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PubMed1999

Predicting the level of herd infection for outbreaks of foot-and-mouth disease in vaccinated herds.

Foot-and-mouth disease (FMD) is a highly contagious virus infection of sheep, goats, cattle, pigs and other, non-domesticated species of artiodactyls, and causes both clinical and subclinical infection according to the natural or acquired immunity of the host. Within vaccinated dairy herds FMD may appear as an acute, mild or subclinical infection, dependent upon the immune status of the herd, the level of challenge and the efficacy of the vaccine used. In the large dairy herds of Saudi Arabia, sub-clinical FMD was on a number of occasions, found to have spread amongst the cattle before signs of disease were seen. Such undetected transmission resulted in a large incidence on the first day of diagnosis and curtailed the impact of post-outbreak vaccination (PoV). First day incidence (FDI) for these herds was found to correlate with the final cumulative incidence of clinical disease. Since FDI is available at the start of an outbreak it can be used as a predictive tool for the eventual outcome of an FMD outbreak. During the past 11 years 47 % of dairy herds examined in Saudi Arabia have experienced FMD initially as sub-clinical disease. For the remaining 53 %, waning vaccinal protection did not suppress clinical disease in the initially infected animals, and these showed severe rather than mild signs. Hence, in such herds there was a very low initial level of subclinical infection, so PoV was more effective, and the timing of PoV was found to give a good correlation with cumulative herd incidence: an early PoV resulted in low prevalence of clinically infected animals whilst late PoV permitted high prevalence. PoV timing can thereby be used in tandem with FDI as a predictive tool for future outbreaks, estimating the final cumulative incidence (or prevalence) of clinical FMD cases.

Animals↗

PubMed1999

Meningococcal disease at the University of Southampton: outbreak investigation.

In October 1997, an outbreak of meningococcal disease occurred at the University of Southampton. All six cases were first year students living in halls of residence. Microbiological characterization of case and carrier strains, case interviews, and a meningococcal carriage prevalence survey were used to investigate the outbreak. Five cases were due to serogroup C strains, one case was unconfirmed. Serotyping did not distinguish between the strains but gene sequencing permitted identification of two distinct strains in the outbreak. Although none of the cases was known to each other, three had attended the same nightclub one evening 3-4 days before illness. Meningococcal carriage rates in undergraduates were within the range expected (147/587, 25%), but no carriers of outbreak strains were identified in this sample. The findings suggest that in communities with a high degree of social interaction, the introduction of highly virulent meningococcal strains may result in enhanced transmission with clustering of cases.

Adolescent↗

PubMed1999

Outbreak of meningococcal disease in western Norway due to a new serogroup C variant of the ET-5 clone: effect of vaccination and selective carriage eradication.

A new sulphonamide resistant (SR) C: 15:P1.7,16 meningococcal strain, a variant of the ET-5 clone, dominated in an outbreak of 22 cases in western Norway commencing in 1995. The first eight patients were 15-21 years old from the Nordhordland area, initiating a carrier study in the local high schools. Carriage of SR serogroup C meningococci was detected by routine methods and treated with a single dose of ofloxacin 400 mg. Of 20 treated carriers, 14 harboured the outbreak strain C: 15:P1.7,16. Vaccination of 4000 children, adolescents and close contacts of patients was also performed. After the intervention, 14 additional cases of meningococcal disease occurred, 8 due to the outbreak strain. However, incidence rates dropped from 180 to 30 per 100000 per year in the student population, but increased from 0 to 13 in the rest of the population in Nordhordland. Carriage eradication is not generally recommended in Norway. However, tracing and treating meningococcal carriage may have reduced transmission and disease in this outbreak situation.

Adolescent↗

PubMed2000

An outbreak of Escherichia coli O157:H7 infections and haemolytic uraemic syndrome associated with consumption of unpasteurized apple cider.

During October 1996, an outbreak of Escherichia coli O157:H7 infections among Connecticut residents occurred. An epidemiologic investigation included enhanced surveillance and a case-control study. Clinical isolates of Escherichia coli O157:H7 were typed by pulsed-field gel electrophoresis (PFGE). Implicated cider samples were analysed by culture and polymerase chain reaction (PCR). Consumption of implicated cider was associated with illness; (matched odds ratio = undefined, 95 % confidence interval = 3.5-infinity). Ultimately, a total of 14 outbreak-associated patients were identified. All isolates analysed by PFGE yielded the outbreak-associated subtype. Escherichia coli O157:H7 was not cultured from three cider samples; PCR analysis detected DNA fragments consistent with Escherichia coli O157:H7 in one. This outbreak was associated with drinking one brand of unpasteurized apple cider. PFGE subtyping supported the epidemiologic association. PCR analysis detected microbial contaminants in the absence of live organisms. Washing and brushing apples did not prevent cider contamination.

Adolescent↗

PubMed2000

A secondary school outbreak of mumps following the childhood immunization programme in England and Wales.

Since the introduction of routine measles, mumps and rubella immunization for children in England and Wales in 1988, the incidence of mumps has declined steadily. We describe an outbreak of mumps in 1996 attacking 34 of a cohort of 98 schoolchildren born in 1982 and 1983. This is the largest outbreak in the UK since the introduction of the vaccine into the childhood immunization schedule. Salivary IgM assay was used as a simple, minimally invasive test to confirm the diagnosis. The occurrence of the outbreak demonstrates that British children who were just too old to receive mumps immunization in 1988 continue to be at risk of this disease as a result of diminished natural exposure. Further cases and outbreaks in this cohort are to be expected. Cohorts born before 1982 appear to be at less risk, presumably because of naturally acquired infection before the introduction of immunization.

Adolescent↗

PubMed2000

A community outbreak of hepatitis A in a religious community in Indiana: failure of immune serum globulin to prevent the spread of infection.

An outbreak of hepatitis A occurred in a religious community in Indiana, USA. Sixty-nine cases were ascertained among the 4466 residents over a year, and the highest attack rate was in children. The management of the outbreak included the widespread use of prophylactic immune serum globulin (ISG). Despite this, further cases occurred. To guide further ISG administration, a survey was undertaken to ascertain what proportion remained susceptible to HAV infection. From a random sample of 600 people in the affected community 440 saliva specimens (73%) were obtained. Of these, 12.5% were found to be immune (95% confidence intervals from 9-16%). No changes were made to the ISG administration policy. There was no evidence to suggest that administration of ISG had any effect on the duration of the outbreak. There was a low rate of symptomatic infection among young children (less than 10 years); as ISG does not prevent the spread of the virus its use is not recommended in future outbreak situations.

Adolescent↗

PubMed2000

Estimation of the basic reproduction number of measles during an outbreak in a partially vaccinated population.

From March to July 1996 a measles outbreak occurred in northern Luxembourg with 110 reported cases centered around two primary schools (85 cases) and the surrounding community (25 cases). Eighty four suspected cases were confirmed serologically. Vaccine coverage was estimated from questionnaire-based surveys at the two primary schools to be 70 and 76%, respectively. Vaccine efficacy during the outbreak was estimated to be 94.6% [95% confidence interval (CI) 90.4-97.0]. Using the information from the, school surveys, we obtained estimates of the basic reproduction number of measles of 7.7 (95% CI 4.4-11.0) and 6.2 (95% CI 3.5-8.9), respectively. Assuming a 95% vaccine efficacy, these estimates correspond to minimal vaccine coverages of 91.6% (95% CI 81.4-95.7) and 88.3% (95% CI 75.5-93.4) which would have been necessary to minimize the chances of a major outbreak occurring. We can confirm that major outbreaks in similar school settings can only be prevented if vaccination coverage exceeds 90%.

Adult↗

PubMed2000

Widespread environmental contamination with Norwalk-like viruses (NLV) detected in a prolonged hotel outbreak of gastroenteritis.

A protracted outbreak of Norwalk-like virus (NLV)-associated gastroenteritis occurred in a large hotel in North-West England between January and May 1996. We investigated the pattern of environmental contamination with NLV in the hotel during and after the outbreak. In the ninth week, 144 environmental swabs taken from around the hotel were tested for NLV by nested RT-PCR. The sites were categorized according to the likelihood of direct contamination with vomit/faeces. The highest proportion of positive samples were detected in directly contaminated carpets, but amplicons were detected in sites above 1.5 m which are unlikely to have been contaminated directly. The trend in positivity of different sites paralleled the diminishing likelihood of direct contamination. A second environmental investigation of the same sites 5 months after the outbreak had finished were all negative by RT-PCR. This study demonstrates for the first time the extent of environmental contamination that may occur during a large NLV outbreak.

Caliciviridae Infections↗

PubMed1999

Outbreak of cholera in Ibadan, Nigeria.

The changing epidemiology of cholera in Ibadan, Nigeria, has become a public health challenge, and outbreaks of the disease have been occurring with increasing frequency since the first outbreak in modern times in 1970. In this outbreak, 1384 persons were seen, diagnosed and treated for the disease at the cholera unit, Ibadan from January to December 1996. The outbreak lasted for a whole year. No child under one year was seen. The age adjusted case fatality rate was 5.3%. Diarrhoea and vomiting were the most common combination of symptoms present in 97.3% of all cases, followed by diarrhoea, vomiting and dehydration (84.3%). The median number of days spent on admission was only 2 days. Cholera cases were clustered within the densely populated and poorly planned areas of the city. Though significantly more cases were seen during the rainy season than during the dry season (p<0.01), the deaths were not seasonally related (p = 0.67). Contamination of otherwise potable sources of water, late presentation to the cholera treatment unit and low levels of knowledge about diseases need to be addressed in order to effectively control this disease in the community. Progress should also be made towards developing a suitable vaccine for the control of this internationally important public health disease so that the responsibility of its control is not left entirely to individuals and communities, particularly in developing countries.

Adolescent↗

PubMed2003

An outbreak of diarrhoea in one-week-old piglets caused by group A rotavirus genotypes P[7],G3 and P[7],G5.

Thirty-two group A isolates of rotavirus detected in faecal samples from diarrhoeic piglets, were selected for P and G genotyping using a Multiplex RT-PCR. Ten isolates, from animals less than 8 days old, characterized an outbreak of diarrhoea caused by group A rotavirus in animals. P[7],G3 (CRW8-like) and P[7],G5 (OSU-like) genotypes were detected in 5 animals each. Isolates of a group A rotavirus of genotypes compatible with the OSU prototype were those most frequently identified in single infections in older animals (20/32 strains). In addition to these, 20 isolates from piglets with diarrhoea caused by group A rotavirus, collected between May 1998 and June 1999, but not from the outbreak month, were analysed. These isolates were used to compare the types observed on the farm outside the outbreak in May 1999 and the CRW8-like genotype was found in none of these faecal samples. P[7],G5 was the most frequent genotype (10/20 strains). No outbreak of diarrhoea caused by rotavirus in 1-week-old piglets was found in any other period during the 13 months of this study.

Animals↗

PubMed2026

Deciphering the etiology of the 2024 outbreak of undiagnosed febrile illness in Panzi, Democratic Republic of the Congo.

In late 2024, an outbreak of over 400 cases of undiagnosed febrile illness, predominantly presenting as fever and cough, was reported in Panzi Health Zone, southwestern Democratic Republic of the Congo. Here we conducted an epidemiological and laboratory investigation to determine the etiology of the outbreak. Clinical data and specimens were prospectively collected from 108 individuals, of whom 59/108 (54.6%) were female. Children aged <5 years were the most affected (47/108, 43.5%); 14/32 (43.7%) were malnourished. Oro/nasopharyngeal swabs from 96/108 individuals were PCR tested; 26 blood samples were sequenced. Plasmodium falciparum was detected in 56/108 (51.8%) individuals. Co-infections were also detected, with influenza A(H1N1)pdm09 virus in 16/56 (28.6%) and severe acute respiratory syndrome coronavirus 2 in 10/56 (17.9%) individuals. No novel pathogens were detected via metagenomics. Our findings suggest that the outbreak was primarily associated with a surge in malaria cases, with concurrent viral respiratory infections. Increasing decentralized laboratory capacity and strengthening broader health systems remain crucial for faster outbreak detection and investigation.

Disease Outbreaks↗

PubMed2005

A model for the management of an atypical endophthalmitis outbreak.

PURPOSE OF STUDY: To present a model for the assessment, investigation, and management of an atypical outbreak of infectious endophthalmitis of indeterminate aetiology. METHODS: A published statistical model was used to determine when the case-load constituted an outbreak. Intraocular surgery was discontinued and a multidisciplinary infection control team was formed aimed at identifying potential causative factors among the following categories: environment around theatre, preoperative preparation, intraoperative theatre practices, intraoperative surgical practices, postoperative practices, equipment maintenance guidelines, cleaning/sterilization practices, and microbiological screening. RESULTS: Five cases of postoperative endophthalmitis developed following uncomplicated phacoemulsification cataract surgery by different surgeons over a 7-month period. Despite full investigation no single focus of infection could be determined. Four out of five cases were culture positive. Three grew Streptococcus viridans of different strains. The fourth culture grew Staphylococcus aureus. In the absence of a single causative factor, it was postulated the combined effect of multiple potential factors may have led to an increased bacterial load and subsequent infection rate. Improved practices were initiated including new cleaning protocols to combat the build-up of debris on phacoemulsification instruments. Cataract surgery was resumed with 3-monthly microbiological monitoring. There have been no further cases in the 12 months following the changes. CONCLUSION: Outbreaks of endophthalmitis typically present over a short time period and could often be attributed to a single infective cause. We present our experience of detecting and managing this cluster and recommend a 'ground-up' multidisciplinary model to manage future outbreaks of this devastating condition.

Aged↗

PubMed2000

Viewpoint: filovirus haemorrhagic fever outbreaks: much ado about nothing?

The recent outbreak of Marburg haemorrhagic fever in the Democratic Republic of Congo has put the filovirus threat back on the international health agenda. This paper gives an overview of Marburg and Ebola outbreaks so far observed and puts them in a public health perspective. Damage on the local level has been devastating at times, but was marginal on the international level despite the considerable media attention these outbreaks received. The potential hazard of outbreaks, however, after export of filovirus from its natural environment into metropolitan areas, is argued to be considerable. Some avenues for future research and intervention are explored. Beyond the obvious need to find the reservoir and study the natural history, public health strategies for a more timely and efficient response are urgently needed.

Democratic Republic of the Congo↗

PubMed2002

An outbreak of Ebola in Uganda.

An outbreak of Ebola disease was reported from Gulu district, Uganda, on 8 October 2000. The outbreak was characterized by fever and haemorrhagic manifestations, and affected health workers and the general population of Rwot-Obillo, a village 14 km north of Gulu town. Later, the outbreak spread to other parts of the country including Mbarara and Masindi districts. Response measures included surveillance, community mobilization, case and logistics management. Three coordination committees were formed: National Task Force (NTF), a District Task Force (DTF) and an Interministerial Task Force (IMTF). The NTF and DTF were responsible for coordination and follow-up of implementation of activities at the national and district levels, respectively, while the IMTF provided political direction and handled sensitive issues related to stigma, trade, tourism and international relations. The international response was coordinated by the World Health Organization (WHO) under the umbrella organization of the Global Outbreak and Alert Response Network. A WHO/CDC case definition for Ebola was adapted and used to capture four categories of cases, namely, the 'alert', 'suspected', 'probable' and 'confirmed cases'. Guidelines for identification and management of cases were developed and disseminated to all persons responsible for surveillance, case management, contact tracing and Information Education Communication (IEC). For the duration of the epidemic that lasted up to 16 January 2001, a total of 425 cases with 224 deaths were reported countrywide. The case fatality rate was 53%. The attack rate (AR) was highest in women. The average AR for Gulu district was 12.6 cases/10 000 inhabitants when the contacts of all cases were considered and was 4.5 cases/10 000 if limited only to contacts of laboratory confirmed cases. The secondary AR was 2.5% when nearly 5000 contacts were followed up for 21 days. Uganda was finally declared Ebola free on 27 February 2001, 42 days after the last case was reported. The Government's role in coordination of both local and international support was vital. The NTF and the corresponding district committees harmonized implementation of a mutually agreed programme. Community mobilization using community-based resource persons and political organs, such as Members of Parliament was effective in getting information to the public. This was critical in controlling the epidemic. Past experience in epidemic management has shown that in the absence of regular provision of information to the public, there are bound to be deleterious rumours. Consequently rumour was managed by frank and open discussion of the epidemic, providing daily updates, fact sheets and press releases. Information was regularly disseminated to communities through mass media and press conferences. Thus all levels of the community spontaneously demonstrated solidarity and response to public health interventions. Even in areas of relative insecurity, rebel abductions diminished considerably.

Adolescent↗

PubMed2003

Control of an outbreak of BCG complications in Gaza.

OBJECTIVE: We aim to describe Bacille Calmette Guerin (BCG) complications in Gaza using two studies: one during an outbreak and the other after control of the possible contributing factors to this outbreak. METHODOLOGY: The first study was conducted on 6145 newborn infants vaccinated in 21 primary care centres in Gaza with BCG vaccine, Pasteur Paris, batch number 5122 from July to October 2001. The study was repeated after changing the BCG vaccine and training 63 nurses from November to December 2001. The training program included theoretical lectures on BCG and tuberculosis and practical training in strict intradermal injection. The second study included 6877 newborn infants vaccinated with BCG vaccine, batch number 101023, Denmark, from January to April 2002. RESULTS: During the outbreak, BCG complications occurred in 225 infants with a complication rate of 36.61 per 1000 vaccinations. The mean age at presentation was 4 months. The commonest complications were regional lymphadenitis in 138 (61.33%) infants, local abscess in 48 (21.33%) infants, local ulcer in 26 (11.56%) infants, keloid scar in 12 (5.33%) infants and one (0.44%) infant who died from disseminated disease had severe combined immunodeficiency. In the follow-up study, BCG complications occurred in 43 infants with a complication rate of 6.25 per 1000 vaccinations, which is significantly lower (P < 0.001) than that during the initial outbreak. CONCLUSION: The study supports the use of a less virulent vaccine and proper vaccination techniques to minimize the incidence of BCG complications. The training of nurses in strict intradermal injection should be maintained and the proper selection of those receiving the vaccines should be considered to avoid the vaccination of any infant with immunodeficiency.

Adjuvants, Immunologic↗

PubMed1999

Clinical experiences in Sakai City Hospital during the massive outbreak of enterohemorrhagic Escherichia coli O157 infections in Sakai City, 1996.

In the middle of July, 1996, a massive outbreak of hemorrhagic colitis (HC) occurred among elementary schoolchildren in Sakai city. This is the most widespread outbreak of O157 infection ever experienced to our knowledge. Lunch foods supplied in the elementary schools in Sakai were contaminated by Escherichia coli (E. coli) O157. One hundred and twenty-one cases developed hemolytic uremic syndrome (HUS) from 12,680 symptomatic patients, including putative secondary infections, and three girls died during this outbreak. Sakai City Hospital is one of the core medical facilities in this community; hence, 425 children with HC were treated at the hospital. Antibiotics were used extensively on all patients. Among them, 12 children developed HUS. All 425 children, including the patients with HUS, recovered without significant sequelae. In the present paper, the clinical experiences during this massive outbreak of E. coli O157 infection in Sakai City Hospital are described.

Anti-Bacterial Agents↗

PubMed2000

Vancomycin resistance emerging in a clonal outbreak caused by ampicillin-resistant Enterococcus faecium.

OBJECTIVES: To describe the first nosocomial outbreak of ampicillin-resistant Enterococcus faecium (ARE) in Norway, where a few vancomycin-resistant strains have also been identified. METHODS: All cases of ARE and vancomycin-resistant Enterococcus faecium (VRE) diagnosed by the medical microbiological laboratories in a region inhabited by approximately 1 million people were registered. Isolates obtained during the period 1 January 1995 to 31 December 1996 were characterized by pulsed field-gel electrophoresis and the clinical data were recorded. RESULTS: One hundred and forty-nine patients (64 males, 85 females, mean age 70.5 years) were infected with ARE. Isolates from 115 cases were genomically related to the outbreak strain. Infections included bacteremia (14), wound infections (31), urinary tract infections (97) and other infections (seven). Most had a severe underlying disease and 93% of the patients had received antibiotics for a mean time of 23 days. Twenty-four patients (16.1%) died during hospitalization. Four infections were caused by a vanB-type VRE that was genomically related to the ARE outbreak strain. The prescription rate for vancomycin was low, but an increase in vancomycin use paralleled the appearance of VRE. The highest monthly incidence rate was 2.5 per 1000 patient admissions in July 1996 declining to 0.5 in December 1996. CONCLUSIONS: The first nosocomial outbreak caused by ARE was observed in 1995 in Norway and is still ongoing. One year after the onset, VRE occurred in wards which had a relatively high consumption of vancomycin.

Aged↗

PubMed2000

Detection of specific IgM antibody in the investigation of an outbreak of pneumonia due to Legionella pneumophila serogroup 1.

OBJECTIVE: Management of outbreaks of pneumonia due to Legionella pneumophila serogroup 1 (SG1) infection requires rapid and accurate diagnostic tests. Current serologic approaches, based on detection of seroconversion for total antibody, do not fulfil this requirement. METHODS: A diagnostic test based on detection of IgM antibody to L. pneumophila SG1 by indirect immunofluorescence was developed and used to evaluate serum samples from patients involved in a community outbreak of L. pneumophila SG1 pneumonia that occurred in Spain. RESULTS: Testing of samples from serologically proven, sporadic cases of pneumonia due to L. pneumophila SG1 (14), cases of atypical pneumonia due to other infectious agents (16) and healthy controls (100) supported the sensitivity and specificity of the assay. On samples from the outbreak, the IgM assay recognized five of six cases with isolation of L. pneumophila SG1 from respiratory secretions or lung tissue and more than 70% of cases with confirmed or presumptive diagnosis as determined by the current serologic criteria. In addition, the IgM assay was positive in 23-70% of patients who fulfilled the clinical and epidemiologic criteria of case definition but did not display diagnostically significant serologic results or who lacked a detectable antibody response in the routine assay. Among cases confirmed by the current criteria, detection of specific IgM was occasionally achieved before the conventional serology gave significant results. CONCLUSION: Incorporation of IgM antibody detection in the current diagnostic criteria for L. pneumophila SG1 infection may help to improve the management of outbreaks of pneumonia due to this agent.

Antibodies, Bacterial↗