Pattern of shedding of the Norwalk particle in stools during experimentally induced gastroenteritis in volunteers as determined by immune electron microscopy.

In 11 of 23 volunteers the Norwalk virus-like particle was visualized by immune electron microscopy in at least one stool specimen obtained during the acute phase of experimentally induced nonbacterial gastroenteritis. Examination of multiple stool specimens obtained during the course of illness in these 11 volunteers revealed maximal concentration of Norwalk virus-like particle at the onset of illness and shortly thereafter; in no case was the Norwalk particle visualized in stools obtained before the onset of illness. This finding further suggests that the Norwalk particle was the etiological agent of the Norwalk gastroenteritis outbreak. The limit of reliability of our immune electron microscopy assay system for particle counting was examined.     

The discovery of the 27-nm Norwalk virus: an historic perspective

In 1972, a 27-nm virus-like particle was discovered by use of immune electron microscopy (IEM) in an infectious stool filtrate derived from an outbreak of gastroenteritis in an elementary school in Norwalk, Ohio. IEM enabled the direct visualization of antigen-antibody interaction, as the particles were aggregated and coated by specific antibodies. This allowed the recognition and identification of a 27-nm virus-like particle that did not have a distinctive morphology, was low-titered, and was among the smallest viruses known. Serum antibody responses to the 27-nm particle were demonstrated in key individuals infected under natural or experimental conditions; this and other evidence suggested that this virus-like particle was the etiologic agent of the Norwalk gastroenteritis outbreak. The fastidious 27-nm Norwalk virus is now considered to be the prototype strain of a group of noncultivatable viruses that are important etiologic agents of epidemic gastroenteritis in adults and older children.     

Human enteric coronaviruses: antigenic relatedness to human coronavirus OC43 and possible etiologic role in viral gastroenteritis

In a group of infants with acute nonbacterial gastroenteritis, examination of paired sera for antibody to human coronavirus (HCV) OC43 and neonatal calf diarrhea coronavirus showed a peculiar pattern of serological response, restricted only to HCV OC43 surface antigens, in a significantly higher proportion than among age-matched controls. In another group of infants and young children with acute nonbacterial gastroenteritis, fecal excretion of coronavirus-like particles was detected by electron microscopy in 34 (16.3%) of 208 patients as compared with three (1.6%) of 182 controls (P less than .01). Two strains of human enteric coronavirus (HECV) were purified from stools of two patients, and immune sera were raised in mice and guinea pigs. Immune electron microscopy showed a two-way cross-reactivity between HECV and HCV OC43 when tested with immune sera and convalescent-phase sera from patients with infection due to HECV or HCV OC43.     

Reovirus-like agent in acute epidemic gastroenteritis in Japanese infants: fecal shedding and serologic response.

The reovirus-like agent, sometimes referred to as duovirus or rotavirus, was visualized by electron microscopy in stool extracts from Japanese infants and young children with acute epidemic gastroenteritis. The virus particles measured 70 nm in diameter and had double-shelled capsids. One hundred ten (89%) of 124 patients with the gastroenteritis had such virus particles in stools obtained during the acute phase. The virus particles were excreted in the stools usually during the first eight days of illness. Agglutination of virus particles by antibody present in convalescent-phase sera was demonstrated by immune electron microscopy. Complement-fixing antibody was detected as early as day 3 of illness, and antibody titers peaked during the second and third weeks of the disease. The antibody appearing in the acute and early convalescent phases was sensitive to 2-mercaptoethanol. Antibody resistant to 2-mercaptoethanol was produced approximately 10 days after the onset of the symptoms. The serologic evidence suggests that a primary infection with the reovirus-like agent was responsible for the clinical attack of acute gastroenteritis.     

Atypical rotavirus isolated from acute infectious nonbacterial gastroenteritis in Fukuoka

An outbreak of epidemic diarrhea (nonbacterial acute gastroenteritis) in Fukuoka was studied electron microscopically and electrophoretically. From the result of electron microscopy, rotavirus particles about 70 nm in diameter were observed in fecal samples. However, the serological study did not reveal any antigenic relatedness to the ordinary rotaviruses by RPHA. The outbreak appeared to be caused by group C rotaviruses, based on the pattern of the RNA genome segments in polyacrylamide gels.     

Detection by immune electron microscopy of 26- to 27-nm viruslike particles associated with two family outbreaks of gastroenteritis.

Viruslike particles 26-27 nm in size were detected by immune electron microscopy in stools of volunteers who were ill after administration of bacteria-free fecal filtrates derived from two separate family outbreaks of acute epidemic nonbacterial gastroenteritis. Fluorocarbon treatment and concentration of the filtrates were necessary to provide enough antigen to test sera by immune electron microscopy. Serum antibody responses were detected in both naturally occurring and experimentally induced cases of illness. The Montgomery County viruslike particle appeared to be related to the previously described Norwalk particle, whereas the Hawaii particle appeared to be unrelated to the Norwalk particle.     

Norwalk virus in Norway: an outbreak of gastroenteritis studied by electron microscopy and radioimmunoassay

An outbreak of acute gastroenteritis affected approximately half of 40 children staying at a holiday centre in Southern Norway. By direct electron microscopy Norwalk-like viruses were demonstrated in 4/8 available stool specimens. No other pathogens were detected. Antibody against these viruses was demonstrated by immune electron microscopy in all of 7 convalescent phase sera but in none of 11 acute phase sera collected. Radioimmunoassay examination showed a rise in titre of Norwalk virus antibody in 6 available paired sera. This outbreak of Norwalk virus gastroenteritis in Norway was thus documented by a combined use of direct and immune electron microscopy and radioimmunoassay.     

Experimental infection of chimpanzees with hepatitis A virus.

The susceptibility of chimpanzees to viral hepatitis type A was examined with immine electron microscopy. Of four seronegative infant chimpanzees, two were inoculated with a hepatitis A acute-phase stool filtrate rich in 27 nm virus-like hepatitis A antigen (HA Ag) particles, and two were inoculated with an HA Ag-negative preinfection stool filtrate. One of each pair of chimpanzees was inoculated intravenously, the other orally. One month later both chimpanzees that had received the HA Ag-positive filtrate developed biochemical, histologic, and clinical evidence of acute viral hepatitis. HA Ag particle (27 nm) were detected in their stools by immune electron microscopy; particle shedding followed a pattern similar to that in human volunteers. Immune electron microscopy also showed that antibody HA Ag had developed in the convalescent-phase sera of the infected chimpanzees. Control animals remained free of illness at this time but did develop hepatitis three to five weeks after exposure to the two infected chimpanzee-. The infectious inoculum was titrated in two additional seronegative chimpanzees. It was concluded that hepatitis a can be successfully transmitted to seronegative chimpanzees. Moreover, these studies provide further evidence that the 27-nm virus-like HA Ag particle is the etiologic agent of viral hepatitis type A.     

Small round viruses isolated from acute infectious nonbacterial gastroenteritis in Fukuoka

The existence of virus in fecal specimens was investigated by electron microscopy in five outbreaks of nonbacterial acute gastroenteritis. Small round viruses (SRV) were found in all outbreaks. The negatively stained particles were about 30-35 nm in diameter and with ragged edges. Morphological characteristics resembled each other. Immune electron microscopical examination revealed large aggregates of SRV particles and antibody in convalescent sera from patients of all outbreaks. Furthermore, the second outbreak caused by oysters contaminated with SRV seemed to be associated with the Hawaii agent.     

Foodhandler-associated outbreak of hepatitis type A. An immune electron microscopic study.

Immune electron microscopy, which can detect hepatitis A antigen and antibody (anti-HA), was used to study a foodhandler-associated outbreak of hepatitis among 136 naval recruits. In stool specimens collected during the acute phase of illness, 27-nm viruslike hapatitis A antigen particles were shown, but only in patients with icteric hepatitis. Detection was possible in stools collected as early as 10 days before peak serum aminotransferase activity and up to the time of peak enzyme activity, but not thereafter. The immunologic similarity of these viruslike particles to those found in acute phase stools of volunteers inoculated with the MS-1 strain of hepatitis A virus was determined, and an increase in anti-HA was shown between acute and convalescent serums from 25 of the recruits. These data support the view that the MS-1 strain of hepatitis A virus is serologically related to naturally acquired type A hepatitis.     

A reovirus-like agent (rotavirus) in gastroenteritis of children. Virus detection and serological studies.

A reovirus-like agent (rotavirus) was detected in 26 children (44%) when fecal specimens from 59 children with acute gastroenteritis were examined by electron microscopy. No rotavirus was detected in the feces of 49 children with other diseases. Sera from the acute and the convalescent phase from 40 children with acute gastroenteritis and from 18 other patients were examined for antibodies against a bovine rotavirus by an indirect fluorescent antibody test. 26 of the patients with gastroenteritis (65%) developed antibodies during their disease, whereas none of the other patients showed a rise in antibody titre. The specimens were submitted to the laboratory from hospitalized children during the period January 1973 through March 1975. Most of the cases of rotavirus gastroenteritis occurred during late autumn and early winter among children between 0.5 and 3 years of age. It is concluded that electron microscopy is a sensitive diagnostic technique during the acute phase of the disease, and that the serological test with bovine rotavirus antigen served as a useful diagnostic tool.     

医院内诺如病毒性急性胃肠炎暴发的流行病学与临床特点分析

目的通过对我院急性胃肠炎聚集病例的调查,了解诺如病毒性急性胃肠炎流行及临床特点。方法调查与分析我院2006年冬季(2006年11月28日—2006年12月24日)聚集发生的急性胃肠炎的临床表现和流行特点,采用PCR法检测患者便标本诺如病毒核酸和免疫印迹法查血清抗体。结果本次流行的急性胃肠炎患者共87例,中老年人发病占大多数,主要临床特点为腹泻、呕吐、腹痛等,大便细菌培养阴性。用PCR法检测20例患者大便标本,其中12例诺如病毒呈阳性。检测24例患者血标本,19例诺如病毒抗体阳性。结论证实2006年我院发生的急性胃肠炎是诺如病毒性急性胃肠炎医院感染的暴发流行,潜伏期24~48h,多表现为腹泻、呕吐等非细菌性胃肠炎,在医院中该病传染性极强,冬季好发,中老年人易感,饮食、接触污染物表面及人与人密切接触等是主要的传播方式。提高对该病的认识、及时识别对治疗与控制具有重要意义。     

Viral gastroenteritis induced by the Hawaii agent: Jejunal histopathology and serologic response

Peroral jejunal biopsies were performed in seven normal volunteer subjects prior to, 48 hours after and two weeks after the administration of the Hawaii agent of viral gastroenteritis. Light and electron microscopic examination revealed an intact mucosa with blunted villi, shortened and distorted microvilli, swollen mitochondria and intercellular edema. These histologic changes were seen only in acutely ill volunteer subjects and were absent two weeks after illness in three of four who were previously ill. This reversible lesion was similar to, but not identical with, that previously described in viral gastroenteritis induced by the Norwalk agent.Serum antibody increases in response to the Hawaii agent as measured by immune electron microscopy were present in three of four ill volunteer subjects and in none of three who remained well.     

An epidemic of rotavirus-associated gastroenteritis in a nursing home for the elderly

92 cases of acute gastroenteritis were registered among 256 individuals during an outbreak in a nursing home for the elderly, the majority of patients being between 70 and 90 years of age. Most cases appeared in 4 of the 8 wards; 66% of the inmates of these wards became ill. Characteristic symptoms were initial nausea and vomiting followed by diarrhoea and low fever. A number of patients were severely ill. One patient died. Rotavirus infection was diagnosed by virus detection and/or antibody titre rise during the acute phase of the illness in 13 of 16 patients examined. At the end of the outbreak, high titres of complement-fixing antibodies against rotavirus (greater than or equal to 64) were detected in serum from 21/22 patients convalescing from the disease, as compared to only 5/45 individuals with no signs of disease. It is tentatively suggested that the outbreak became extensive and rather severe because of lowered immunity against rotavirus infection among the elderly.     

一起由星状病毒1型引起的新生儿腹泻暴发的病原确证

目的 对一起新生儿急性胃肠炎暴发事件进行病原确证.方法 2008年12月至2009年2月,内蒙古自治区某妇幼医院新生儿室发生腹泻流行,高峰期采集38例患儿的45份粪标本,ELISA法检测轮状病毒、腺病毒和星状病毒病原,RT-PCR法检测星状病毒核酸,其中13份星状病毒核酸阳性标本进行测序分析和进化树分析,4份星状病毒及病毒核酸均阳性的标本进行免疫电子显微镜观察.结果 45份粪标本中,轮状病毒、腺病毒病原检测均阴性.30份标本ELISA检测星状病毒病原阳性,阳性率为66.7%;31份标本星状病毒核酸阳性,阳性率为68.9%.采用星状病毒分型引物进行分型,均为星状病毒1型.选择13株与GenBank中星状病毒1型参考株进行比较,其核苷酸序列同源性为90.9%～96.3%.13株星状病毒1型株彼此间核苷酸序列同源性为94.7%～100.0%.随机选择的4份阳性标本,免疫电子显微镜下2份有大量星状病毒颗粒.结论 此起新生儿腹泻暴发由星状病毒1型引起.     

Incidence and epidemiology of irritable bowel syndrome after a large waterborne outbreak of bacterial dysentery

BACKGROUND & AIMS: Postinfectious irritable bowel syndrome (PI-IBS) is a common clinical phenomenon. To better define its incidence and epidemiology, a large cohort study was initiated after the contamination of a municipal water supply led to a large outbreak of acute Escherichia coli 0157:H7 and Campylobacter jejuni gastroenteritis. METHODS: Local residents were invited to undergo structured assessments at research clinics established 2 years after the outbreak. Permanent adult residents with no prior history of inflammatory bowel disease or IBS were eligible. Standardized questionnaires defined past and current health. The cohort was divided into controls without gastroenteritis, subjects with clinically suspected gastroenteritis, and subjects with only self-reported gastroenteritis that could not be substantiated by another source. A modified Bowel Disease Questionnaire identified IBS according to Rome criteria. The incidence and epidemiology of PI-IBS was characterized. Risk factors were assessed using multiple logistic regression. RESULTS: There were 2069 eligible study participants. Rome I criteria were met by 71 of 701 controls (10.1%) vs 249 of 904 subjects with self-reported gastroenteritis (27.5%) and 168 of 464 subjects with clinically suspected gastroenteritis (36.2%) (all comparisons, P < 001). Independent risk factors for PI-IBS included younger age, female sex, bloody stools, abdominal cramps, weight loss, and prolonged diarrhea. PI-IBS was more likely than sporadic IBS to show diarrhea-predominant features. CONCLUSIONS: PI-IBS is common after gastroenteritis from water contamination and often is diarrhea-predominant. Characteristics of the acute illness identify patients at increased risk for PI-IBS.