The Application of New Molecular Methods in the Investigation of a Waterborne Outbreak of Norovirus in Denmark, 2012

In December 2012, an outbreak of acute gastrointestinal illness occurred in a geographical distinct area in Denmark covering 368 households. A combined microbiological, epidemiological and environmental investigation was initiated to understand the outbreak magnitude, pathogen(s) and vehicle in order to control the outbreak. Norovirus GII.4 New Orleans 2009 variant was detected in 15 of 17 individual stool samples from 14 households. Norovirus genomic material from water samples was detected and quantified and sequencing of longer parts of the viral capsid region (>1000 nt) were applied to patient and water samples. All five purposely selected water samples tested positive for norovirus GII in levels up to 1.8×10(4) genomic units per 200 ml. Identical norovirus sequences were found in all 5 sequenced stool samples and 1 sequenced water sample, a second sequenced water sample showed 1 nt (<0.1%) difference. In a cohort study, including 256 participants, cases were defined as residents of the area experiencing diarrhoea or vomiting onset on 12-14 December 2012. We found an attack rate of 51%. Being a case was associated with drinking tap-water on 12-13 December (relative risk = 6.0, 95%CI: 1.6-22) and a dose-response relation for the mean glasses of tap-water consumed was observed. Environmental investigations suggested contamination from a sewage pipe to the drinking water due to fall in pressure during water supply system renovations. The combined microbiological, epidemiological and environmental investigations strongly indicates the outbreak was caused by norovirus contamination of the water supply system

The usefulness of school-based syndromic surveillance for detecting malaria epidemics: experiences from a pilot project in Ethiopia.

BACKGROUND: Syndromic surveillance is a supplementary approach to routine surveillance, using pre-diagnostic and non-clinical surrogate data to identify possible infectious disease outbreaks. To date, syndromic surveillance has primarily been used in high-income countries for diseases such as influenza--however, the approach may also be relevant to resource-poor settings. This study investigated the potential for monitoring school absenteeism and febrile illness, as part of a school-based surveillance system to identify localised malaria epidemics in Ethiopia. METHODS: Repeated cross-sectional school- and community-based surveys were conducted in six epidemic-prone districts in southern Ethiopia during the 2012 minor malaria transmission season to characterise prospective surrogate and syndromic indicators of malaria burden. Changes in these indicators over the transmission season were compared to standard indicators of malaria (clinical and confirmed cases) at proximal health facilities. Subsequently, two pilot surveillance systems were implemented, each at ten sites throughout the peak transmission season. Indicators piloted were school attendance recorded by teachers, or child-reported recent absenteeism from school and reported febrile illness. RESULTS: Lack of seasonal increase in malaria burden limited the ability to evaluate sensitivity of the piloted syndromic surveillance systems compared to existing surveillance at health facilities. Weekly absenteeism was easily calculated by school staff using existing attendance registers, while syndromic indicators were more challenging to collect weekly from schoolchildren. In this setting, enrolment of school-aged children was found to be low, at 54%. Non-enrolment was associated with low household wealth, lack of parental education, household size, and distance from school. CONCLUSIONS: School absenteeism is a plausible simple indicator of unusual health events within a community, such as malaria epidemics, but the sensitivity of an absenteeism-based surveillance system to detect epidemics could not be rigorously evaluated in this study. Further piloting during a demonstrated increase in malaria transmission within a community is recommended

Norovirus transmission dynamics: a modelling review.

Norovirus is one of the leading causes of viral gastroenteritis worldwide and responsible for substantial morbidity, mortality and healthcare costs. To further understanding of the epidemiology and control of norovirus, there has been much recent interest in describing the transmission dynamics of norovirus through mathematical models. In this study, we review the current modelling approaches for norovirus transmission. We examine the data and methods used to estimate these models that vary structurally and parametrically between different epidemiological contexts. Many of the existing studies at population level have focused on the same case notification dataset, whereas models from outbreak settings are highly specific and difficult to generalise. In this review, we explore the consistency in the description of norovirus transmission dynamics and the robustness of parameter estimates between studies. In particular, we find that there is considerable variability in estimates of key parameters such as the basic reproduction number, which may mean that the effort required to control norovirus at the population level may currently be underestimated.Takeda Pharmaceutical

Climate change and water-related infectious diseases

Background: Water-related, including waterborne, diseases remain important sources of morbidity and mortality worldwide, but particularly in developing countries. The potential for changes in disease associated with predicted anthropogenic climate changes make water-related diseases a target for prevention. Methods: We provide an overview of evidence on potential future changes in water-related disease associated with climate change. Results: A number of pathogens are likely to present risks to public health, including cholera, typhoid, dysentery, leptospirosis, diarrhoeal diseases and harmful algal blooms (HABS). The risks are greatest where the climate effects drive population movements, conflict and disruption, and where drinking water supply infrastructure is poor. The quality of evidence for water-related disease has been documented. Conclusions: We highlight the need to maintain and develop timely surveillance and rapid epidemiological responses to outbreaks and emergence of new waterborne pathogens in all countries. While the main burden of waterborne diseases is in developing countries, there needs to be both technical and financial mechanisms to ensure adequate quantities of good quality water, sewage disposal and hygiene for all. This will be essential in preventing excess morbidity and mortality in areas that will suffer from substantial changes in climate in the future

Prevalence of Enteropathogens in Dogs Attending 3 Regional Dog Parks in Northern California.

BackgroundThe prevalence and risk factors for infection with enteropathogens in dogs frequenting dog parks have been poorly documented, and infected dogs can pose a potential zoonotic risk for owners.Hypothesis/objectivesTo determine the prevalence and risk factors of infection with enteropathogens and zoonotic Giardia strains in dogs attending dog parks in Northern California and to compare results of fecal flotation procedures performed at a commercial and university parasitology laboratory.AnimalsThree-hundred dogs attending 3 regional dog parks in Northern California.MethodsProspective study. Fresh fecal specimens were collected from all dogs, scored for consistency, and owners completed a questionnaire. Specimens were analyzed by fecal centrifugation flotation, DFA, and PCR for detection of 11 enteropathogens. Giardia genotyping was performed for assemblage determination.ResultsEnteropathogens were detected in 114/300 dogs (38%), of which 62 (54%) did not have diarrhea. Frequency of dog park attendance correlated significantly with fecal consistency (P = .0039), but did not correlate with enteropathogen detection. Twenty-seven dogs (9%) were infected with Giardia, and genotyping revealed nonzoonotic assemblages C and D. The frequency of Giardia detection on fecal flotation was significantly lower at the commercial laboratory versus the university laboratory (P = .013), and PCR for Giardia was negative in 11/27 dogs (41%) that were positive on fecal flotation or DFA.Conclusions and clinical importanceEnteropathogens were commonly detected in dogs frequenting dog parks, and infection with Giardia correlated with fecal consistency. PCR detection of Giardia had limited diagnostic utility, and detection of Giardia cysts by microscopic technique can vary among laboratories

Molecular Epidemiology of Acute Infectious Diarrhoea in Paediatric Cases at the Winnipeg Children’s Hospital Emergency Room

Acute infectious diarrhea (AcID) causes a significant health burden on the population of developed countries, and even a higher burden in the developing world. The only investigation into the causes of AcID in Winnipeg was conducted in the late 1970s. That study determined that 3%-5% of Children’s Hospital Emergency Room (CHER) visits were due to AcID, and about 50% of those were due to rotavirus infections. We conducted a prospective case-control study to reveal the current spectrum of viral pathogens associated with AcID and the distribution and frequency of their occurrence among the pediatric population of Winnipeg. In this study, nucleic acid detection (NAD) and genome sequence information confirmed the presence and identity of each pathogen, and established whether an etiological shift in the distribution of pathogens, both between families and strains of specific pathogens, occurred. Stool samples were collected from pediatric cases with AcID at the ER along with asymptomatic cases for control. A panel of viral nucleic acid detection (NAD) assays was established by the Viral Gastroenteritis Study Group for human astro, calici (Noro and Sapo), entro, polio, hepA, rota and reo viruses according to the published procedures. A new assay for Aichivirus was developed, and the VGSG has established a novel rotavirus assay which is capable of detecting rotavirus from at least 4 different host species (Human, bovine, porcine and simian). Amplified viral targets were sequenced and the information submitted to GeneBank to confirm the strain of each isolate. A total of 1128 patients visited WCHER and WC during the study period and among them 242 patients were enrolled. In 104 cases viruses were identified. A total number of 114 viruses were identified either by NAD or EM assay. Out of 114 viruses, prevalence of HAdV, NoV GI/II and HRV were 44%, 23% and 23% respectively. Mixed infections were found in 4% of cases.This knowledge of pathogen distribution will facilitate design of effective methods for prevention, treatment and intervention in the spread of AcID pathogens.February 201

Impact of the SARS-CoV-2 Pandemic on the Prevalence and Incidence of Gastrointestinal Viruses in Children up to Five Years Old: a Retrospective Cohort Study

The aim is determining the impact of non-pharmaceutical measures (NPIs) against SARS-CoV-2 in the incidence and prevalence of gastrointestinal viruses (GV) in children. Demographic, analytical, and clinical data of children from which samples were received at the Hospital Universitario La Paz (Madrid, Spain) and that had a gastrointestinal infection with a positive sample through multiplex-PCR for GV were collected. The time periods included were prepandemic (P1): March 14, 2019 to March 14, 2020 and pandemic (P2): March 15, 2020 to March 15, 2021. The global prevalence, relative incidence (RI, per 1,000 admissions) and absolute incidence (AI, per 100,000 population) of GV were compared for both time periods. The prevalence of GV versus SARS-CoV-2 was determined for P2. Seven-hundred and 50 out of 2,547 children analyzed in P1 and 106 out of 1,368 in P2 were positive by PCR for GV (46.3% decrease in P2). Prevalence and RI of GV declined in P2, except for the RI of rotavirus. Adenovirus showed the largest decreased of prevalence and RI (100%), followed by sapovirus. Astrovirus reduction was less pronounced (3.1% versus 0.4%). Norovirus was the most frequent virus in both time periods and its prevalence and RI also decreased in P2 (15.2% versus 4.7% and 3.40 versus 1.74, respectively). Rotavirus had the smallest decrease in prevalence (2.6% versus 2.5%), and its RI increased during P2 from 0.7 to 0.93. After removing the rotavirus vaccine strains from the analysis, the prevalence and RI decreased during P2 (2.1% to 0.7% and 0.5 to 0.3, respectively). The AI decreased during P2 in all GV, and the prevalence of SARS-CoV-2 and GV was inversely proportional over time. Prevalence and incidence of GV have decreased during the pandemic, probably due to the implementation of NPIs against this virus and the reduction of health care attention to infections other than COVID-19. The differences in the decrease of prevalence and incidence for each virus may be explained by differences in the transmission and the resistance in the environment. Prevalence and RI of rotavirus might be biased since the PCR used detects both the infecting and the vaccine strains. IMPORTANCE Our original article contains an analysis of the impact of the measures applied against SARS-CoV-2 on the prevalence and incidence of GV in children. The small number of studies published to date that analyze the impact of these measures individually on each of the GV makes our study of great interest at this tim

Risk assessment of norovirus infection considering indirect impacts of seasonal flood in Southeast Asia

岩手大学博士（農学）doctoral thesi

Diarrhoeal disease in children under the age of five in Ho Chi Minh City, Vietnam

The focus of the global diarrhoeal disease burden is in low and middle-income countries, where the disease epidemiology and aetiology is highly variable and not well characterised. The aim of this thesis was to challenge the knowledge gaps regarding diarrhoeal disease in children under the age of five in Ho Chi Minh City (HCMC), Vietnam. Firstly, a pilot surveillance in southern Vietnam demonstrated a preponderance of enteric viruses in hospitalised diarrhoeal children and reported the first rotavirus G12 in Vietnam; despite being geographically disproportional distributed, rotavirus (RoV) predominated followed by norovirus (NoV). On the basis of these data, a prospective multi-centre hospitalbased surveillance was conducted in HCMC to study diarrhoeal disease in detail and investigate the extent and the epidemiology of the hypothesized NoV emergence. Faecal specimens from diarrhoea patients and diarrhoea-free children were screened for a panel of pathogens; RoV was again identified as the predominant agent, followed by NoV. Enteric bacteria were found at smaller proportions, and exhibited excessive antimicrobial resistance. As NoV was found to be highly endemic and a major cause of hospitalisation, a risk factor analysis for NoV infections was performed. Risk factors included young age, residential crowding and contact with symptomatic individuals. Additional analysis on the phylogenetic structure of NoV strains demonstrated diverse genotypes circulating, most commonly belonging to the GII.4 lineage. A spatiotemporal analysis of GII.4 variants, GII.4-2006b (Minerva) and the novel emergent GII.4-2010 (New Orleans), suggested a strain replacement phenomenon and detected a cluster of GII.4-2010 in the northeastern part of the city. These studies indicate prominent disease dynamics involved rapid evolution of viruses, necessitate studies on strain distribution and genomic analyses and potential source additionally contributing to genetic variations (animal reservoirs), and suggest considerable impact of RoV and NoV immunisation in Vietnam