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Biomedical subjects

R I Glass

Publications and source records attributed to R I Glass.

At least 91 records · Page 5Linked to original sources
PubMed1998

Astrovirus infection in association with acute, persistent and nosocomial diarrhea in Bangladesh.

BACKGROUND: Diarrhea is an important public health concern in developing countries such as Bangladesh. Diarrhea in children that persists for 14 days or more occurs in 7% of patients in Bangladesh and frequently results in death. Astrovirus has been demonstrated as a cause of acute and nosocomial diarrhea and can be excreted for prolonged periods, yet its importance as a cause of diarrhea among children in a developing country like Bangladesh has not been investigated. METHODS: We tested 629 stool specimens from patients with acute diarrhea, 153 from patients with persistent diarrhea, 175 specimens from 76 patients hospitalized for diarrhea who were sampled repeatedly to detect nosocomial infection and 428 from nonhospitalized healthy children (controls). All children enrolled in the study were <5 years of age. Astrovirus was detected by enzyme immunoassay and other enteropathogens were detected by standard techniques. RESULTS: The detection of astrovirus increased significantly with the duration of diarrhea. Astrovirus was found in 23 (15%) specimens from patients with persistent diarrhea, 26 (4%) patients with acute diarrhea, but only 8 (2%) healthy controls. This trend remained when we limited our analysis to infants <12 months of age and to episodes in which astrovirus was the sole pathogen. Among patients with nosocomial diarrhea, 16% of postadmission specimens were positive for astrovirus when the admission specimen was negative. CONCLUSION: The observation that astrovirus is detected more frequently with diarrhea of increasing duration suggests the need for further studies to determine whether astrovirus plays a causative role in persistent diarrhea or is a secondary agent.

Acute Disease↗
PubMed1998

A prospective study of astrovirus diarrhea of infancy in Mexico City.

AIM: To describe the epidemiologic and clinical characteristics of astrovirus-associated diarrhea in a cohort of young children from a periurban community in Mexico City. METHODS: From November, 1988, through December, 1991, a total of 214 children were enrolled in a longitudinal study of diarrhea and monitored from birth to 18 months of age. A stool specimen was collected during each episode of diarrhea. Specimens from a total of 510 diarrhea episodes were tested for astrovirus by enzyme immunoassay and examined for other enteric pathogens. The antigenic types of astrovirus were determined by a typing enzyme immunoassay. RESULTS: Astrovirus was detected in 26 (5%) of 510 diarrhea episodes, with an incidence rate of 0.1 episode/child year; the highest rate was in children 13 to 18 months of age. Astrovirus-associated diarrhea was characterized by a median of 4 stools (range, 2 to 10) during the first 24 h, a median duration of 3 days (range, 1 to 21), vomiting (20%), and fever (7%). No cases of dehydration or repeat symptomatic infections were observed. Coinfection with another pathogen was detected in 11 of the 26 episodes (42%). Serotype 2 (35%) was most common, followed by serotypes 4 (15%), 3 (11%), and 1 and 5 (4% each); 31% were nontypable. Astrovirus-associated diarrhea was less severe, as measured by the number of stools (4.3 +/- 1.9), than diarrhea caused by rotavirus (7.1 +/- 2.8) or when coinfections occurred (5.5 +/- 1.6; P = 0.008). CONCLUSIONS: Astrovirus was associated with 5% of the episodes of diarrhea in this cohort of young Mexican children and presented as a mild secretory diarrhea. Five predominant antigenic types were detected with type 2 being the most common.

Astroviridae Infections↗
PubMed1998

Lack of maternal antibodies to P serotypes may predispose neonates to infections with unusual rotavirus strains.

Rotavirus (RV) strains infecting newborns often have unique neutralization antigens (P serotypes) on their outer capsids that are distinct from those found on RV strains that cause diarrhea in older children. We examined the hypothesis that unusual RV strains preferentially infect newborns because the newborns lack maternal neutralizing antibodies to these strains. To test this hypothesis, sera and saliva samples collected from neonates infected with 116E-like (P[11]G9) strains in the maternity ward of the All India Institute of Medical Sciences (AIIMS) hospital in New Delhi were tested for neutralizing antibodies against common RV strains and those infecting newborns and these titers were compared with those of newborns who did not become infected (controls). The infected neonates had significantly lower levels of cord blood neutralizing antibodies to 116E than the controls, suggesting that immunity to neonatal RV infection is acquired transplacentally through maternal antibodies. Further, this study confirmed the immunogenicity of the AIIMS neonatal strain 116E, a vaccine candidate, in its ability to evoke a potent RV-specific immunoglobulin A and neutralizing antibody response in serum and saliva among the infected babies. Our findings have important implications for the development of an effective RV vaccine. In India, where G9 strains are common in the community, the use of 116E as a vaccine, together with the rhesus tetravalent vaccine, may provide a broader protection against all the circulating RV serotypes, including serotype G9, which is not represented in the current rhesus RV tetravalent vaccine (G1-G4).

Antibodies, Viral↗
PubMed1998

Detection and characterization of novel rotavirus strains in the United States.

We recently established a rotavirus strain surveillance system in the United States to monitor the prevalent G serotypes before and after the anticipated implementation of a vaccination program against rotavirus and to identify the emergence of uncommon strains. In this study, we examined 348 rotavirus strains obtained in 1996 to 1997 from children with diarrhea in 10 U.S. cities. Strains were characterized for P and G types, subgroups, and electropherotypes by using a combination of monoclonal antibody immunoassay, reverse transcription-PCR, and hybridization. The four strains most commonly found worldwide comprised 83% of the isolates (P[8]G1, 66.4%; P[4]G2, 8.3%; P[8]G3, 6.9%; P[8]G4, 1.4%), but 9.2% were unusual strains (P[6]G9, 5.5%; P[8]G9, 1.7%; P[6]G1, 1.4%; and P[4]G1 and P[8]G2, 0. 3% each). Strains not typeable for P or G type accounted for 5.5% of the total, while 2.3% of the strains had more than one G type (mixed infections). All P[6]G9 strains tested had short electropherotypes and subgroup I specificity and were detected in 4 of 10 cities, while P[8]G9 strains had long electropherotypes and subgroup II VP6 antigens. Both sequence analysis of the VP7 open reading frame (about 94 to 95% amino acid identity with the VP7 gene of G9 prototype strain WI61) and binding to a G9-specific monoclonal antibody strongly suggest that U.S. G9 strains belong to serotype G9. The high detection rates of unusual rotaviruses with G9 (7.2%) or P[6] (6.9%) specificity in multiple U.S. cities suggest the emergence of new strains or inadequate diagnosis in the past. The epidemiologic importance of these strains remains to be determined.

Antibodies, Monoclonal↗
PubMed1998

Prevalence of astrovirus infection among Chilean children with acute gastroenteritis.

The frequency of astrovirus infection in 456 Chilean children with diarrhea was determined by enzyme-linked immunosorbent assay, reverse transcriptase PCR, and cell culture. Astrovirus was detected in 16.5% of rotavirus-negative and 7% of rotavirus-positive samples obtained from emergency rooms or hospitals and in 11% of samples from day care centers. HAst-1 was the predominant serotype identified.

Acute Disease↗
PubMed1998

Anticipating rotavirus vaccines: review of epidemiologic studies of rotavirus diarrhea in Argentina.

Rotavirus is the most common cause of severe diarrhea in children worldwide, and vaccines currently being field-tested could be available for childhood immunization in several years. To assess the rotavirus disease burden in Argentina and the value of future national surveillance for the disease, we reviewed available data on rotavirus detections reported by published and unpublished studies conducted in nine Argentine cities and by a multicenter study. Data from these studies indicated that rotavirus was detected in 20% of 5,226 specimens (within a range of 6% to 54% for different studies) from children hospitalized for diarrhea and in 9% of 6,587 specimens (within a range of 5% to 22% for different studies) from children who were outpatients, members of mixed populations (hospitalized patients and outpatients), or survey subjects in community-based studies. The hospital data showed that while rotavirus was detected throughout the year, a peak occurred during the winter months (May-July) when up to half of the children with diarrhea were found positive for rotavirus. Attempted serotyping of 294 rotavirus-positive specimens for G-protein by three laboratories was successful in 230 cases (78%); the resulting data indicated that serotype G1 was the most common (being present in 60% of the successfully serotyped specimens), followed by G2 (in 20%), G4 (in 14%), and G3 (in 5%). Based on national data for Argentina, we estimate that in 1991 there were roughly 84,500 rotavirus-associated outpatient visits (1 for every 8 births) and 21,000 hospitalizations averaging 4 days in length (1 for every 31 births), all of which entailed direct medical costs estimated at US$ 27.7 million. These preliminary data show that the rotavirus disease burden in Argentine children is extensive and could be decreased by a safe and effective vaccine. Further surveillance is needed to improve our understanding of the epidemiology and distribution of rotavirus strains in Argentina, to more accurately assess the cost-effectiveness of a rotavirus vaccine program, and to indicate what methods might best be used to monitor such a program's impact.

Argentina↗
PubMed1998

Epidemiology of rotavirus diarrhoea in Africa: a review to assess the need for rotavirus immunization.

Rapid progress towards the development of rotavirus vaccines has prompted a reassessment of the disease burden of rotavirus diarrhoea in developing countries and the possible impact of these vaccines in reducing diarrhoeal morbidity and mortality among infants and young children. We examined the epidemiology and disease burden of rotavirus diarrhoea among hospitalized and clinic patients in African countries through a review of 43 published studies of the etiology of diarrhoea. The studies were carried out from 1975 through 1992, and only those in which a sample of more than 100 patients with diarrhoea were specifically screened for rotavirus by using an established diagnostic test were included. Rotavirus was detected in a median of 24% of children hospitalized for diarrhoea and in 23% who were treated as outpatients; 38% of the hospitalized patients with rotavirus were < 6 months and 81% were < 1 year of age. Rotavirus was detected year-round in nearly every country and generally exhibited distinct seasonal peaks during the dry months. In 5 countries where rotavirus strains had been G-typed, 74% of strains were of one of the four common serotypes (G1 to G4), G1 was the predominant serotype, and 26% were non-typeable. This cumulative experience from 15 African countries suggests that rotavirus is the most important cause of severe diarrhoea in African children and that most strains in circulation today belong to common G types that are included in reassortant vaccines. Wherever large numbers of cases of rotavirus diarrhoea occur early in infancy, immunization at birth may protect the children before their first symptomatic infection.

Africa↗
PubMed1997

Failure of cooking to prevent shellfish-associated viral gastroenteritis.

BACKGROUND: In January 1995, Florida experienced the largest outbreak of oyster-associated gastroenteritis ever reported. METHODS: We interviewed both the cohort of persons from 38 gatherings where illness was reported and a sample of harvesters and harvest-area residents. Oysters were traced by means of tags and dealer records, and water quality measures in harvest areas were reviewed. We examined stool specimens for small round structured viruses by means of electron microscopy and amplification of RNA by reverse-transcriptase polymerase chain reaction. We also tested serum specimens for antibodies to Norwalk virus. RESULTS: Of 223 oyster eaters, 58% (129/223) became ill, compared with 3% (2/76) of non-oyster eaters (relative risk, 22; 95% confidence interval, 5.6-87.0). Most oyster eaters (67% [149/223]) ate only cooked (grilled, stewed, or fried) oysters. Oyster eaters who reported eating only thoroughly cooked oysters were as likely to become ill as those who ate raw oysters (relative risk, 0.68; 95% confidence interval, 0.45-1.0; P = .1). In 29 clusters, implicated oysters were from Apalachicola Bay, Florida. A community outbreak occurred in 2 bayside communities before the oyster harvest, leading to an increase in the reportedly common practice of overboard dumping of feces. Small round structured viruses were identified in the stool specimens of 2 harvest-area residents and 9 persons from 8 clusters. Results of water quality tests for fecal coliforms were within acceptable limits. CONCLUSIONS: This large outbreak of gastroenteritis associated with oysters may have resulted from overboard dumping of feces during a community outbreak of diarrheal illness. Our findings of acceptable water quality measures for fecal contamination and the lack of appreciable protective effect from cooking leave the consumer with no assurance of safety.

Adolescent↗
PubMed1997

Correlation of patient immune responses with genetically characterized small round-structured viruses involved in outbreaks of nonbacterial acute gastroenteritis in the United States, 1990 to 1995.

Small round-structured viruses (SRSVs) are a genetically and antigenically diverse group of caliciviruses that are the most common cause of outbreaks of acute nonbacterial gastroenteritis. We have applied both molecular techniques to characterize SRSVs in fecal specimens and serologic assays using four different expressed SRSV antigens to examine the distribution of outbreak strains in the United States and determine if the immune responses of patients were strain specific. Strains from 23 outbreaks of SRSV gastroenteritis were characterized by reverse transcription-PCR and nucleotide sequencing of a 277-base region of the capsid gene. These strains segregated into two distinct genogroups, I and II, comprising four and six clusters of strains respectively, each representing a distinct phylogenetic lineage. Serum IgG responses in patients were measured by enzyme immunoassay using expressed capsid antigens of Norwalk virus (NV), Toronto virus (TV), Hawaii virus (HV), and Lordsdale virus (LV), representing four of the 10 clusters. While strains in genogroups I and II were antigenically distinct, within genogroups, the specificity of the immune response varied greatly. Patients infected with genogroup I strains which had as much as 38.5% aa divergence from NV demonstrated relatively homologous seroresponses to the single NV antigen. In contrast, in genogroup II, homologous seroresponses to TV and HV were only present when the infecting strains showed less than 6.5% aa divergence from these antigens. These results suggest that TV and HV represent not only separate genetic clusters in genogroup II but also separate antigenic groups, each of which is related but distinguishable. In addition, two genetically distinct SRSV strains were identified for which we have no homologous antigen. This study suggests that while current molecular diagnostics are capable of detecting the full range of SRSVs, additional expressed antigens will be required to detect an immune response to SRSV infection caused by all the antigenically diverse strains.

Acute Disease↗
PubMed1997

Cryptosporidiosis in children during a massive waterborne outbreak in Milwaukee, Wisconsin: clinical, laboratory and epidemiologic findings.

During the spring of 1993 an estimated 403000 residents of the greater Milwaukee, Wisconsin area experienced gastrointestinal illness due to infection with the parasite Cryptosporidium parvum following contamination of the city's water supply. To define the clinical, laboratory and epidemiologic features of outbreak-associated cryptosporidiosis in children, medical and laboratory records for all children submitting stool samples to the microbiology laboratory of the Children's Hospital of Wisconsin between 7 April and 13 May 1993 were reviewed retrospectively. Interviews with parents were also conducted to obtain additional clinical history. Cryptosporidium, as the sole pathogen, was identified in stools from 49 (23%) of the 209 children enrolled in the study. Children with laboratory-confirmed cryptosporidiosis were more likely to live in areas of Milwaukee supplied with contaminated water (RR = 1.92, CI = 1.19-3.09), to be tested later in their illness (P < 0.05), to have submitted more than one stool specimen (P = 0.01), to have an underlying disease that altered their immune status (RR = 2.78, CI = 1.60-4.84), and to be older than 1 year of age (RR = 2.02, CI = 1.13-3.60). Clinical illness in these patients was more prolonged and associated with weight loss and abdominal cramps compared with Cryptosporidium-negative children. In the context of this massive waterborne outbreak relatively few children had documented infection with Cryptosporidium. If many children who tested negative for the parasite were truly infected, as the epidemiologic data suggest, existing laboratory tests for Cryptosporidium were insensitive, particularly early in the course of illness.

Adolescent↗
PubMed1997

Sequence analysis demonstrates that VP6, NSP1 and NSP4 genes of Indian neonatal rotavirus strain 116E are of human origin.

We have sequenced the genes encoding the inner capsid protein VP6 and the nonstructural proteins NSP1 and NSP4 of the Indian neonatal serotype P8[11]G9 human/bovine reassortant candidate vaccine rotavirus strain 116E. These three genes share a high degree of sequence and deduced amino acid homology with human prototype strain Wa. Our results confirm and extend those of previous RNA-RNA hybridization studies which suggested that these genes are of human origin, and will facilitate examination of the host immune response to 116E induced by natural infection and vaccination.

Amino Acid Sequence↗
PubMed1997

Association of torovirus with acute and persistent diarrhea in children.

OBJECTIVE: To study the etiologic role of toroviruses as a cause of gastroenteritis in humans. METHODS: The design was a case-control study. We compared the rate of torovirus detection in fecal specimens from a selection of children with acute or persistent diarrhea and controls without diarrhea from a study of childhood diarrhea in an urban Brazilian slum. Stool samples were coded and tested in a blinded fashion for the presence of torovirus antigen by enzyme-linked immunosorbent assay, other enteropathogens, toxins and fecal leukocytes. RESULTS: Thirty-three children with acute diarrhea, 41 children with persistent diarrhea and 17 controls were enlisted in the study. Torovirus antigen was detected in 9 (27%) samples from children with acute diarrhea, 11 (27%) samples from children with persistent diarrhea and none of the samples from controls (P < 0.05). In addition the presence of enteroaggregative E. coli was associated with persistent diarrhea and the presence of Cryptosporidium oocysts was common although not significant (P = 0.08); torovirus and Cryptosporidium occurred in different subsets of samples, whereas torovirus and enteroaggregative Escherichia coli were commonly found in combination. CONCLUSIONS: These data indicate that toroviruses, alone or in combination with enteroaggregative E. coli, may play a pathogenic role in acute and possibly persistent diarrhea. Further studies are warranted to determine the etiologic role of toroviruses in gastroenteritis.

Acute Disease↗
PubMed1997

Visualizing geographic and temporal trends in rotavirus activity in the United States, 1991 to 1996. National Respiratory and Enteric Virus Surveillance System Collaborating Laboratories.

BACKGROUND: Rotavirus is the leading cause of severe pediatric gastroenteritis worldwide. A vaccine may soon be licensed for use in the United States to prevent this disease. To characterize US geographic and temporal trends in rotavirus activity, we made contour maps showing the timing of peak rotavirus activity. METHODS: From July, 1991, through June, 1996, 79 laboratories participating in the National Respiratory and Enteric Virus Surveillance System reported on a weekly basis the number of stool specimens that tested positive for rotavirus. The peak weeks in rotavirus detections from each laboratory were mapped using kriging, a modeling technique originally developed for geostatistics. RESULTS: During the 5-year period 118,716 fecal specimens were examined, of which 27,616 (23%) were positive for rotavirus. Timing of rotavirus activity varied by geographic location in a characteristic pattern in which peak activity occurred first in the Southwest from October through December and last in the Northeast in April or May. The Northwest exhibited considerable year-to-year variability (range, December to May) in the timing of peak activity, whereas the temporal pattern in the remainder of the contiguous 48 states was relatively constant. CONCLUSION: Kriging is a useful method for visualizing geographic and temporal trends in rotavirus activity in the United States. This analysis confirmed trends reported in previous years, and it also identified unexpected variability in the timing of peak rotavirus activity in the Northwest. The causes of the seasonal differences in rotavirus activity by region are unknown. Tracking of laboratory detections of rotavirus may provide an effective surveillance tool to assess the impact of a rotavirus vaccination campaign in the United States.

Humans↗
PubMed1997

Anticipating rotavirus vaccines: hospital-based surveillance for rotavirus diarrhea and estimates of disease burden in Bangladesh.

OBJECTIVES: Rotavirus is the most common cause of severe diarrhea in children worldwide, and a vaccine may soon be licensed and available for use in immunization programs. To assess the need for a rotavirus vaccine in Bangladesh, we estimated the disease burden of rotavirus diarrhea from national vital statistics for births and diarrheal deaths, together with hospital surveillance data on the proportion of severe childhood diarrhea attributed to rotavirus. METHODS: From 1990 through 1993, hospital surveillance was conducted of a systematic, random 4% sample of >80,000 patients with diarrhea who sought care each year at the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B). RESULTS: Rotavirus was detected in 20% (1561 of 7709) of fecal specimens from children with diarrhea <5 years of age; 92% of all cases (1436) occurred in children <2 years of age, but only 3% (50) of cases occurred in infants <3 months of age. Children infected with rotavirus were more likely to have watery stools (P < 0.001), severe vomiting (P < 0.001) but less severe dehydration (P = 0.007) than children infected with other enteropathogens. CONCLUSIONS: We estimate that in this setting, where 18% of children die by age 5 and about 25% of these succumb to diarrhea, between 14,850 and 27,000 of the 3 million Bangladeshi children born in 1994 will die of rotavirus by the age of 5 years, equivalent to 1 rotavirus death per 111 to 203 children. The estimated burden of rotavirus diarrhea in Bangladesh is sufficiently great to warrant field testing of rotavirus vaccines for possible inclusion in the current immunization program.

Bangladesh↗
PubMed1997

A one-tube method of reverse transcription-PCR to efficiently amplify a 3-kilobase region from the RNA polymerase gene to the poly(A) tail of small round-structured viruses (Norwalk-like viruses).

Amplification of a 3-kb genome region from the RNA polymerase gene to the 3' poly(A) tail of small round-structured virus (SRSV) by reverse transcription-PCR (RT-PCR) has been difficult to achieve because of a stable secondary structure in a region between the RNA polymerase gene and the 5' end of the second open reading frame. We have developed a one-tube RT-PCR method to efficiently amplify this region. The method comprises three procedures: purification of poly(A)+ RNA from a starting RNA solution by oligo(dT)30 covalently linked to latex particles, buffer exchange, and continuous RT and PCR in a single tube containing all reaction components. The key elements of this method are (i) first-strand cDNA synthesis with the Superscript II version of RNase H- Moloney murine leukemia virus reverse transcriptase at 50 degrees C for 10 min by using the RNA-oligo(dT)30 hybrid on the latex particles as the template and primer, and (ii) PCR by Taq and Pwo DNA polymerases mixed together with a mixture of 12 phased oligo(dT)25 antisense primers. The detection threshold of the one-tube RT-PCR method was as little as 0.2 ng of the crude RNA used as the source of the template. Using this method, we obtained 3-kb products from 24 SRSV strains previously characterized into four genetic groups. These included 5 P1-A, 4 P1-B, 5 P2-A, and 10 P2-B strains. Because SRSVs have not yet been cultivated in vitro, this novel method should facilitate molecular characterization of SRSVs to provide a firm scientific foundation for improvements and refinements of SRSV diagnostics.

Base Sequence↗