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A community-wide outbreak of hepatitis A in a religious community: impact of mass administration of immune globulin.

Community-wide outbreaks of hepatitis A are frequently prolonged and difficult to control. An extensive outbreak of hepatitis A in a religious community provided an opportunity to assess the effect of mass administration of immune globulin on the course of the outbreak. Between July 1, 1988 and May 30, 1989, 204 cases occurred among 3,500 residents (58/1,000), with persons aged 5-19 years having the highest attack rate. It was found that 89% of persons older than age 19, but no persons under age 20, had evidence of prior hepatitis A infection. During a 5-day campaign, immune globulin (0.02 ml/kg) was administered to 2,287 (65%) of the 3,500 residents. The cost of vaccine and syringes was less than $3,500. New cases among immune globulin recipients virtually stopped 2 weeks after the campaign, and the incidence of hepatitis in the community decreased from 9.6/week to 1.9/week. Among persons younger than age 20 years, the efficacy of immune globulin was 88.9% (95% confidence interval 77.9-94.5) for seven months. Although the authors cannot be sure that the outbreak will not recur, they believe that mass administration of immune globulin appears to have been partially effective at controlling this community-wide outbreak.

Adolescent↗

A school-based measles outbreak: the effect of a selective revaccination policy and risk factors for vaccine failure.

Persons who received measles vaccine between 12 and 14 months of age have been found to be at increased risk of measles compared with those vaccinated at greater than or equal to 15 months of age. Because of this, in 1987 the Immunization Practices Advisory Committee of the US Public Health Service recommended that, during measles outbreaks, revaccination of persons vaccinated at 12-14 months of age be considered. During a school-based outbreak in New Mexico in 1987, the authors evaluated the effect of a mandatory revaccination policy in affected schools. Before the effect of revaccination, the overall attack rate in persons vaccinated at greater than or equal to 12 months of age was 4.1 cases/1,000 students; afterward, the risk was significantly reduced by 73%, to 1.1/1,000 students. The attack rate among students targeted for revaccination declined 100%, compared with 41% among those not revaccinated. Overall, attack rates were significantly lower in schools conducting revaccination early compared with schools holding later revaccination. In a retrospective cohort study of single-dose vaccines in one school, age at vaccination was not associated with risk of disease; however, persons vaccinated greater than or equal to 10 years before the outbreak were at increased risk, independently of age at vaccination. Revaccination of persons whose most recent vaccination was between 12 and 14 months of age appeared to control transmission in this outbreak. Further studies are needed to confirm these observations and to evaluate the effect of other revaccination efforts during outbreaks.

Adolescent↗

A statewide outbreak of Escherichia coli O157:H7 infections in Washington State.

In November 1986, a statewide outbreak of Escherichia coli O157:H7 infections in Washington State was identified after a physician in an eastern Washington community hospitalized three patients with hemorrhagic colitis which progressed to thrombotic thrombocytopenic purpura. Epidemiologic investigation identified 37 cases in this community and linked the illnesses to a local restaurant which had served ground beef that was the suspected initial vehicle of transmission. The plasmid profile and toxin production pattern (Shiga-like toxin II alone) of the outbreak strain provided a unique strain marker. E. coli O157:H7 infections caused by this strain were simultaneously seen in other parts of the state among nursing home residents and in patients with the hemolytic-uremic syndrome, and an increase in sporadic cases of hemorrhagic colitis was noted at a Seattle health maintenance organization. It is suspected that a contaminated product, probably ground beef distributed statewide, was the common source. Tracing of this meat led to farms where rectal swabs from six (1%) of 539 cattle tested yielded E. coli O157:H7, although the plasmids and toxin production patterns of these isolates differed from the human outbreak strain. Introduction of a single strain of E. coli O157:H7 has the potential to cause widespread concurrent outbreaks. Such outbreaks are likely to escape recognition until heightened screening and surveillance for E. coli O157:H7 is established.

Adolescent↗

An outbreak of shigellosis at an outdoor music festival.

In August 1988, an estimated 3,175 women who attended a 5-day outdoor music festival in Michigan became ill with gastroenteritis caused by Shigella sonnei. Onset of illness peaked 2 days after the festival ended, and patients were spread throughout the United States by the time the outbreak was recognized. An uncooked tofu salad served on the last day was implicated as the outbreak vehicle (odds ratio = 3.4, p less than 0.0001). Over 2,000 volunteer food handlers prepared the communal meals served during the festival. This large foodborne outbreak had been heralded by a smaller outbreak of shigellosis among staff shortly before the festival began and by continued transmission of shigellosis from staff to attendees during the festival. S. sonnei isolated from women who became ill before, during, and after the festival had identical antimicrobial susceptibility patterns and plasmid profiles. Limited access to soap and running water for handwashing was one of the few sanitary deficits noted at this gathering. This investigation demonstrates the need for surveillance and prompt public health intervention when Shigella infections are recognized in persons attending mass outdoor gatherings, the singular importance of handwashing in reducing secondary transmission of shigellosis, and the potential for explosive outbreaks when communal meals are prepared by large numbers of food handlers.

Adult↗

Use of the case-control method in outbreak investigations.

The authors carried out a critical assessment of the literature to learn about the extent of use of the case-control method in outbreak investigations, and to identify problems observed in the use of this method to investigate outbreaks. The literature search comprised reports of outbreak investigations from the MEDLINE system, Morbidity and Mortality Weekly Report, and six epidemiologic and medical journals. The proportion of these reports that used the case-control method increased from one article out of 519 in the 1960-1965 period to 144 out of 845 reported outbreaks in the 1980-1985 period. A comparison of the case-control studies of outbreak investigations in the 1970-1975 period with those in the 1980-1985 period revealed relatively more sophisticated methods of analysis in the latter period.

Case-Control Studies↗

Multiple methicillin-resistant Staphylococcus aureus strains as a cause for a single outbreak of severe disease in hospitalized neonates.

Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of nosocomial infection. Outbreaks of infection caused by these pathogens are generally considered to be traceable to introduction of single strains into a hospital population. A large outbreak of bacteremic disease that recently occurred in our neonatal intensive care unit (11 episodes in 10 patients) involved 9 low birth weight infants and was associated with serious infection (4 episodes of meningitis). To determine the role of a single point source in this outbreak, isolates were characterized based on phenotypic and genotypic analyses. Phenotypic analysis included assessing hemolytic activity, phage typing, antimicrobial susceptibility testing and methicillin resistance population analysis. Genotypic analysis included assessment of plasmid profiles, dot-blot hybridization, restriction enzyme fragment pattern analysis and hybridization analysis of chromosomal DNA using a panel of staphylococcal gene probes. This analysis established that at least two distinct strains of MRSA were responsible for disease during this outbreak. This experience demonstrates the potential for MRSA to cause severe disease in the neonatal intensive care unit and indicates that the epidemiology of MRSA outbreaks is more complex than the spread of a single strain of bacteria.

Cross Infection↗

Outbreak of parainfluenza virus type 3 in an intermediate care neonatal nursery.

BACKGROUND: Of the four serotypes of human parainfluenza virus, parainfluenza type 3 causes the majority of infections in young children and infants. Parainfluenza type 3 can occur in newborns, although most are born with neutralizing antibodies. There have been only infrequent reports of parainfluenza type 3 causing nosocomial respiratory infection in the newborn nursery setting. We report an outbreak occurring in the intermediate care nursery (IMCN) at St. Boniface Hospital, Winnipeg, Canada. METHOD: On August 6, 1996, nursing staff of IMCN notified Infection Control that six infants had developed respiratory tract symptoms including nasal discharge and cough. Three more cases were recognized by August 8, 1996. Infection control precautions including cohorting of infant cases and ill staff, gowning and reinforcement of hand washing practices and visitor regulations were instituted. When two further cases occurred on August 9, 1996, the unit was closed to all admissions and remained closed until August 30, 1996. The last infant case occurred on August 10, 1996. RESULTS: The attack rate among infants was 63% (12 of 19). No mortality was associated with this outbreak and morbidity was minimal (no ventilator support was required), although one-half of the infants developed radiologic pulmonary infiltrates and one-half required supplemental oxygen therapy. Parainfluenza type 3 was isolated from nasopharyngeal secretions in 6 of 12 infant cases. There was a significant difference (P = 0.02) in age between the ill and non-ill infants; ill infants were a mean age of 42 days compared with a mean age of 11 days for non-ill infants at the midpoint of the outbreak. Sixteen of 65 (25%) IMCN nursing/medical staff reported an upper respiratory tract illness between July 10 and August 18, 1996. None of the staff was cultured. CONCLUSIONS: High patient census, limited numbers of full time staff, inadequate cohorting attempts because of staffing constraints and crowding in the IMCN were thought to be contributors to this outbreak. Institution of basic barrier precautions and temporary closure of the unit were effective in preventing further spread of the outbreak.

Canada↗

A case exercise in public health preparedness: a community outbreak of influenza-like illness.

Public health emergency preparedness has been a priority of local and state health departments as well as other community partners for several years. This article provides a tool for teaching a wide audience of learners the essential steps in training for a disease outbreak. This teaching case involves an investigation of and the community's response to an outbreak of influenza-like illness. Students learn skills in surveillance and hypothesis generation with regard to the outbreak. During the exercise, the learners are divided into teams to develop a response plan. The teams include Command and Coordination, Public Communication, Hospitals and Health Care Providers, Emergency Management and Public Safety, and Public Health. While the teams are developing their response plan, the etiology of the outbreak becomes clear. Once the etiology is known, each of the teams then develops an action plan to minimize the impact of the outbreak.

Disaster Planning↗

Effectiveness of measles vaccination after household exposure during a measles outbreak: a household contact study in Coburg, Bavaria.

BACKGROUND: A measles outbreak was recently observed in Coburg, Bavaria, in a population with vaccination rates of 76.5% in 5- to 6-year-old children in the years preceding the outbreak. Only a small proportion of children had received 2 vaccinations against measles. Vaccine effectiveness is estimated in a household contact study and also by a screening method. METHODS: A household contact study was conducted in families with at least 1 measles case by standardized computer-assisted telephone interviews to assess secondary attack rate and to estimate vaccine effectiveness. Vaccine effectiveness was also estimated with Farrington's screening method with information from school entry examinations and from questionnaires of confirmed measles cases in the Coburg outbreak. RESULTS: Thirty-eight children were primary cases. Of their contacts, 20 children were included in the study as secondary cases (1 vaccinated), and 23 children were contacts who did not develop measles (12 vaccinated once and 4 vaccinated twice), resulting in a vaccine effectiveness of 90% (95% confidence interval, 35-97%) for one vaccine dose. The proportion of the population vaccinated reached 81.5% during the outbreak and the proportion of the cases vaccinated was 10.9%, resulting in a vaccine effectiveness estimated using the screening method of 97.2% (95% confidence interval, 95.7-98.3%). CONCLUSIONS: With the use of 2 approaches to estimate the effectiveness of measles vaccination, a consistently high vaccine effectiveness of 90% or above was shown during a measles outbreak in Western Europe.

Child↗

A community outbreak of conjunctivitis caused by nontypeable Streptococcus pneumoniae in Minnesota.

BACKGROUND: The Minnesota Department of Health (MDH) was notified of an outbreak of conjunctivitis in city A with cultures positive for Streptococcus pneumoniae. METHODS: MDH staff contacted clinics and schools in city A and city B regarding conjunctivitis cases, reviewed clinical findings of conjunctivitis cases in city A and collected isolates for subtyping. RESULTS: Between September 1 and December 12, 2003, cities A and B reported 735 conjunctivitis cases. Fifty-one percent of the cases were reported from schools, childcare centers and colleges. Adults were more likely to report itching, burning or swelling of the eye(s); children were more likely to report crusty eyes (P < 0.05). Forty-nine percent of conjunctival cultures (71 of 144) were positive for S. pneumoniae. All isolates were nontypeable by serotyping. Pulsed field gel electrophoresis identified 3 clonal groups with 84% of isolates belonging to one clonal group. Multilocus sequence typing revealed that isolates had the same multilocus sequence type as isolates from a 2002 outbreak at a New England college. CONCLUSIONS: This outbreak was widespread in the community and conjunctivitis clinical presentation varied by age. The predominant strains in this outbreak were related to a pneumococcal strain implicated in prior conjunctivitis outbreaks, suggesting these strains have a predilection for causing conjunctivitis.

Adolescent↗

An outbreak of serious illness and death among injecting drug users in England during 2000.

An outbreak of serious illness and death occurred in injecting drug users during 2000 in Scotland, Ireland and England. National and international collaboration was necessary for the investigation and management of this outbreak. In England and Wales active case-finding was initiated, coupled with standardised data collection and microbiological investigation of cases. Twenty-six definite or probable cases were identified in England between 1 April and 31 Aug. 2000; 17 of these occurred in the North. The overall case fatality was 50% (13/26). The principal apparent risk factor was a history of intramuscular or subcutaneous injection of heroin and the limited duration of the outbreak suggested that the problem might have been related to a particular supply of heroin. Clostridium novyi was isolated from two English cases. Taken in conjunction with contemporaneous microbiological and epidemiological results from Scottish and Irish cases, the probable aetiology for this outbreak was infection with C. novyi associated with both a particular supply of heroin and the method of preparation and injection used. A 'toolkit' was distributed in Sept. 2000 to all Consultants for Communicable Disease Control in England and Wales to assist them with the ongoing surveillance, investigation and management of this condition. Lessons learned have been used to produce guidance for the investigation and management of outbreaks of unexplained serious illness of possible infective aetiology.

Adult↗

Use of ribosomal RNA gene restriction patterns to investigate two outbreaks of Campylobacter enteritis in Melbourne, Australia.

The analysis of ribosomal RNA (rRNA) gene patterns (ribotyping) has been used to differentiate strains within bacterial species. We used this method to investigate two outbreaks of campylobacter enteritis that occurred recently in Melbourne, Australia. The first outbreak involved seven patients although isolates from only five patients were available for typing. The second outbreak consisted of three patients infected with human immunodeficiency virus (HIV) on the same ward of a hospital. Analysis of the rRNA gene patterns revealed identical patterns for the isolates from five patients in the first outbreak, suggesting that these isolates were from the same source. However, ribotyping of the four isolates from the second outbreak showed three distinct ribotypes indicative of contact with unrelated sources. This study demonstrated that ribotyping is a useful, reliable and convenient typing scheme for epidemiological purposes.

Australia↗

Molecular characterisation of an outbreak strain of multiresistant Salmonella enterica serovar Typhimurium DT104 in the UK.

A major national outbreak of multiresistant Salmonella enterica serovar Typhimurium definitive phage type 104 (MR DT104) occurred in England and Wales in the summer of 2000. Isolates of MR DT104 were characterised by antimicrobial resistance type (R-type), pulsed-field gel electrophoresis (PFGE), plasmid profiling and fluorescent amplified fragment length polymorphism (fAFLP) analysis. Results of R-type, PFGE and fAFLP showed that summer 2000 outbreak-associated isolates were indistinguishable from most MR DT104 isolates collected in England and Wales during the 1980s and 1990s. However, outbreak-associated isolates all had an additional 2-MDa plasmid (PP D), and this distinct profile allowed outbreak cases to be distinguished from background MR DT104 infections, thereby facilitating the epidemiological investigation by improving the specificity of the case definition. The study demonstrated the highly clonal nature of MR DT104 and the importance of a hierarchical approach to molecular subtyping for outbreak investigations.

Animals↗

Outbreak investigations: Community participation and role of community and public health nurses.

Community and public health nurses (C/PHNs) may play a vital role in the investigation of disease outbreaks. C/PHNs possess skills in conducting interviews on sensitive subjects and in collaborating with communities. C/PHNs maintain key links to community providers, symptomatic clients, their families and associates, as well as community institutions where outbreaks occur. This combination of skills makes C/PHNs ideally suited to perform outbreak investigations. There are, however, pressing questions about whether C/PHNs are adequately prepared to contribute to investigation outcomes, to foster participation of affected communities, and to fully apply nursing skills to outbreak investigations to stop the spread of disease. Using one case study, the authors explore investigation outcomes, community participation issues, educational preparation, and public health funding and workforce policies required to achieve these ends successfully. One model of community participation in the steps of outbreak investigation and several Quad Council domains and competencies are proposed for use in practice. Questions regarding the use of emergency preparedness funding and employment of C/PHNs in epidemiology roles are raised.

Caliciviridae Infections↗

Two outbreaks of severe respiratory disease in nursing homes associated with rhinovirus.

OBJECTIVES: To characterize illness and identify the etiology for two nursing home outbreaks of respiratory illness. DESIGN: Multisite outbreak investigations; cohort. SETTING: Two nursing homes in Pennsylvania. PARTICIPANTS: Facility A residents (n = 170), Facility B residents (n = 124), and employees (n = 91). MEASUREMENTS: Medical records for Facility A and B residents were reviewed, and employees from Facility B self-administered a questionnaire to identify risk factors for illness. Serological, oropharyngeal, and nasopharyngeal specimens were collected for both outbreaks, and testing for respiratory pathogens was performed. RESULTS: In Facility A, 40 (24%) of 170 residents were identified with respiratory illness; 13 (33%) case-patients had radiographically confirmed pneumonia, 15 (38%) were taken to a hospital, and two (5%) died. Of 10 specimens collected from symptomatic Facility A case-patients, four (40%) tested positive using reverse transcription polymerase chain reaction for rhinovirus. In Facility B, 77 (62%) of 124 residents had respiratory illness, and 40 (52%) had radiographically confirmed pneumonia; 12 (16%) case-patients were hospitalized, and five (6%) died. Of 19 respiratory specimens collected from symptomatic Facility B case-patients, six (32%) were positive for rhinovirus; one was from an employee. Five (50%) of 10 rhinovirus-positive cases in both outbreaks had clinical and radiographic evidence of pneumonia. CONCLUSION: These investigations suggest that rhinoviruses may be an underrecognized cause of respiratory outbreaks in nursing homes, capable of causing pneumonia and perhaps death.

Acute Disease↗

Control of a community outbreak of measles which started in a poorly immunised high school population.

An outbreak of measles occurred in Darwin from February to March 1991. The first case was in a 13-year-old high school student who had returned from a holiday overseas. She was symptomatic on the second day of the new school term. She infected an infant while both waited in a doctor's surgery. Outbreak control measures were instituted 18 days later when the Communicable Diseases Centre was first alerted of cases through the laboratory notification scheme. Through active surveillance, we identified 76 cases of measles, of whom 92 per cent (70 cases) were under 20 years of age. Of these, 46 were students at the index high school in which the attack rate was 39.2 per 1,000. They transmitted the disease to six unvaccinated siblings aged 11 to 18 years, resulting in a secondary attack rate of 113 per 1,000 in this age group (relative risk of disease in siblings 2.8, 95 per cent confidence interval 1.2 to 6.2). The outbreak affected one other high school, a number of primary schools, one tertiary institution, and nine children under five years. Only four of the cases had a verified history of previous immunisation against measles. The outbreak was arrested within two weeks of instituting community-wide control measures. Inadequate immunisation coverage among school-aged children and delays in notification contributed to the severity of the outbreak. Improved measles surveillance systems, including telephone notification of clinical cases are needed so that control measures can be instituted immediately within the household and in the community.

Adolescent↗

[On the outbreak of Shigellosis in Tokyo, 1992].

In 1992, the number of cases of shigellosis in Tokyo increased remarkably, and a total of 10 separate outbreaks were confirmed. Except for 1 series where the causative strains was Shigella flexneri 3a, the other 9 outbreaks were caused by Shigella sonnei. Of note, 7 outbreaks were familial with less than 5 patients. The remaining 3 outbreaks occurred in a restaurant, a school and the dormitory of an orphanage, in which the organism was detected in 6 to 14 patients. In 4 of the familial outbreaks occurring in distant areas during August, ark shell was presumed to be the vehicle by epidemiological investigations and laboratory examinations. Analysis of isolates such as the antibiotic resistance pattern, plasmid profile, or colicine type in Shigella sonnei was useful in clarifying the commonality of each case and identifying the vehicle or transmission.

Adult↗

[Outbreak of aseptic meningitis in Iwamizawa, 1997, caused by echovirus 30].

To investigate the clinical character of an outbreak of aseptic meningitis in Iwamizawa 1997 caused by echovirus 30, and to investigate the spreading of the outbreak, we analyzed clinical character of 75 hospitalized patients in our hospital, and mapped the patients' distribution in Iwamizawa City each week. We detected in our hospital an epidemic outbreak of acute enteroviral meningitis caused by echovirus type 30 in Iwamizawa, from September to December, 1997. Regarding the patients, there was little prevalence in males, with an average age of 6 years and a range of 0 to 13 years of age. The most constant symptoms were three major one such as headache (90%), fever up (89%), vomiting/nausea (87%), sometimes sorethroat (30%) and abdominal pain (15%). One case had a febrile convulsion temporally, and two cases had acute meningoencephalopathy and- encephalitis. In the cereblospinal fluid (CSF), we found no predominance of mononuclear cell (MNC) (58%) in the differential cell count. The mean of the peak of CSF cell counts was 654/3. White blood cell (WBC) was 8940/microliters, and CRP 1.4 mg/dl. None of them was detected in the bacterial culture of the CSF. Viral cultures were performed on CSF in 26 cases. Echovirus type 30 was isolated in 4 cases of hospitalized patients, and in one case with meningismus without pleocytosis. The beginning of the outbreak was observed in two kindergarten and one elementary school side by side. The peak of the whole outbreak was detected in the 3rd to 6th week, however the school spreading peak was detected in the 3rd and 4th week, and spreading was going in the whole city.

Acute Disease↗