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PubMed2001

Poliovirus circulation among schoolchildren during the early phase of the 1992-1993 poliomyelitis outbreak in The Netherlands.

During the 1992-1993 outbreak of poliomyelitis in The Netherlands, we examined 866 childrenat 7 schools for evidence of infection with the outbreak virus, poliovirus type 3(PV3), to determine the extent of the outbreak and the protection of the herd immunity. Seventy-seven children (8.9%) showed evidence of recent wild-type PV3 infection, as determined by virus isolation and/or poliovirus type-specific IgM assay. Most infected children lived in the same area as the index case patient, attended an orthodox-reformed (OR) primary school, and had not been vaccinated. At the OR school, as many as 22% of children immunized with inactive poliovirus vaccine were found to have evidence of recent infection, which is a significantly lower rate than that among unvaccinated children (59.5%). No evidence of vaccination was seen in 25.5%-43.1% of children at OR schools. Seroprevalence of antibodies against the 3 types of poliovirus suggested that no poliovirus circulation had occurred between the 1978 and 1992-1993 outbreaks.

Adolescent↗

PubMed2002

Outbreak of avian influenza A(H5N1) virus infection in Hong Kong in 1997.

The first outbreak of avian influenza A(H5N1) virus in humans occurred in Hong Kong in 1997. Infection was confirmed in 18 individuals, 6 of whom died. Infections were acquired by humans directly from chickens, without the involvement of an intermediate host. The outbreak was halted by a territory-wide slaughter of more than 1.5 million chickens at the end of December 1997. The clinical spectrum of H5N1 infection ranges from asymptomatic infection to fatal pneumonitis and multiple organ failure. Reactive hemophagocytic syndrome was the most characteristic pathologic finding and might have contributed to the lymphopenia, liver dysfunction, and abnormal clotting profiles that were observed among patients with severe infection. Rapid diagnosis with the use of reverse-transcription polymerase chain reaction and monoclonal antibody-based immunofluorescent assay were of great clinical value in the management of the outbreak. The experience of the H5N1 outbreak in Hong Kong underscores the importance of continuous surveillance of influenza virus strains in humans and in other animal species.

Adolescent↗

PubMed2003

Tonsillopharyngitis caused by foodborne group A streptococcus: a prison-based outbreak.

An outbreak of tonsillopharyngitis due to Streptococcus pyogenes occurred among inmates of a rural correctional center in New South Wales, Australia. A total of 72 (28%) of 256 inmates became ill in December 1999. S. pyogenes type M-75, T-25, which was opacity factor positive, was isolated from throat swab specimens obtained from 5 of 57 inmates with primary cases and from 4 of 15 inmates with secondary cases, as well as from specimens obtained from the hand wounds and throat of one of the food handlers. The consumption of curried egg rolls (i.e., curried egg salad sandwiches) was the most likely association with this outbreak. The presumed source of the food contamination was the food handler who had infected hand wounds. There has been only one other outbreak of streptococcal pharyngitis reported from a prison. Other outbreaks have been reported from military bases, nursing homes, and community picnics.

Disease Outbreaks↗

PubMed2002

Homologous versus heterologous immune responses to Norwalk-like viruses among crew members after acute gastroenteritis outbreaks on 2 US Navy vessels.

Host immune responses to human caliciviruses are difficult to study because of the lack of a clear definition of antigenic or serological types. This report describes antibody responses to several Norwalk-like viruses in large outbreaks of acute gastroenteritis on 2 US Navy ships. Enzyme immunoassays (EIAs) were used to measure antibody responses. To understand the antibody response to a homologous strain causing the outbreaks, the viral capsid gene of one isolate (C59) was expressed in baculovirus and included in the EIAs. Significantly greater seroresponses were detected in patients against the homologous strain than against the heterologous strains. Strains within genogroups reacted more strongly than did strains between genogroups. Significantly higher antibody titers against the outbreak strain were detected in acute serum samples from control subjects than in those from case patients. These results indicate that recombinant EIAs are useful for outbreak investigation and that the homologous antibody might be protective against reinfection.

Acute Disease↗

PubMed2003

Measles outbreak in Sri Lanka, 1999-2000.

A large measles outbreak occurred in Sri Lanka from October 1999 through June 2000 following a period of low incidence. During this period, >15,000 suspected cases were reported to the central Epidemiological Unit of the Department of Health Services. The outbreak was investigated through review of surveillance data for 1999-2000, which were compared with previous surveillance data. Among the clinically confirmed cases, the highest morbidity rate (114/100,000 population) was observed among children <9 months of age. Nearly 54% of the cases were among persons >/=15 years old, and this percentage had increased over the previous decade. Forty percent of cases had a history of measles vaccination. There were 5 deaths, giving a case-fatality rate of 0.1%. Action taken during the outbreak and plans for future outbreak prevention strategies were also evaluated.

Adolescent↗

PubMed2004

Norovirus outbreak among primary schoolchildren who had played in a recreational water fountain.

BACKGROUND: A gastroenteritis outbreak was associated with playing in a norovirus-contaminated recreational fountain. OBJECTIVE AND STUDY DESIGN: A retrospective cohort study was performed to estimate the magnitude of the outbreak and identify its source. Epidemiological investigation included standardized questionnaires about sex, age, school, class, risk exposures, and illness characteristics. Stool samples and environmental water samples were analyzed for the presence of bacteria, viruses, and parasites. RESULTS: Questionnaires were returned for 191 schoolchildren (response rate, 83%) with a mean age of 9.2 years, of whom 47% were ill (diarrhea and/or vomiting). Children were more likely to have been ill if they had played in the recreational fountain (relative risk, 10.4). Norovirus (Birmingham) was detected in 22 (88%) stool specimens from ill children and in 6 (38%) specimens from healthy children. The water sample from the fountain contained a norovirus strain that was identical to the RNA sequence found in stools. CONCLUSIONS: Recreational water may be the source of gastroenteritis outbreaks. Adequate water treatment can prevent these types of outbreak.

Caliciviridae Infections↗

PubMed2004

Molecular epidemiology of outbreaks of viral gastroenteritis in New York State, 1998-1999.

This investigation evaluated the role of Norwalk-like virus (NLV) and other viruses (rotavirus, enteric adenovirus, and enterovirus) in 11 outbreaks of acute nonbacterial gastroenteritis that occurred in multiple settings in a span of 18 months in New York State. To determine the etiology of illness, patients' stool specimens were analyzed with a combination of reverse-transcription polymerase chain reaction (RT-PCR) and nucleotide sequencing, cell culture, and ELISA diagnostic techniques. NLV was detected from all of these outbreaks, with an overall detection rate of 64% (51 of 79) for all specimens tested. Repeated attempts to isolate other viral pathogens were unsuccessful. Phylogenetic analysis of a subset of 27 specimens from these outbreaks showed the presence of both genogroup I and genogroup II NLVs. A spectrum of different nucleotide sequences were detected, demonstrating interoutbreak sequence variation and unrelated infections. NLV is a significant causative agent of diarrhea outbreaks in New York State.

Amino Acid Sequence↗

PubMed2004

A multistate outbreak of Escherichia coli O157:H7 infection linked to consumption of beef tacos at a fast-food restaurant chain.

We investigated a multistate outbreak of Escherichia coli O157:H7 infections. Isolates from 13 case patients from California, Nevada, and Arizona were matched by pulsed-field gel electrophoresis subtyping. Five case patients (38%) were hospitalized, and 3 (23%) developed hemolytic uremic syndrome; none died. The median age was 12 years (range, 2-75 years), and 10 (77%) were female. Case-control studies found an association between illness and eating beef tacos at a national Mexican-style fast-food restaurant chain (88% of cases versus 38% of controls; matched OR, undefined; 95% confidence interval, 1.49 to infinity; P=.009). A trace-back investigation implicated an upstream supplier of beef, but a farm investigation was not possible. This outbreak illustrates the value of employing hospital laboratory-based surveillance to detect local clusters of infections and the effectiveness of using molecular subtyping to identify geographically dispersed outbreaks. The outbreak investigation also highlights the need for a more efficient tracking system for food products.

Adolescent↗

PubMed2005

Typhoid fever: a massive, single-point source, multidrug-resistant outbreak in Nepal.

BACKGROUND: In the summer of 2002, a total of 5963 cases of typhoid fever were recorded in Bharatpur, Nepal (population, 92,214) during a 7-week period. A team from the Armed Forces Research Institute of Medical Sciences in Bangkok, Thailand, and the CIWEC Travel Medicine Clinic (Kathmandu, Nepal) assisted the Nepal National Public Health Laboratory (Kathmandu, Nepal) in the further investigation of this large, explosive febrile disease outbreak. METHODS: Investigators conducted a thorough epidemiologic and laboratory investigation to assess the size and scope of the outbreak. In addition to subculturing of previously collected samples, blood samples were obtained from 100 febrile patients, and culture and susceptibility testing were done by standard laboratory methods. Pulsed field gel electrophoresis (PFGE) and plasmid analysis were done. RESULTS: The majority of the isolates, including 1 from the municipal water supply, were multidrug resistant. The minimum inhibitory concentrations (MICs) of ciprofloxacin ranged from 0.19 microg/mL to 0.125 microg/mL. With use of PFGE, all isolates, including isolates from the water supply, showed an analytical similarity of 96%-100%. Multidrug-resistant isolates had a plasmid encoding for resistance, and those with resistance to nalidixic acid had a single-point mutation. CONCLUSIONS: To the best of our knowledge, this outbreak is the largest single-point source outbreak of multidrug-resistant typhoid fever yet reported, and it was molecularly traced to the city's single municipal water supply. Isolates were uniformly resistant to nalidixic acid, there was a decrease in their susceptibility as measured by MIC of fluoroquinolones, and 90% of isolates obtained were resistant to >1 antibiotic.

Adult↗

PubMed2005

Multistate outbreak of Listeria monocytogenes infection linked to delicatessen turkey meat.

BACKGROUND: Despite a decreasing incidence of listeriosis in the United States, molecular subtyping has increased the number of recognized outbreaks. In September 2000, the New York City Department of Health identified a cluster of infections caused by Listeria monocytogenes isolates with identical molecular subtypes by pulsed-field gel electrophoresis (PFGE) and ribotyping. METHODS: To determine the magnitude of the outbreak and identify risk factors for infection, we notified state health departments and conducted a case-control study. A case was defined as a patient or mother-infant pair infected with Listeria monocytogenes whose isolate yielded the outbreak PFGE pattern. Controls were patients infected with Listeria monocytogenes whose isolate yielded a different PFGE pattern. Patients were asked about food and drink consumed during the 30 days before the onset of illness. RESULTS: Between May and December 2000, there were 30 clinical isolates of Listeria monocytogenes with identical PFGE patterns identified in 11 US states. Cases of infection caused by these isolates were associated with 4 deaths and 3 miscarriages. A case-control study implicated sliced processed turkey from a delicatessen (Mantel-Haenszel odds ratio, 8.0; 95% confidence interval, 1.2-43.3). A traceback investigation identified a single processing plant as the likely source of the outbreak, and the company voluntarily recalled 16 million pounds of processed meat. The same plant had been identified in a Listeria contamination event that had occurred more than a decade previously. CONCLUSIONS: Prevention of persistent L. monocytogenes contamination in food processing plants presents a critical challenge to food safety professionals.

Adult↗

PubMed2006

Nosocomial pertussis: costs of an outbreak and benefits of vaccinating health care workers.

BACKGROUND: In September 2003, 17 symptomatic cases of pertussis among health care workers (HCWs) resulted from a 1-day exposure to an infant who was later confirmed to have pertussis. These HCWs identified 307 close contacts. The hospital implemented extensive infection-control measures. The objective of this study was to determine direct and indirect costs incurred by the hospital and symptomatic HCWs as a result of the September 2003 outbreak and to estimate possible benefits of vaccinating HCWs from the hospital perspective. METHODS: We determined costs by interviewing infection-control and hospital personnel, reviewing billing records, and surveying symptomatic HCWs. We calculated the benefits and costs of a vaccination program for HCWs, using a probabilistic model to estimate the number of pertussis exposures that would require control measures annually. Sensitivity and threshold analyses were performed. RESULTS: The outbreak cost to the hospital was 74,870 dollars. The total measured cost of the outbreak was 81,382 dollars, including costs incurred by HCWs (6512 dollars). Our model predicted that vaccinating HCWs against pertussis would prevent >46% of exposures from HCWs with pertussis per year and would provide net savings. The benefit for the hospital was estimated to be 2.38 times the dollar amount invested in vaccinating HCWs. The number of exposures prevented and the benefit-cost ratio were sensitive to the number of exposures identified, the incidence of pertussis among HCWs, and HCW turnover. CONCLUSIONS: A single nosocomial pertussis outbreak resulted in substantial disruption and costs to the hospital and to HCWs. Our model suggests that cost savings and benefits could be accrued by vaccinating HCWs against pertussis.

Cost Control↗

PubMed2006

Genotyping and preemptive isolation to control an outbreak of vancomycin-resistant Enterococcus faecium.

BACKGROUND: Control of vancomycin-resistant Enterococcus faecium (VRE) in European hospitals is hampered because of widespread asymptomatic carriage of VRE by healthy Europeans. In 2000, our hospital (The University Medical Center Utrecht, Utrecht, The Netherlands) was confronted with a large outbreak of VRE. INTERVENTION: On the basis of genotyping (by pulsed-field gel electrophoresis), epidemic and nonepidemic VRE strains were distinguished, and infection-control measures were exclusively targeted toward epidemic VRE. The outbreak was retrospectively divided into 3 periods of different infection-control measures. Compliance with use of alcohol-based hand rubs was enforced during all periods. Period I involved active surveillance, isolation of carriers, and cohorting (duration, 4 months); preemptive isolation of high-risk patients for VRE colonization was added in period II (7 months); and cohorting and preemptive isolation were abandoned in period III (18 months). METHODS: When the outbreak was identified, 27 patients in 6 wards were colonized; 93% were colonized with an epidemic VRE strain. Detection rates of nonepidemic VRE were 3.5%, 3.0%, and 2.9% among 683, 810, and 977 screened patients in periods I, II, and III, respectively, comparable to a prevalence of 2% (95% confidence interval [CI], 1%-3.5%) among 600 nonhospitalized persons. The relative risks of detecting epidemic VRE in periods II and III, compared with period I, were 0.67 (95% CI, 0.41-1.10) for period II and 0.02 (95% CI, 0.002-0.6) for period III. Infection-control measures were withheld for patients colonized with nonepidemic VRE (76 [54%] of 140 patients with a test result positive for VRE). Use of alcohol-based hand rubs increased by 31%-275% in outbreak wards. CONCLUSION: Genotyping-targeted infection control, isolation of VRE carriers, enhancement of hand-hygiene compliance, and preemptive isolation successfully controlled nosocomial spread of epidemic VRE infection.

Disease Outbreaks↗

PubMed1999

Two consecutive outbreaks of Stenotrophomonas maltophilia (Xanthomonas maltophilia) in an intensive-care unit defined by restriction fragment-length polymorphism typing.

OBJECTIVE: To investigate and control consecutive outbreaks of Stenotrophomonas maltophilia infections in intensive-care-unit (ICU) patients. DESIGN: Epidemiological investigation; restriction fragment-length polymorphism typing by pulsed-field gel electrophoresis (PFGE) of genomic DNA of outbreak strains; institution of infection control measures to limit spread. SETTING: The medical-surgical ICU in an 800-bed tertiary-care center in Calgary, Alberta, Canada. RESULTS: S. maltophilia was recovered from 14 ICU patients (12 infected, 2 colonized) between February 1993 and February 1994. Ten of the 14 patient isolates and 1 environmental isolate were available for PFGE typing. Patient isolates from 6 of the first 10 patients were identical. Isolates from the next 3 of 4 patients and an isolate recovered from a ventilator being used by a patient not infected with S. maltophilia also were identical, but different from the first 6. The ventilator isolate was temporally associated with the latter 4 patients. CONCLUSION: Molecular typing allowed us to determine that there were two separate consecutive S maltophilia outbreaks rather than a single protracted outbreak. Recovery of S. maltophilia from patient ventilators and an in-line suction catheter suggests that the organism may have been spread by cross-contamination from contaminated equipment or from an environmental source.

Aged↗

PubMed2002

Disruption of services in an internal medicine unit due to a nosocomial influenza outbreak.

OBJECTIVE: To describe a nosocomial influenza A outbreak, how it was managed, what impact it had on subsequent delivery of health care, and the additional charges attributable to it DESIGN: Prospective cohort study and microbiological investigation. SETTING: One internal medicine unit in an acute care, university-affiliated hospital. PARTICIPANTS: Twenty-three patients and 22 staff members from February 28 to March 6, 1999. RESULTS: Attack rates were 41% (9 of 22) among patients and 23% (5 of 22) among staff members, with 3 of 14 cases being classified as "certain." The influenza virus isolates were typed as A/SYDNEY/5/97 (H3N2). The index case was a patient who shared a room with the first nosocomial case. Vaccination rates for influenza virus were 43% (10 of 23) among patients and 36% (8 of 22) among staff members. The outbreak resulted in staff members' taking 14 person-days of sick leave. Furthermore, 8 scheduled admissions were postponed and all emergency admissions were suspended for 11 days. Hospital charges attributable to the influenza outbreak totaled $34,179 and the average extra charge per infected patient was $3,798. CONCLUSIONS: Nosocomial influenza outbreaks increase charges and alter the quality of care delivered in acute care settings. Strategies for their prevention need to be evaluated in acute care settings.

Cross Infection↗

PubMed2002

Nosocomial outbreak of Serratia marcescens in a neonatal intensive care unit.

OBJECTIVES: To investigate and describe an outbreak of Serratia marcescens in a neonatal intensive care unit (NICU) and to report the interventions leading to cessation of the outbreak. SETTING: A 2,168-bed, tertiary-care, university teaching hospital in Vienna, Austria, with an 8-bed NICU. DESIGN: We conducted a case-control study to identify risk factors for colonization and infection with S. marcescens. A case-patient was defined as any neonate in the NICU with a positive culture for S. marcescens between October 1, 2000, and February 28, 2001. Polymerase chain reaction was applied to type isolates. METHODS: During unannounced observations, the NICU was examined and existing policies were reviewed. Staff were reinstructed in hand antisepsis and gloving policies. Admissions were halted on December 27. During previously planned technical maintenance of the ward, the NICU was closed for 10 days and thorough aldehyde-based disinfection of the NICU was performed. RESULTS: Ten neonates met the case definition: 6 with infections (among them 3 with cerebral abscesses) and 4 with asymptomatic colonization. Previous antibiotic treatment of the mothers with cefuroxime was the single significant risk factor for colonization or infection (P = .028; odds ratio, 17; 95% confidence interval, 1.3 to 489.5). CONCLUSIONS: S. marcescens can cause rapidly spreading outbreaks associated with fatal infections in NICUs. With aggressive infection control measures, such outbreaks can be stopped at an early stage. Affected neonates themselves may well be the source of cross-infection to other patients on the ward. Antibiotic treatment of mothers should be reevaluated to avoid unnecessary exposure to antibiotics with the potential of over-growth of resistant organisms.

Antibiotic Prophylaxis↗

PubMed2003

A preventable outbreak of pneumococcal pneumonia among unvaccinated nursing home residents in New Jersey during 2001.

OBJECTIVE: To characterize risk factors for invasive pneumococcal infection in a nursing home outbreak. DESIGN: Outbreak investigation, case-control study. SETTING: A 114-bed nursing home in New Jersey. PARTICIPANTS: Case-patients were nursing home residents hospitalized with febrile respiratory illness and radiographic findings consistent with pneumonia, and either sputum specimens positive for diplococci or blood cultures positive for Streptococcus pneumoniae, with illness onset during April 3-24, 2001. Control-patients were selected randomly from remaining residents without respiratory symptoms. METHODS: Chart reviews were performed for case-patients and control-patients. Serotyping and susceptibility testing were performed on S. pneumoniae isolates. Long-term-care facilities (LTCFs) were surveyed to assess compliance with a state regulation mandating pneumococcal vaccination of residents 65 years and older. RESULTS: Nine case-patients were identified, with a median age of 86 years (range, 78 to 100 years). The median age of control-patients was 86 years (range, 58 to 95 years). No case-patients versus 9 (50%) control-patients received pneumococcal vaccine before the outbreak (OR, 0; CI95, 0-0.7). Recent antibiotic use, pneumonia history, and physical functioning were not associated with illness. Illness attack rate was 16% among all unvaccinated residents versus 0 among vaccinated residents. S. pneumoniae serotype 14, included in pneumococcal vaccine, was isolated from blood cultures of 7 case-patients. Of 361 LTCFs (42%) that replied to the survey, 28 (8%) were not complying with state immunization regulations. CONCLUSIONS: This outbreak occurred in an LTCF with low vaccine coverage. Implementing standing order programs, enforcing regulations, documenting vaccinations, and providing education might increase coverage among nursing home residents.

Aged↗

PubMed2003

An outbreak of methicillin-resistant Staphylococcus aureus in a neonatal intensive care unit.

OBJECTIVE: To describe the epidemiologic and molecular investigations that successfully contained an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) in a neonatal intensive care unit (NICU). DESIGN: Isolates of MRSA were typed by pulsed-field gel electrophoresis (PFGE) and S. aureus protein A (spa). SETTING: A level III-IV, 45-bed NICU located in a children's hospital within a medical center. PATIENTS: Incident cases had MRSA isolated from clinical cultures (eg, blood) or surveillance cultures (ie, anterior nares). INTERVENTIONS: Infected and colonized infants were placed on contact precautions, cohorted, and treated with mupirocin. Surveillance cultures were performed for healthcare workers (HCWs). Colonized HCWs were treated with topical mupirocin and hexachlorophene showers. RESULTS: From January to March 2001, the outbreak strain of MRSA, PFGE clone B, was harbored by 13 infants. Three (1.3%) of 235 HCWs were colonized with MRSA. Two HCWs, who rotated between the adult and the pediatric facility, harbored clone C. One HCW, who exclusively worked in the children's hospital, was colonized with clone B. From January 1999 to November 2000, 22 patients hospitalized in the adult facility were infected or colonized with clone B. Spa typing and PFGE yielded concordant results. PFGE clone B was identified as spa type 16, associated with outbreaks in Brazil and Hungary. CONCLUSIONS: A possible route of MRSA transmission was elucidated by molecular typing. MRSA appears to have been transferred from our adult facility to our pediatric facility by a rotating HCW. Spa typing allowed comparison of our institution's MRSA strains with previously characterized outbreak clones.

Cross Infection↗

PubMed2003

A Chryseobacterium meningosepticum outbreak in a neonatal ward.

OBJECTIVE: To report epidemiologic, bacteriologic, and clinical features of a Chryseobacterium meningosepticum outbreak. DESIGN: Outbreak investigation. SETTING: A neonatal intensive care unit (NICU) of a referral teaching hospital. METHODS: During 2 weeks in September 2001, four neonates in the NICU developed sepsis and underwent laboratory investigation. Multiple samples were obtained for cultures from endotracheal tubes, mechanical ventilators and humidifier boxes, infant incubators, parenteral and antiseptic solutions, feeding bottles, sinks, faucets, doors, and healthcare workers. RESULTS: C. meningosepticum was isolated from the blood cultures of four patients. The first isolate was identified 5 days after the death of the index case. Although all isolates were ciprofloxacin susceptible in vitro, the remaining three patients did not respond to ciprofloxacin therapy given for 6 or 7 days. Therapy was switched to vancomycin and rifainpin and all three patients survived, with one having a complication (hydrocephalus). Environmental surveillance revealed C. meningosepticum in the stock lipid solution as the source of the epidemic. The outbreak was controlled after discontinuation of intravenous lipid solution, restriction of further neonatal admissions, and thorough disinfection of the unit and its equipment. CONCLUSION: Early identification of an epidemic and its source is important in avoiding morbidity and mortality. A contaminated lipid stock bottle was the source of this outbreak associated with multiple cases and one death.

Chryseobacterium↗