microgram to 10 pg of one adenovirus type from each human subgenus, lambda phage, and HEp 2 cells. The sensitivity of hybridization with the HPII probe (92.7%), containing the conserved hexon gene, compared well with EM (54.6%), culture and neutralization (45.5%), and enzyme immunoassay (61.8%). The sensitivity of detection of enteric adenovirus isolates by the cloned Bg/II D fragment probe (92.9%) and by a synthetic probe (85.7%), manufactured from type-specific sequences of the Ad41 hexon gene were comparable to Ad40/Ad41 specific enzyme immunoassay (84.6%). Hybridization was found to be a sensitive method of adenovirus detection in comparison to traditional methods of laboratory diagnosis. Synthetic oligonucleotides enable specific detection of individual enteric adenovirus types. Hybridization had additional advantages over other tests in identifying cases of infection with more than one adenovirus type and in allowing an estimate of the concentration of adenovirus in the specimen.

[Acute diarrhea associated viruses : An update]

Viruses recovered in stools are either cultivable viruses (enteroviruses, adenoviruses excepted type 40 and 41), or "fastidious" non cultivable viruses (rotaviruses adenoviruses 40 and 41, Norwalk, calcivirus, astrovirus, SRSV and SRV). Non cultivable viruses have been associated with many cases of diarrhea. Norwalk, two strains of calicivirus and SRV/SRSV, appear to be capable of causing outbreak. Rotavirus, astrovirus and most fastidious adenoviruses are associated with endemic spread. Specific or catch-all methods are used for diagnosis. Among the latter, electron microscopy is the most commonly used when the virus is recognizable and present in sufficient quantities. Small spherical viruses in the range 20-35 nm present greater difficulties. Polyacrylamide gel electrophoresis gives interesting epidemiological results for rotavirus. Specific methods are latex agglutination and enzyme immunoassays essentially for rotavirus and adenoviruses (all types or only 40 and 41). False positive results are few with well-designed kits. False negative results are seen in atypical strains and antigenic variants. In an outbreak, it is essential to make electron microscopic examinations. In individual cases, if no electron microscope is available, it is possible to make the diagnosis of rotavirus - and perhaps adenovirus 40 and 41 with a commercial kit. However a small number of stools contain more than one virus and they may act in synergy. In contrast many asymptomatic children may carry viruses.

Fastidious human adenovirus type 40 can propagate efficiently and produce plaques on a human cell line, A549, derived from lung carcinoma

Human adenovirus type 40 (Ad40) cannot propagate in conventional established human cell lines such as KB or HeLa cells. However, it has been shown that Ad40 DNA replicates in KB18 cells which express Ad2 E1B genes, suggesting that Ad40 is defective in the E1B gene function in KB or HeLa cells. We show here that Ad40 can propagate and produce plaques on A549 cells which do not contain Ad E1B genes. Our experiments show that the levels of replication of Ad40 DNA and production of infectious Ad40 virus in A549 cells are the same as or higher than those in 293 or KB18 cells. Dot blot analysis shows that the levels of Ad40 E1A and E1B mRNAs expressed in A549 cells at early to intermediate times postinfection are at least 10-fold higher than those in KB or KB18 cells. Northern (RNA) blot analysis shows that large E1B mRNA species (approximately 24S to 26S) are synthesized prior to the onset of DNA replication in A549 cells. No E1B mRNA species are synthesized in KB or KB18 cells at early times postinfection, and no differences in the expression of E1B mRNAs are seen between KB and KB18 cells. The experiment suggests that A549 cells have a cellular factor(s) which activates Ad40 E1B mRNA synthesis and that the E1B mRNA synthesis helps Ad40 propagation. In contrast, Ad40 can propagate in KB18 cells by using Ad2 E1B gene products that are constitutively expressed in this cell line. Furthermore, this result shows that Ad40 cannot propagate in KB cells because of the failure in the expression of E1B genes at early times postinfection.

Human viral gastroenteritis

During the last 15 years, several different groups of fastidious viruses that are responsible for a large proportion of acute viral gastroenteritis cases have been discovered by the electron microscopic examination of stool specimens. This disease is one of the most prevalent and serious clinical syndromes seen around the world, especially in children. Rotaviruses, in the family Reoviridae, and fastidious fecal adenoviruses account for much of the viral gastroenteritis in infants and young children, whereas the small caliciviruses and unclassified astroviruses, and possibly enteric coronaviruses, are responsible for significantly fewer cases overall. In addition to electron microscopy, enzyme immunoassays and other rapid antigen detection systems have been developed to detect rotaviruses and fastidious fecal adenoviruses in the stool specimens of both nonhospitalized patients and those hospitalized for dehydration and electrolyte imbalance. Experimental rotavirus vaccines have also been developed, due to the prevalence and seriousness of rotavirus infection. The small, unclassified Norwalk virus and morphologically similar viruses are responsible for large and small outbreaks of acute gastroenteritis in older children, adolescents, and adults. Hospitalization of older patients infected with these viruses is usually not required, and their laboratory diagnoses have been limited primarily to research laboratories.

Comparison of enteric adenovirus infection in various human cell lines

Growth of the fastidious enteric adenoviruses 40 and 41 was compared in different human cell lines. Purified virions were used to infect the following cell lines: A549; KB; Chang's conjunctiva; 293; HeLa. Both types of enteric adenovirus were infectious for each cell line, with the exception of adenovirus 40 in HeLa cells. Relatively low infectious titers were obtained from each cell type following infection with adenovirus 40 (TCID50 average = 10(-1.5)), whereas adenovirus 41 replicated to significantly higher titer (TCID50 average = 10(-3.0)). For both viruses, the highest infectious titers were obtained with A549 and KB cells. A time course experiment performed to quantitate the amount of hexon present in A549 and KB cells infected with each virus indicated that while the kinetics of accumulation were similar for both viruses, the concentration of type 41 hexon was significantly greater than that for type 40 in either cell line. The concentration of type 41 hexon was similar in each cell type; for type 40, a greater concentration of hexon was obtained in the A549 cell line than in the KB cells. The results indicate the distinct replication characteristics exhibited by adenovirus 40 are not due to a restriction in a specific host cell, and, because purified virions were used, not attributable to interference that might occur with co-infection from multiple viruses present in the same clinical specimen. We conclude the differences observed in the replication of these viruses are independent of host cell type and are associated, uniquely, with each virus.

Acute gastroenteritis in children attending day-care centres with special reference to rotavirus infections. II. Clinical manifestations

In a prospective study of a cohort of 214 children (aged 6 months-7 years) attending day-care centres, a total of 197 episodes of acute gastroenteritis (GE) occurred in 109 children (i.e. 51% of the participants) during a 12-month observation period. Rotavirus, pathogenic bacteria and Giardia lamblia caused GE in 24%, 6% and 2% of the cases, respectively. The aetiology of the remaining 68% was not discovered. Generally, the symptoms of GE were light and only two episodes led to hospitalization. Thirty-two rotavirus infections were asymptomatic. Two rotavirus GE reinfections occurred. They showed less severe symptoms than the primary infections. The older children (greater than 1.5 years) with rotavirus GE had lighter symptoms than the younger ones (less than or equal to 1.5 years). Compared with children with non-rotavirus GE, those with rotavirus GE showed the following clinical features: (1) Age between 6 months and 2 years. (2) Occurrence of rotavirus GE almost exclusively during the rotavirus season, i.e. January to April (winter). (3) High frequency of vomiting, the onset of which often preceded that of diarrhoea. However, these signs did not form a safe basis for the clinical diagnosis of rotavirus GE. One or more upper respiratory manifestations (URM) were observed in 39% of the children with rotavirus GE and in 36% of those with non-rotavirus GE. The occurrence of URM was age-related being highest in children less than 2 years. Consequently, the existence of a rotavirus syndrome is questioned. It is argued that URM in children with rotavirus GE may be due to a co-infection of the upper respiratory tract by a different micro-organism.