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PubMedDate not supplied

Investigation of multistate foodborne disease outbreaks.

The U.S. food supply is characterized increasingly by centralized production and wide distribution of products, and more foodborne disease outbreaks are dispersed over broad geographic areas. Such outbreaks may present as a gradual, diffuse, and initially unapparent increase in sporadic cases. Recognition and reporting by clinicians and local public health officials and the ordering of laboratory tests by clinicians continue to be cornerstones of detecting all outbreaks. New methods--such as active laboratory-based surveillance, automated algorithms for detecting increases in infection rates, and molecular subtyping--facilitate detection of diffuse outbreaks. Routines have evolved for the investigation of multistate outbreaks; they are characterized by rapid communication between local, state, and federal public health officials; timely review of epidemiologic data by expert panels; collaboration on tracebacks with food safety regulatory agencies; and communication with the public and media. Rapid, efficient investigation of multistate outbreaks may result in control of acute public health emergencies, identification and correction of hazardous food production and processing practices, and consequent improvement in food safety.

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

PubMed2000

Escherichia coli O157:H7; an economic assessment of an outbreak.

BACKGROUND: The aim of the study was to assess the impact of an outbreak of Escherichia coli O157:H7 that occurred in 1994 in a rural community, with a population of approximately 107,000, to the west of Edinburgh. METHODS: The impact of the outbreak was assessed during the acute phase of the illness and in the subsequent 12 months. The method involved three surveys of confirmed cases using general practice notes, hospital records and interviews with cases. Key persons involved in the investigation and control of the outbreak were also interviewed. The impact of the illness on cases and their families was estimated and the resources used to treat cases and to control the outbreak were costed and long-term costs projected. RESULTS: There were 71 cases whose ages ranged from 7 months to 84 years. The mortality rate was 1.4 per hundred cases. There were 10 cases of haemolytic uraemic syndrome (HUS) and one case of thrombotic thrombocytopenia purpura (TTP). Two children were on long-term dialysis. Co-morbidity involving the immune system was associated with hospital admission. The illness lasted on average 6.9 weeks. Twenty-six per cent of cases reported symptoms 12 months later. The average cost per HUS case was 62,353 pound sterlings, the TTP case cost 21,422 pound sterlings, non-HUS and non-TTP cases cost 1,030 pound sterlings. The costs of investigating and controlling the outbreak were 171,848 pound sterlings. The costs of cases projected over 30 years were 11.9 million pound sterlings, or 168,032 pound sterlings per case. CONCLUSIONS: The impact on the health of cases was considerable and the costs were high. Every effort should be made to prevent the disease and to identify and control outbreaks quickly.

Adolescent↗

PubMed1995

High incidence of congenital rubella syndrome after a rubella outbreak.

Previous studies of the incidence of congenital rubella syndrome (CRS) after rubella outbreaks have been limited because most women with infection during the first trimester elected to have their pregnancies terminated. After a rubella outbreak in 1991 we measured prospectively the impact of maternal infection on CRS among the Amish in one county in Pennsylvania. We compared rubella serology of Amish women delivering before and after the outbreak and cord blood rubella IgM from Amish and non-Amish infants. Before the outbreak 20% of Amish women were susceptible to rubella; after the outbreak 4% were (P = 0.001). Of Amish infants 15% tested positive for rubella IgM; no non-Amish infants did (P < 0.001). This rubella outbreak in a largely unimmunized community led to a high rate of CRS. The annual CRS rate among the Amish was 2130/100,000 live births. Health care providers should promote immunization in all clients and intensify efforts among the Amish.

Antibodies, Viral↗

PubMed1997

Impact of a massive waterborne cryptosporidiosis outbreak on child care facilities in metropolitan Milwaukee, Wisconsin.

OBJECTIVE: We describe the impact of the 1993 waterborne cryptosporidiosis outbreak on metropolitan Milwaukee child care homes and centers. METHODS: Information on outbreak-related illness and changes in policies and practices was collected from directors of 117 facilities. Stool specimens from 129 diapered children from 11 centers were screened for Cryptosporidium. RESULTS: Most (74%) facility directors reported children or staff with diarrhea during the outbreak; however, only 4 (3.4%) facilities closed because of illness among staff or children. During the outbreak child care homes were less likely to exclude children with diarrhea than were child care centers. Among diapered children attending centers the Cryptosporidium prevalence was 30%; 29% of infected children had no history of diarrhea associated with the Milwaukee outbreak. CONCLUSIONS: Facilities continued to operate during the outbreak despite considerable illness among children and staff. The news media were effective means for providing public health information to child care facilities. Although secondary transmission undoubtedly took place in child care facilities, the presence of children with asymptomatic Cryptosporidium infections did not result in an increased risk of diarrhea in infant and toddler rooms.

Adult↗

PubMed1999

Evaluating the use of penicillin to control outbreaks of acute poststreptococcal glomerulonephritis.

INTRODUCTION: Outbreaks of acute poststreptococcal glomerulonephritis (APSGN), occur every few years in remote Australian Aboriginal communities. Intervention with benzathine penicillin G (BPG) to all children is effective in reducing streptococcal carriage in a community, but its effectiveness in arresting outbreaks of APSGN has not been established. OBJECTIVE: To study nine recent community outbreaks of APSGN in Australia's Northern Territory and compare them with outbreaks reported in the literature to assess the impact of intervention with BPG. METHODS: Because randomized controlled trials have not been conducted for this purpose, we assessed data from published observational studies and relevant experiences in the Northern Territory (NT). Eight of the nine outbreaks in the NT were studied prospectively. An outbreak was defined as two or more clinical cases of APSGN occurring within 1 week in a single community. Three intervention methods were used: intramuscular BPG to all children ages 3 to 15 years; BPG only to children with skin lesions; and BPG only to child contacts of clinical cases. The attack rates, number of clinical cases before and after the interventions were documented and the coverage of children with penicillin were estimated. RESULTS: A review of the literature found very little evidence either for or against the effectiveness of intervention with BPG. In our study four communities used the first method of intervention. The community with the lowest uptake of penicillin continued to have cases in untreated children for 9 further weeks, two communities had no new cases from 3 weeks after the intervention and the fourth had a single further case after 4 weeks. The one community that used the second method had a high initial attack rate but no further cases from 1 week after the intervention. Three communities used the third method and in one community no intervention was attempted. CONCLUSION: Our observational study supports the use of BPG in the community to prevent new cases of APSGN. It suggests that targeted treatment of children with skin sores and household contacts of cases, rather than attempted treatment of all children in the community, could be an effective method of intervention.

Acute Disease↗

PubMed1994

Outbreaks of syphilis in rural Texas towns, 1991-1992.

Between 1986 and 1990, rates of primary and secondary syphilis increased 134% in rural counties in the South. Reasons for the increases are speculative. During the 14 months ending in October 1992, outbreaks in four eastern Texas counties provided an opportunity to characterize syphilis in rural Texas. We reviewed records for 118 patients and 339 sex partners. Three outbreaks were concentrated in neighborhoods where crack cocaine dealers conducted business and exchange of sex for drugs or money was common; the fourth outbreak involved out-of-town prostitutes who visited undocumented alien workers. Among the 118 syphilis cases, 15 (13%) were primary, 35 (30%) were secondary. Most patients were black (105, 89%); the male-female ratio was 1:1. One woman gave birth to an infant with congenital syphilis. Almost half of the sex partners were infected. HIV pretest counseling was completed for only 55 patients (47%), and only 23 (19%) were tested for the human immunodeficiency virus. These four rural outbreaks of syphilis associated with crack cocaine and the exchange of sex for drugs or money mirror recent urban syphilis outbreaks. Patients in these rural syphilis outbreaks are at risk for HIV infection, but HIV testing has not been emphasized by public health workers.

Adult↗

PubMed2001

Amplification dynamics: predicting the effect of HIV on tuberculosis outbreaks.

HIV affects the pathogenesis and the transmission of Mycobacterium tuberculosis. We used a discrete event simulation model to predict the potential impact of HIV on increasing the probability and the expected severity of tuberculosis outbreaks. Our predictions reveal that an HIV epidemic can significantly increase the frequency and severity of tuberculosis outbreaks, but that this amplification effect of HIV on tuberculosis outbreaks is very sensitive to the tuberculosis treatment rate. At moderate or low treatment rates, even a moderate HIV epidemic can cause the average size of tuberculosis outbreaks to almost double in comparison with the expected outbreak size when HIV is absent. However, we determined that the amplification effect of HIV can be substantially reduced if the treatment rate of tuberculosis is very high. We discuss the significant implications of these results for the global control of tuberculosis. Our results also reveal that occasionally a "normal-virulence" strain of M. tuberculosis can be expected to generate a large outbreak. We discuss the implications of these results in understanding the virulence of M. tuberculosis and in the planned elimination of tuberculosis in the United States.

Antitubercular Agents↗

PubMed2003

Burden of congenital rubella syndrome after a community-wide rubella outbreak, Rio Branco, Acre, Brazil, 2000 to 2001.

BACKGROUND: During 1999 and 2000 rubella outbreaks were reported in 20 of 27 states in Brazil, many among young adults. We investigated a large rubella outbreak in Rio Branco, Acre, in northwestern Brazil, where rubella vaccination targeting children 1 to 11 years old had been introduced in April 2000. Surveillance for congenital rubella syndrome (CRS) was initiated after the outbreak. METHODS: Suspected rubella cases were detected through active and passive surveillance. Confirmed rubella cases were patients with fever, rash and rubella-specific IgM antibodies. Suspected CRS cases were infants born with CRS-compatible defects or born to mothers with a history of rubella during pregnancy. Confirmed cases were infants with CRS-compatible defects and rubella-specific IgM antibodies. RESULTS: From April 1 to December 31, 2000, 391 confirmed rubella cases were reported. The incidence among persons ages 12 to 19 years (3.3 per 1000 population) was increased 3.7-fold relative to children ages 1 to 4 years (95% confidence interval, 2.4 to 5.8). Of 21 infants with suspected CRS cases, 17 (91%) were tested for rubella-specific antibodies, of whom 7 were IgM-positive and 5 had confirmed CRS. The peak incidence of confirmed CRS (4.3 per 1000) was in March 2001, 7 months after the outbreak peak, with an annualized incidence of 0.6 per 1000. CONCLUSIONS: Vaccination among school age children was insufficient to prevent a rubella outbreak among young adults that resulted in the occurrence of at least 5 cases of CRS. To prevent further cases of CRS, outbreak vaccination of young adults was conducted in November 2000 and among women ages 12 to 39 years in 2001 as part of a national campaign, with a coverage of 98% statewide.

Adolescent↗

PubMed2005

Medical and economic impact of a respiratory syncytial virus outbreak in a neonatal intensive care unit.

BACKGROUND: Respiratory syncytial virus (RSV) causes frequent nosocomial outbreaks in general pediatric wards but is less commonly reported in neonatal intensive care units (NICUs). We investigated an outbreak of RSV infection in a NICU and its impact on health care delivery, outcomes and costs. METHODS: Retrospective chart review was performed after an RSV outbreak occurred in the NICU. A case was defined as an infant with a nasopharyngeal aspirate positive for RSV by viral culture. Nucleotide sequencing of the isolates was done to determine relatedness. Hospital bills for all RSV culture-positive infants were reviewed. RESULTS: Nine infants (mean age, 34 days; mean birth weight, 1757 g; and mean estimated gestational age 31 weeks and 5 days) were infected with RSV subgroup B during this outbreak. By nucleotide sequencing, the isolates were identical. Clinical manifestations included cough, congestion, increased oxygen requirement, apnea and respiratory failure. The 5 infants requiring intubation had a significantly lower mean birth weight (1301 g versus 2328 g, P = 0.027), mean estimated gestational age (28 weeks and 5 days versus 35 weeks and 2 days, P = 0.014) and mean weight at onset of symptoms (2093 g versus 2989 g, P = 0.049) than the 4 nonintubated infants. More than 1.15 million dollars in hospital charges were attributable to the outbreak. All infants survived. CONCLUSION: Infants in a NICU who develop cough, congestion or apnea should be tested for RSV and other common respiratory viruses during the winter respiratory season. Even in a closed NICU, nosocomial outbreaks of these viruses can occur and have a major effect on healthcare delivery, costs and outcomes.

Cross Infection↗

PubMed2006

Varicella vaccine effectiveness during an outbreak in a partially vaccinated population in Spain.

BACKGROUND: An outbreak of varicella occurred between December 2004 and April 2005 in the primary school and day-care center of a town of 5430 inhabitants in Spain. Although the varicella vaccine is not included in the infant vaccination program, some children had been vaccinated before the outbreak. STUDY AIM: The aim of this study was to estimate varicella vaccine effectiveness during an outbreak that took place in a partially vaccinated population of children. METHODS: A cohort study was carried out. Cases were identified through notification by doctors and active search. Information was gathered on the current disease, history of varicella and previous vaccinations together with age, course, school year and other sociodemographic factors. The relative risk (RR) of varicella and the contribution of the previously mentioned factors to the probability of contracting the disease was estimated for vaccinated and unvaccinated children. RESULTS: Participation reached 96.5% (387 of 401 children) in the school and 91.2% (31 of 34 children) in the day-care center. Of 269 children with no history of varicella and with a documented vaccination record, 96 (35.7%) had been previously vaccinated. During the outbreak, 148 cases of varicella were observed. The overall attack rate was 54.4%, 22.9% in vaccinated and 72.8% in unvaccinated children. RR of varicella in vaccinated children was 0.31 (95% confidence interval [CI] = 0.21-0.46). The overall adjusted vaccine effectiveness against varicella was 69.5% (95% CI = 50.5-81.5%) and 96.9% (95% CI = 77.5-99.6%) against mild and severe forms. Only time since vaccination was associated with vaccine failure. CONCLUSIONS: In the varicella outbreak studied, we conclude that vaccine was effective in the prevention of the disease, particularly in its moderate and severe forms, but because the proportion of vaccinated children was low, an outbreak still occurred.

Age Factors↗

PubMed2005

Outbreaks of viral gastroenteritis: what's new in 2004?

PURPOSE OF REVIEW: Descriptions of outbreaks of viral gastroenteritis have become a prominent feature in scientific journals and other media such as the electronic reporting service 'promed'. A review of outbreak reports was done to further our understanding of the burden of disease, common and rare modes of transmission, complications, and possibilities for control and prevention. RECENT FINDINGS: Viral gastroenteritis outbreaks occur worldwide. In 2004, besides outbreak reports and surveys, there was considerable attention paid to food and waterborne outbreaks and the difficulties in proving these modes of transmission. Costs of viral gastroenteritis outbreaks are high. Complications and unusual manifestations of viral gastroenteritis, such as convulsions, transplant rejection, and chronic infection, may have been underreported. SUMMARY: Viral gastroenteritis is a very common illness in health care settings that can cause significant disruption. Clinicians working in these settings should be familiar with the epidemiology and the possible modes of transmission of enteric viruses to be able to translate them into strategies for prevention or intervention. Research is needed to support these strategies.

Communicable Diseases, Emerging↗

PubMed2001

Multiple outbreaks of Norwalk-like virus gastro-enteritis associated with a Mediterranean-style restaurant.

The role of diverse infectious agents, particularly Norwalk-like viruses (NLV), in three successive gastro-enteritis outbreaks in one setting (a restaurant) was evaluated. Methods included standard bacteriological tests, specific tests for Escherichia coli, tests for verocytotoxins, electron microscopy (EM) for viruses and reverse transcription-PCR (RT-PCR) methodology for NLV. No pathogenic bacteria were detected. Verocytotoxin genes, although detected by PCR in the first outbreak, could not be confirmed in the E. coli isolated, so they did not appear to be of significance. NLV was the main agent detected in each of the three outbreaks. DNA sequencing and phylogenetic analysis of the amplified products obtained from the RT-PCR positive specimens indicated that only one NLV strain was involved in each outbreak, but the NLV strains responsible for the three outbreaks were different from each other. PCR technology for detection of NLV proved highly sensitive, but failed to detect one specimen which was positive by EM. The restaurant associated with the outbreaks is a Mediterranean-style restaurant where food from a common platter is typically eaten with fingers. The findings indicate that NLV was introduced by guests or staff and was not due to a long-term reservoir within the setting.

Caliciviridae Infections↗

PubMed1998

Epidemiologic study of Shigella sonnei from sequential outbreaks and sporadic cases using different typing techniques.

We noted that eight outbreaks of Shigella sonnei from an unknown source occurred sequentially in Aichi Prefecture, Japan, between October 1992-June 1993. For comparative purposes we analyzed 53 outbreak-related isolates of Shigella sonnei using different subtyping methods and studied the epidemiology of the outbreaks. It appeared from our study that DNA-based techniques such as plasmid typing and pulsed-field gel electrophoresis (PFGE) were more useful tools for subtyping Shigella sonnei than colicin typing and the antimicrobial susceptibility test. Moreover, according to PFGE analysis, four genetically related isolates of Shigella sonnei were responsible for the eight sequential outbreaks. To further investigate the epidemiology of outbreaks, 58 sporadic isolates of Shigella sonnei from overseas travelers with shigellosis during the same period were also examined. We found that some sporadic isolates from travelers in Asia were genetically related to those of the outbreak-related isolates, indicating that genetically related isolates prevailed in Asia during this period, probably because of the extensive movement of people or food.

Bacterial Typing Techniques↗

PubMed2005

Mortality patterns in infectious salmon anaemia virus outbreaks in New Brunswick, Canada.

Mortality levels attributed to infectious salmon anaemia viral (ISAV) infections were examined at the net pen and site level in the 1996 smolt year class in three areas of New Brunswick, Canada. The year class in this region was the first known to have potential exposure to ISAV beginning at the time of seawater transfer. There was considerable variability in mortality patterns among net pen groups of fish. Net pen outbreak definitions were based on at least seven high mortality days in which there were at least 100 per 100 000 fish per day or >5% cumulative mortality for the study period. There were 106 net pen outbreaks in a study population consisting of 218 net pens. Although the number of new cases decreased as water temperature decreased, overall mortality levels at the study sites did not decrease noticeably. The median peak daily mortality rate during outbreaks was 492 per 100 000 fish per day, with 10% of cases experiencing >5200 mortalities per 100 000 fish per day. The median duration of outbreaks in net pens for which the fish were not slaughtered during the outbreak was 33 days and the median total loss in those outbreaks was 6600 per 100 000 fish.

Animals↗

PubMed1989

Treatment of an influenza A outbreak in a teaching nursing home. Effectiveness of a protocol for prevention and control.

The safety and efficacy of current ACIP guidelines for the prevention and control of influenza in nursing home populations are uncertain. An outbreak of influenza A/Sichuan (H3N2) in a teaching nursing home during 1988 gave us the opportunity to evaluate the effectiveness of an influenza vaccination and amantadine prophylaxis protocol. Over 13 days, 12 of 60 residents developed influenza. Prior influenza vaccination had been given to 94% of the residents. Protection from infection occurred in those tested who had antibody levels greater than or equal to 1:16 to the A/Leningrad (H3N2) antigen contained in the standard 1987-88 trivalent vaccine. However, five of 17 vaccinated residents who were tested had antibody levels less than or equal to 1:16 at the start of the outbreak. Amantadine (less than or equal to 100 mg/day) was given to all but one resident starting on the third day of the outbreak, and to employees starting on the sixth day of the outbreaks. Seven residents developed illness after the start of amantadine, although amantadine appeared to ameliorate their symptoms. Although amantadine was generally well tolerated by residents, employees receiving amantadine identified a high incidence of side effects and only 44% of employees took at least 70% of the prescribed amantadine. In our opinion, early detection and protocol-directed intervention probably abated a more severe influenza outbreak. Therefore we support existing recommendations that formal nursing home policies be established to ensure that residents and employees receive annual influenza vaccine and that chemoprophylaxis be used when outbreaks of influenza A are suspected.

Aged↗

PubMed2006

Escherichia coli O157:H7 infection in nursing homes: review of literature and report of recent outbreak.

Escherichia coli O157:H7 is a well-described cause of hemorrhagic colitis in isolated cases and outbreaks. The postdiarrhea complications of this infection (thrombotic thrombocytopenic purpura and hemolytic uremic syndrome) have historically been linked to illness in children aged 5 to 10, but in an elderly, institutionalized population, E. coli O157:H7 is associated with high morbidity and mortality. This geriatric population is at high risk for developing gastrointestinal infections for a number of reasons, including age- and medication-related achlorhydria, antibiotic usage, and comorbid medical conditions. The combination of age-related risk factors with those associated with group living makes nursing facilities a high-risk environment for outbreaks of infectious diseases. E. coli O157:H7 may be more likely to cause disease outbreaks in this population because of the low inoculum required for clinical infection. Moreover, the prevalence of potential competing diagnoses, such as lower gastrointestinal bleeding from neoplastic or diverticular disease, complicates the diagnosis. Clinical presentation and laboratory studies are unpredictable and pose diagnostic challenges. This report reviews the literature on nursing home outbreaks of E. coli O157:H7 and presents an outbreak that occurred in an assisted living community in San Mateo County, California, in October 2003. The purpose of this literature review and report of an outbreak is to heighten awareness of the unique susceptibility of elderly, institutionalized patients for E. coli O157:H7 infection and its sequelae.

Aged↗

PubMed1995

Characterisation of Pasteurella multocida isolated from fowl cholera outbreaks on turkey farms.

Biochemical profiles, restriction endonuclease analysis (REA) and ribotyping were used to investigate Pasteurella multocida isolates from outbreaks of fowl cholera on 7 turkey farms in New South Wales. While only a single isolate was available from 5 of the farms, multiple isolates, 4 and 12 respectively, were available from the other 2 farms. The available field evidence suggested that 8 outbreaks had occurred with one farm suffering 2 outbreaks. The isolates obtained were all confirmed as Pasteurella multocida. Biochemical profiles allocated the isolates to 4 groups, 3 being variants of P multocida subsp multocida and the fourth being P multocida subsp septica. REA performed with HpaII established 7 groups. Ribotyping using the HpaII digests probed with the 16S rRNA operon of Haemophilus paragallinarum recognised the same 7 groups as REA. Unlike the biochemical profiles, both REA and ribotyping provided a fine subdivision that identified outbreaks as either related or unrelated. The REA and ribotyping patterns as well as biochemical profiles were stable for all isolates from the outbreaks in which multiple isolates were obtained from either the same bird or from different birds. REA and ribotyping were found to be superior to biotyping methods for the investigation of fowl cholera outbreaks.

Animals↗

PubMed2003

Waterborne outbreak of gastroenteritis associated with a norovirus.

The Wyoming Department of Health investigated an outbreak of acute gastroenteritis among persons who dined at a tourist saloon in central Wyoming during October 2001. Human caliciviruses (HuCVs) were suspected as the etiological agent of the outbreak based on the incubation period, duration of illness, and symptoms observed in ill patrons. A retrospective cohort study demonstrated that ill patrons were 4.5 times more likely to have exposure to drinking water and/or ice than nonill patrons. No food items were associated with illness. An environmental investigation gave evidence that the saloon's groundwater was contaminated with sewage. Water from the saloon's only well was processed for viruses. The processed water sample and stool samples collected from three ill patrons were analyzed by reverse transcription-PCR (RT-PCR) for the presence of HuCV. All positive RT-PCR results were confirmed by sequence and phylogenetic analyses of cloned RT-PCR products. A genogroup I, subtype 3, HuCV stain was found to be present in the well water sample and two stool samples. In addition, a genogroup II, subtype 6, strain was detected in one stool sample. The identification of the same HuCV strain in both the well water and stool samples strongly suggests a link between exposure to well water and the outbreak of gastroenteritis. The presence of a genogroup II, subtype 6, strain in one of the stool samples suggests that multiple HuCV strains may have been involved in this outbreak. The laboratory isolation of HuCV strains from outbreak-associated drinking water is relatively novel in the United States. This investigation outlines the procedure for virus isolation and illustrates the utility of RT-PCR for the identification of HuCV in large volumes of water and stool samples obtained during outbreaks of acute nonbacterial gastroenteritis.

Base Sequence↗