Mutation in a Lordsdale norovirus epidemic strain as a potential indicator of transmission routes

An increase in norovirus outbreaks was reported internationally during 2002 and 2003 and was also observed in Oxfordshire (United Kingdom) hospitals. To understand their epidemiological relationships, viruses from 22 outbreaks (15 from one hospital) were subjected to nucleotide sequencing. The 3'-terminal 3,255 nt or complete genomes were determined for 49 viruses. All outbreaks were caused by a genogroup II norovirus related to the Lordsdale virus (GII 4), common in healthcare settings. The norovirus mutation rate was sufficiently high that the 3,255-nucleotide sequences allowed separate and potentially connected outbreaks to be identified, since all outbreaks with identical sequences were temporally or geographically linked. The high mutation rate was further indicated by four mutations and three microheterogeneities in 3,255 nucleotides during 17 days of norovirus shedding by an immunocompromised patient. The data suggested that multiple virus introductions from the community, occasional transmission among wards, and one instance of ongoing environmental contamination had occurred. The accumulation, or lack, of mutations within an outbreak was also used to indicate the predominant transmission route. In an outbreak where person-to-person spread was thought to predominate, six mutations were detected throughout the genome, whereas one mutation was detected when point source infection was suspected. This norovirus epidemic strain differed from its closest previously described relative by 11.4 to 13.6% in the outer P2 domain of the capsid, which also had a single-amino-acid insertion. Alterations to the capsid structure compared to previous noroviruses may explain the increased number of outbreaks during 2002 and 2003.     

National comparative audit of the use of platelet transfusions in the UK

The objective of this national audit was to examine the use of platelet transfusions against audit standards developed from national guidelines. Hospitals were asked to provide data on 40 consecutive patients receiving platelet transfusions (15 haematology patients, 10 cardiac, 10 critical care and five in other clinical specialties). One hundred and eighty-seven UK hospitals participated, including 168/263 (64%) hospitals in England. A total of 4421 patients receiving platelet transfusions were audited. The reason for transfusion was documented in the medical records for 93% of transfusions and 57% were used for prophylaxis (in the absence of bleeding). Overall 3726/4421 (84%) of the transfusions were evaluable and 43% (1601/3726) were found to be non-compliant with the audit standards. A major non-compliance was failure to measure the platelet count before transfusion (29% of transfusions). Other non-compliances included the use of platelet transfusion in the absence of bleeding in 11% of cardiac surgery patients receiving platelet transfusions, the use of a threshold platelet count more than 10 x 10(9)/L for 60% of prophylactic platelet transfusions in haematology patients without risk factors indicating the need for a higher threshold, and a threshold platelet count more than 30 x 10(9)/L for 59% of prophylactic platelet transfusions in critical care. The reasons for the high rate of non-compliance were not explored in this audit, but this is a topic worthy of further study. The main recommendations were that hospitals should ensure there are written local guidelines for platelet transfusions, clinicians must be provided with training about their appropriate use, and hospitals should carry out regular audits of practice. More research should be carried out to develop the evidence base for the use of platelet transfusions, more detailed guidelines should be developed for platelet transfusions in critical care and cardiac surgery, and the audit should be repeated in about three years.     

Comparison of Xpert Norovirus and RidaGene Norovirus assays for the detection of noroviruses in clinical fecal specimens

The purpose of this study was to investigate the usability and performance of the Xpert Norovirus and RidaGene Norovirus assays for the detection of noroviruses in fecal specimens. Of the 186 stool specimens, 53 (28.5%) were considered true-positive for norovirus (NoV). Of the true-positive specimens, Xpert detected 53 and RidaGene detected 52. The respective sensitivity and specificity were 100% and 94.7% [95% confidence interval (CI), 91.0–98.5%] for the Xpert assay, and 98.1% (95% CI, 94.4–100%) and 97.0% (95% CI, 94.1–99.9%) for the RidaGene assay. Positive and negative predictive values (PPVs and NPVs) were 88.3% and 100% for the Xpert assay, and 92.9% and 99.2% for the RidaGene assay, respectively. Based on this study, it can be concluded that there were no significant differences (p-value?>?0.5) between the results of the Xpert and RidaGene Norovirus assays. We found that both assays are useful for the detection of noroviruses in clinical stool samples.     

Multicenter Evaluation of the Xpert Norovirus Assay for Detection of Norovirus Genogroups I and II in Fecal Specimens

Norovirus is the most common cause of sporadic gastroenteritis and outbreaks worldwide. The rapid identification of norovirus has important implications for infection prevention measures and may reduce the need for additional diagnostic testing. The Xpert Norovirus assay recently received FDA clearance for the detection and differentiation of norovirus genogroups I and II (GI and GII), which account for the vast majority of infections. In this study, we evaluated the performance of the Xpert Norovirus assay with both fresh, prospectively collected (n = 914) and frozen, archived (n = 489) fecal specimens. A Centers for Disease Control and Prevention (CDC) composite reference method was used as the gold standard for comparison. For both prospective and frozen specimens, the Xpert Norovirus assay showed positive percent agreement (PPA) and negative percent agreement (NPA) values of 98.3% and 98.1% for GI and of 99.4% and 98.2% for GII, respectively. Norovirus prevalence in the prospective specimens (collected from March to May of 2014) was 9.9% (n = 90), with the majority of positives caused by genogroup II (82%, n = 74). The positive predictive value (PPV) of the Xpert Norovirus assay was 75% for GI-positive specimens, whereas it was 86.5% for GII-positive specimens. The negative predictive values (NPV) for GI and GII were 100% and 99.9%, respectively.     

Norovirus infection in immunocompromised hosts

Acute gastroenteritis caused by noroviruses often has a duration of 2–0 days and is characteristically self-limiting. In contrast, chronic infection caused by noroviruses in immunocompromised individuals can last from weeks to years, making clinical management difficult. The mechanisms by which noroviruses establish persistent infection, and the role of immunocompromised hosts as a reservoir for noroviruses in the general human population, are not known. However, study of this patient cohort may lead to new insights into norovirus biology and approaches to treatment.     

Reliability of the diagnosis of cerebrospinal meningitis during an epidemic. The epidemic in Chad in 1988

The authors analysed the positive predictive value (PPV) of the clinical diagnosis during an epidemic of meningococcal meningitidis in Africa. This PPV was globally 73.3 +/- 11.2%. This PPV was fluctuating according to the standards of the diagnosis. Typical clinical meningitic syndrome without spinal picture: 85.7 +/- 10.3%, Non typical syndrome and macroscopical aspect of cerebrospinal fluid: 62.5 +/- 16.4%.     

诺如病毒检测技术研究

诺如病毒是非细菌性腹泻暴发的主要病原之一,对相关检测技术的研究十分必要。本文通过引物、探针、染料的选择,结合适用范围、灵敏度、特异性、重复性的评估对常规反转录-聚合酶链反应、荧光定量RT-PCR、反转录-环介导等温扩增、基因芯片、酶联免疫吸附测定和荧光微球检测条快速检测诺如病毒的技术进行了综述。着重关注了食品和水中诺如病毒检测的病毒富集技术,并提出平衡准确灵敏与简便高效对诺如病毒检测技术的研究具有重要意义。     

Comparing the epidemic in U.S. and Britain

Cultural differences between the United States and Britain influence how the AIDS/HIV epidemic is being addressed and why AIDS rates are smaller in the United Kingdom. The author proposes that highly diverse and racist societies, like in the United States, may cause distrust among different groups in the effort to challenge the spread of HIV/AIDS, leaving people to fend for themselves. Because of racism and distrust between ethnic and racial groups, as well as differences in financial resources between groups, the AIDS epidemic in the United States is being fought on too many fronts without the benefit of a uniform response. Ironically, this problem has also spurred a greater ability among US AIDS service providers to work with diverse communities during the course of the epidemic.     

Norovirus genotypes causing gastroenteritis outbreaks in Finland 1998-2002.

BACKGROUND: Outbreak investigation methods for enteric viruses were improved in 1990s when gene amplification techniques were established in viral laboratories. OBJECTIVES: The objective of the study was to determine the causative agents for Finnish viral gastroenteritis outbreaks. Our aim was also to further characterise the norovirus strains, reveal the temporal occurrence of norovirus (NV) genotypes and to study some epidemiological aspects concerning the outbreaks. STUDY DESIGN: A total of 416 Finnish viral gastroenteritis outbreaks that occurred during 5 years (1998-2002), excluding those among hospitalised children, were investigated for enteric viruses. Stool samples were screened by electron microscopy as well as analyzed by specific noro- and astrovirus RT-PCR tests. Amplicon sequence analysis was used to find out norovirus genotypes. RESULTS: Noroviruses caused 252 (60.6%) of the outbreaks; other viruses, astro- or rotavirus, caused four epidemics. Norovirus epidemics occurred in all kinds of settings, most often in hospitals (30.6%) and in restaurants and canteens (14.3%). Both NV genogroups were found every year, but NV GGII outbreaks always outnumbered those of GGI. All but one outbreak at hospitals and nursing homes were of genotype GII. Polymerase sequence analysis revealed a variety of NV genotypes; six GI and at least eight GII genotypes. The GI.3 Birmingham-like and GII.4 Bristol-like genotype appeared every year, whereas the other types were circulating for shorter periods or sporadically. During the study period the genotypes GII.4 (Bristol), GII.1 (Hawaii), an emerging genotype GIIb, and a new variant of GII.4 predominated in that order. Indication for rapid genetic changes in the genotype GII.4 was also noticed. CONCLUSIONS: Noroviruses were the most prevalent causative agents in the outbreaks. Many NV genotypes were circulating, and a shift in the predominant genotypes was evident between epidemic seasons.