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PubMed1999

Molecular epidemiological investigation using a randomly amplified polymorphic DNA assay of Burkholderia cepacia isolates from nosocomial outbreaks.

We experienced two Burkholderia cepacia outbreaks over a 1-year period. During this period, 28 B. cepacia isolates were obtained from clinical specimens, and 2 were obtained from environmental specimens (i.e., from a nebulizer solution and a nebulizer tube). These 30 isolates were subjected to the PCR-based randomly amplified polymorphic DNA (RAPD) assay as well as to pulsed-field gel electrophoresis (PFGE). In the first outbreak, in which eight patients hospitalized in the Trauma and Critical Care Center were involved, the RAPD assay revealed that all 20 isolates obtained from clinical specimens and the 2 isolates from environmental specimens had identical DNA profiles. These RAPD data enabled us to pinpoint a possible source and to take countermeasures to prevent further spread of the epidemic-causing strain. In the second outbreak, two consecutive B. cepacia infection/colonization cases were seen in the surgery ward. The RAPD profiles of four isolates obtained were again identical, but they were distinct from those seen in the first outbreak, clearly indicating that the second outbreak was not related to the first. Thus, our experience demonstrated that the RAPD assay is a useful and reliable tool for epidemiological studies of B. cepacia isolates from nosocomial outbreaks. Since the RAPD assay could provide discriminatory potential and reproducibility comparable to those of the widely used PFGE assay with less complexity and in a shorter time, the introduction of the RAPD assay into hospital microbiology laboratories as a routine technique may help prevent nosocomial outbreaks.

Bacterial Typing Techniques↗

PubMed1999

Molecular subtyping of Clostridium perfringens by pulsed-field gel electrophoresis to facilitate food-borne-disease outbreak investigations.

Clostridium perfringens is a common cause of food-borne illness. The illness is characterized by profuse diarrhea and acute abdominal pain. Since the illness is usually self-limiting, many cases are undiagnosed and/or not reported. Investigations are often pursued after an outbreak involving large numbers of people in institutions, at restaurants, or at catered meals. Serotyping has been used in the past to assist epidemiologic investigations of C. perfringens outbreaks. However, serotyping reagents are not widely available, and many isolates are often untypeable with existing reagents. We developed a pulsed-field gel electrophoresis (PFGE) method for molecular subtyping of C. perfringens isolates to aid in epidemiologic investigations of food-borne outbreaks. Six restriction endonucleases (SmaI, ApaI, FspI, MluI, KspI, and XbaI) were evaluated with a select panel of C. perfringens strains. SmaI was chosen for further studies because it produced 11 to 13 well-distributed bands of 40 to approximately 1,100 kb which provided good discrimination between isolates. Seventeen distinct patterns were obtained with 62 isolates from seven outbreak investigations or control strains. In general, multiple isolates from a single individual had indistinguishable PFGE patterns. Epidemiologically unrelated isolates (outbreak or control strains) had unique patterns; isolates from different individuals within an outbreak had similar, if not identical, patterns. PFGE identifies clonal relationships of isolates which will assist epidemiologic investigations of food-borne-disease outbreaks caused by C. perfringens.

Centers for Disease Control and Prevention, U.S.↗

PubMed2001

Molecular epidemiology of a Shigella flexneri outbreak in a mountainous township in Taiwan, Republic of China.

An outbreak of shigellosis occurred in a township of Nantou Conuty in central Taiwan from August to October in 1996. The infections extended to two neighboring townships and continued to the end of 1996. Forty cases were confirmed during the period, in contrast to only one confirmed case in Nantou County in 1996 before the outbreak. All of these 41 cases in 1996 were identified as infections with Shigella flexneri serotype 2a. In order to trace the source of the infections, the 41 isolates recovered were analyzed by plasmid profile and pulsed-field gel electrophoresis (PFGE). There was no correlation between the plasmid profile results and the PFGE results, and the latter were used for subtyping of the 41 isolates. Twenty-two isolates (53%) had the same NotI and XbaI PFGE patterns, and 4 isolates (10%) had an additional unstable plasmid band in their NotI patterns but otherwise had the same NotI and XbaI patterns as the 22 isolates. These 26 isolates were designated the outbreak strain, and of these, 24 appeared in eight villages in one township and 2 appeared in a neighboring township. Fourteen of the remaining 15 isolates, including the isolate recovered 7 months before the outbreak, had both NotI and XbaI PFGE patterns closely related to those of the outbreak strain, indicating that Shigella infections were endemic in the area. By tracing the first isolation dates of the outbreak strain in individual villages and the neighboring township, it was found that the strain spread along the major arterial road and its branch road as time passed. Our molecular typing results and epidemiological data demonstrated the endemic nature of the outbreak strain as well as a person-to-person mode of transmission for the widespread infections the strain caused.

Adolescent↗

PubMed1989

Outbreaks of salmonella infection in hospitals in England and Wales 1978-87.

A total of 248 outbreaks of salmonella infection in hospital affecting over 3000 patients and 110 associated deaths were ascertained in England and Wales in 1978-87, compared with 522 outbreaks of salmonella in 1968-77. The largest reduction was found in outbreaks from children's units and maternity units. Fifty seven (24%) outbreaks were considered to be due to foodborne salmonellosis, and 70 (30%) were reported as person to person spread of the infection. The psychiatric hospital was the type of hospital in which foodborne outbreaks most often occurred, but the risk of being affected in an outbreak not due to food seemed to be highest in maternity units. Better control of infection and better surveillance should lead to earlier investigation and control of outbreaks.

Cohort Studies↗

PubMed2001

Gastroenteritis outbreaks associated with Norwalk-like viruses and their investigation by nested RT-PCR.

BACKGROUND: Norwalk-like viruses are the most common cause of gastroenteritis outbreaks and sporadic cases of vomiting and diarrhoea. In healthy individuals infection is often mild and short-lived but in debilitated patients infection can be severe. It is essential that the virus laboratory can offer a sensitive and specific test, delivered in a timely manner. METHODS: We have developed a nested reverse transcriptase PCR based on published primers against the RNA polymerase gene and after comparison with electronmicroscopy used the assay to investigate 31 outbreaks of gastroenteritis. These were in diverse situations including nursing homes, small district hospitals, large general hospitals, a ferry ship, hotels, restaurants and staff canteens. RESULTS: A positive diagnosis was made in 30/31 outbreaks investigated giving an overall outbreak positive detection rate of 97%. At an individual patient level there was a positive diagnostic rate of 11.5% in a large hospital environment to 100% in smaller outbreak situations. The average patient positive rate was 34%. In addition we investigated 532 control faecal specimens from adults. Of these 530 were negative and 2 were repeatedly positive. CONCLUSIONS: It is essential that insensitive electronmicroscopy is replaced with the more sensitive reverse transcription PCR assays. These tests should be made available "on call" at weekends and public holidays. It is also important that outbreaks of NLV infection are monitored using sensitive RT-PCR assays so that the laboratory information can be used in ascertaining the spread and duration of the outbreak.

Adolescent↗

PubMed2001

Varicella outbreak at a summer camp for human immunodeficiency virus-infected children.

OBJECTIVES: Varicella can result in severe, persistent, or recurrent disease in human immunodeficiency virus (HIV)-infected children. In the summer of 1997, we were notified of a suspected varicella outbreak among attendees of a summer camp for HIV-infected children. We investigated this outbreak to determine the extent and sequelae of the outbreak, and to identify factors that contributed to the outbreak to identify measures for preventing such outbreaks at the camp in the future. DESIGN: To identify varicella-susceptible persons and those developing varicella after camp and to evaluate the camp's varicella prevention measures, we reviewed camp records for the 110 campers and 96 staff at the implicated camp session, mailed questionnaires to the campers' parents/guardians and physicians, and interviewed susceptible staff. We defined a case as varicella in a person who attended the session with onset </=21 days after the session ended. RESULTS: Eleven of 31 susceptible children (36%) and 2 of 4 susceptible adults developed varicella. Two children were hospitalized. One developed cellulitis. Cases occurred among children in 5 of 15 cabins. The most likely index case was a child with active zoster at camp, reported to the camp after the session ended. The camp had varicella-prevention measures in place, but the varicella-susceptibility and exposure information provided to the camp was often incomplete or inaccurate. Staff with no varicella history underwent serologic testing, but susceptible staff members were not vaccinated. CONCLUSIONS: Widespread varicella transmission occurred at the camp. A case of zoster was the most likely source. The risk for such outbreaks can be minimized through vaccinating susceptible staff members, considering vaccination for asymptomatic or mildly symptomatic HIV-infected children according to Advisory Committee on Immunization Practices and American Academy of Pediatrics guidelines, rigorously collecting recent varicella and zoster exposure information, excluding anyone with active varicella or zoster or with recent varicella or zoster exposure, and considering varicella and zoster exposures at camp to be potentially camp-wide.varicella, human immunodeficiency virus infections, disease outbreaks, intravenous immunoglobulin.

Adolescent↗

PubMed1989

Results of routine restaurant inspections can predict outbreaks of foodborne illness: the Seattle-King County experience.

To analyze the association between the results of routine inspections and foodborne outbreaks in restaurants, we conducted a matched case-control study using available data from Seattle-King County, Washington. Case restaurants were facilities with a reported foodborne outbreak between January 1, 1986 and March 31, 1987 (N = 28). Two control restaurants with no reported outbreaks during this period were matched to each case restaurant on county health district and date of routine inspection (N = 56). Data from the routine inspection that preceded the outbreak (for case restaurants) or the date-matched routine inspection (for control restaurants) were abstracted from computerized inspection records. Case restaurants had a significantly lower mean inspection score (83.8 on a 0 to 100 point scale) than control restaurants (90.9). Restaurants with poor inspection scores and violations of proper temperature controls of potentially hazardous foods were, respectively, five and ten times more likely to have outbreaks than restaurants with better results. Although this study demonstrates that Seattle-King County's routine inspection form can successfully identify restaurants at increased risk of foodborne outbreaks, it also illustrates that more emphasis on regulation and education is needed to prevent outbreaks in restaurants with poor inspection results.

Disease Outbreaks↗

PubMed2000

Isolation of respiratory bovine coronavirus, other cytocidal viruses, and Pasteurella spp from cattle involved in two natural outbreaks of shipping fever.

OBJECTIVE: To identify cytocidal viruses and Pasteurella spp that could be isolated from cattle involved in 2 natural outbreaks of shipping fever. ANIMALS: 105 and 120 castrated male 4- to 8-month-old feedlot cattle involved in 1997 and 1998 outbreaks, respectively. PROCEDURES: Nasal swab specimens and blood samples were collected, and cattle were vaccinated on arrival at an order-buyer barn from 4 local auction houses. Four days later, they were transported to a feedlot, and additional nasal swab specimens and blood samples were collected. Nasal swab specimens were submitted for virus isolation and bacterial culture; blood samples were submitted for measurement of respiratory bovine coronavirus (RBCV) hemagglutinin inhibition titers. RESULTS: 93 of 105 cattle and 106 of 120 cattle developed signs of respiratory tract disease during 1997 and 1998, respectively, and RBCV was isolated from 81 and 89 sick cattle, respectively, while at the order-buyer's barn or the day after arrival at the feedlot. During the 1997 outbreak, bovine herpesvirus 1 was isolated from 2 cattle at the order-buyer's barn and from 5 cattle 7 and 14 days after arrival at the feedlot, and parainfluenza virus 3 was isolated from 4 cattle 14 days after arrival at the feedlot. During the 1998 outbreak, bovine herpesvirus 1 was isolated from 2 cattle at the order-buyer's barn and on arrival at the feedlot and from 5 cattle 7 and 14 days after arrival at the feedlot, and parainfluenza virus 3 was isolated from 1 animal the day of, and from 18 cattle 7 and 14 days after, arrival at the feedlot. Pasteurella spp was cultured from 4 and 6 cattle at the order-buyer's barn and from 92 and 72 cattle on arrival at the feedlot during the 1997 and 1998 outbreaks, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that RBCV may play a causative role in outbreaks of shipping fever in cattle. More than 80% of the sick cattle shed RBCV at the beginning of 2 outbreaks when the Pasteurella spp infection rate was low.

Animals↗

PubMed1993

Comparative studies on pharyngeal carriage of Neisseria meningitidis during a localized outbreak of serogroup C meningococcal disease.

An outbreak involving 20 cases of serogroup C meningococcal disease, predominantly among teenagers, occurred over a 7-month period in the Randers area of Denmark. The cases were caused by serogroup C:2a:P1.2 sulphonamide-resistant strains. The available evidence was against the transmission being related to particular schools. The outbreak was experienced as 3 clusters. At 2 schools involved in the first and the third cluster of the outbreak, 351 students were examined regarding pharyngeal carriage of meningococci, 282 of whom were tested again 17 weeks later; 308 students attending two similar schools in a nearby area were examined once. The majority of strains isolated from group C carriers in the high-risk area were serologically indistinguishable from the outbreak strain (13/14 = 95%), but less often sulphonamide-resistant (5/13 = 38%). In both areas, the overall rate (30%), the overall group C rate (3%), the carrier rate for the outbreak strain (1%) were the same. The attack rate for the outbreak strain differed significantly: 1/40 in the high-risk area versus 1/2,500 in the normal risk area. No conditions that might explain this difference were revealed. Immediately after recognition of the first and the third cluster, 780 and 13,300 students, respectively, were vaccinated with meningococcal polysaccharide vaccine A+C. It was concluded that the definition of target groups for vaccination should be liberal, because the "at risk" population may be difficult to recognize at the onset of an outbreak.

Adolescent↗

PubMed1996

Use of interrepeat PCR fingerprinting to investigate an Acinetobacter baumannii outbreak in an intensive care unit.

An epidemiological investigation of an outbreak of Acinetobacter baumannii among patients on 2 closely related intensive care units (ICU) was performed by molecular typing with interrepeat polymerase chain reaction (interrepeat PCR). 31 A. baumannii isolates obtained from 15 ICU patients were characterized. All patients were infected or colonized with A. baumannii. After identification of the outbreak, 6 environmental isolates were collected from tap-water, sinks and cleaning detergents. PCR fingerprinting identified 3 genotypes among the outbreak-related strains. One predominant genotype was demonstrated in 14/15 patients and this genotype was also found among all environmental isolates. The cluster of A. baumannii represented an outbreak of 1 genotype, suggesting cross-contamination. The finding of the identical genotype among all environmental strains indicated a common environmental source causing the outbreak. The outbreak was controlled after reimplementation of an effective disinfection of workplace surfaces. This survey proved interrepeat PCR to be a rapid and reliable method to differentiate A. baumannii strains, thereby allowing epidemiological surveillance of large amounts of strains and early interventions to control outbreaks.

Acinetobacter↗

PubMed1999

Hepatitis A outbreaks among illicit drug users and their contacts in Queensland, 1997.

OBJECTIVE: To describe five outbreaks of hepatitis A virus (HAV) infection associated with illicit drug use during a statewide outbreak of HAV infection in Queensland. DESIGN: Risk factor prevalence survey. PATIENTS AND SETTING: All 875 cases of HAV infection notified to Public Health Units in Queensland in the 12 months to 30 November 1997. MAIN OUTCOME MEASURE: Type and prevalence of illicit drug use. RESULTS: Risk factor assessment was completed for 804 cases (91.9%). We identified five outbreaks of HAV infection linked to illicit drug use. These outbreaks accounted for 24.6% (215/875) of all notified cases and 39% (190/482) of notified cases in the 15-34 years age group. The main type of illicit drug use in four of the five outbreaks was injecting drug use (74%; 118/160), while in the other outbreak it was sharing of smoking implements for marijuana (38%; 21/55). CONCLUSION: Illicit drug use may be an under-recognised risk factor for HAV infection, particularly in young people. Faecal-oral transmission through poor personal hygiene, including sharing of implements for smoking marijuana, is the most probable route of transmission in these drug-linked outbreaks. The role of contaminated drug and needle-sharing remains to be clarified.

Adolescent↗

PubMed1999

Outbreaks of Shigella sonnei infection associated with eating fresh parsley--United States and Canada, July-August 1998.

In August 1998, the Minnesota Department of Health reported to CDC two restaurant-associated outbreaks of Shigella sonnei infections. Isolates from both outbreaks had two closely related pulsed-field gel electrophoresis (PFGE) patterns that differed only by a single band. Epidemiologic investigations implicated chopped, uncooked, curly parsley as the common vehicle for these outbreaks. Through inquiries to health departments and public health laboratories, six similar outbreaks were identified during July-August (in California [two], Massachusetts, and Florida in the United States and in Ontario and Alberta in Canada). Isolates from five of these outbreaks had the same PFGE pattern identified in the two outbreaks in Minnesota. This report describes the epidemiologic, traceback, environmental, and laboratory investigations, which implicated parsley imported from a farm in Mexico as the source of these outbreaks.

Apiaceae↗

PubMed2000

A multi-state outbreak of tuberculosis among members of a highly mobile social network: implications for tuberculosis elimination.

SETTING: Baltimore, Maryland. OBJECTIVE: To describe a tuberculosis (TB) outbreak among a highly mobile population and the efforts required to control it. DESIGN: Epidemiologic outbreak investigation. RESULTS: Between June 1998 and January 2000, 20 TB outbreak cases were identified, of which 18 were culture-confirmed. Seventeen isolates of Mycobacterium tuberculosis had an identical 11-band DNA fingerprint; another isolate had one additional band and was considered a match. Two cases were diagnosed in New York City; another patient lived primarily in Atlanta, but was diagnosed in Baltimore. Persons in the outbreak were predominantly young (median age 24 years), black, male, infected with the human immunodeficiency virus (HIV), and gay, transvestite or transsexual. Activities common among many TB cases included attending two nightclubs, membership in one of three social 'Houses', attending balls or pageants in East Coast cities, marijuana use, and prostitution. Community outreach, extended contact tracing, DNA fingerprinting, directly-observed therapy, and expanded use of preventive therapy were utilized to assess and control the outbreak. During the outbreak period the Baltimore City TB rate declined by 10%. However, additional public health personnel were required to control the outbreak, resulting in a 17% increase in TB clinic staff. CONCLUSION: As TB rates decline, remaining cases are likely to occur in difficult-to-reach populations. Increased resources per case of TB treated will be required to eliminate TB.

AIDS-Related Opportunistic Infections↗

PubMed2001

Community surveys of self-reported diarrhoea can dramatically overestimate the size of outbreaks of waterborne cryptosporidiosis.

This paper describes a community-based study undertaken to assess the size of a waterborne outbreak of cryptosporidiosis in the North West region of England. The outbreak was linked to a single reservoir in the English Lake District and provided drinking water to over 1.2 million people. There were some 308 laboratory confirmed cases. We conducted a community-based survey for self-reported diarrhoea in four towns within the outbreak area and four control towns. The rate of self-reported diarrhoea was higher in the control towns than in the outbreak towns. It would appear that retrospective community-based studies of diarrhoeal disease are subject to recall bias that would overestimate the incidence of illness, especially following reporting in the media. In the light of our findings, we reviewed the study undertaken during the Milwaukee outbreak that produced the estimated size of 405,000 cases. It is suggested that the estimate of the size of the Milwaukee outbreak is severely flawed, and the actual size of this outbreak was between 1% and 10% of that claimed.

Bias↗

PubMed2001

General outbreaks of infectious intestinal disease linked with poultry, England and Wales, 1992-1999.

Between 1992 and 1999, 1426 foodborne general outbreaks of infectious intestinal disease (IID) were reported to the Public Health Laboratory Service Communicable Disease Surveillance Centre. A fifth were associated with the consumption of poultry. Chicken was implicated in almost three quarters of these outbreaks, turkey in over a fifth and duck in 2% of outbreaks. The organisms most frequently reported were Salmonella (30% of outbreaks), Clostridium perfringens (21%) and Campylobacter (6%). Over 7000 people were affected, with 258 hospital admissions and 17 deaths. During the summer, outbreaks were mainly of salmonellosis and attributed to the consumption of chicken. In December, C. perfringens and turkey were the organism and vehicle most often implicated. Most outbreaks occurred on commercial catering premises (56%) or in private houses (21%). The highlight of this surveillance period was the fall in outbreaks of salmonellosis linked with poultry products, probably due, at least in part, to the vaccination of poultry flocks.

Animals↗

PubMed1990

[The main characteristics of outbreaks of hospital infections in the USSR in 1986-1988].

The analysis of 69 outbreaks of hospital infections in different regions of the USSR in 1986-1989 (the number of patients affected by these infections was 1,517) showed that most of these outbreaks (41) occurred at hospital wards for newborn infants. Acute enteric infections prevailed in the total structure of the outbreaks (73.7%). Purulent septic infections among newborns constituted a quarter of all outbreaks. Opportunistic microbes, and mainly Klebsiella, were the dominating element in the etiology of outbreaks in hospital wards for newborn infants. In pediatric wards in among adult hospital patients the etiology of outbreaks was completely, or almost completely, determined by pathogenic microorganisms, mainly salmonellae and shigellae. Outbreaks among hospital patients of three above-mentioned groups were characterized by differences in sources, routes and factors of the transmission of infection.

Adult↗

PubMed1988

Three outbreaks of yersinia pseudotuberculosis infection.

Three outbreaks of Yersinia pseudotuberculosis infection during 1982 to 1984 in Okayama Prefecture, Japan are described. In outbreak A, Yersinia pseudotuberculosis a causal organism was detected in 16 patients (serotype 5A). The latent period of the infection was 2 to 20 days estimating, from time of ingesting food suspected of being contaminated and onset of the illness. Outbreak B and C occurred in remote mountain areas. In outbreak B, Yersinia pseudotuberculosis bacilli were detected in the feces of 35 out of 276 people (serotype 4B in 34 stools, 2C and 4B in one stool). In outbreak C, 12 children became sick; one of the 4 patients whose stools were examined, showed an organism belonging to serotype 4B. The inhabitants in the area of outbreak B and C took unchlorinated mountain stream and well water for drinking. After the outbreak B and C, we examined water and wild animals fecea in these areas for the bacilli. As a result, they were detected in 3 out of 51 water samples (serotype 4A in one, 6 in 2 samples) and 2 out of 57 wild animal fecal samples (serotype 2C in 2 samples) in B area, and 4 out of 33 water samples (serotype 4A in 2, 4B in 2 samples) in C area.

Adolescent↗

PubMed1988

An outbreak of typhoid fever due to contamination of the municipal water supply in northern Israel.

An outbreak of typhoid fever followed a large outbreak of dysentery in northern Israel. Both outbreaks resulted from contamination of a drilled well that supplied water to the municipal water system. The well was contaminated with sewage from a broken main-pipe coming from Shefaram (an Arab town). The outbreak of typhoid involved 77 persons, of whom 75 were hospitalized. In 67, phage-type C1 (the phage type dominant in Shefaram since the 1950s) was isolated. The incubation period was relatively long, between 12 and 40 days (median 22) following exposure. Over 50% of the cases were children aged 0 to 14, and only two patients were older than 35 years; the sex ratio among the patients was 1:1. The incidence rate in Shefaram was 2.3 times higher than in the Krayot (outlying suburbs of Haifa). This difference was due mainly to the high incidence in young females in Shefaram. The opposite was observed during the outbreak of dysentery, when the attack rates of the disease were higher in the Krayot. Relapses occurred in 12% (9 cases). This outbreak demonstrates the potential that still exists for serious outbreaks due to contamination of the municipal water supply.

Adolescent↗