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PubMed2004

A nosocomial outbreak of Salmonella enteritidis associated with lyophilized enteral nutrition.

Outbreaks of Salmonella spp. gastro-enteritis in hospitals are of concern because of the increased susceptibility of patients and associated high morbidity. This study is a report of a nosocomial outbreak of Salmonella enteritidis associated with enteral nutrition. In December 1999, one sample of enteral feed tested positive for S. enteritidis. During the subsequent 6 weeks, eight cases of nosocomial salmonellosis occurred. Patients involved in the outbreak were aged 19-79 years (median = 36.5), and salmonella was isolated from the blood of two patients. All patients were receiving enteral nutrition at the time and all had diarrhoea. Three patients died. All 13 employees of the Nutrition Department were asymptomatic and their stool samples were negative. Environmental and water samples were also negative. The diet, however, contained lyophilized egg albumin. Molecular typing showed that the isolates of seven patients were indistinguishable from the one obtained from the enteral diet. It was thought that the nosocomial salmonellosis probably occurred due to the use of a commercial lyophilized diet. Another method of processing diets may be necessary to ensure patient safety.

Adult↗

PubMed2005

Control of an outbreak of multi-drug-resistant Acinetobacter baumannii in an intensive care unit and a surgical ward.

We describe an outbreak of multi-drug-resistant Acinetobacter baumannii (MRAB) that occurred in an intensive care unit (ICU) and a surgical ward from December 2003 to March 2004. Mapping patient movements on a timeline indicated that the outbreak was confined to these two areas. Investigation by the hospital's infection prevention service found that a possible source of spread was improper cleaning methods used on respiratory equipment. Pulsed-field gel electrophoresis analysis of available isolates indicated the presence of two distinct strains. One strain was seen in patients from the ICU and the other strain was seen in the surgical ward patients. Cleaning and environmental decontamination as well as staff education were implemented to halt further immediate spread. The deficiencies identified during the investigation were also resolved. The final outcome was the successful termination of this outbreak.

Acinetobacter Infections↗

PubMed2005

Epidemiological investigation of a Serratia liquefaciens outbreak in a neurosurgery department.

Between February 2001 and March 2003, 17 patients from the neurosurgery department of the University Hospital of Rangueil (Toulouse, Southern France) developed Serratia liquefaciens infections. Due to the atypical antibiotype displayed by the clinical isolates (i.e. gentamicin resistance), an outbreak was suspected. Molecular analysis carried out by pulsed-field gel electrophoresis demonstrated a genetic link for all patients. Furthermore, the patient who introduced the epidemic Serratia strain was also identified and shown to be related to the two epidemic peaks observed during the outbreak period. Investigation failed to reveal a reservoir among the antiseptics and soaps, or among the mechanical ventilators used. However, when the colonization of patients was investigated, positive carriage was observed and could be considered as a potential risk for the spread of the epidemic strain. Due to the delay between antibiotherapy and S. liquefaciens colonization, a selection effect had to be considered. Finally, implementation of hygiene measures was accompanied by control of the outbreak.

Anti-Infective Agents, Local↗

PubMed2006

The risk of hepatitis A infection among healthcare workers: a review of reported outbreaks and sero-epidemiologic studies.

All reports of hepatitis A (HA) outbreaks in healthcare settings published between 1975 and 2003 were studied to determine the background immunity or susceptibility of healthcare workers (HCWs) to HA. Twenty-six reports were found. The number of infected personnel ranged from one to 66 and, in most outbreaks, nurses accounted for the majority of personnel infected, reflecting high attack rates reaching 15-41%. In addition, we found 23 sero-epidemiological studies for HA among HCWs that had been performed in 13 different countries. Seroprevalence rates of HCWs with anti-HA antibody ranged between 4% among paramedical workers in Germany to 88% among hospital maintenance workers in Portugal. Effective infection control of HA outbreaks in hospitals demands early recognition, including awareness of atypical presentations of the infection, and strict adherence to universal infection control measures. Education programmes are of special importance for HCWs in neonatal, paediatric and intensive care units. The findings of the current study suggest that a pre-employment screening policy and administration of active vaccination to susceptible HCWs, particularly nurses, should be seriously considered in high-risk settings.

Adolescent↗

PubMed2005

What is the best screening method to detect Serratia marcescens colonization during an outbreak in a neonatal intensive care nursery?

Serratia marcescens can cause outbreaks in neonatal intensive care units (NICUs), but the optimum method of screening for carriage has not been determined in this group of patients. During an outbreak of S. marcescens infections across two geographically distinct NICUs, babies were screened for both respiratory and gastrointestinal carriage. A total of 58 babies were colonized (N = 47) or infected (N = 11) with S. marcescens over a nine-month period. Forty-four colonized babies had paired respiratory and gastrointestinal tract specimens collected. Of these, 39% were positive from the gastrointestinal tract and 22% from respiratory tract specimens alone, and 39% had growth from both sites. Enrichment prior to inoculation on to solid media increased the detection of respiratory tract carriers. During an outbreak of S. marcescens, both respiratory and gastrointestinal samples should be collected in order to maximize the identification of colonized infants. Broth enrichment adds an additional day to obtaining results but increases the yield of positive results from respiratory specimens.

Australia↗

PubMed2006

Control of a methicillin-resistant Staphylococcus aureus (MRSA) outbreak in a day-care institution.

This article describes an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) in two institutions for multi-handicapped children in Copenhagen. The aim of the study was to determine whether it was possible to eradicate MRSA in a setting with multi-handicapped children and staff where there was a high degree of physical interaction. This was a prospective interventional uncontrolled cohort study that took place from January 2003 to March 2005. All individuals in close contact with the two institutions and/or in close contact with an MRSA-colonized subject from the outbreak were included in the study: 38 children, 60 staff members and 12 close relatives of colonized subjects. Infection control measures included screening all individuals. When MRSA infection or colonization was found, an attempt was made to eradicate MRSA, staff education was undertaken and attempts were made to determine the route of transmission. Eleven individuals were found to be positive for MRSA (10.0%). All isolates were identical by pulsed-field gel electrophoresis and harboured the staphylococcal cassette chromosome mec (SCCmec) type IV. All colonized and infected individuals were associated with a single room in one of the institutions. MRSA was eradicated from all the colonized and infected subjects. This study shows that it is possible to control an MRSA outbreak in institutions for multi-handicapped children where there is a high degree of physical contact.

Adult↗

PubMed2005

Network theory and SARS: predicting outbreak diversity.

Many infectious diseases spread through populations via the networks formed by physical contacts among individuals. The patterns of these contacts tend to be highly heterogeneous. Traditional "compartmental" modeling in epidemiology, however, assumes that population groups are fully mixed, that is, every individual has an equal chance of spreading the disease to every other. Applications of compartmental models to Severe Acute Respiratory Syndrome (SARS) resulted in estimates of the fundamental quantity called the basic reproductive number R0--the number of new cases of SARS resulting from a single initial case--above one, implying that, without public health intervention, most outbreaks should spark large-scale epidemics. Here we compare these predictions to the early epidemiology of SARS. We apply the methods of contact network epidemiology to illustrate that for a single value of R0, any two outbreaks, even in the same setting, may have very different epidemiological outcomes. We offer quantitative insight into the heterogeneity of SARS outbreaks worldwide, and illustrate the utility of this approach for assessing public health strategies.

Adult↗

PubMed2025

Diagnostic and phylogenetic perspectives of the 2023 Murray Valley encephalitis virus outbreak in Australia: an observational study.

BACKGROUND: An outbreak of Murray Valley encephalitis virus (MVEV), the largest since 1974, was observed in Australia between Jan 1 and July 31, 2023. This study aims to characterise the utility of diagnostic platforms, testing algorithms, and genomic characteristics of MVEV to facilitate a comprehensive framework for MVEV testing and surveillance in the outbreak setting. METHODS: In this observational study, we assessed flavivirus diagnostics for all patients with suspected Murray Valley encephalitis in Australia from Jan 1 to July 31, 2023. We included all patients with confirmed Murray Valley encephalitis, probable Murray Valley encephalitis, or acute unspecified flavivirus infection using the Communicable Diseases Network Australia case definition. Cases were excluded if an alternative diagnosis was identified. We collected blood, serum, cerebrospinal fluid, brain tissue, urine, or a combination of these samples, as appropriate and at the discretion of the treating clinician. We conducted multimodal diagnostic testing, which included flavivirus-specific serological and nucleic acid amplification testing. Metagenomic next-generation sequencing, including next-generation deep sequencing, target-enrichment, and targeted amplification, was conducted on human and representative mosquito-derived samples obtained from established mosquito population surveillance programmes for phylogenetic analysis. FINDINGS: 27 patients with encephalitis were assessed for MVEV between Jan 1, 2023, and July 31, 2023, 23 (85%) of whom fulfilled national case definitions for confirmed Murray Valley encephalitis. Patient ages ranged from 6 weeks to 83 years (median 62·0 years [IQR 31·0-67·5]) and patients were mostly male (21 [78%] male patients and six [22%] female patients). Incidence varied widely by geographical region and was highest in the Northern Territory (32·0 per 1 000 000 population). Diagnostic specimen collection generally occurred promptly (median 6·0 days [IQR 4·0-14·5] from symptom onset to diagnostic specimen collection). In seven patients, case assignation relied on convalescent serum samples to assess for seroconversion or an appropriate rise in antibody titre (to four times the initial value or greater), or both. MVEV-specific IgM was detectable in serum samples of 17 (81%) of 21 patients tested by day 7 and MVEV IgG or total antibody (TAb) were detected in 18 (100%) of 18 patients tested by day 30. MVEV-specific IgM (or TAb) and MVEV RNA were detected in cerebrospinal fluid collected within 14 days of symptom onset in nine (39%) of 23 patients and seven (28%) of 25 patients, respectively. Phylogenetic analysis revealed two circulating MVEV genotypes, G1A and G2, in mosquitoes and humans in 2023. In southeast Australia, only G1A was detected and probably introduced from enzootic foci in northern Australia. INTERPRETATION: This study provides a comprehensive overview of the diagnostic workflows and phylogenetic evaluations used during the 2023 MVEV outbreak in Australia, emphasising the importance of a multimodal approach for accurate and timely confirmation of flavivirus infection. Further One Health surveillance for MVEV and other zoonotic flaviviruses is key, given potential expanded ecological niches in the context of episodic climatic events. FUNDING: None.

Humans↗

PubMed2006

An outbreak of adenovirus serotype 41 infection in infants and children with acute gastroenteritis in Maizuru City, Japan.

A total of 337 fecal specimens were collected from infants and children with acute gastroenteritis in Maizuru City, Japan from July 2004 to June 2005 and tested for the presence of rotavirus, norovirus, sapovirus, astrovirus, and adenovirus by RT-multiplex PCR. Among diarrheal viruses detected, norovirus was the most prevalent (13.6%, 46 of 337), followed by adenovirus (8%, 27 of 337), group A rotavirus (5%, 17 of 337), astrovirus (1.8%, 6 of 337), and sapovirus (1.8%, 6 of 337), respectively. Adenovirus was subjected to molecular genetic analysis by sequencing. Adenovirus detected in this study was classified into five serotypes, namely Ad1, Ad2, Ad3, Ad5, and Ad41. Of these, Ad41 was the most predominant serotype that accounted for 85.2% (23 of 27). It was noteworthy to point out that Ad41 infection was apparently confined only to the period of 4 months (October 2004 through January 2005). This pattern of infection implied the outbreak of Ad41 in these subjects, which was the first outbreak of acute gastroenteritis attributed to adenovirus in Maizuru City, Japan. Another interesting feature of the study was the existence of two Ad41 subtypes co-circulating in this outbreak. This report confirmed the presence of adenovirus as one of an important cause of acute gastroenteritis among Japanese infants and children.

Acute Disease↗

PubMed2006

Impaired neutrophil functions in the pathogenesis of an outbreak of recurrent furunculosis caused by methicillin-resistant Staphylococcus aureus among mentally retarded adults.

Staphylococcus aureus is an important cause of skin infections. We recently described an outbreak of recurrent furunculosis involving methicillin-resistant S. aureus among mentally retarded adults. We sought to determine the role of impaired neutrophil functions in its pathogenesis. Blood neutrophil functions were determined during both the outbreak (1997) and a disease-free period (2000). Chemotaxis was measured by migration toward formyl-methionyl-leucyl-phenylalanine (FMLP), specifically and randomly; phagocytosis of opsonized zymosan (OZ) was assessed by microscopy; superoxide production was determined by cytochrome c reduction in unstimulated neutrophils and after stimulation with 50 ng/ml phorbol myristate acetate, 1 mg/ml OZ or 5 x 10(-7)M FMLP. Functions were compared between recurrent furunculosis (n=10) and non-recurrent furunculosis patients (n=13). During 2000, functions were normal among the 23 subjects, except for specific/nonspecific chemotaxis (mean 68%+/-26 and 69%+/-28). During infection, recurrent furunculosis patients had a significantly increased basal superoxide production as compared to disease-free period (10.5+/-4.7 vs. 4.9+/-1.9 nmol O(-)(2)/10(6) cells/min, p=0.003). During the disease-free period, recurrent furunculosis patients had lower basal superoxide production (4.9+/-1.9 vs. 7.7+/-3.5, p=0.067) and impaired specific chemotaxis (57%+/-28 vs. 76%+/-21, p<0.05) as compared to non-recurrent furunculosis patients. Only specific chemotaxis was an independent risk factor for recurrent furunculosis. Mentally retarded adults have impaired chemotaxis, with recurrent furunculosis cases having an even greater impairment. Abnormal specific chemotaxis is an independent risk factor for recurrent furunculosis. Impaired neutrophil functions thus have a role in the pathogenesis of outbreaks of recurrent furunculosis.

Adult↗

PubMed2005

A rapid method for extracting oocyst DNA from Cryptosporidium-positive human faeces for outbreak investigations.

We describe a rapid method for extracting and concentrating Cryptosporidium oocysts from human faecal samples with subsequent DNA preparation for mainstream PCR applications. This method consists of extracting faecal lipids using a modified water-ether treatment and releasing DNA from semi-purified oocysts by freeze thawing in lysis buffer. Following immunomagnetisable separation (IMS), recovery rates of 29.5%, 43.2% and 49.8% were obtained from oocyst-negative solid, semi-solid and liquid faeces, respectively, seeded with 100 +/- 2 C. parvum oocysts, which were enumerated by flow cytometry. A retrospective analysis was conducted on 92 positive human faecal samples including 78 oocyst-positive cases from 2 UK cryptosporidiosis outbreaks (outbreak A = 34 samples, outbreak B = 44 samples) and 14 oocyst-positive, sporadic cases. We used primers targeting the Cryptosporidium oocyst wall protein gene (COWP; STN-COWP), the 18S rRNA (direct PCR) and the dihydrofolate reductase gene (dhfr, MAS-PCR) fragments to evaluate extracted DNA by PCR. PCR inhibitors were present in 20 samples when template was co-amplified with the 18S rRNA gene primers and an internal control. Template dilution (1/5) in polyvinylpyrrolidone (10 mg ml(-1), pH 8.0) transformed four PCR-negative samples to PCR-positive and increased amplicon intensity in previously positive samples. Eighteen of 20 PCR-negative samples produced visible amplicons when Taq polymerase concentration in the STN-COWP PCR was increased from 2.5 to 5 U. The STN-COWP PCR assay amplified 90 of 92 samples (97.8%) and the MAS-PCR assay amplified 70 of 92 samples (76.1%) tested. In the absence of inhibitors, DNA equivalent to 3 C. parvum oocysts was amplified.

Animals↗

PubMed2006

[Use of molecular subtyping methods to investigate two nosocomial outbreaks due to Salmonella Livingstone in Sfax hospital, Tunisia].

OBJECTIVE: The aim of the study was to investigate two nosocomial outbreaks due to Salmonella Livingstone in a pediatric ward in Sfax hospital using molecular typing techniques. MATERIALS AND METHODS: We included 84 strains of S. Livingstone isolated from patients hospitalized in a pediatric ward between November 1999 through August 2002 in addition to one environmental sample. Three epidemiological unrelated strains of S. Livingstone were also tested. The molecular typing techniques were: plasmid analysis, enterobacterial repetitive intergenic consensus (ERIC-PCR), random amplification of polymorphic DNA (RAPD-PCR) and pulsed field gel electrophoresis (PFGE). RESULTS: The plasmid analysis and the ERIC-PCR generated a similar profile for outbreak isolates including the environmental sample while the epidemiologically unrelated strains demonstrated distinct patterns. The RAPD-PCR applied on 20 strains showed three patterns but one profile was predominating. All the strains isolate of S. Livingstone, except the veterinary strain, could not be typed by PFGE. CONCLUSION: Using the molecular typing techniques, we showed that these two outbreaks in the pediatric ward were due to the clonal spread of a single strain of S. Livingstone. The identification of the source of contamination and the improvement of hygiene conditions are required.

Bacterial Typing Techniques↗

PubMed2006

Hydrographics and the timing of infectious salmon anemia outbreaks among Atlantic salmon (Salmo salar L.) farms in the Quoddy region of Maine, USA and New Brunswick, Canada.

Infectious salmon anemia (ISA) has caused severe morbidity and mortality in farmed Atlantic salmon in North America, Norway, Scotland and the Faroe Islands. The Quoddy region of Maine, United States of America (USA), and New Brunswick (NB), Canada is characterized by extensive tidal mixing and close proximity between farms. This region is also prone to recurrent appearances of ISA, though control measures limit disease spread and severity on infected farms. We conducted a retrospective longitudinal analysis of the apparent impact of hydrographics on the incidence and timing of ISA outbreaks on Atlantic salmon (Salmo salar L.) farms in the Quoddy region from May 2002 to August 2004. A time-series cross-sectional regression of 32 farms over 28 months demonstrated a limited, but statistically significant, spatio-temporal clustering of ISA outbreaks linked hydrographically. New outbreaks correlated temporally with those occurring on-site 1 and 3 months prior, and those occurring within one tidal-excursion upstream the same month. Other risk factors included holdover of previous year-class fish, wharf sharing, and possibly harvests of cages infected in previous months. Conclusions suggest that tidal dispersion does play a role in ISAV transmission in the Quoddy region. Dispersal of free virus and/or tidal distribution of lice or other hydrographically influenced vectors or fomites could all contribute to the spatio-temporal patterns described.

Animals↗

PubMed2006

Four dengue virus serotypes found circulating during an outbreak of dengue fever and dengue haemorrhagic fever in Jakarta, Indonesia, during 2004.

Periodic outbreaks of dengue have emerged in Indonesia since 1968, with the severity of resulting disease increasing in subsequent years. In early 2004, a purported dengue outbreak erupted across the archipelago, with over 50,000 cases and 603 deaths reported. To confirm the disease aetiology and to provide an epidemiological framework of this epidemic, an investigation was conducted in ten hospitals within the capital city of Jakarta. Clinical and laboratory findings were determined from a cohort of 272 hospitalised patients. Exposure to dengue virus was determined in 180 (66.2%) patients. When clinically assessed, 100 (55.6%) of the 180 patients were classified as having dengue fever (DF), 31 (17.2%) as DF with haemorrhagic manifestations and 49 (27.2%) as dengue haemorrhagic fever (DHF). Evidence from haemagglutination inhibition assays suggested that 33/40 (82.5%) of those with DHF from which laboratory evidence was available suffered from a secondary dengue infection. All four dengue viruses were identified upon viral isolation, with DEN-3 being the most predominant serotype recovered, followed by DEN-4, DEN-2 and DEN-1. In summary, the 2004 outbreak of dengue in Jakarta, Indonesia, was characterised by the circulation of multiple virus serotypes and resulted in a relatively high percentage of a representative population of hospitalised patients developing DHF.

Adolescent↗

PubMed2004

Can oral cholera vaccination play a role in controlling a cholera outbreak?

Control measures to limit the spread of a cholera outbreak in Pohnpei Island (Micronesia), included mass vaccination with the single-dose live-attenuated oral cholera vaccine CVD 103-HgR as a potential adjunct measure. The outbreak provided a unique opportunity to evaluate the practicality of use and effectiveness of this vaccine. Under field conditions encountered in Pohnpei, crude vaccine efficacy was estimated at 79.2% (95% CI: 71.9-84.6%) in the target population. Retrospective analysis suggests that mass vaccination with oral cholera vaccines can be a useful adjunct tool for controlling outbreaks, particularly if implemented early in association with other standard control measures.

Administration, Oral↗

PubMed2005

Protection of chickens against overt clinical disease and determination of viral shedding following vaccination with commercially available Newcastle disease virus vaccines upon challenge with highly virulent virus from the California 2002 exotic Newcastle disease outbreak.

During 2002-2003, exotic Newcastle disease (END) virus caused a major outbreak among commercial and backyard poultry in southern California and adjacent states. The outbreak raised concerns regarding the protective immunity of commercially available vaccines for prevention and control of this virus in poultry. We sought to determine if existing commercial live and inactivated Newcastle disease virus (NDV) vaccines could provide protection against the 2002-2003 END virus, and whether current commercial NDV-vaccination programs for broiler-breeders (BB) and broilers (Br) would protect against END-challenge. In the first experiment, birds received a single dose of either inactivated or live B1-type vaccine at 2 weeks-of-age and were challenged 2 weeks post-vaccination with a lethal dose of END. In the second experiment, a high (10(6.9)EID50/bird) or low (10(3.9)EID50/bird) dose of live B1 was applied to 8-week-old chickens, followed by lethal END challenge. In the third experiment, NDV field-vaccinated commercial BB (65 weeks-of-age) and Br (36 days-of-age) were challenged against END virus. Results indicated that both the live and inactivated vaccines protected against morbidity and mortality and significantly reduced the incidence and viral titers shed from chickens in comparison with sham controls, but did not prevent infection and virus shedding. In addition, both doses of live vaccine protected birds and significantly decreased the number of birds shedding virus. All unvaccinated control chickens challenged with END died within 6 days post-challenge (pc). Protection from disease correlated with the presence of antibody titers (determined by enzyme-linked immunosorbent assay (ELISA) or hemagglutination inhibition (HI)) at day of challenge. Commercial BB were protected from disease and exhibited low incidence and titer of challenge virus shed. In contrast, commercial Br exhibited 66% mortality and shed significantly more virus than the BB birds. These results underscore the need to develop new NDV vaccines and vaccine strategies for use during outbreak situations to protect birds from both disease and infection to reduce virus shedding.

Animals↗

PubMed2005

Vaccination against foot-and-mouth disease virus confers complete clinical protection in 7 days and partial protection in 4 days: Use in emergency outbreak response.

Recent outbreaks of foot-and-mouth disease virus (FMDV) demonstrate that this highly contagious viral infection of cloven hoofed animals continues to be a significant economic problem worldwide. Debate about the most effective way to respond to outbreaks of FMDV in disease free countries continues to center on the use of vaccines. In this report, we present data showing that a commercially available, standard dose vaccine formulation can fully protect cattle against direct challenge with the virus in as little as 7 days with no carrier transmission to naïve animals. Cattle challenged 4 days after vaccination have reduced disease severity, no detectable virus in blood and little virus shedding from nasal secretions. These significant effects at 4 days post vaccination, confirmed in two separate trials, support the value of using currently available vaccines as a first line of defense against foot-and-mouth disease (FMD) outbreaks.

Animals↗

PubMed2005

Multiple outbreaks of severe acute BVDV in North America occurring between 1993 and 1995 linked to the same BVDV2 strain.

The first reported outbreak of bovine viral diarrhea (BVD) in 1946 described a transmissible acute disease characterized by severe leukopenia, high fever, gastrointestinal erosions and hemorrhages. However, in the ensuing years, the most commonly observed acute form of BVD was clinically mild. There was limited viral shed and spread following these acute infections. This led to the assumptions that acute infections with BVD viruses (BVDV) were clinically unimportant, spread of the virus within a group was always due to the presence of a persistently infected animal and transmission between healthy immunocompetent cattle was insignificant. These assumptions were challenged when outbreaks of severe acute BVDV were observed in North America starting in the late 1980s. This study demonstrates that widespread outbreaks of severe acute BVD observed in 1993 in North America can be traced to a single strain of BVDV that apparently spread explosively following acute infection. These findings are notable in that they draw into question management of acute BVD infection, design of studies examining virulence and nomenclature used to identify strains for GenBank submission.

Acute Disease↗