Occurrence Of Enteric Viruses Research Articles

Occurrence of enteric viruses causing clinical diarrhea in small ruminants in northern Indian plains: a reverse transcription PCR based molecular study.

Fowlpox virus (FPV) infects chickens and turkeys giving rise to pock lesions on various body parts like combs, wattles, legs, shanks, eyes, mouth, etc. The birds, affected with FPV, also show anemia and a ruffled appearance which are clinical symptoms of reticuloendotheliosis. Interestingly, the field strains of FPV are integrated with the provirus of reticuloendotheliosis virus (REV). Due to this integration, the infected birds, upon replication of FPV, give rise to free REV virions, causing severe immunosuppression and anemia. Pox scabs, collected from the infected birds, not only show positive PCR results upon performing FPV-specific 4b core protein gene PCR but also show positive results for the PCR of REV-specific env gene and FPV-REV 5'LTR junction. Homogenized suspension of the pock lesions, upon inoculating to the chorio-allantoic membrane (CAM) of 10-day-old specific pathogen-free embryonated chicken eggs, produces characteristic pock lesions in serial passages. However, the lesions also harbor REV mRNA or free virion, which can be identified by performing REV-specific env gene PCR using REV RNA from FPV-infected CAMs. The study suggests successful replication and availability of REV mRNA and free virion alongside the FPV, although the CAM is an ill-suited medium for any retroviral (like REV) growth and replication.

Occurrence of enteric viruses and faecal indicators in submarine groundwater discharges in the coastal environment of the Mexican Caribbean

AbstractThe occurrence of faecal microorganisms such as total coliforms (TCs), Escherichia coli (E. coli), coliphages (somatic and F+ specific) and the genomes of faecal viruses: human adenovirus (HAdV), norovirus (NoV) genogroup I (GI) and II (GII), enterovirus (EV), aichi virus (AiV) and Pepper mild mottle virus (PMMoV), was explored in submarine groundwater discharges (SGDs) in the Mexican Caribbean. Ultra‐filtrated water samples were subjected to nucleic acid extraction and real‐time quantitative polymerase chain reaction (PCR). Results showed the presence of TC bacteria at all sites, whereas the detection of E. coli occurred only during the dry season. Coliphages occurred during the rainy and dry seasons, with concentrations ranging from 10 to 2560 plaque forming units (PFU/100 ml). HAdV and AiV were detected in 50% and 41% of the samples, at concentrations ranging from 102 to 104 genome copies per litre (GC/L) and from 102 to 106 GC/L, respectively. NoV GI and II were detected in 25% and 16% of the samples, at concentrations of 101 GC/L and 102–103 GC/L, respectively. PMMoV was detected in 50% of the samples at concentrations ranging from 101 to 103 GC/L. The EV genomes were not detected. These findings demonstrate that faecal microorganisms can be transported through SGDs in the Mexican Caribbean, potentially contributing to human health risks for recreation.

Occurrence and Accumulation of Human Enteric Viruses and Phages in Process Water from the Fresh Produce Industry.

The virological quality of process water (PW) used by the produce industry has received limited attention. As a first step to overcoming technical limitations in monitoring viruses in PW, the analytical performance of ultrafiltration was assessed to concentrate viral particles from 20 L of spiked PW. The selected method used for sample concentration of PW was carefully validated, thus enabling the accurate quantification and estimation of viral titers of human enteric viruses and phages. PW from the produce industry was collected periodically from the washing tanks of commercial facilities. The analysis of coliphages was performed by plaque assay, while the occurrence of enteric viruses and crAssphage was determined by molecular techniques. Significant differences in the physicochemical composition of PW, mostly due to the different nature of fresh produce types and differences in the sanitizer used in commercial operation, were observed. Accumulation of crAssphage and coliphages was observed in PW, but correlation with human enteric viruses was not possible due to the low prevalence of these pathogens in the PW analyzed. The obtained results showed that depending on the type of product washed, the product/water ratio and the residual concentrations of the sanitizers, the prevalence and concentration of bacteriophages changed significantly.

The prevalence and levels of enteric viruses in groundwater of private wells in rural Alberta, Canada

The prevalence and levels of enteric viruses in untreated groundwater of private wells used for drinking and/or agricultural practices in rural Alberta were studied using the qPCR panel assay, integrated cell culture with qPCR and cell culture in the volume of 500 liters per sample through serial sampling. Seven viruses were assessed including adenovirus, rotavirus, norovirus, astrovirus, sapovirus, reovirus and JC virus. Five viruses were detected with an overall positive detection rate of 6.33 % (45 of 711 samples). The most frequently detected virus was adenovirus (48.9%, 22/45) followed by rotavirus (44.4%, 20/45), reovirus (20%, 9/45), JC virus (6.7%, 3/45) and norovirus (6.7%, 3/45). There was no significant difference in the positive detection rates, ranging from 1.1% to 3.4% by various well settings used for broiler farms, cow/calf farms, feedlots and rural acreages. Effects of well characteristics (aquifer type, well depth, static level of water, well seal) and well completion lithology on potential viral contamination of groundwater of private wells were also analyzed upon available data. The findings demonstrate that occurrence of enteric viruses is low and viral contamination is sporadic in groundwater of private wells in rural Alberta. Conventional fecal bacterial indicators (coliform and/or E. coli) were not a representative marker for viral contamination in groundwater wells in rural Alberta.

Contamination sources of the enteric virus in recreational marine water shift in a seasonal pattern

Human enteric virus occurrence in bathing beaches poses a potential health risk to swimmers. They may come from several sources, but the understanding of the seasonal contribution of contamination sources to virus occurrence is still lacking. Here, the surveillance of human enteric viruses at the First Bathing Beach in Qingdao was performed January–December 2018. The occurrence of Enteric viruses, assayed with quantitative polymerase chain reaction (qPCR), was analyzed at temporal and spatial levels to determine the viral contamination sources. The results showed that only Astroviruses (AstVs) and Adenoviruses (HAdVs) were found in the swimming area. Their occurrence correlated significantly with the sewage-polluted area, but HAdVs were only found in autumn and AstVs in spring. Meanwhile, enteric viruses in the swimming area showed significantly higher levels than the surrounding area, particularly AstVs in summer with the swimmer crowd. All these data imply that sewage discharge and swimmers co-contribute to the viral occurrence in a seasonal pattern, with the former being more focused in warm seasons (spring and autumn) and the latter in hot seasons (summer). These results indicate that sewage discharge and crowd swimmers, as unsafe swimming conditions, should be avoided to improve public health at the bathing beaches.

Occurrence of Enteric Viruses in Surface Water and the Relationship with Changes in Season and Physical Water Quality Dynamics

Environmental water quality issues have dominated global discourse and studies over the past five decades. Significant parameters of environmental water quality include changes in biological and physical parameters. Some of the biological parameters of significance include occurrence of enteric viruses. Enteric viruses can affect both human and animal's health by causing diseases such as gastrointestinal and respiratory infections. In this study, the relationship between the occurrence of enteric viruses with reference to adenoviruses and enteroviruses and the physical water quality characteristics was assessed from water samples collected from Lake Victoria (LV) in Kenya. In order to understand the dynamics of season driven enteric viruses' contamination of the lake waters, we additionally analysed seasonal behavior of the lake's catchment area in terms of rainfall effects. Physical quality parameters were measured on-site while viral analysis was carried out by molecular methods using the nested polymerase chain reaction (nPCR). From 216 samples that were analysed for viral contamination, enteric viral genomes were discovered in 18 (8.3%) of the samples. Out of half of the samples (108) collected during the rainy season, enteric viral genomes were detected in 9.26% (10) while 8 (7.41%) samples tested positive from the other half of the samples (108) collected during the dry season. There was, however, no significant correlation noted between the physical water quality characteristics and the enteric viruses' occurrence. Neither wet season nor dry season was significantly associated with the prevalence of the viruses. In Lake Victoria waters, most of the samples had an average of physical water quality parameters that were within the range accepted by the World Health Organization (WHO) for surface waters with exemption of turbidity which was above the recommended 5 NTU as recorded from some sampling sites. Continuous and long-term surveillance of the lake water to accurately monitor the contaminants and possible correlation between chemical, physical, and biological characteristics is recommended. This would be important in continuous understanding of the hydrological characteristics changes of the lake for proper management of its quality with reference to the WHO standards. A multiple varied-sampling approach in different geographical regions during different seasons is recommended to establish the geographical distribution and relatedness to seasonal distribution patterns of the viruses. The data generated from this study will be useful in providing a basis for assessment of seasonally driven fecal pollution load of the lake and enteric virus contamination for proper management of the sanitary situation around the lake.

Occurrence and molecular characterization of enteric viruses in bivalve shellfish marketed in Vietnam

Viral contamination of bivalve molluscs is an extensively document food safety issue. Limited data are available, however, on the prevalence and quantitative levels of such viruses in countries, as Vietnam, with an important shellfish production, both for internal consumption and for export. The aim of this study was to evaluate both the occurrence and the quantitative levels of different viruses, including Norovirus (NoV genogroups I, II and IV), Hepatitis A (HAV), Hepatitis E (HEV), Astrovirus (AstV), and Aichi virus (AiV), in bivalve shellfish commercialized in Vietnam.A total of 121 samples (63 Pacific oysters and 58 white hard clams) were collected over nine months in two fish markets and two supermarkets in Hanoi, Vietnam. Norovirus was the most frequently detected virus (81.8% of samples) with viral loads ranging from below the quantification limit (LOQ) to 2.8 × 104 genome copies (g.c.)/g of shellfish digestive tissue and an average contamination of 3.8 × 103 g.c./g. HAV, HEV and AstV were detected in 1.7%, 11.6% and 12.4% of samples respectively (average concentrations: 1.3 × 102 g.c./g for HAV, 1.2 × 102 for HEV and 1.5 × 103 for AstV). AiV were also frequently detected (11.6% of samples), while NoV GIV was never observed. Contamination by at least one virus and by more than one virus was present in 83.5% and 52.9% of samples, respectively. Molecular characterization of NoV revealed circulation, over the observed period, of a wide variety of strains (four and nine genotypes for NoV GI and NoV GII respectively: GI.2, GI.4, GI.5, GI.6, GII.3, GII.4, GII.6, GII.7, GII.13, GII.14, GII.17, GII.18, GII.21).To our knowledge, this study is the first to provide quantitative information on the occurrence of enteric viruses in bivalve shellfish marketed in Vietnam, which will help outlining monitoring plans and setting appropriate control measures.

Enteric Viruses and Fecal Bacteria Indicators to Assess Groundwater Quality and Suitability for Irrigation.

According to Italian Ministerial Decree No. 185 of 12 June 2003, water is considered suitable for irrigation if levels of fecal bacteria (i.e., Escherichia coli and Salmonella) are within certain parameters. The detection of other microorganisms is not required. The aim of this study is to determine the bacteriological quality of groundwater used for irrigation and the occurrence of enteric viruses (Norovirus, Enterovirus, Rotavirus, Hepatovirus A), and to compare the presence of viruses with the fecal bacteria indicators. A total of 182 wells was analyzed. Widespread fecal contamination of Apulian aquifers was detected (141 wells; 77.5%) by the presence of fecal bacteria (i.e., E. coli, Salmonella, total coliforms, and enterococci). Considering bacteria included in Ministerial Decree No. 185, the water from 35 (19.2%) wells was unsuitable for irrigation purposes. Among 147 wells with water considered suitable, Norovirus, Rotavirus, and Enterovirus were detected in 23 (15.6%) wells. No Hepatovirus A was isolated. Consequently, 58 wells (31.9%) posed a potential infectious risk for irrigation use. This study revealed the inadequacy of fecal bacteria indicators to predict the occurrence of viruses in groundwater and it is the first in Italy to describe the presence of human rotaviruses in well water used for irrigation.

Occurrence of enteric viruses in reclaimed and surface irrigation water: relationship with microbiological and physicochemical indicators.

To assess the prevalence of enteric viruses in different irrigation water sources and in the irrigated produce, and the possible links with microbiological and physicochemical water characteristics. The prevalence and levels of Escherichia coli, Norovirus (NoV) genogroup I (GI) and II (GII), as well as Hepatitis A virus were assessed in three types of water: surface water (surface-W), reclaimed water subjected to secondary treatment (secondary-W) and reclaimed water subjected to tertiary treatment (tertiary-W), as well as in zucchini irrigated with these irrigation water sources. Chemical oxygen demand (COD), turbidity, total suspended solids, alkalinity and maximum filterable volume (MFV) were also measured in the water. Higher prevalence of NoV in secondary-W (GI 100%, GII 55·6%) and tertiary-W (GI 91·7%, GII 66·7%) compared with surface-W (GI 58·4%, GII 22·2%) was observed. Nov GI showed positive correlation with E.coli (Spearman's correlation coefficient=0·68, P<0·01), and with some physicochemical parameters such as COD (0·52, P<0·01), turbidity (0·52, P<0·01) and MFV (0·54, P<0·01). Escherichia coli and enteric viruses were not detected in zucchini. There is a potential risk of contamination of crops with NoV when reclaimed water is used for irrigation. Increase the knowledge on the prevalence of enteric viruses in different irrigation water sources, and its consequences for fresh produce safety.

The occurrence of enteric viruses in Light Turkey Syndrome

Two studies were conducted to determine the role of enteric viruses in Light Turkey Syndrome (LTS), which is characterized by lower weight in market age turkeys than their standard breed character. In the surveillance study, we selected four LTS and two non-LTS turkey flocks in Minnesota and collected faecal samples at 2, 3, 5 and 8-weeks of age. Astrovirus, rotavirus, and reovirus were detected alone or in various combinations in both LTS and non-LTS flocks. No coronavirus was detected in LTS flocks and no corona- or reovirus was detected in non-LTS flocks. In the second study, 2-week-old turkey poults were divided into two groups; Group A (challenged) was inoculated orally with 10% pooled faecal suspension from LTS flocks and group B (control) was inoculated with phosphate buffered saline (PBS). Clinical signs of depression, huddling, and lack of uniform size were observed in the challenged group but not in the control group. diarrhoea was observed in both groups but was more severe in the challenged group than in the control group. Birds in the challenged group shed astrovirus, rotavirus and reovirus, while the control group shed only astrovirus. Virus shedding in both groups was observed for up to nine weeks of age. Significantly lower body weights were seen in the challenged group starting at seven weeks of age and lasting until 20 weeks of age. These findings suggest that viral enteritis at an early age may set up conditions for the development of LTS in adult turkeys.

Study of the Detection of Enteric Viruses and Bacteria in Spring-water and Groundwater in Busan ('10~'11)

We analyzed the occurrence of enteric viruses and bacteria at 22 places of drinkable groundwater (civil defense emergency water-supply facility), 8 places of the groundwater used for drinking water in group food services, and 10 places of spring-water. When the 40 concentrated samples were analyzed using nested RT-PCR and real-time RT PCR methods, norovirus and other enteric viruses were not detected in all samples tested. The detection percentages for total coliforms, Escherichia coli, Yersinia enterocolitica of fecal indicator were 57.5%, 22.5% and 7.5%, respectively. Colipages were not detected. These results suggest that high levels of fecal indicator bacteria in groundwater and spring-water are not directly related to occurrence of enteric viruses.

Occurrence of enteric viruses in shellfish and relation to climatic-environmental factors

To investigate the presence of enteric viruses [hepatitis A (HAV) and norovirus (NoV)] in shellfish harvested from the deltaic area of the Po river in relation to environmental factors. Fortnightly sampling of shellfish was carried out in two lagoon areas (category B production areas) and one sea area (category A). Environmental parameters in the lagoon and hydrometric level of the tributary river were monitored throughout the sampling period. Samples (n = 120) were analysed for bacterial (E. coli and Salmonella) and viral (HAV and NoV) contamination; samples from category B areas were analysed before and after purification treatment. All the samples were negative for HAV whereas 10 samples (8.3%), all harvested in the lagoon areas, were positive for NoV. Sequencing identified the strains as genotypes II.4 and II.b. None of the samples was found to be contaminated after depuration. The monitoring showed a low frequency of NoV presence; viral contamination, detected exclusively in shellfish collected from the deltaic area (category B), could be influenced by the flow of the tributary river. The data collected are useful for the design of targeted prevention strategies and for the modulation of control plans after meteorological events.

Bacteriophages as indicators of enteric viruses and public health risk in groundwaters.

Low concentrations of all types of bacteriophages in groundwater limit their power to predict the presence of enteric viruses. There is little concordance in the literature regarding phage detection methods, thus making comparisons extremely difficult. Different authors have used different hosts, phage concentration methods, and end-point determinations. Also, markedly different volumes of sample have been employed, varying from 1 litre to 400 l. Bacteriophage concentration methods are not reproducible. There has been marked variability among groups in the natural substrates used (for example, beef extract), the type of adsorbing filter used, centrifugation instruments and conditions, and the delivery of the concentrate to the host cells. There is no consensus on the best bacterial host strain. Currently, several are employed with each showing differential sensitivities and specificities. In particular, host stability must be considered. Host stability has two components: the ability of the host to continue to be receptive to the bacteriophage after continued sub-culture, and the lack of lysogenic or temperate bacteriophage in the host cell line which may be randomly and unpredictably activated. There is a lack of consistent recovery of bacteriophages from individual faecal specimens. In particular, only approximately 3% of individual humans carry the FRNA phages. While there is some evidence to indicate that the phages multiply in sewage, it is not clear how they do so since the host pili should not be produced at lower temperatures. These ecological factors need to be understood. Of all the phages thus far studied, Bacteroides fragilis HSP40 has the highest recovery rate from individual people. However, Bacteroides, being an anaerobe, is a difficult host for routine laboratory analysis. Methods for the enumeration of F(+)-specific phages and Bacteroides phages are complex, time-consuming, costly and not reproducible. Conversely, somatic coliphage methods are simpler and results can be available in 4-6 h. The occurrence of phages and viruses in groundwater depends on physicochemical characteristics that control their fate and transport in the groundwater/aquifer environment. There are very little actual data taken from the field that allow an understanding of the ecology and life span of phages in their natural environment. Moreover, the ability of phages to serve as a source of food for other microbes needs to be understood. There has been a lack of association of bacteriophage recovery with gastroenteritis outbreaks due to enteric viruses. There is only a small epidemiological database concerning the occurrence of enteric viruses in groundwater.

The Occurrence of Enteric Viruses in Polluted Water, Correlation to Indicator Organisms and Factors Influencing their Numbers

Samples from a stream polluted with treated domestic effluent were examined for the presence of enteric viruses and indicator organisms viz. total and faecal coliforms, faecal streptococci and coliphages. Strong seasonal patterns in both the occurrence and number of enteric viruses, coliphages, and to a lesser extent faecal streptococci, were observed. The incidence of the highest and lowest number of enteric viruses and coliphages plotted on a time scale followed a sine curve as opposed to the variations of temperature which followed an inverted sine curve. Indications are that the survival of these organisms is inversely proportional to temperature with lower temperatures (below 13°C) being conducive to a slower die-off rate. The square of the correlation coefficient between the viral numbers and temperature was calculated at R2 = 0.4. This coefficient of determination only improved to R2 = 0.46 by combining data from other physical and physico-chemical and biological determinations. Temperature may be considered a useful aid in predicting the possible presence or absence of enteric viruses in raw water. Of all the indicator organisms examined only results on coliphages behaved similar to that of enteric viruses and should therefore be considered the best biological indicator for viral behaviour under these circumstances.

Occurrence of Enteroviruses and Rotaviruses in Drinking Water in Colombia

Relatively few studies have been conducted on the occurrence of enteric viruses in drinking water in developing countries. In this study, we sought to apply positively charged microporous filters to the detection of enteric viruses in the drinking water of several major Colombian cities. Finished drinking water samples were collected at several drinking water plants whose treatment included flocculat ion, sand filtration and chlorination. Drinking water samples were also collected from the taps of private homes, hotels and community taps. Viruses were concentrated by passage of 20-99 liters of water through 50S Zeta-plus or 1 MDS Virosorb positively charged filters. Adsorbed viruses were eluted with 10% tryptose phosphate broth adjusted to pH 9.5 and concentrated to a final volume of 2 ml by ultracentrifugation before assay. Enteroviruses were detected by assay on BGM cells and rotavirus by assay on MA-104 cells. Out of eight samples of finished drinking water leaving the plants studied, three were found to contain enteric viruses. Rotaviruses were detected in two samples and enterovirus in one. Two of the samples containing enteric viruses also contained greater than 100 coliforms/100 ml. Rotaviruses were isolated from three tapwater samples and enteroviruses from one. All the tapwater samples which contained enteric viruses had visible turbidity and also contained coliform bacteria.

Viral pollution of the marine environment

The marine environment is a vital global resource which continues to be used for the disposal of man's waste. Its role as a waste disposal medium, however, is inimical to its value as a source of food and recreation. The present article discusses the role of ocean disposal of municipal sludge in the recycling of human pathogens in the marine environment. Particular attention will be paid to the occurrence, fate, and transport of human enteric viruses in marine waters, sediments, and marine organisms. The relationship of fecal indicator bacteria with the occurrence of enteric viruses will also be delineated.

Viruses in groundwater beneath sewage irrigated cropland

The occurrence of enteric viruses in groundwater and soil was examined beneath three different sites where slow rate sewage irrigation of cropland is practiced. At all sites, the sewage was secondarily treated (aeration) before land application. Enteric viruses were isolated from wells beneath all sites. The lowest frequency of isolation was from wells beneath the one site practicing chlorination before application by spray irrigation. Viruses were detected in wells as deep as 27.5 m.

Enteric Bacterial and Viral Pathogens and Indicator Bacteria in Hard Shell Clams

Enteric bacteria and virus levels were determined in hard shell clams, Mercenaria mercenaria, harvested from areas open or closed for commercial shellfishing on the basis of total coliform levels in water. Four pairs of open and closed stations were sampled seasonally over a 1-year period. Enteric viruses were isolated from 3 of 13 100-g clam samples from open beds and 6 of 15 samples from closed beds. Salmonella was found in 1 of 15 samples from closed areas, but not in any samples from open areas. No Shigella or Yersinia were isolated from clams taken from either open or closed beds. Levels of Vibrio parahaemolyticus, an indigenous estuarine microorganism, were similar in clams from open and closed areas. No statistically significant difference was found in the occurrence of enteric viruses in clams from open and closed areas. Product-moment correlations between concentrations of enteric viruses and bacteria in clams or water demonstrated no statistically significant correlations between virus concentrations in clams and total coliforms or fecal coliforms in water or total coliforms, fecal coliforms, fecal streptococci or aerobic plate counts in clams.

Bacterial Indicators and Environmental Factors as Related to Contamination of Oysters by Enteroviruses

Enteric viruses previously have been reported in marine waters and shellfish which met acceptable bacteriological standards for recreational use and shellfish harvesting. Unfortunately, previous data on occurrence of enteric viruses are limited and usually not quantitative. In this report, results of studies conducted along the upper Texas Gulf coast, where a substantial amount of quantitative virological data was collected, are compared to bacteriological indicators and other environmental factors on a statistical basis. A product-moment correlation matrix showed that there was a moderate correlation between viruses in water and total coliforms in water, total coliforms in oysters and fecal coliforms in oysters. However, presence of viruses in water was not found to be correlated with presence of viruses in oysters. The only significant regression coefficient found for the model relating the concentration of viruses in water to bacterial indicators and other environmental variables was concentration of coliforms in oysters. Multiple regression analysis showed that approximately 25% of the variance in the number of viruses detected in water was statistically accounted for by the linear correlation with the total coliforms in oysters. The amount of variation in the number of viruses explained by this indicator, however, was not large enough to make the concentration of coliforms in oysters a good predictor of the concentration of viruses in water. Furthermore, none of the bacterial or other environmental variables was found to be a good predictor of the concentration of viruses detected in oysters. Our failure to find a strong predictive relationship between viruses in marine water and in oysters, and the occurrence of viruses in high frequency in waters which met current bacteriological standards, indicate that these standards do not reflect the occurrence of enteroviruses in marine waters.

Detection and Occurrence of Enteric Viruses in Shellfish: A Review

During feeding, bivalve mollusks (oysters, mussels and clams) can accumulate pathogenic human enteric viruses when present in sewage-polluted seawater. It has been well established that infectious hepatitis virus is transmitted by consumption of raw or inadequately cooked shellfish. But because of the lack of epidemiologic techniques, transmission of other enteric viruses by shellfish has not been established. Other enteric viruses, such as polio, echo, coxsackie and reo, have been detected in shellfish. Enteroviruses have been detected in shellfish taken from both “open” and “closed” areas, based on bacteriological standards used at present in the United States. Field and laboratory studies have indicated that enteric viruses can survive for long periods in seawater and in shellfish. Recent advances in methodology have led to development of more rapid and less expensive methods for detection of a greater number of enteric viruses in shellfish.