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[An outbreak of rubella among hospital personnel and measures taken against hospital infection--cost-benefits of the measure].

There is no nationwide outbreak of rubella after 1992 in Japan, but a local outbreak remains. Recently, some cases of congenital rubella syndrome (CRS) were reported after a local outbreak. An outbreak of rubella among hospital personnel occurred in our hospital located on Tanegashima Island on March and April 2003 after a visit of one rubella patient. Fifteen employees, including 7 clerks, 6 nurses, one doctor, and one radiologist, experienced rubella. A total of 259 employees in our hospital employees were examined for anti rubella hemagglutination inhibition (HI) tests with informed consent and recommended to take rubella vaccines. Sixty-seven employees (26%) among 257 examined for tests were found susceptible to rubella, and 53 employees were vaccinated. After vaccination, the outbreak was stamped out immediately. There was no rubella patient infected from employee. Nine among the 15 infected employees had declared to have a history of rubella or rubella vaccines before onsets, suggesting interviews are not reliable. There were many susceptible persons and rubella patients among elderly women and male personnel; therefore, measures are needed for elderly personnel as well as younger employees. In addition, adequate measures should be taken to prevent CRS, because many female personnel capable of pregnancy work in hospitals. The cost of the rubella HI tests and vaccination was approximately yen 200,000 (about dollar 1,600). The absence due to illness per one person was 6 days, and the wage per one day was about yen 12,000 (about dollar 100) on the average. The overall cost required in the outbreak was estimated to be approximate yen 1,400,000 (about dollar 12,000). Considering that an outbreak of rubella causes not only a large amount of expenditure but also loss of hospital income, the investment to prevent a rubella outbreak is quite valuable in the management of a hospital.

Adult↗

Hospital outbreaks caused by Pseudomonas aeruginosa: importance of serogroup O11.

Suspected outbreaks caused by pseudomonas aeruginosa in 19 hospitals and two motels were studied. On the basis of epidemiological analysis, serological typing, and antibiotic resistance patterns, 17 were classified as single-strain outbreaks. Six were classified as common-source outbreaks: of these, three were caused by contaminated urological instruments or solutions, two involved bathing in contaminated whirlpools, and one was caused by contaminated lens prostheses implanted during eye surgery. The ability of P. aeruginosa to survive or grow in wet environments was important in each of these six outbreaks. Eight outbreaks were classified as cross-infection. Two involved the urinary tract and were caused by antibiotic-resistant strains. Six involved the respiratory tract, but only one was caused by an antibiotic-resistant strain. In 2 of the 17 single-strain outbreaks, the exact mode of transmission could not be determined. One was an outbreak of pseudobacteremia in which patient blood cultures were contaminated with a single strain, presumably during collection of specimens or culture processing, P. aeruginosa serogroup O11 caused 9 of 17 (53%) single-strain outbreaks, a surprising finding since this serogroup represents only about 8% of endemic hospital isolates of this species. Serotyping was very useful in epidemiological analysis, but antibiotic susceptibility patterns were less useful.

Anti-Bacterial Agents↗

Diagnosis and epidemiological association of Listeria monocytogenes strains in two outbreaks of listerial encephalitis in small ruminants.

Two outbreaks of epizootic listerial encephalitis, one in sheep and one in goats, were investigated through pathology, microbiology, and DNA amplification-based techniques. Efforts were made to survey the diversity of Listeria monocytogenes strains in the silage consumed by affected animals and to verify the causal relationship between silage and disease outbreak. In both outbreaks, L. monocytogenes was isolated from silage and brain tissue samples. Random amplified polymorphic DNA patterns revealed two distinct L. monocytogenes strains, one of which was identical to the sheep brain isolate, in the silage associated with the outbreak in sheep. Three brain isolates and one silage isolate, all of which had different random amplified polymorphic DNA patterns, were found in the outbreak involving goats. All isolates from both outbreaks were indistinguishable in an in vitro assay for cell-to-cell spread and growth in macrophages. All brain isolates from the goat outbreak had identical intracellular ActA patterns, which were different from the pattern for the silage isolate. While the sheep brain isolate had an ActA pattern different from that of the corresponding silage isolate, the patterns for the brain isolates from the two outbreaks were not identical. This survey demonstrates the diversity of L. monocytogenes in silage and suggests the existence of one or more selective processes by which certain strains are more prone to give rise to disease.

Animals↗

Molecular epidemiology of a fast-food restaurant-associated outbreak of Escherichia coli O157:H7 in Washington State.

We studied the molecular epidemiology of the recent fast-food restaurant chain-associated Escherichia coli O157:H7 outbreak in Washington State. Genomic DNAs prepared from strains isolated from 433 patients were probed with radiolabelled Shiga-like toxin (SLT) I and SLT II genes and bacteriophage lambda DNA and were subsequently analyzed for their restriction fragment length polymorphism (RFLP) patterns. The SLT RFLP and lambda RFLP profiles of an E. coli O157:H7 strain isolated from the incriminated beef and prototype patient were compared with those of the patient isolates for determination of the concordance between patterns. Of the 377 patients with primary and secondary cases of infection epidemiologically linked to the outbreak, isolates from 367 (97.3%) of the patients displayed SLT RFLP and lambda RFLP profiles identical to those of the outbreak strains. Isolates from 10 of the 377 (2.6%) patients possessed SLT RFLP and lambda RFLP profiles different from those of the outbreak strains, and the patients from whom those isolates were obtained were subsequently characterized as having non-outbreak-related infections. The E. coli O157:H7 strains isolated from 31 of 44 (70.4%) patients who were epidemiologically excluded from the outbreak were linked to the outbreak by RFLP typing. Our results indicate that SLT RFLP and lambda RFLP analyses are stable and sensitive methods, and when they are used in conjunction with an epidemiological investigation they could result in an earlier recognition of outbreaks and their sources, hence prompting measures to prevent the continued transmission of E. coli O157:H7.

Animals↗

Survival of Acinetobacter baumannii on dry surfaces: comparison of outbreak and sporadic isolates.

Acinetobacter spp. are important nosocomial pathogens reported with increasing frequency in outbreaks of cross-infection during the past 2 decades. The majority of such outbreaks are caused by Acinetobacter baumannii. To investigate whether desiccation tolerance may be involved in the ability of certain strains of A. baumannii to cause hospital outbreaks, a blind study was carried out with 39 epidemiologically well-characterized clinical isolates of A. baumannii for which survival times were determined under simulated hospital conditions. The survival times on glass coverslips of 22 strains isolated from eight well-defined hospital outbreaks in a German metropolitan area were compared with the survival times of 17 sporadic strains not involved in outbreaks but rather isolated from inpatients in the same geographic area. All sporadic isolates have been shown by pulsed-field gel electrophoresis to represent different strain types. There was no statistically significant difference between the survival times of sporadic strains of A. baumannii and outbreak strains (27.2 versus 26.5 days, respectively; P < or = 0.44) by the Wilcoxon-Mann-Whitney test. All investigated A. baumannii strains, irrespective of their areas of endemicity or epidemic occurrence, have the ability to survive for a long time on dry surfaces. Antimicrobial susceptibility testing showed that A. baumannii outbreak strains were significantly more resistant to various broad-spectrum antimicrobial agents than sporadic strains. Both desiccation tolerance and multidrug resistance may contribute to their maintenance in the hospital setting and may explain in part their propensity to cause prolonged outbreaks of nosocomial infection.

Acinetobacter↗

Use of rapid genomic deletion typing to monitor a tuberculosis outbreak within an urban homeless population.

Beginning in mid-2002, a large tuberculosis outbreak occurred among homeless persons in King County, Washington. In order to further monitor the outbreak following its peak in 2003, Mycobacterium tuberculosis isolates from all new King County tuberculosis (TB) patients in 2004 and the first half of 2005 (n = 220) were genotyped by using a rapid comparative genomics-based (genomic deletion-typing) approach, with confirmation by mycobacterial interspersed repetitive units and repetitive-sequence-based PCR (rep-PCR). Results were compared to retrospective genotypic data from 1995 to 2003. The outbreak strain SBRI9, which was not seen among King County homeless persons prior to 2002, accounted for 16 out of 30 TB cases (53%) within this population in 2002. This trend continued with 27 out of 35 cases (77%) caused by the outbreak strain in 2003, 11 out of 13 cases (85%) caused by the outbreak strain in 2004, and 4 out of 10 cases (40%) caused by the outbreak strain in the first 5 months of 2005. Thus, the outbreak strain remained well established within this homeless population throughout the study period. At least four SBRI9 cases were in people who had previously been infected by other strains. The novel PCR-based strain-typing approach used in this investigation proved to be cost-effective and very rapid. In most cases, it was possible to analyze DNA extracted directly from primary isolation (Mycobacterium growth indicator tube) cultures submitted by clinical laboratories, a feature that markedly reduced the delay between diagnosis and strain typing results. This rapid turnaround facilitated public health efforts to prevent new outbreaks involving this strain.

Bacterial Typing Techniques↗

Molecular epidemiology of norovirus in outbreaks of gastroenteritis in southwest Germany from 2001 to 2004.

The identification and molecular epidemiology of norovirus in outbreaks of gastroenteritis were studied during a 3-year period in Germany. Specimens (n = 316) from 159 nonbacterial gastroenteritis outbreaks from March 2001 to June 2004 were analyzed for the presence of noroviruses by reverse transcriptase PCR. Outbreaks were most frequent in elderly people's homes and care centers (43%), followed by hospitals (24%). Molecular analyses of strains from 148 outbreaks showed that there were up to 12 genotypes involved in the outbreaks. Genogroup II noroviruses were responsible for 95% of the outbreaks. Cocirculation of more than one strain in the same outbreak and cocirculation of genogroup I and II strains in the same place were observed. Genogroup II4 (Grimsby-like) was the most prevalent strain, accounting for 48% and 67% of the outbreaks in 2002 and 2003, respectively. The genogroup IIb (Castell/Suria) genotype was observed in all the years of the study. Epidemiological and molecular data indicated that there was a major shift of the predominant strain that coincided with the appearance of a new variant of genogroup II4 in 2002. By the application of reverse transcriptase PCR, this study has demonstrated the importance and dynamism of noroviruses in Germany.

Caliciviridae Infections↗

Outbreak of coagulase negative staphylococcus highly resistant to ciprofloxacin in a leukaemia unit.

OBJECTIVE: To define an outbreak of bacteraemia due to coagulase negative staphylococci highly resistant to ciprofloxacin in a leukaemia unit, investigate the source and mode of spread of the outbreak strain, and assess control measures. DESIGN: The outbreak strain was characterised by five different typing methods. Surveillance of patients, staff, and environment was carried out during the outbreak and five months after control measures were introduced. SETTING: A unit with 10 beds for adults with leukaemia and patients receiving bone marrow transplants. The outbreak occurred during a trial of ciprofloxacin for empirical treatment of neutropenic fevers. INTERVENTIONS: Ciprofloxacin was withdrawn from use in the unit and daily bathing with chlorhexidine gluconate solution started. Main outcome measure--The absence of bacteraemia due to the outbreak strain for five months after control measures. RESULTS: During the study 49 patients developed 21 episodes of bacteraemia due to the outbreak strain, which was ciprofloxacin resistant (minimum inhibitory concentration greater than or equal to 128 mg/l), susceptible to phage 155 A9C, and SII biotype and had characteristic immunoblot and DNA fingerprint features. There was a high amount of colonisation of patients but not staff with this strain, which was also wide spread in the environment. The control measures led to rapid resolution of the outbreak and disappearance of the strain from the unit. CONCLUSIONS: In areas where coagulase negative staphylococcal infections are common doctors must be aware of the possibility of cross infection with single strain, and the availability of more discriminatory methods of typing will facilitate the identification and control of such episodes.

Cancer Care Facilities↗

Epidemiological investigations of the 2001 foot-and-mouth disease outbreak in Argentina.

A total of 2126 herds, an attack rate of 0.82 per cent, were affected during an epidemic of foot-and-mouth disease in Argentina in 2001. The spatial and temporal distribution of the epidemic was investigated using nearest-neighbour and spatial scan tests and by estimating the frequency distributions of the times to intervention, and distances and times between outbreaks. The outbreaks were clustered and associated significantly (P<0.01) with herd density; 94 per cent were located in the Pampeana region, where the cattle population is concentrated, which had an attack rate of 1.4 per cent. The clustering results suggested that the virus had spread locally between outbreaks. Most of the outbreaks were separated by one day and the maximum distance between outbreaks was almost 2000 km, indicating that the infection spread rapidly over large distances. The index outbreak was detected more than 15 days after the primary outbreak, and restrictions on the movement of cattle were probably not enforced until about one month after infection occurred. As in other major epidemics, the period between the first outbreaks and the effective application of control strategies was probably crucial in determining the progress of the epidemic.

Animals↗

Molecular epidemiology of two fowl cholera outbreaks on a free-range chicken layer farm.

Two outbreaks of fowl cholera on a multiage free-range egg farm were investigated. The outbreaks occurred in 1994 and 2002. A total of 22 strains of Pasteurella multocida were available for study, 11 from the 1994 outbreak and 11 from the 2002 outbreak. Lesions typical of acute fowl cholera were seen in the 1994 outbreak, whereas both acute and chronic fowl cholera occurred in the 2002 outbreak. The isolates were examined in an extended phenotypic typing methodology, by a P. multocida-specific polymerase chain reaction (PCR), by the Heddleston somatic serotyping scheme, and by restriction endonuclease analysis (REA) typing using the enzyme HpaII. All 22 strains had the same phenotypic properties, all were confirmed as P. multocida by PCR, all were Heddleston serovar 4, and all had the same REA pattern. The results indicate that these 2 outbreaks were caused by the same clone of P. multocida--despite the 8-year time period between the outbreaks.

Animal Husbandry↗

Two successive outbreaks of mumps in Nova Scotia among vaccinated adolescents and young adults.

BACKGROUND: Before the widespread use of vaccine, mumps was the most common cause of viral meningitis (up to 10% of mumps infections). Vaccination programs have resulted in a drop of more than 99% in the number of reported mumps cases in the United States and Canada. Although rare in Canada, outbreaks have recently occurred throughout the world, including a large outbreak in the United Kingdom, where more than 56,000 cases were reported in 2004-2005. METHODS: Two recent outbreaks in Nova Scotia were investigated by public health officials. Cases were defined by laboratory confirmation of infection (i.e., isolation of mumps virus by culture) or clinical diagnosis in people epidemiologically linked to a laboratory-confirmed case. The people infected were interviewed to determine possible links and to identify contacts. Mumps virus was cultured from urine and throat specimens, identified via reverse-transcriptase polymerase chain reaction (RT-PCR) and subjected to phylogenetic analysis to identify the origin of the strain. RESULTS: The first outbreak involved 13 high-school students (median age 14 yr): 9 who had previously received 2 doses of measles-mumps-rubella vaccine (MMR) and 4 who received a single dose. The second outbreak comprised 19 cases of mumps among students and some staff at a local university (median age 23 yr), of whom 18 had received only 1 dose of MMR (the other received a second dose). The viruses identified in the outbreaks were phylogenetically similar and belonged to a genotype commonly reported in the UK. The virus from the second outbreak is identical to the strain currently circulating in the UK and United States. INTERPRETATION: The predominance in these outbreaks of infected people of university age not only highlights an environment with potential for increased transmission but also raises questions about the efficacy of the MMR vaccine. The people affected may represent a "lost cohort" who do not have immunity from natural mumps infection and were not offered a 2-dose schedule. Given the current level of mumps activity around the world, clinicians should remain vigilant for symptoms of mumps.

Adolescent↗

The frequency of a Norwalk-like pattern of illness in outbreaks of acute gastroenteritis.

Records of 642 outbreaks of acute gastroenteritis were reviewed to determine the proportion of outbreaks that were clinically and epidemiologically consistent with Norwalk-like virus infection. Using as our criteria stool cultures negative for bacterial pathogens, mean (or median) duration of illness 12-60 hours, vomiting in greater than or equal to 50 per cent of cases, and, if known, mean (or median) incubation period of 24-48 hours, we found that 23 per cent of waterborne outbreaks, 4 per cent of foodborne outbreaks, and 67 per cent, 60 per cent, and 28 per cent of outbreaks in nursing homes, in summer camps, and on cruise ships, respectively, satisfied the criteria for Norwalk-like pattern. Of 54 outbreaks that satisfied the criteria for Norwalk-like pattern, 14 were investigated for virus etiology. Ten of these (71 per cent) yielded serologic evidence of Norwalk-like virus infection. Norwalk-like viruses are probably an important cause of outbreaks of acute gastroenteritis. Investigation for Norwalk virus antibody in outbreaks that are clinically and epidemiologically consistent with Norwalk-like virus infection is likely to yield diagnostically useful results.

Acute Disease↗

Two contiguous outbreaks of dengue type 2 in north Queensland.

OBJECTIVES: To investigate two outbreaks of dengue type 2 in north Queensland, one in the Torres Strait beginning in late 1996, the other in a Cairns suburb in early 1997. DESIGN: Epidemiological investigation of all laboratory-confirmed cases of dengue, entomological investigation of the local environment, and laboratory analysis of the isolated dengue viruses. MAIN OUTCOME MEASURES: Numbers of confirmed and of locally acquired cases; virus serotype; comparison of nucleotide sequences between viruses isolated from the two outbreaks; and Breteau Index (BI = number of containers with larvae of the mosquito vector Aedes aegypti found per 100 houses investigated) on the affected islands and in the Cairns suburb. RESULTS: There were 201 confirmed cases of dengue in the Torres Strait outbreak, which lasted nearly seven months, and seven confirmed cases in the Cairns outbreak, which lasted about nearly 11 weeks. Most (190) were confirmed as dengue type 2. Nucleotide sequencing of viruses isolated from the two outbreaks showed they were identical. Ae. aegypti breeding sites were very common on the five Torres Strait islands surveyed (BIs, 73-219--high risk), but less so in the Cairns suburb (BI, 23). The most common breeding sites were water storage reservoirs, particularly rainwater tanks, on the outer Torres Strait islands, discarded containers (such as plastic containers, buckets and tyres) on Thursday Island, and garden items (such as flowerpot bases and jars) in Cairns. CONCLUSIONS: The virus responsible for the Cairns outbreak was most probably introduced from the Torres Strait, whereas the virus responsible for the Torres Strait outbreak was imported from Papua New Guinea. Preventive strategies tailored to specific locations are needed to reduce breeding of Ae. aegypti in north Queensland, and the consequent risk of future outbreaks of dengue.

Adolescent↗

Infectious diarrheal outbreaks in the Israeli military, 1988-2002.

We analyzed 865 diarrheal outbreaks with an identified bacterial pathogen or unknown cause that occurred in the Israeli military between 1988 and 2002. The number of outbreaks per year declined over the study period, as did the proportion of outbreaks with an identified pathogen. Shigella, Salmonella, and Staphylococcus species were the bacteria most commonly isolated. Seventy percent of the outbreaks involved < 35 cases and only 5% involved > 100 cases. More than one-half of the outbreaks occurred in field units, but these outbreaks were smaller than those in other units. The most commonly identified cause of the outbreaks was a lapse in maintaining standards of food preparation. Improvements in infrastructure and enhanced attention to surveillance, education, and infection control have resulted in a marked decline in the number of outbreaks in recent years.

Disease Outbreaks↗

Role of molecular typing in an outbreak of Salmonella paratyphi A.

During the post monsoon season of 1996 an outbreak of human Salmonellosis caused by Salmonella serovar-paratyphi A occurred in New Delhi and had continued for over 2 months. A total of 36 clinically diagnosed enteric-fever cases were reported during this outbreak. The isolates were compared following their characterisation by biotyping, antibiogram-analysis, plasmid-profiling and IS200 probing, to study the relatedness in order to delineate a common source. The study included representative strains from both outbreak (15) and sporadic (7) cases for comparative analysis. Biotyping, antibiogram, whole cell protein-analysis and plasmid-profiling could not discriminate sporadic cases from outbreak strains, suggesting that a single clone/type (PT-1) may be prevalent in our region. In contrast, molecular-typing using IS200-probing revealed 2 clonally related strains circulating during the outbreak, as compared to the unrelated sporadic strains which exhibited considerable genetic diversity. Molecular analysis by IS200-probing, helped to assign an index case which provided a history of later outbreaks, since paratyphi A was repeatedly cultured in later outbreaks also. The study also suggests that genetic rearrangements can occur during the emergence of outbreaks. It reaffirmed the usefulness of IS200-probing in epidemiological investigations of Salmonella enterica serovars.

Bacterial Typing Techniques↗

An analysis of a presumed major outbreak of pseudorabies virus in a vaccinated sow herd.

We describe a major outbreak of pseudorabies virus (PRV) in a sow herd in which the sows were vaccinated simultaneously three times a year with a vaccine containing Bartha strain. Also in the associated rearing herd in which the gilts were vaccinated twice an outbreak of PRV occurred. The outbreak was analysed with mathematical models, statistical methods and Monte-Carlo simulation. Under the assumption that the outbreak started with one introduction of virus the reproduction ratio R(ind)--as a measure of transmission of PRV between individuals--in the sow herd was estimated with a Generalized Linear Model to be 1.6. Also under the assumption of one introduction of virus R(ind) in the rearing herd was estimated with a martingale estimator to be 1.7. Both estimates were significantly larger than 1. Mathematical analysis showed that heterogeneity in the sow herd, because of the presence of not-optimally immunized replacement sows could not be the only cause of the observed outbreak in the sow herd. With Monte-Carlo simulations, the duration of an outbreak after a single introduction of virus and R(ind) = 1.6 did not mimic the data and thus the hypothesis of a single introduction with R(ind) = 1.6 could also be rejected and R(ind) is thus, not necessarily above 1. Moreover, with statistical analysis, endemicity in the combination of herds as a cause for the observed outbreak could be rejected. Endemicity in the rearing herd alone could not be excluded. Therefore, multiple introductions from outside and most probably from the rearing herd were possibly the cause of the observed outbreak(s). The implications for eradication of pseudorabies virus were discussed.

Animals↗

Relationship of increased fowl cholera outbreaks in turkeys with high environmental temperatures.

The relationship of an increase in fowl cholera outbreaks in turkeys with an increase in environmental temperatures during June, July, August, and September between 1959 and 1992 was analyzed. High environmental temperatures were found to be influential in the development of fowl cholera in turkeys. When the average monthly maximum environmental temperatures for 5 mo of July and 7 mo of August during the 13 yr between 1967 and 1979 were above 30.5 C, there was a significantly (P < 0.05) higher number of fowl cholera outbreaks in turkeys for each month than during the same months when the average maximum temperatures were below 30.5 C. To test the hypothesis that an increase in fowl cholera outbreaks was preceded by an increase in temperature, the pre- and postoutbreak temperatures for 46 selected outbreak clusters occurring between 1959 and 1992 were averaged. Both the average maximum and minimum temperatures for the latter 9 days of the preoutbreak period were highly significantly (P < 0.001) higher than those of the average cluster outbreak day and the following four postoutbreak days. Also, for the nine individual days of the latter pre-outbreak period, the daily average maximum temperature was significantly (P < 0.05) higher for 3 days and partially significantly (P < 0.10) higher for 3 days than that of the average cluster outbreak day, and the daily average minimum temperature was significantly (P < 0.05) higher for 2 days and partially significantly (P < 0.10) higher for 1 day than that for the average cluster outbreak day.

Animals↗

Framework for evaluating public health surveillance systems for early detection of outbreaks: recommendations from the CDC Working Group.

The threat of terrorism and high-profile disease outbreaks has drawn attention to public health surveillance systems for early detection of outbreaks. State and local health departments are enhancing existing surveillance systems and developing new systems to better detect outbreaks through public health surveillance. However, information is limited about the usefulness of surveillance systems for outbreak detection or the best ways to support this function. This report supplements previous guidelines for evaluating public health surveillance systems. Use of this framework is intended to improve decision-making regarding the implementation of surveillance for outbreak detection. Use of a standardized evaluation methodology, including description of system design and operation, also will enhance the exchange of information regarding methods to improve early detection of outbreaks. The framework directs particular attention to the measurement of timeliness and validity for outbreak detection. The evaluation framework is designed to support assessment and description of all surveillance approaches to early detection, whether through traditional disease reporting, specialized analytic routines for aberration detection, or surveillance using early indicators of disease outbreaks, such as syndromic surveillance.

Disease Outbreaks↗