SEARCH · Search PubMed

Results for “Outbreak”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources

PubMed2006

One dose of varicella vaccine does not prevent school outbreaks: is it time for a second dose?

OBJECTIVES: The implementation of a routine childhood varicella vaccination program in the United States in 1995 has resulted in a dramatic decline in varicella morbidity and mortality. Although disease incidence has decreased, outbreaks of varicella continue to be reported, increasingly in highly vaccinated populations. In 2000, a varicella vaccination requirement was introduced for kindergarten entry in Arkansas. In October 2003, large numbers of varicella cases were reported in a school with high vaccination coverage. We investigated this outbreak to examine transmission patterns of varicella in this highly vaccinated population, to estimate the effectiveness of 1 dose of varicella vaccine, to identify risk factors for vaccine failure, and to implement outbreak control measures. METHODS: A retrospective cohort study involving students attending an elementary school was conducted. A questionnaire was distributed to parents of all of the students in the school to collect varicella disease and vaccination history; parents of varicella case patients were interviewed by telephone. A case of varicella was defined as an acute, generalized, maculopapulovesicular rash without other apparent cause in a student or staff member in the school from September 1 to November 20, 2003. Varicella among vaccinated persons was defined as varicella-like rash that developed >42 days after vaccination. In vaccinated persons, the rash may be atypical, maculopapular with few or no vesicles. Cases were laboratory confirmed by polymerase chain reaction, and genotyping was performed to identify the strain associated with the outbreak. RESULTS: Of the 545 students who attended the school, 88% returned the questionnaire. Overall varicella vaccination coverage was 96%. Forty-nine varicella cases were identified; 43 were vaccinated. Three of 6 specimens tested were positive by polymerase chain reaction. The median age at vaccination of vaccinated students in the school was 18 months, and the median time since vaccination was 59 months. Forty-four cases occurred in the East Wing, where 275 students in grades kindergarten through 2 were located, and vaccination coverage was 99%. In this wing, varicella attack rates among unvaccinated and vaccinated students were 100% and 18%, respectively. Vaccine effectiveness against varicella of any severity was 82% and 97% for moderate/severe varicella. Vaccinated cases were significantly milder compared with unvaccinated cases. Among the case patients in the East Wing, the median age at vaccination was 18.5 and 14 months among non-case patients. Four cases in the West Wing did not result in further transmission in that wing. The Arkansas strains were the same as the common varicella-zoster virus strain circulating in the United States (European varicella-zoster virus strain). CONCLUSIONS: Although disease was mostly mild, the outbreak lasted for approximately 2 months, suggesting that varicella in vaccinated persons was contagious and that 99% varicella vaccination coverage was not sufficient to prevent the outbreak. This investigation highlights several challenges related to the prevention and control of varicella outbreaks with the 1-dose varicella vaccination program and the need for further prevention of varicella through improved vaccine-induced immunity with a routine 2-dose vaccination program. The challenges include: 1-dose varicella vaccination not providing sufficient herd immunity levels to prevent outbreaks in school settings where exposure can be intense, the effective transmission of varicella among vaccinated children, and the difficulty in the diagnosis of mild cases in vaccinated persons and early recognition of outbreaks for implementing control measures. The efficacy of 2 doses of varicella vaccine compared with 1 dose was assessed in a trial conducted among healthy children who were followed for 10 years. The efficacy for 2 doses was significantly higher than for 1 dose of varicella vaccine. This higher efficacy translated into a 3.3-fold lower risk of developing varicella >42 days after vaccination in 2- vs 1-dose recipients. Of the children receiving 2 doses, 99% achieved a glycoprotein-based enzyme-linked immunosorbent assay level of > or =5 units (considered a correlate of protection) 6 weeks after vaccination compared with 86% of children who received 1 dose. The 6-week glycoprotein-based enzyme-linked immunosorbent assay level of > or =5 units has been shown to be a good surrogate for protection from natural disease. Ten years after the implementation of the varicella vaccination program, disease incidence has declined dramatically, and vaccination coverage has increased greatly. However, varicella outbreaks continue to occur among vaccinated persons. Although varicella disease among vaccinated persons is mild, they are contagious and able to sustain transmission. As a step toward better control of varicella outbreaks and to reduce the impact on schools and public health officials, in June 2005, the Advisory Committee on Immunization Practices recommended the use of a second dose of varicella vaccine in outbreak settings. Early recognition of outbreaks is important to effectively implement a 2-dose vaccination response and to prevent more cases. Although the current recommendation of providing a second dose of varicella vaccine during an outbreak offers a tool for controlling outbreaks, a routine 2-dose recommendation would be more effective at preventing cases. Based on published data on immunogenicity and efficacy of 2 doses of varicella vaccine, routine 2-dose vaccination will provide improved protection against disease and further reduce morbidity and mortality from varicella.

Chickenpox↗

PubMed1991

Foodborne disease outbreaks in nursing homes, 1975 through 1987.

OBJECTIVE: --To describe the epidemiology of foodborne disease outbreaks in nursing homes and to identify where preventive efforts might be focused. DATA SOURCES: --Reports by state and local health departments of foodborne disease outbreaks occurring from January 1, 1975, through December 31, 1987. STUDY SELECTION: --Foodborne disease outbreaks reported to the Centers for Disease Control, Atlanta, Ga, on standard investigation forms. DATA EXTRACTION: --Each foodborne disease outbreak report was examined by an epidemiologist or statistician. Outbreaks were considered to have a known pathogen if confirmed by laboratory tests, and a known vehicle when an epidemiologic investigation implicated a specific food item. DATA SYNTHESIS: --From 1975 through 1987, 26 states reported 115 outbreaks of foodborne disease in nursing homes, causing illness in 4944 persons and death in 51. These outbreaks represented 2% of all reported foodborne disease outbreaks and 19% of outbreak-associated deaths in this period. Of 52 outbreaks with a known cause, Salmonella was the most frequently reported pathogen, accounting for 52% of outbreaks and 81% of deaths. Salmonella enteritidis outbreaks accounted for 56% of the Salmonella-associated deaths since 1981. The implicated food vehicles in S enteritidis outbreaks were made with eggs or prepared with equipment contaminated with eggs. Staphylococcal foodborne disease was the next most commonly identified cause, accounting for 23% of outbreaks. CONCLUSIONS: --Since the elderly are at high risk for serious morbidity from foodborne disease, nursing homes should practice careful food handling, preparation, and storage procedures; provide education for food handlers; and have active infection control programs to rapidly detect and control outbreaks of foodborne disease.

Aged↗

PubMed2006

Surveillance for waterborne disease and outbreaks associated with recreational water--United States, 2003-2004.

PROBLEM/CONDITION: Since 1971, CDC, the U.S. Environmental Protection Agency, and the Council of State and Territorial Epidemiologists have collaboratively maintained the Waterborne Disease and Outbreak Surveillance System for collecting and reporting waterborne disease and outbreak (WBDO)-related data. In 1978, WBDOs associated with recreational water (natural and treated water) were added. This system is the primary source of data regarding the scope and effects of WBDOs in the United States. REPORTING PERIOD: Data presented summarize WBDOs associated with recreational water that occurred during January 2003-December 2004 and one previously unreported outbreak from 2002. DESCRIPTION OF THE SYSTEM: Public health departments in the states, territories, localities, and the Freely Associated States (i.e., the Republic of the Marshall Islands, the Federated States of Micronesia, and the Republic of Palau, formerly parts of the U.S.-administered Trust Territory of the Pacific Islands) have primary responsibility for detecting, investigating, and voluntarily reporting WBDOs to CDC. Although the surveillance system includes data for WBDOs associated with drinking water, recreational water, and water not intended for drinking, only cases and outbreaks associated with recreational water are summarized in this report. RESULTS: During 2003-2004, a total 62 WBDOs associated with recreational water were reported by 26 states and Guam. Illness occurred in 2,698 persons, resulting in 58 hospitalizations and one death. The median outbreak size was 14 persons (range: 1-617 persons). Of the 62 WBDOs, 30 (48.4%) were outbreaks of gastroenteritis that resulted from infectious agents, chemicals, or toxins; 13 (21.0%) were outbreaks of dermatitis; and seven (11.3%) were outbreaks of acute respiratory illness (ARI). The remaining 12 WBDOs resulted in primary amebic meningoencephalitis (n = one), meningitis (n = one), leptospirosis (n = one), otitis externa (n = one), and mixed illnesses (n = eight). WBDOs associated with gastroenteritis resulted in 1,945 (72.1%) of 2,698 illnesses. Forty-three (69.4%) WBDOs occurred at treated water venues, resulting in 2,446 (90.7%) cases of illness. The etiologic agent was confirmed in 44 (71.0%) of the 62 WBDOs, suspected in 15 (24.2%), and unidentified in three (4.8%). Twenty (32.3%) WBDOs had a bacterial etiology; 15 (24.2%), parasitic; six (9.7%), viral; and three (4.8%), chemical or toxin. Among the 30 gastroenteritis outbreaks, Cryptosporidium was confirmed as the causal agent in 11 (36.7%), and all except one of these outbreaks occurred in treated water venues where Cryptosporidium caused 55.6% (10/18) of the gastroenteritis outbreaks. In this report, 142 Vibrio illnesses (reported to the Cholera and Other Vibrio Illness Surveillance System) that were associated with recreational water exposure were analyzed separately. The most commonly reported species were Vibrio vulnificus, V. alginolyticus, and V. parahaemolyticus. V. vulnificus illnesses associated with recreational water exposure had the highest Vibrio illness hospitalization (87.2%) and mortality (12.8%) rates. INTERPRETATION: The number of WBDOs summarized in this report and the trends in recreational water-associated disease and outbreaks are consistent with previous years. Outbreaks, especially the largest ones, are most likely to be associated with summer months, treated water venues, and gastrointestinal illness. Approximately 60% of illnesses reported for 2003-2004 were associated with the seven largest outbreaks (>100 cases). Deficiencies leading to WBDOs included problems with water quality, venue design, usage, and maintenance. PUBLIC HEALTH ACTIONS: CDC uses WBDO surveillance data to 1) identify the etiologic agents, types of aquatic venues, water-treatment systems, and deficiencies associated with outbreaks; 2) evaluate the adequacy of efforts (i.e., regulations and public awareness activities) to provide safe recreational water; and 3) establish public health prevention priorities that might lead to improved regulations and prevention measures at the local, state, and federal levels.

Bathing Beaches↗

PubMed2026

Waterborne norovirus outbreaks in China, 2000-2022: a systematic review.

In China, waterborne transmission is a relatively rare route for norovirus outbreaks; however, once it occurs, the outbreaks tend to be large in scale, prolonged in duration, and difficult to control. This systematic review characterizes the epidemiological features of such outbreaks in China. We searched the WANFANG, CNKI, PubMed, and Web of Science databases for literature on waterborne norovirus outbreaks published up to November 2023. From 2000 to 2022, a total of 112 outbreaks were reported in China among the 97 articles included. These outbreaks involved approximately 19,796 cases and 565,485 exposures, median of 98 cases per outbreak, with a median attack rate of 6.09 %. Most outbreaks occurred in southern regions, particularly in coastal provinces, with schools (59, 52.68 %) and towns or villages (25, 22.52 %) being the most common settings. The highest number of outbreaks was reported in February and the lowest in July, with an average of 8.25 outbreaks per month. Higher attack rates were associated with outbreaks occurring in winter, in primary schools, and in southern regions of the Qinling-Huaihe line. Contamination of barreled water and self-provided wells was the primary risk factor for waterborne norovirus outbreaks. Although waterborne transmission is a relatively rare route for norovirus outbreaks in China, it can cause large-scale outbreaks in a short period. Consequently, it is still necessary to enhance protection of water sources, rigorous water quality monitoring, and public health education on water sanitation.

Humans↗

PubMed2005

Epidemiology of acute gastroenteritis outbreaks caused by Noroviruses in Okayama, Japan.

Noroviruses (called formerly "Norwalk-like viruses") cause food-borne gastroenteritis outbreaks. These outbreaks were thought to be related to shellfish consumption, although non-shellfish related outbreaks also occurred frequently in Japan. To clarify the epidemiology of Norovirus outbreaks, 435 stool samples were collected from 60 acute non-bacterial gastroenteritis outbreaks occurring over 8 years in Okayama, Japan. Using reverse transcription-PCR (RT-PCR), Noroviruses were detected in 257 cases (59.1% of all samples) from 46 outbreaks (77% of all outbreaks). The majority of the 46 Norovirus outbreaks (89%) occurred during November to March; notably one-third occurred in December. Restaurants, schools, and welfare institutions accounted for the major settings in 50%, 20%, and 15% of the Norovirus outbreaks, respectively. This was similar to other reports from Japan, but differed from those from the United Kingdom. The transmission routes were assigned in 27 of the Norovirus outbreaks. In 18 outbreaks the routes were related to human contact (7 from food handlers and 11 from person-to-person contact), whereas those related directly to shellfish occurred only in 9 outbreaks. These results suggest that transmission routes related to human contact are more important than recognized previously in the context of preventive medicine. Furthermore, all outbreaks in which some of the samples contained dual genogroups of Noroviruses were related to shellfish, suggesting that consumption of contaminated shellfish frequently results in mixed Norovirus infections in contrast to other transmission routes and that coexistence of genogroups is a useful marker for shellfish-related outbreaks.

Adolescent↗

PubMed2006

Increased case-fatality rate associated with outbreaks of Neisseria meningitidis infection, compared with sporadic meningococcal disease, in the United States, 1994-2002.

BACKGROUND: Outbreaks of meningococcal disease are infrequent but important public health events. We characterize outbreak-associated cases in the United States and compare them with sporadic disease. METHODS: Outbreaks of meningococcal disease that occurred during the period of 1 July 1994 through 30 June 2002 were identified through state health departments, Centers for Disease Control and Prevention records, and a review of newspapers and the medical literature. Cases associated with outbreaks were compared with sporadic cases identified through population-based surveillance. RESULTS: We identified 69 outbreaks of Neisseria meningitidis infection (median, 9.5 outbreaks per year; range, 3-14 outbreaks per year), which involved 229 patients from 30 states. Forty-three (62%) of the outbreaks involved N. meningitidis serogroup C, 17 (25%) involved serogroup B, and 9 (13%) involved serogroup Y. Twenty-five outbreaks (36%) occurred in communities, and 44 (64%) were organization based, including 12 that occurred in colleges and universities, 19 that occurred in primary and secondary schools, and 8 that occurred in nursing homes. Vaccination campaigns (with the A/C/Y/W-135 meningococcal polysaccharide vaccine) were conducted for 31 outbreaks (28 involving serogroup C and 3 involving serogroup Y). After controlling for age, serogroup, and clinical presentation, outbreak-associated cases were associated with a higher case-fatality rate than were sporadic cases (21% vs. 11%; odds ratio, 3.3; 95% confidence interval, 2.0-5.5). CONCLUSIONS: Outbreaks remain an important but infrequent public health issue, representing <2% of all cases of meningococcal disease. However, given the increased case-fatality rate found among outbreak-related cases of N. meningitidis infection, additional investigation of factors that favor the transmission and virulence of outbreak-related strains is warranted.

Adolescent↗

PubMed2005

Characterization of Enterococcus hirae outbreaks in broiler flocks demonstrating increased mortality because of septicemia and endocarditis and/or altered production parameters.

In Denmark, increased problems associated with streptococci and enterococci have been observed in broilers and broiler parent flocks, resulting in increased mortalities, uneven flocks, and subsequent downgrading and increased condemnations. Postmortem lesions associated with recent outbreaks due to Enterococcus hirae have been accompanied or dominated by septicemia and endocarditis. As a result of infection at an early age and relatively low mortality rates, outbreaks are not always clearly defined and may go unnoticed or may be attributed to poor chick quality. For the same reasons, the pathogenesis and epidemiology of observed outbreaks has only remained speculative. Four separate outbreaks associated with E. hirae infections in broiler flocks occurring between 1998 and 2002 have been investigated. Two of the outbreaks indicated evidence of two separate clones, with 89% and 79% of isolates involved in the individual outbreaks belonging to a single pulsed-field gel electrophoresis (PFGE) profile, respectively. Another outbreak (outbreak 4) demonstrated clear clonality, with all isolates demonstrating affinity to one of two PFGE profiles that differed by only two bands. However, all three outbreaks demonstrated a different clone. The remaining outbreak was nondonal, with isolates distributed between six separate PFGE profiles. One of the outbreaks (outbreak 4) was descended from a parent broiler flock previously associated with an outbreak of Streptococcus gallinaceus; the flock also exhibited septicemia and endocarditis. Initial indications suggested the possibility of vertical transmission of S. gallinaceus to the current broiler flock, causing infection. By extended phenotypic characterization and subsequent genetic characterization, including 16S rRNA sequencing, all strains from the four outbreaks were confirmed as E. hirae. This investigation highlights the problems associated with characterizing enterococci infections in broiler flocks.

Animal Husbandry↗

PubMed2000

Surveillance for foodborne-disease outbreaks--United States, 1993-1997.

PROBLEM/CONDITION: Since 1973, CDC has maintained a collaborative surveillance program for collection and periodic reporting of data on the occurrence and causes of foodborne-disease outbreaks (FBDOs) in the United States. REPORTING PERIOD COVERED: This summary reviews data from January 1993 through December 1997. DESCRIPTION OF SYSTEM: The Foodborne-Disease Outbreak Surveillance System reviews data concerning FBDOs, defined as the occurrence of two or more cases of a similar illness resulting from the ingestion of a common food. State and local public health departments have primary responsibility for identifying and investigating FBDOs. State, local, and territorial health departments use a standard form to report these outbreaks to CDC. RESULTS: During 1993-1997, a total of 2,751 outbreaks of foodborne disease were reported (489 in 1993, 653 in 1994, 628 in 1995, 477 in 1996, and 504 in 1997). These outbreaks caused a reported 86,058 persons to become ill. Among outbreaks for which the etiology was determined, bacterial pathogens caused the largest percentage of outbreaks (75%) and the largest percentage of cases (86%). Salmonella serotype Enteritidis accounted for the largest number of outbreaks, cases, and deaths; most of these outbreaks were attributed to eating eggs. Chemical agents caused 17% of outbreaks and 1% of cases; viruses, 6% of outbreaks and 8% of cases; and parasites, 2% of outbreaks and 5% of cases. INTERPRETATION: The annual number of FBDOs reported to CDC did not change substantially during this period or from previous years. During this reporting period, S. Enteritidis continued to be a major cause of illness and death. In addition, multistate outbreaks caused by contaminated produce and outbreaks caused by Escherichia coli O157:H7 remained prominent. ACTIONS TAKEN: Current methods to detect FBDOs are improving, and several changes to improve the ease and timeliness of reporting FBDO data are occurring (e.g., a revised form to simplify FBDO reporting by state health departments and electronic reporting methods). State and local health departments continue to investigate and report FBDOs as part of efforts to better understand and define the epidemiology of foodborne disease in the United States. At the regional and national levels, surveillance data provide an indication of the etiologic agents, vehicles of transmission, and contributing factors associated with FBDOs and help direct public health actions to reduce illness and death caused by FBDOs.

Disease Outbreaks↗

PubMed1991

Waterborne-disease outbreaks, 1989-1990.

For the 2-year period 1989-1990, 16 states reported 26 outbreaks due to water intended for drinking; an estimated total of 4,288 persons became ill in these outbreaks. Giardia lamblia was implicated as the etiologic agent for seven of the 12 outbreaks in which an agent was identified. The outbreaks of giardiasis were all associated with ingestion of unfiltered surface water or surface-influenced groundwater. An outbreak with four deaths was attributed to Escherichia coli O157:H7, the only bacterial pathogen implicated in any of the outbreak investigations. An outbreak of remitting, relapsing diarrhea was associated with cyanobacteria (blue-green algae)-like bodies, whose role in causing diarrheal illness is being studied. Two outbreaks due to hepatitis A and one due to a Norwalk-like agent were associated with use of well water. Eighteen states reported a total of 30 outbreaks due to the use of recreational water, which resulted in illness for an estimated total of 1,062 persons. These 30 reports comprised 13 outbreaks of whirlpool- or hot tub-associated Pseudomonas folliculitis; 13 outbreaks of swimming-associated gastroenteritis, including five outbreaks of shigellosis; one outbreak of hepatitis A associated with a swimming pool; and three cases of primary amebic meningoencephalitis caused by Naegleria. The national surveillance of outbreaks of waterborne diseases, which has proceeded for 2 decades, continues to be a useful means for characterizing the epidemiology of waterborne diseases.

Communicable Diseases↗

PubMed1996

Surveillance for foodborne-disease outbreaks--United States, 1988-1992.

PROBLEM/CONDITION: Since 1973, CDC has maintained a collaborative surveillance program for collection and periodic reporting of data concerning the occurrence and causes of foodborne-disease outbreaks (FBDOs). REPORTING PERIOD COVERED: This summary reviews data from January 1988 through December 1992. DESCRIPTION OF SYSTEM: The surveillance system reviews data concerning FBDOs--defined as the occurrence of two or more cases of a similar illness resulting from the ingestion of a common food. Before 1992, only one case of intoxication by chemical, marine toxin, or Clostridium botulinum toxin as a result of the ingestion of food was required to constitute an FBDO. Since 1992, two or more cases have been required. State and local public health departments have primary responsibility for the identifying and investigating FBDOs. State and territorial health departments report these outbreaks to CDC on a standard form. RESULTS: During 1988-1992, a total of 2,423 outbreaks of foodborne disease were reported (451 in 1988, 505 in 1989, 532 in 1990, 528 in 1991, and 407 in 1992). These outbreaks caused a reported 77,373 persons to become ill. Among outbreaks for which the etiology was determined, bacterial pathogens caused the largest percentage of outbreaks (79%) and the largest percentage of cases (90%). Salmonella serotype Enteritidis accounted for the largest number of outbreaks, cases, and deaths; most of these outbreaks were attributed to eating undercooked, infected eggs. Chemical agents caused 14% of outbreaks and 2% of cases; parasites, 2% of outbreaks and 1% of cases; and viruses, 4% of outbreaks and 6% of cases. INTERPRETATION: The number of FBDOs reported per year did not change substantially during the first 4 years but declined in 1992 as a result of the revised definition of an outbreak. During this reporting period, S. Enteritidis continued to be a major cause of morbidity and mortality. In addition, multistate outbreaks caused by contaminated produce and outbreaks caused by Escherichia coli O157:H7 became more prominent. ACTIONS TAKEN: State and local public health departments investigate FBDOs. At the regional and national level, surveillance data provide an indication of the etiologic agents, vehicles of transmission, and contributing factors associated with FBDOs and help direct public health actions.

Disease Outbreaks↗

PubMed1996

Risk factors for outbreaks of infectious intestinal disease linked to domestic catering.

The epidemiology of general outbreaks of infectious intestinal disease associated with domestic catering for large numbers is described and compared with foodborne outbreaks in other settings. From 1 January 1992 to 31 December 1994, the PHLS Communicable Disease Surveillance Centre identified 101 foodborne general outbreaks of infectious intestinal disease associated with domestic catering in England and Wales (16% of all foodborne outbreaks). Salmonella species were associated with 77 of the 101 outbreaks and S. enteriditis phage type 4 accounted for 57. Small round structured viruses were implicated in five outbreaks, Clostridium perfringens in four, Bacillus cereus in two, and Campylobacter sp and Escherichia coli in one each. No pathogen was identified in 11 outbreaks. Outbreaks occurred most commonly in summer. The commonest vehicles implicated were poultry/eggs in 44 outbreaks, desserts in 13, and meat/meat products in nine. Salad/vegetables, sauces, and fish/shellfish were each implicated in eight outbreaks. Raw shell eggs were implicated in a fifth of outbreaks. Inappropriate storage was the commonest fault, reported in association with 50 outbreaks (ambient temperature for long periods before serving in 29), inadequate heat treatment was reported in 35, cross contamination in 28, an infected food handler in 11, and other faults in 14. Outbreaks associated with catering on domestic premises were independently more likely than outbreaks in other settings to be associated with salmonellas, inappropriate storage of food, and consumption of poultry, eggs, or sauces. Public health services need to direct messages about the use, preparation, and storage of food to those who cater on domestic premises.

Disease Outbreaks↗

PubMed2026

Mapping High-Rate Clusters of Animal Contact-Related Human Salmonella enterica Single-State Outbreaks in the United States, 2009-2022: A Spatial Epidemiological Approach to Inform Public Health Surveillance.

INTRODUCTION: Nontyphoidal Salmonella enterica (NTS) is a major zoonotic enteric pathogen. Animal contact-related NTS outbreaks have increased in the United States over the last decade. Geospatial analysis can identify locations with elevated risk of NTS outbreaks where public health authorities can focus their NTS prevention and intervention efforts. METHODS: We analysed NTS outbreak data reported from individual states to the Centers for Disease Control via the National Outbreak Reporting System between 2009 and 2022 across the continental contiguous United States. A geospatial analytical framework that included disease mapping, spatial interpolation, and global and local clustering methods was applied to identify regions with high NTS outbreak rates. Given that the study period (2009-2022) included the COVID-19 pandemic, an interrupted time series negative binomial model was used to assess changes in NTS incidence before and after 2020. RESULTS: A total of 104 NTS single-state outbreaks were reported to the National Outbreak Reporting System (NORS) during the study period. The mean annual incidence rate was 0.02 NTS outbreaks per million person-years. The primary animal contact categories associated with outbreaks were mammals (cattle, pigs, sheep, and horses), birds (backyard chickens, ducklings, and turkeys), and reptiles (turtles and lizards). Exposure settings included farms, fairgrounds, agricultural feed stores, veterinary clinics, dairy/agricultural settings, and residential settings. The local cluster detection methods consistently identified areas with significantly high NTS animal contact-related outbreak rates in the Mountain West, Midwest, and Northeast of the US. The interrupted time series analysis indicated a reduction in incidence following the onset of the COVID-19 pandemic (IRR = 0.03; p = 0.06). CONCLUSION: NTS animal contact-related single-state outbreaks revealed distinct spatial clustering across the United States, with higher risks in the Mountain West, Midwest, and Northeast. Diversity of animal-contact sources and exposure settings depicted complex transmission dynamics of NTS. A decline in reported NTS outbreaks was observed after the COVID-19 pandemic. Focused prevention and control programs are needed in high-risk areas to mitigate the burden of NTS outbreaks.

United States↗

PubMed1999

Seafood-associated disease outbreaks in New York, 1980-1994.

BACKGROUND: Seafood-associated disease outbreaks in New York were examined to describe their epidemiology and to identify areas for prevention and control efforts. METHODS: We reviewed reports submitted to the New York State Department of Health (NYSDOH) of seafood-associated outbreaks occurring from January 1, 1980, through December 31, 1994. RESULTS: During 1980-1994, 339 seafood-associated outbreaks were reported, resulting in 3959 illnesses, 76 hospitalizations, and 4 deaths. During this period, seafood-associated outbreaks accounted for 19% of all reported foodborne outbreaks and 10% of foodborne illnesses. Shellfish, the most frequently implicated seafood item, accounted for 64% of seafood outbreaks, followed by finfish (31% of outbreaks). Of the 148 seafood-associated outbreaks with a confirmed etiologic agent, Norwalk virus and scombrotoxin were the most frequently identified agents: Norwalk virus accounted for 42% of outbreaks and 42% of illnesses, and scombrotoxin accounted for 44% of outbreaks and 19% of illnesses. Three of the 4 seafood-associated deaths were caused by Clostridium botulinum; the remaining death was caused by Vibrio vulnificus. CONCLUSIONS: Reducing the number of seafood outbreaks will require continued and coordinated efforts by many different agencies, including those involved with water quality; disease surveillance; consumer education; and seafood harvesting, processing, and marketing. New York's foodborne disease surveillance data highlight potential areas on which to focus prevention efforts, including: (1) commodities and associated pathogens causing the largest number of seafood-associated outbreaks and illnesses, namely shellfish-associated viral gastroenteritis and finfish-associated scombroid fish poisoning, and (2) venues at which seafood were most frequently consumed in reported outbreaks, such as commercial food establishments and catered events.

Disease Outbreaks↗

PubMed2002

Foodborne disease outbreaks in United States schools.

BACKGROUND: The objective of this study was to describe the epidemiology of foodborne disease outbreaks in schools and to identify where preventive measures could be targeted. METHODS: Reports by state and local health departments of foodborne disease outbreaks occurring in primary and secondary schools, colleges and universities from January 1, 1973, through December 31, 1997, were reviewed. Data from ill persons identified through foodborne outbreak investigations and subsequently reported to the Centers for Disease Control and Prevention in the Foodborne Outbreak Surveillance System were examined. The number and size of foodborne disease outbreaks, as well as the etiologic agents, food vehicles of transmission, site of food preparation and contributing factors associated with outbreaks were also examined. RESULTS: From 1973 through 1997, states and local health departments reported 604 outbreaks of foodborne disease in schools. The median number of school outbreaks annually was 25 (range, 9 to 44). In 60% of the outbreaks an etiology was not determined, and in 45% a specific food vehicle of transmission was not determined. Salmonella was the most commonly identified pathogen, accounting for 36% of outbreak reports with a known etiology. Specific food vehicles of transmission were epidemiologically identified in 333 (55%) of the 604 outbreaks. The most commonly implicated vehicles were foods containing poultry (18.6%), salads (6.0%), Mexican-style food (6.0%), beef (5.7%) and dairy products excluding ice cream (5.0%). The most commonly reported food preparation practices that contributed to these school-related outbreaks were improper food storage and holding temperatures and food contaminated by a food handler. CONCLUSIONS: Strengthening food safety measures in schools would better protect students and school staff from outbreaks of foodborne illness. Infection control policies, such as training and certification of food handlers in the proper storage and cooking of foods, meticulous hand washing and paid sick leave for food handlers with gastroenteritis, could make meals safer for American students.

Adolescent↗

PubMed2006

Societal learning in epidemics: intervention effectiveness during the 2003 SARS outbreak in Singapore.

BACKGROUND: Rapid response to outbreaks of emerging infectious diseases is impeded by uncertain diagnoses and delayed communication. Understanding the effect of inefficient response is a potentially important contribution of epidemic theory. To develop this understanding we studied societal learning during emerging outbreaks wherein patient removal accelerates as information is gathered and disseminated. METHODS AND FINDINGS: We developed an extension of a standard outbreak model, the simple stochastic epidemic, which accounts for societal learning. We obtained expressions for the expected outbreak size and the distribution of epidemic duration. We found that rapid learning noticeably affects the final outbreak size even when learning exhibits diminishing returns (relaxation). As an example, we estimated the learning rate for the 2003 outbreak of severe acute respiratory syndrome (SARS) in Singapore. Evidence for relaxation during the first eight weeks of the outbreak was inconclusive. We estimated that if societal learning had occurred at half the actual rate, the expected final size of the outbreak would have reached nearly 800 cases, more than three times the observed number of infections. By contrast, the expected outbreak size for societal learning twice as effective was 116 cases. CONCLUSION: These results show that the rate of societal learning can greatly affect the final size of disease outbreaks, justifying investment in early warning systems and attentiveness to disease outbreak by both government authorities and the public. We submit that the burden of emerging infections, including the risk of a global pandemic, could be efficiently reduced by improving procedures for rapid detection of outbreaks, alerting public health officials, and aggressively educating the public at the start of an outbreak.

Communicable Diseases, Emerging↗

PubMed2006

Salmonella outbreaks in restaurants in Minnesota, 1995 through 2003: evaluation of the role of infected foodworkers.

The 23 restaurant-associated salmonellosis outbreaks that occurred in Minnesota from 1995 through 2003 were reviewed to characterize the role of infected foodworkers. The median duration of the outbreaks was 21 days (range, 1 to 517 days). The median number of culture-confirmed patron cases per outbreak was seven (range, 1 to 36 cases). The median incubation for patron cases ranged from 9 h to 5.9 days. A specific food vehicle was implicated in four outbreaks and suspected in five. Salmonella of the same serotype and pulsed-field gel electrophoresis subtype as that found in patrons was recovered from foodworkers in 19 outbreaks. Overall, 12% (129 of 1,033) of foodworkers tested positive for Salmonella. Sixty-four (53%) of 121 Salmonella-positive foodworkers reported not having had a recent gastrointestinal illness. Overall, the median duration of Salmonella shedding was 16 days. Among foodworkers who reported gastrointestinal illness, the median shedding duration was 30 days as compared with 3 days for asymptomatic foodworkers. Positive environmental samples were recovered in 4 (33%) of 12 outbreaks. No specific food vehicle was identified in any outbreaks associated with Salmonella-positive environmental samples. The median duration of outbreaks with positive environmental samples (187 days) was significantly longer than the median duration of outbreaks with negative environmental results (26 days, P = 0.03). A higher proportion of Salmonella-positive foodworkers (22 versus 8%) was identified in outbreaks with positive environmental samples. Salmonella outbreaks in restaurants are frequently prolonged yet produce a small number of confirmed patron cases. Prolonged outbreak durations suggest a persistent reservoir of contamination. Infected foodworkers likely serve as an important source for Salmonella transmission. Therefore, assessment of foodworker infection is essential for controlling restaurant outbreaks.

Consumer Product Safety↗

PubMed1992

Waterborne disease outbreaks in the United States of America: causes and prevention.

National statistics on waterborne outbreaks in the United States of America show that 1,702 waterborne outbreaks with 542,018 cases of illness and 1,089 deaths have been reported. Almost all deaths prior to 1940 were due to typhoid fever; 9 deaths from other causes have occurred since 1971. During the past decade, 291 waterborne outbreaks were reported in community (43%) and noncommunity (33%) systems, and from the ingestion of contaminated water from recreational (14%) and individual (10%) water sources. Although several large waterborne outbreaks occurred during the past decade, most were in small communities. The number of illnesses per outbreak in noncommunity systems during the past decade is much larger than that reported during any previous period, and the magnitude of these outbreaks indicates the potential effect on the travelling, transient population. During 1981-1990, contaminated, untreated groundwater or inadequately disinfected groundwater was responsible for 43% of all reported waterborne outbreaks, and contaminated, untreated surface water or inadequately treated surface water was responsible for 24% of all reported outbreaks. The use of untreated groundwater has declined in importance as a cause of outbreaks, and more outbreaks are now caused by inadequate or interrupted disinfection of groundwater. The increased occurrence of outbreaks in disinfected groundwater systems may be due to (i) increased use of disinfection with little effort to reduce or eliminate sources of contamination, and (ii) not providing effective, continuous disinfection. In surface-water systems, outbreaks occur primarily because of inadequate or interrupted disinfection in systems that do not provide filtration, but a large increase in outbreaks has recently occurred in filtered systems.(ABSTRACT TRUNCATED AT 250 WORDS)

Disease Outbreaks↗

PubMed2006

[Study of tuberculosis outbreaks reported in Catalonia, 1998-2002].

OBJECTIVE: To analyze the characteristics of tuberculosis outbreaks declared under vigilance programs in Catalonia. METHODS: Descriptive study of outbreaks from 1998 through 2002 for which reports were available. An outbreak was defined as 3 or more associated cases appearing within a year. For 2 health care regions, outbreaks for which there were full surveillance reports with contact tracing were compared to outbreaks identified but which had not been fully reported. RESULTS: Twenty-seven outbreaks were analyzed. Nineteen (70%) occurred within families. A total of 22 outbreaks were declared upon identification of the true index case and 5 upon detection of secondary cases. The mean annual incidence of outbreaks was 0.40/100,100 inhabitants. Most cases were in males 16 to 40 years of age and involved cavitary lesions and a clinically significant diagnostic delay. Twenty-seven outbreaks caused 69 secondary cases. A longer diagnostic delay was seen to correspond to a larger number of secondary cases (P=.08). In the 2 health care regions analyzed, full surveillance reports with contact tracing were issued for 2 of the 14 outbreaks detected (14.4%). CONCLUSIONS: Tuberculosis outbreaks are common but investigative follow-up is scarce. The size of the outbreak is related to the length of diagnostic delay. Rapid diagnosis, contact tracing, and the issuance of a public health report should be priorities in all outbreaks detected.

Adult↗