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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↗

PubMed1995

[Outbreak of serogroup C meningococcal disease among teenagers in Randers--preventive measures and examination of the meningococcal carrier conditions].

An outbreak involving 20 cases of serogroup C meningococcal disease, predominantly among teenagers, occurred over a seven-month period in the Randers area of Denmark. The cases were caused by a serogroup C:2a:P1.2 sulphonamide-resistant strain. The available evidence was against the transmission being related to particular schools. The outbreak was experienced as three clusters. At two 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 carrier rate (30%), the overall group C rate (3%) and, 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↗

PubMedDate not supplied

Complicated infectious coryza outbreaks in Argentina.

Seventeen complicated outbreaks of infectious coryza in layer, broiler-breeder, and broiler flocks were studied. In the layer flock outbreaks, drops in egg production of up to 35% were seen. In the broiler flocks and several of the layer flocks, losses due to persistent mortality and/or culling varied between 2 and 5%. Signs of infectious coryza in both layers and broiler-breeders were typical; in broilers, however, swollen head-like syndrome was seen. Except in one flock, no viral diseases were clinically or serologically detected. Excluding broiler-breeders, birds from most other flocks were serologically positive for Mycoplasma gallisepticum, and some were also positive for M. synoviae. Haemophilus paragallinarum was isolated from all of the outbreaks, but only as a pure culture in three outbreaks. Isolation of H. paragallinarum from sites such as liver, kidney, and particularly tarsal arthritis and ocular globes appears to be reported for the first time. Serovar A was isolated in eight outbreaks, serovar B in six, serovar C in one, and untypable serovars in two. The severity of these infectious coryza outbreaks may have been increased by concurrent salmonellosis, pasteurellosis, and mycoplasmosis, although under certain conditions H. paragallinarum is able to cause septicemia. Ten of the outbreaks occurred in birds vaccinated against infectious coryza; this may be due to the use of vaccines that do not provide protection against the types of H. paragallinarum that affect poultry in the region.

Animals↗

PubMed1996

Outbreaks of infectious intestinal disease in schools and nurseries in England and Wales 1992 to 1994.

We present data on outbreaks of infectious intestinal disease in schools and nurseries obtained from the surveillance scheme of all general outbreaks of infectious intestinal disease in England and Wales reported to the PHLS Communicable Disease Surveillance Centre between 1992 and 1994. A minimum set of data was received for 1280 outbreaks, 95 of which (7%) arose in schools and nurseries. The commonest pathogens were salmonellas, Shigella sonnei, and small round structured viruses. The mode of transmission was described as mainly from person to person in 55 outbreaks and mainly foodborne in 30. The mean attack rate was 30% and median duration was 10 days. The attack rate and duration varied with the pathogen involved. Forty-five of the 3118 people reported to have been ill were admitted to hospital. Outbreaks in schools and nurseries are common. Attack rates are high and such outbreaks are often prolonged. Effective infection control policies and appropriate training of staff are needed. Good local systems for surveillance can help identify outbreaks quickly and allow control measures to be applied early.

Adolescent↗

PubMed1996

Food-borne disease outbreaks in Taiwan, 1994.

In 1994, 102 outbreaks of food-borne disease involving 4,726 cases were reported to the Taiwan Department of Health. This is the highest number of outbreaks and cases in recent years in Taiwan. Of these outbreaks, 72.5% (74/102) were caused by bacterial pathogens, with Vibrio parahaemolyticus responsible for 56.7% (42/74), Staphylococcus aureus 20.3% (15/74), Bacillus cereus 14.9% (11/74) and Salmonella spp other than S. typhi and S. paratyphi 8.1% (6/74). V. parahaemolyticus has been a leading cause of problems in Taiwan for many years. Contamination of seafood with this organism has been reported frequently, particularly in the warmer months. In 1994, small outbreaks (fewer than 5 cases) and large outbreaks (more than 50 cases) represented 31.4% (32/102) and 12.7% (13/102), respectively, of the total. The median outbreak size was 10 cases. A high proportion (54%, 7/13) of the large outbreaks was associated with commercial lunch-boxes supplied to elementary and junior high schools. Health education to improve food sanitation and supervision of food sanitation practices need to be strengthened.

Bacillus cereus↗

PubMed1996

Outbreaks of foodborne viral gastroenteritis in England and Wales: 1992 to 1994.

Outbreaks of foodborne viral gastroenteritis in England and Wales from 1992 to 1994 have been analysed using data from the national surveillance scheme for general outbreaks of infectious intestinal disease. The cause was virologically confirmed for 389 (31%) of the 1280 outbreaks for which a minimum set of data were collected. Forty-seven of the 389 were attributed to foodborne transmission, 41 of which were caused by small round structured viruses (SRSV). An infected food handler was suspected to be a contributing factor in 14 and the consumption of oysters in eight of these 41 foodborne SRSV outbreaks. No seasonal pattern emerged. The highest incidences occurred in Wales, West Midlands, and South Western regional health authorities. The annual rate of outbreaks did not increase during the three year period (Chi square for linear trend 0.6; p = 0.4). Much remains to be discovered about the epidemiology of foodborne viruses, and outbreaks present an opportunity to enhance our knowledge. As molecular diagnostic techniques become routinely available, it is likely that the role of viruses in foodborne outbreaks will be increasingly recognised.

Data Collection↗

PubMed1996

General outbreaks of infectious intestinal disease in England and Wales 1992 to 1994.

Data from the surveillance scheme of general outbreaks of infectious intestinal disease in England and Wales, reported to the PHLS Communicable Disease Surveillance Centre (CDSC), were used to review 1280 of the 1594 outbreaks identified between 1 January 1992 and 31 December 1994 for which a minimum data set was captured. The number of outbreaks reported in each regional health authority ranged from 31 in Mersey to 221 in Yorkshire. The commonest pathogens reported were salmonellas in 32% (412) of outbreaks, small round structured virus (SRSV) in 27% (342), Clostridium perfringens in 7% (90), and Shigella sonnei in 4% (46). The main mode of transmission was described as foodborne in 50% (642), over half of which were caused by salmonellas, and person to person in 39% (496), over half of which were caused by SRSV. Most outbreaks transmitted from person to person occurred in hospitals and in residential institutions for elderly people. Outbreaks lasted from one to 217 days (median five days) and their duration varied with the pathogen. The median attack rate was 37%. Illness was reported in 34,158 people, 751 of whom (2%) were admitted to hospital. There were 55 deaths, 28 of which were associated with salmonella and 12 with SRSV. Most of the outbreaks reported and the associated morbidity and mortality could have been prevented by following standard food hygiene practices, implementing infection control policies, and ensuring that food entering kitchens was of the highest microbiological quality possible.

Clostridium Infections↗

PubMed1998

[Measles outbreaks in the Bern canton].

Currently, overall vaccination coverage against measles among infants ranges between 77% and 89% in Switzerland. Experience in other countries has shown that this level of vaccination is not sufficient to prevent measles outbreaks, especially among schoolchildren. During 1992 surveillance for measles outbreaks in closed populations was conducted in the Canton of Berne. Outbreaks were investigated for vaccine efficacy. Two measles outbreaks in schoolchildren were observed during the study period. In 2 Bernese suburban schools 6 measles cases in children (median age 12.5 years) occurred over a period of 37 days. One of the cases had been vaccinated. Vaccination rate in the healthy control children was 89.7%. Estimated vaccine efficacy was 97.7% (95% confidence interval [CI]: 68%, 99%). The second outbreak occurred in a rural region and comprised 21 measles cases (median age 7.5 years) within 43 days. 10 (47.6%) of the cases attended the same school. None of the cases had been vaccinated. Of the healthy control children 82.6% had received measles vaccine. Estimated vaccine efficacy was 100% (CI: 87%, 100%). These two measles outbreaks were due to failure to vaccinate rather than low vaccine efficacy. Surveillance for measles cases is currently not sufficient for the detection of measles outbreaks in our population. Laboratory confirmation of measles, especially in vaccinated persons, has become more important in a time of relatively low measles incidence.

Adolescent↗

PubMed1998

General outbreaks of infectious intestinal disease in England and Wales: 1995 and 1996.

One thousand nine hundred and nineteen general outbreaks of infectious intestinal disease in England and Wales were reported to the PHLS Communicable Disease Surveillance Centre (CDSC) between 1 January 1995 and 31 December 1996, compared with 1073 in the previous two years. A minimum data set was received for 1568 (82%) of the 1919 outbreaks. Over 40,000 people were affected and about 2% of those who were ill were admitted to hospital. Seventy-one deaths were reported. The duration of outbreaks varied between less than one day and 202 days (median six days) according to the pathogen. Small round structured virus (SRSV) (43%) and salmonellas (15%) were the most commonly reported pathogens. In almost a quarter of the outbreaks (24%) the aetiology was unknown. Over half the outbreaks (64%) were reported to be transmitted from person to person, most of which were due to SRSV and occurred in residential homes and hospitals. Twenty-two per cent of outbreaks were described as mainly foodborne, 51% of which were due to salmonellas. The number of outbreaks reported in each region ranged from 52 in Wales to 512 in Northern and Yorkshire.

Caliciviridae Infections↗

PubMed2026

Responding to a protracted tuberculosis outbreak: lessons from multiple rounds of investigation in a Chinese boarding school.

PURPOSE: This study analysed a multi-semester pulmonary tuberculosis (PTB) cluster outbreak in a Chinese boarding school to provide evidence for future epidemic control. METHODS: Contacts were screened via symptoms, infection tests and chest radiography. Screening expanded progressively from close contacts to same-floor contacts, then all students and staff. Whole-genome sequencing (WGS) with single nucleotide polymorphism (SNP) and bioinformatics analysis was used for lineage classification, transmission clustering (≤12 SNPs defining a cluster) and drug resistance prediction. RESULTS: From 2020 to 2022, 20 students were diagnosed with PTB, half laboratory-confirmed. Most cases clustered in class 16 and were epidemiologically linked to the primary case (case 0), who had household PTB exposure. Case 0 and case 1 had diagnostic delays exceeding 3 and 6 months, respectively. WGS of five isolates (case 1, 3, 4, 9 and 10) collected over three semesters showed all belonged to lineage 2 and differed by ≤12 SNPs, confirming the same transmission chain. The infection rate in class 16 (46.34%) was significantly higher than other case classes (19.05%) and classes without cases (8.27%) (χ2 = 61.169, p < 0.001). No new cases were detected during a one-year follow-up of students involved in the outbreak after the final round of screening, nor among household contacts of all cases followed up to the present. CONCLUSIONS: Lack of entry health examinations facilitated the outbreak. Delayed diagnosis, incomplete contact screening and absence of preventive treatment led to cross-semester persistence. The infection rate disparity confirms class 16 as the outbreak epicentre. Improving community case management, extending contact follow-up and enhancing cluster outbreak measures are recommended to prevent future outbreaks.

Humans↗

PubMed2025

Incorporating Epidemiological Data into the Genomic Analysis of Partially Sampled Infectious Disease Outbreaks.

Pathogen genomic data are increasingly being used to investigate transmission dynamics in infectious disease outbreaks. Combining genomic data with epidemiological data should substantially increase our understanding of outbreaks, but this is highly challenging when the outbreak under study is only partially sampled, so that both genomic and epidemiological data are missing for intermediate links in the transmission chains. Here, we present a new dynamic programming algorithm to perform this task efficiently. We implement this methodology into the well-established TransPhylo framework to reconstruct partially sampled outbreaks using a combination of genomic and epidemiological data. We use simulated datasets to show that including epidemiological data can improve the accuracy of the inferred transmission links compared with inference based on genomic data only. This also allows us to estimate parameters specific to the epidemiological data (such as transmission rates between particular groups), which would otherwise not be possible. We then apply these methods to two real-world examples. First, we use genomic data from an outbreak of tuberculosis in Argentina, for which data was also available on the HIV status of sampled individuals, in order to investigate the role of HIV coinfection in the spread of this tuberculosis outbreak. Second, we use genomic and geographical data from the 2003 epidemic of avian influenza H7N7 in the Netherlands to reconstruct its spatial epidemiology. In both cases, we show that incorporating epidemiological data into the genomic analysis allows us to investigate the role of epidemiological properties in the spread of infectious diseases.

Humans↗

PubMed2025

Temporal reconstruction of a Salmonella Enteritidis ST11 outbreak in New Zealand.

Outbreaks caused by Salmonella Enteritidis are commonly linked to eggs and poultry meat internationally, but this serovar had never been detected in Aotearoa New Zealand (NZ) poultry prior to 2021. Locally designated genomic cluster Salmonella Enteritidis_2019_C_01, was implicated in a 2019 outbreak associated with a restaurant in Auckland. Four Enteritidis_2019_C_01 sub-clusters have since been identified, two retrospectively, in the Auckland region. Authorities initiated a formal outbreak investigation after genomically indistinguishable S. Enteritidis was isolated from the NZ poultry production environment. This study analysed 231 S. Enteritidis genomes obtained from the outbreak using Bayesian phylodynamic tools to gain insight into the outbreak's dynamics and origin. We used Bayesian integrated coalescent epoch plots to estimate the change of the Enteritidis ST11 population size over time and marginal structured coalescent approximation to estimate transmission between poultry producers. We investigated human and poultry isolates to elucidate the time and location of the most recent common ancestor of the outbreak and transmission pathways. The median most recent common ancestor was estimated to be February 2019. We found evidence of amplification and spread of strain Enteritidis_2019_C_01 within the poultry industry, as well as transmission events throughout the production chain. The intervention by the public health and food safety authorities coincided with a drop in the effective population size of the S. Enteritidis ST11 as well as notified human cases. This information is crucial for understanding and preventing the transmission of S. Enteritidis in NZ poultry to ensure poultry meat and eggs are safe for consumption.

Salmonella enteritidis↗

PubMed1983

Economic impact of a botulism outbreak. Importance of the legal component in food-borne disease.

Legal expenses arising from food-borne outbreaks have not been reported in the medical literature, to the best of our knowledge. Expenses of an outbreak of food-borne botulism involving 34 victims in 1978 exceeded +5.8 million. These included outbreak investigation and control (3.2% of total), medical care for patients with botulism from April 1978 through October 1981 (12.3%), and settlements and legal charges (84.4%). Legal actions following food-borne outbreaks must be recognized for several reasons. First, the delay between the outbreak and the conclusion of legal activity (three years in this instance) mandates prompt and meticulous written documentation of investigation and control work. Second, legal expenses may make a large contribution to the total societal impact of food-borne disease outbreaks. Finally, awareness of the legal expense strengthens the rationale for public and private expenditures on food-borne disease prevention in this country.

Botulism↗

PubMed1991

Analysis of plasmid pattern in paediatric intensive care unit outbreaks of nosocomial infection due to Enterobacter cloacae.

Sequential outbreaks of nosocomial infection due to multiply-resistant Enterobacter cloacae occurred in September 1987, and between December 1988 and January 1989, in a paediatric intensive care unit. A total of eight neonates were affected and most had received ventilatory support. Initially, we were unable to determine whether the two outbreaks were caused by the same strain of E. cloacae. After applying plasmid profile analysis to identify epidemic strains, we established that the strain from the first outbreak was different from the second outbreak strain, as each had its own plasmid pattern. During the second outbreak, an environmental bacteriological survey was carried out. We found that the distilled water containers were contaminated with E. cloacae which had the same plasmid profile. After changing the distilled water containers and by reinforcement of aseptic techniques, the nosocomial outbreak was terminated.

Cross Infection↗

PubMed1994

A hospital outbreak due to Norwalk virus.

An outbreak of diarrhoea and vomiting began at a hospital for the elderly on the 25 October 1991. The symptoms and pattern of spread suggested a viral aetiology from a point source. Electron microscopy confirmed the presence of Norwalk virus. The first wave of illness affected 37 patients and 28 staff. Secondary cases occurred on all wards. Analytical studies of food consumed at three lunchtime meetings by staff and visitors to the hospital demonstrated a clear association between eating sandwiches and subsequent illness. The source of the outbreak was probably a food handler involved in the preparation of sandwiches. Control measures were implemented and the outbreak was declared over on the 11 November 1991. At this time 95 patients and 69 staff (including six visitors) had been affected. The implications for the future investigation and prevention of outbreaks of viral gastroenteritis in closed communities are discussed. An audit of the action taken during the outbreak resulted in the development of standards for the investigation and control of local outbreaks.

Caliciviridae Infections↗

PubMedDate not supplied

Comparison of arbitrarily primed polymerase chain reaction and cell envelope protein electrophoresis for analysis of Acinetobacter baumannii and A. junii outbreaks.

Two successive Acinetobacter outbreaks in a neonatal intensive care unit were studied with arbitrarily primed polymerase chain reaction (AP-PCR), cell envelope protein electrophoresis (protein fingerprinting) and antibiotic susceptibility testing. AP-PCR fingerprinting and protein fingerprinting yielded identical clustering of the isolates studied. Susceptibility test results were useful for rapid recognition of the outbreaks, but clustering of several isolates was different from the clustering obtained with AP-PCR fingerprinting and protein fingerprinting. Typing results indicated that the two outbreaks, which occurred at a three-month interval, were each caused by a single strain, and that both strains differed from the strains prevailing in the hospital. The strain of one outbreak was identified as A. junii, a species commonly not involved in outbreaks. A. baumannii isolates collected from different departments of this hospital during a period of four years clustered into only five different types. Moreover, strains from different departments of a second hospital belonged to the type prevailing in the first hospital, although there were no apparent connections between the two institutions. This may indicate that only a limited number of strains of the A. calcoaceticus-baumannii complex are involved in nosocomial outbreaks.

Acinetobacter↗

PubMedDate not supplied

Application of genetic methods to study the relationship between classical swine fever outbreaks.

Eleven viruses isolated between 1993 and 1997 from outbreaks of classical swine fever in the neighbouring countries of Slovakia, The Czech Republic and Austria were compared after partial sequencing of the NS5B and E2 genes. Viruses collected from South-Central and West Slovakia were indistinguishable during a period of four years, even when associated with outbreaks of variable severity. Outbreaks that occurred in the Czech Republic in 1996 involved two types of virus, one of which was related to the Slovakian outbreaks, and the other to Austrian outbreaks. The results show that the molecular-genetic approach can reveal epizootiological relationships between outbreaks that would not otherwise be apparent. Furthermore, the relative genetic stability of the classical swine fever virus in the field, means that quite small sequence differences can have epizootiological significance.

Animals↗