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PubMed2006

Prolonged outbreak of giardiasis with two modes of transmission.

Large outbreaks of giardiasis caused by person-to-person transmission, or a combination of transmission routes, have not previously been reported. A large, prolonged giardiasis outbreak affected families belonging to a country club in a suburb of Boston, Massachusetts, during June-December 2003. We conducted a retrospective cohort study to determine the source of this outbreak. Giardiasis-compatible illness was experienced by 149 (25%) respondents to a questionnaire, and was laboratory confirmed in 97 (65%) of these cases. Of the 30 primary cases, exposure to the children's pool at the country club was significantly associated with illness (risk ratio 3.3, 95% confidence interval 1.7-6.5). In addition, 105 secondary cases probably resulted from person-to-person spread; 14 cases did not report an onset date. This outbreak illustrates the potential for Giardia to spread through multiple modes of transmission, with a common-source outbreak caused by exposure to a contaminated water source resulting in subsequent prolonged propagation through person-to-person transmission in the community. This capacity for a common-source outbreak to continue propagation through secondary person-to-person spread has been reported with Shigella and Cryptosporidium and may also be a feature of other enteric pathogens having low infectious doses.

Adolescent↗

PubMed2006

Outbreaks of waterborne infectious intestinal disease in England and Wales, 1992-2003.

We reviewed the epidemiological and microbiological characteristics of 89 reported outbreaks of waterborne infectious intestinal disease affecting 4321 people in England and Wales over the period 1992-2003. Public water supplies were implicated in 24 outbreaks (27%), private water supplies in 25 (28%), swimming pools in 35 (39%) and other sources in five outbreaks (6%). Cryptosporidium was implicated in 69% of outbreaks, Campylobacter sp. in 14%, Giardia in 2%, E. coli O157 in 3% and Astrovirus in 1%. From 2000, there was a consistent decline in the number of outbreaks of waterborne disease associated with public water supplies. The incidence rate of outbreaks in recipients of private water supplies may be as high as 35 times the rate in those receiving public water supplies (1830 vs. 53 per million population). Private water suppliers need to be aware of the importance of adequate treatment and the prevention of faecal contamination of storage water. Swimming-pool operators need to ensure chlorination and in particular adequate filtration measures are in place.

Communicable Diseases↗

PubMed2006

An outbreak of Escherichia coli O157 gastroenteritis in a care home for the elderly.

In the summer of 2001 an outbreak of Escherichia coli O157 gastroenteritis affected staff and residents of a care home for the elderly in the West Midlands, UK. E. coli O157 phage type 2 was isolated from faeces in eight patients and 12 staff members. Thirty-five staff and 40 residents met the case definition for clinical gastrointestinal infection. Serological testing identified a further 14 possible cases of infection amongst asymptomatic staff and residents. The outbreak was atypical, as the disease seemed to be milder than has been observed in past outbreaks in similar settings. The index case, a member of staff, developed bloody diarrhoea and haemolytic-uraemic syndrome (HUS), but only one resident developed bloody diarrhoea and required hospitalization. No deaths occurred, despite the high-risk nature of the affected population. The source of the outbreak could not be identified. The prolonged nature of the outbreak and observed lapses in infection control practices indicated that person-to-person spread was the likely route of transmission. This outbreak illustrates the importance of observing appropriate infection control measures in the institutions providing residential and nursing care to the elderly.

Aged↗

PubMed2003

Epidemic kerato-conjunctivitis--do outbreaks have to be epidemic?

PURPOSE: To study: the epidemiology of an outbreak of adenoviral keratoconjunctivitis in a UK teaching hospital; disease presentation and its effect on clinical diagnostic efficiency; patterns of viral transmission between staff and patients; the effectiveness of infection control procedures in minimising outbreaks. METHODS: Prospective/retrospective clinical audit and retrospective audit of virological culture results: all viral culture swabs taken during an outbreak of adenoviral keratoconjunctivitis were analysed. The case records of patients whose viral swabs were positive for adenoviral culture were traced. The time for viral cultures to become positive (culture positive time) was calculated. Analysis of the case notes was performed to elucidate (1) the source of infection and (2) the risk factors for acquisition of the infection. Retrospective clinical audit was performed to evaluate the effectiveness of infection control procedures. Adenovirus isolates underwent serotyping. RESULTS: During the 3-month period of study, there were 38 confirmed cases of adenoviral keratoconjunctivitis. This represented a 217% increase in the number of new cases per 3-month period. The case notes for five patients were untraceable. Of the remaining 33 patients, 21 (63%) had acquired their infection either directly or indirectly from the eye department and 22 (67%) had presented with unilateral disease. The rate of misdiagnosis was higher (9/22=42%) in patients presenting with unilateral disease than those presenting with bilateral disease (2/11=18%). Intradepartmental acquisition of infection was associated with invasive procedures, for example use of diagnostic/therapeutic contact lenses. Culture positive times ranged from 3 to 29 days. The introduction of infection control procedures was associated with a dramatic decrease in the incidence of departmentally acquired cases with no new cases after 2 weeks. Multiple serotypes of adenovirus were involved. CONCLUSION: Outbreaks of adenoviral keratoconjunctivitis are a serious public health issue concerning ophthalmic departments. This audit study illustrates several important points: (1) how hospital-acquired infection can account for a significant proportion of the cases seen, (2) how multiple types of adenovirus can be involved in a single outbreak, (3) that severe unilateral disease is associated with a higher rate of misdiagnosis; and (4) how standard viral culture techniques may not be satisfactory in confirming/disproving infection when the diagnosis is in doubt. The potential benefit of infection control procedures in minimising this outbreak could not be proven within this audit.

Adenoviridae↗

PubMed2000

Outbreak of Salmonella braenderup gastroenteritis due to contaminated meat pies: clinical and molecular epidemiology.

OBJECTIVES: To determine the epidemiologic, clinical and molecular characteristics of an outbreak of severe gastroenteritis due to the ingestion of meat pies highly contaminated with Salmonella braenderup. METHODS: In October 1993, we observed an outbreak of Salmonella braenderup gastroenteritis that occurred in the Lausanne area, Canton de Vaud, Switzerland. Cultures of suspected food products, of samples at the incriminated food factory and from workers, as well as a case-control study, were used to determine the source of the epidemics. Ribotyping of representative Salmonella braenderup strains was performed to define the molecular epidemiology. The clinical characteristics of this infection were determined by using a standardized interview performed during and 6 months after the outbreak in 156 of 215 identified patients. RESULTS: The outbreak resulted from the ingestion of pies, heavily contaminated (> 106 CFU/g) with a strain of Salmonella braenderup. The contamination was due to mishandling and recycling of jelly poured on top of the products. According to its ribotype and plasmid characteristics, this strain had not been isolated previously in Switzerland. Ten of the 24 workers of the incriminated food factory were shedding the epidemic strain in their stools, and one of them reported gastroenteritis 3 weeks before the beginning of the outbreak. The estimated attack rate in the exposed population was 7.5%. The median incubation time was 18 h. Among 127 adult patients studied, 98% had diarrhea, 95% abdominal pain, 74% fever > or = 38.5 degrees C, 69% nausea and 35% vomiting. One patient developed prosthetic valve endocarditis, and one reactive arthritis. Long-term complications were not identified, although 12 patients complained of irritable bowel syndrome and 24 of unusual asthenia lasting for more than 6 weeks after infection. Children had more severe signs and symptoms compared to adults, and six of 29 needed hospitalization. CONCLUSIONS: This study showed that ingestion of food highly contaminated with Salmonella braenderup resulted in severe but typical gastroenteritis and indicated mishandling of food during manufacture as the cause of this outbreak.

Adult↗

PubMed2000

Hospital outbreak of Salmonella virchow possibly associated with a food handler.

A foodborne outbreak of salmonella infection at a private hospital in London in 1994 was found to be associated with eating turkey sandwiches prepared by a food handler. One patient, nine staff, and a foodhandler's baby were confirmed to have Salmonella enterica serotype virchow, phage type 26 infection. The attack rate was estimated to be 5% among the approximately 200 patients and staff at risk. A food handler reportedly became ill days after, but her baby days before, the first hospital case. Although it appeared to be a single outbreak, antibiogram analysis, supplemented by plasmid profile typing, demonstrated that there were two strains of S. virchow involved, one with resistance to sulphonamides and trimethoprim and a second sensitive to these antimicrobial drugs. Mother and child had different strains. The investigation demonstrated the importance of full phenotypic characterization of putative outbreak strains including antimicrobial susceptibility testing. Outbreaks of foodborne infection in hospitals are preventable and are associated with high attack rates and disruption of services. There is a need for good infection control policies and training of all staff involved in patient care as well as in catering services. Consultants in Communicable Disease (CCDCs) should include private hospitals in their outbreak control plans. Good working relations between Infection Control Doctors (ICDs) in the private health sector and their local CCDCs are important if outbreaks are to be properly investigated.

Adult↗

PubMed2001

A simultaneous outbreak on a neonatal unit of two strains of multiply antibiotic resistant Klebsiella pneumoniae controllable only by ward closure.

Two aminoglycoside-resistant strains of Klebsiella pneumoniae caused an outbreak on the neonatal unit at St Thomas' Hospital. One, which affected 18 patients, was capsular type K18 and resistant to newer cephalosporins by the production of the extended-spectrum beta-lactamase SHV-2; the other, which colonized four patients, was capsular non-typeable and did not produce extended-spectrum beta-lactamase. Both strains were probably brought into the unit by carrier patients; the probable carrier of the non-typeable strain was transferred from another hospital but was negative on a single admission screen; the probable carrier of the K18 strain was not screened on admission because he had been born at St Thomas', but his mother had been transferred from another hospital. Despite intensive efforts to control the outbreak by standard methods of hand washing, screening, patient isolation and environmental cleaning, a total of 22 neonates on the unit eventually became colonized or infected. One of three patients with bacteraemia died. A small proportion of samples of expressed breast milk, electronic thermometers and oxygen saturation probes were contaminated by the K18 strain and may have contributed to some of the cross-infection, but this did not explain the extent of the outbreak. The outbreak was controlled only by opening a temporary ward for colonized neonates and another for newly born babies, which allowed the closure and cleaning of the main neonatal unit. Multiply antibiotic resistant klebsiellas may be highly epidemic and cause serious, difficult-to-control outbreaks on neonatal units. All patients, regardless of their admission history, should be screened on admission for carriage of multiply resistant enterobacteria by a sensitive method, and units should have plans for temporary ward closure should outbreaks occur.

Aminoglycosides↗

PubMed1986

Widespread outbreaks of clam- and oyster-associated gastroenteritis. Role of Norwalk virus.

Consumption of raw shellfish has long been known to be associated with individual cases and sporadic outbreaks of enteric illness. However, during 1982, outbreaks of gastroenteritis associated with eating raw shellfish reached epidemic proportions in New York State. Between May 1 and December 31, there were 103 well-documented outbreaks in which 1017 persons became ill: 813 cases were related to eating clams, and 204 to eating oysters. The most common symptoms were diarrhea, nausea, abdominal cramps, and vomiting. Incubation periods were generally 24 to 48 hours long, and the duration of illness was 24 to 48 hours. Bacteriologic analyses of stool and shellfish specimens did not reveal a causative agent. Norwalk virus was implicated as the predominant etiologic agent by clinical features of the illness and by seroconversion and the formation of IgM antibody to Norwalk virus in paired serum samples from persons in five (71 percent) of seven outbreaks in which testing was done. In addition, Norwalk virus was identified by radioimmunoassay in clam and oyster specimens from two of the outbreaks. Determining the source of the shellfish was not always possible, but northeastern coastal waters were implicated. The magnitude, persistence, and widespread nature of these outbreaks raise further questions about the safety of consuming raw shellfish.

Antibodies, Viral↗

PubMed1994

A massive outbreak in Milwaukee of cryptosporidium infection transmitted through the public water supply.

BACKGROUND: Early in the spring of 1993 there was a widespread outbreak of acute watery diarrhea among the residents of Milwaukee. METHODS: We investigated the two Milwaukee water-treatment plants, gathered data from clinical laboratories on the results of tests for enteric pathogens, and examined ice made during the time of the outbreak for cryptosporidium oocysts. We surveyed residents with confirmed cryptosporidium infection and a sample of those with acute watery diarrhea consistent with cryptosporidium infection. To estimate the magnitude of the outbreak, we also conducted a survey using randomly selected telephone numbers in Milwaukee and four surrounding counties. RESULTS: There were marked increases in the turbidity of treated water at the city's southern water-treatment plant from March 23 until April 9, when the plant was shut down. Cryptosporidium oocysts were identified in water from ice made in southern Milwaukee during these weeks. The rates of isolation of other enteric pathogens remained stable, but there was more than a 100-fold increase in the rate of isolation of cryptosporidium. The median duration of illness was 9 days (range, 1 to 55). The median maximal number of stools per day was 12 (range, 1 to 90). Among 285 people surveyed who had laboratory-confirmed cryptosporidiosis, the clinical manifestations included watery diarrhea (in 93 percent), abdominal cramps (in 84 percent), fever (in 57 percent), and vomiting (in 48 percent). We estimate that 403,000 people had watery diarrhea attributable to this outbreak. CONCLUSIONS: This massive outbreak of watery diarrhea was caused by cryptosporidium oocysts that passed through the filtration system of one of the city's water-treatment plants. Water-quality standards and the testing of patients for cryptosporidium were not adequate to detect this outbreak.

Adolescent↗

PubMed1999

An outbreak of multidrug-resistant, quinolone-resistant Salmonella enterica serotype typhimurium DT104.

BACKGROUND: Food-borne salmonella infections have become a major problem in industrialized countries. The strain of Salmonella enterica serotype typhimurium known as definitive phage type 104 (DT104) is usually resistant to five drugs: ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline. An increasing proportion of DT104 isolates also have reduced susceptibility to fluoroquinolones. METHODS: The Danish salmonella surveillance program determines the phage types of all typhimurium strains from the food chain, and in the case of suspected outbreaks, five-drug-resistant strains are characterized by molecular methods. All patients infected with five-drug-resistant typhimurium are interviewed to obtain clinical and epidemiologic data. In 1998, an outbreak of salmonella occurred, in which the strain of typhimurium DT104 was new to Denmark. We investigated this outbreak and report here our findings. RESULTS: Until 1997, DT104 infections made up less than 1 percent of all human salmonella infections. The strain isolated from patients in the first community outbreak of DT104 in Denmark, in 1998 was resistant to nalidixic acid and had reduced susceptibility to fluoroquinolones. The outbreak included 25 culture-confirmed cases. Eleven patients were hospitalized, and two died. The molecular epidemiology and data from patients indicated that the primary source was a Danish swine herd. Furthermore, the investigation suggested reduced clinical effectiveness of treatment with fluoroquinolones. CONCLUSIONS: Our investigation of an outbreak of DT104 documented the spread of quinolone-resistant bacteria from food animals to humans; this spread was associated with infections that were difficult to treat. Because of the increase in quinolone resistance in salmonella, the use of fluoroquinolones in food animals should be restricted.

Abattoirs↗

PubMed2004

Public health measures to control the spread of the severe acute respiratory syndrome during the outbreak in Toronto.

BACKGROUND: Toronto was the site of North America's largest outbreak of the severe acute respiratory syndrome (SARS). An understanding of the patterns of transmission and the effects on public health in relation to control measures that were taken will help health officials prepare for any future outbreaks. METHODS: We analyzed SARS case, quarantine, and hotline records in relation to control measures. The two phases of the outbreak were compared. RESULTS: Toronto Public Health investigated 2132 potential cases of SARS, identified 23,103 contacts of SARS patients as requiring quarantine, and logged 316,615 calls on its SARS hotline. In Toronto, 225 residents met the case definition of SARS, and all but 3 travel-related cases were linked to the index patient, from Hong Kong. SARS spread to 11 (58 percent) of Toronto's acute care hospitals. Unrecognized SARS among in-patients with underlying illness caused a resurgence, or a second phase, of the outbreak, which was finally controlled through active surveillance of hospitalized patients. In response to the control measures of Toronto Public Health, the number of persons who were exposed to SARS in nonhospital and nonhousehold settings dropped from 20 (13 percent) before the control measures were instituted (phase 1) to 0 afterward (phase 2). The number of patients who were exposed while in a hospital ward rose from 25 (17 percent) in phase 1 to 68 (88 percent) in phase 2, and the number exposed while in the intensive care unit dropped from 13 (9 percent) in phase 1 to 0 in phase 2. Community spread (the length of the chains of transmission outside of hospital settings) was significantly reduced in phase 2 of the outbreak (P<0.001). CONCLUSIONS: The transmission of SARS in Toronto was limited primarily to hospitals and to households that had had contact with patients. For every case of SARS, health authorities should expect to quarantine up to 100 contacts of the patients and to investigate 8 possible cases. During an outbreak, active in-hospital surveillance for SARS-like illnesses and heightened infection-control measures are essential.

Communicable Disease Control↗

PubMed2002

Direct costs associated with a nosocomial outbreak of adenoviral conjunctivitis infection in a long-term care institution.

BACKGROUND: In October 2000, 41 people were infected during an outbreak of adenoviral keratoconjunctivitis. Such nosocomial outbreaks are frequently reported in long-term care institutions, even though simple measures to prevent or limit such occurrences are well documented. This study describes the significant direct costs incurred as a result of this nosocomial outbreak that involved patients and staff. METHODS: The costs measured in this study were grouped into the following 4 categories: medical, investigative, preventive, and lost productivity. Information about costs incurred by the hospital was gathered from a number of sources. RESULTS: The outbreak cost the hospital US $29,527 ($1085 for medical costs, $8210 for investigative costs, $3048 for preventive measures, and $17,184 for lost productivity). CONCLUSION: This study demonstrates the substantial expense incurred by 1 hospital as a result of an outbreak of a preventable disease. The measures necessary to prevent such a costly outbreak are simple and, therefore, cost-effective.

Adenovirus Infections, Human↗

PubMed2004

Diversity in pathogenicity can cause outbreaks of meningococcal disease.

Neisseria meningitidis, the meningococcus, is a major cause of bacterial meningitis and septicemia worldwide. Infection in most cases leads to asymptomatic carriage and only rarely to disease. Meningococcal disease often occurs in outbreaks, which are both sporadic and highly unpredictable. The occurrence of disease outbreaks in a host population in which the etiological agent is widely carried is not well understood. A potential explanation lies in the fact that meningococci are diverse with respect to disease-causing potential. We formulated a stochastic mathematical model to investigate whether diversity of the bacterial population is related to outbreaks of meningococcal disease. In the model, strains that occasionally cause the disease appear repeatedly in a population dominated by a nonpathogenic strain. When the pathogenicity, i.e., the disease-causing potential, of the pathogenic lineage was low, the model shows distinct outbreaks, the size distribution of the outbreaks follows a power law, and the ratio of the variance to the mean number of cases is high. Analysis of notification data of meningococcal disease showed that the ratio of the variance to the mean was significantly higher for meningococcal diseases than for other bacterial invasive diseases. This result lends support to the hypothesis that outbreaks of meningococcal disease are caused by diversity in the pathogenicity of meningococcal strains.

Disease Outbreaks↗

PubMed2002

Detection and response to a meningococcal disease outbreak following a youth football tournament with teams from four European countries.

An outbreak of meningococcal disease, caused by Neisseria meningitidis, occurred following an international youth football tournament in the summer of 1997, affecting individuals from four European countries. This paper describes the outbreak, focusing on international co-operation in detection, investigation, control and follow-up, identifying weaknesses and exploring opportunities for improved co-operation. Data came from interviews, reports and related documents. The detection and management of the outbreak in each country is analysed. Eleven cases were linked to this outbreak and serotyped as C:2a:P1.5. Control measures varied in each country, reflecting different national guidelines. The outbreak illustrated deficiencies in management of international outbreaks but also demonstrated benefits of international co-operation.

Adolescent↗

PubMed2006

Evaluation of the Dako IDEIA norovirus EIA assay for detection of norovirus using faecal specimens from Australian gastroenteritis outbreaks.

AIMS: New techniques for detection of norovirus, a major cause of gastroenteritis, require ongoing evaluation. The aim of this study was to use material from gastroenteritis outbreaks in Victoria, Australia, to evaluate the sensitivity and specificity of the Dako IDEIA norovirus EIA assay, using both photometric and visual analysis. METHODS: A total of 130 faecal specimens from 41 gastroenteritis outbreaks were tested for norovirus by electron microscopy (EM), a two-round multiplex reverse transcription-polymerase chain reaction (RT-PCR) method and the IDEIA norovirus assay. All specimens with sufficient amplified product were sequenced to determine their norovirus genotype. In addition, six well-established RT-PCR protocols were used to test four EIA-positive, multiplex RT-PCR/EM-negative specimens. Also, a range of RT-PCR protocols was used to test a specimen positive for GII only by the multiplex RT-PCR but positive for GI and GII by the EIA. The effect of multiple freezing-thawing cycles on EIA positivity was tested on seven additional specimens. A further seven specimens, known to contain the gastroenteritis viruses sapovirus, adenovirus, astrovirus and rotavirus were also tested by the IDEIA norovirus assay. RESULTS: The IDEIA norovirus assay gave a single-specimen sensitivity and specificity of 66% and 85%, respectively (visual analysis compared with the multiplex RT-PCR), 63% and 88% (photometric analysis compared with the multiplex RT-PCR), 65% and 87% (visual analysis compared with the multiplex RT-PCR and/or EM) and 62% and 90% (photometric analysis compared with the multiplex RT-PCR and/or EM). None of the four EIA-positive specimens negative by the multiplex RT-PCR and/or EM was positive by any of the six alternative RT-PCR protocols. The specimen positive for GI and GII by EIA but for GII only by the multiplex RT-PCR was not positive for GI by any of the alternative RT-PCR protocols. A minimum of three specimens per outbreak had to be tested by the EIA to ensure that norovirus-positive outbreaks (multiplex RT-PCR and/or EM) were classified as positive for norovirus by the IDEIA norovirus assay (visual or photometric analysis). However, one specimen from a norovirus-negative outbreak (multiplex RT-PCR and/or EM) for which four specimens were provided was positive for norovirus by the IDEIA norovirus assay. Seven norovirus genotypes were identified by open reading frame 1 sequencing analysis and specimens from all seven norovirus genotypes (as well as an EM-positive/multiplex RT-PCR-negative specimen) were detected by the IDEIA norovirus assay by both visual and photometric analysis. Repeated freezing-thawing cycles (up to six) for faecal specimens did not reduce the sensitivity of the EIA assay but could render an EIA-negative specimen EIA-positive. The specimens positive for sapovirus, adenovirus, astrovirus and rotavirus were EIA-negative. CONCLUSIONS: The IDEIA norovirus assay lacks the sensitivity and specificity to ascribe a particular result to a particular specimen, but could be useful for detecting norovirus in a gastroenteritis outbreak where specimens are plentiful, although it is difficult to avoid a risk of false positives. Since visual analysis can be used for result assessment almost as reliably as photometric analysis, the test kit would be useful for laboratories lacking specialist equipment such as a photometric microplate reader.

Caliciviridae Infections↗

PubMed1999

An outbreak of acute respiratory disease caused by Mycoplasma pneumoniae and adenovirus at a federal service training academy: new implications from an old scenario.

Outbreaks of Mycoplasma pneumoniae and adenovirus have been reported in military institutions for several decades. During a recent outbreak in a federal service training academy, we performed an epidemiological and laboratory investigation to better characterize and control the outbreak. Of 586 students responding to a questionnaire, 317 (54%) reported having a respiratory illness during the outbreak period. Among 42 students who underwent complete laboratory testing, 24 (57%) had evidence of M. pneumoniae infection, 8 (19%) had evidence of adenovirus infection, and 4 (10%) had evidence of both. Polymerase chain reaction testing of oropharyngeal swabs revealed more acute M. pneumoniae infections (57% positive) than did serology or culture. Multivariate analysis revealed that visiting the campus health clinic >3 times for a nonrespiratory condition, such as injury, was a significant risk factor for illness among freshmen early in the course of the outbreak, whereas having an ill roommate was a risk factor throughout the duration of the outbreak.

Acute Disease↗

PubMed1998

Molecular epidemiology of "Norwalk-like viruses" in outbreaks of gastroenteritis in the United States.

Fecal specimens from 90 outbreaks of nonbacterial gastroenteritis reported to 33 state health departments from January 1996 to June 1997 were examined to determine the importance of and to characterize "Norwalk-like viruses" (NLVs) in these outbreaks. NLVs were detected by reverse transcription-polymerase chain reaction in specimens from 86 (96%) of 90 outbreaks. Outbreaks were most frequent in nursing homes and hospitals (43%), followed by restaurants or events with catered meals (26%); consumption of contaminated food was the most commonly identified mode of transmission (37%). Nucleotide sequence analysis showed great diversity between strains but also provided evidence indicating the emergence of a common, predominant strain. The application of improved molecular techniques to detect NLVs demonstrates that most outbreaks of nonbacterial gastroenteritis in the United States appear to be associated with these viruses and that sequence analysis is a robust tool to help link or differentiate these outbreaks.

Aged↗

PubMed2001

An outbreak of travel-associated Legionnaires disease and Pontiac fever: the need for enhanced surveillance of travel-associated legionellosis in the United States.

Travel-associated outbreaks of legionnaires disease (LD) and combined outbreaks of LD and Pontiac fever (PF) are rarely identified. During one travel-associated combined outbreak at a hotel, a cohort study of potentially exposed persons and an environmental investigation were performed. Two LD and 22 PF cases were identified. Legionella pneumophila serogroup 6 (Lp6) isolates from the index patient and the hotel whirlpool spa were found to be identical by amplified fragment-length polymorphism typing. Disease occurred in 10 of 26 guests who were exposed to the spa versus 2 of 29 guests who were exposed only to the pool area (38% vs. 7%; P=.005). Immunoglobulin M (IgM) antibody to the outbreak Lp6 strain was more common among persons with PF (4 of 9) than among non-ill persons (2 of 32) (44% vs. 6%; P=.02). Spa exposure correlated with disease (P=.001) and IgM seropositivity (P=.007). New laboratory techniques facilitate outbreak investigation; to expedite outbreak interruption and measure the impact of travel-associated legionellosis, surveillance must be improved.

Adolescent↗