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PubMed2005

Summer outbreak of respiratory disease in an Australian prison due to an influenza A/Fujian/411/2002(H3N2)-like virus.

An outbreak of influenza A occurred in a prison system in New South Wales, Australia in January 2003 during the southern hemisphere summer. This report documents only the third confirmed outbreak of influenza in a prison environment. The outbreak investigation included case ascertainment, state-wide surveillance, a case-control study and interventions to limit the outbreak such as infection control, quarantine, cohorting of cases, and the use of antiviral medication for prophylaxis. A total of 37 clinical cases were identified. Influenza A virus was detected in 11 of the 22 respiratory tract specimens collected. The virus was typed as an influenza A/Fujian/411/2002 (H3N2)-like virus. This strain subsequently became the predominant virus strain during the northern hemisphere winter and the following 2003 Australian southern hemisphere winter influenza season.

Case-Control Studies↗

PubMed2001

Multistate outbreak of Norwalk-like virus gastroenteritis associated with a common caterer.

In February 2000, an outbreak of gastroenteritis occurred among employees of a car dealership in New York. The same meal was also supplied to 52 dealerships nationwide, and 13 states reported illness at dealerships where the banquet was served. A retrospective cohort study was conducted to identify risk factors associated with the illness. Stool samples were collected to detect Norwalk-like virus, and sera were drawn and tested for immunoglobulin A antibodies to the outbreak strain. By univariate analysis, illness was significantly associated with consumption of any of four salads served at the banquet (relative risk = 3.8, 95% confidence interval: 2.5, 5.6). Norwalk-like virus was detected by reverse transcription-polymerase chain reaction assay in 32 of 59 stool samples from eight states. Nucleotide sequences of a 213-base pair fragment from 16 stool specimens collected from cases in eight states were identical, confirming a common source outbreak. Two of 15 workers at caterer A had elevated immunoglobulin A titers to an antigenically related Norwalk-like virus strain. This study highlights the value of molecular techniques to complement classic epidemiologic methods in outbreak investigations and underscores the critical role of food handlers in the spread of foodborne disease associated with Norwalk-like virus.

Adolescent↗

PubMed1991

A large nontypical outbreak of Norwalk virus. Gastroenteritis associated with exposing celery to nonpotable water and with Citrobacter freundii.

The US Air Force Academy experienced a point-source outbreak of gastroenteritis originally believed to be caused by Salmonella. The overall attack rate was 48% among approximately 3000 cadets and staff. Food-specific attack rates implicated chicken salad. The odds ratio for chicken salad consumption in ill cadets was 10.7 (95% confidence interval: 8.2; 13.8). The celery component had been exposed to nonpotable water. Citrobacter freundii were statistically associated with consumption of the suspected vehicle and subsequent illness. Most aspects were consistent with the epidemiology of Norwalk gastroenteritis. However, the clinical presentation was not typical of reported outbreaks. One hundred five cadets required intravenous rehydration. Serum samples implicated Norwalk virus as the most probable cause of this outbreak. The Centers for Disease Control (Atlanta, Ga) recently began national surveillance for viral gastroenteritis. All outbreaks of gastroenteritis associated with nonpotable water should be investigated for evidence of viral cause.

Citrobacter freundii↗

PubMed1998

A foodborne outbreak of Cyclospora cayetanensis at a wedding: clinical features and risk factors for illness.

BACKGROUND: Cyclospora cayetanensis, a coccidian parasite, has increasingly been recognized as a cause of gastrointestinal tract illness. We describe an outbreak of Cyclospora infection following a wedding reception. OBJECTIVES: To investigate and characterize risk factors associated with the outbreak of Cyclospora and to describe the observed clinical course and spectrum of illness. METHODS: Retrospective cohort study involving 94 of the 101 guests who attended a wedding reception at a restaurant in Boston, Mass. RESULTS: Fifty-seven respondents met the case definition of infection; 12 of these had laboratory-confirmed Cyclospora. The epidemic curve was consistent with a point source outbreak with a median incubation period of 7 days. Commonly reported symptoms included diarrhea (100%), weight loss (93%), fatigue (91%), and anorexia (90%). The illness had a characteristic waxing and waning course, with 51 persons (89%) reporting recurring symptoms and 35 (61%) reporting illness lasting more than 3 weeks. By univariate analysis, infection was significantly associated (P<.05) with consumption of wine and a dessert containing raspberries, strawberries, blackberries, and blueberries. Only the dessert remained significant by stratified analysis with an adjusted relative risk of 2.1 (95% confidence interval, 1.4-3.2). CONCLUSIONS: Findings from this study support a point source outbreak of the newly identified pathogen C cayetanensis, with berries as the vehicle of transmission. It suggests that Cyclospora may cause severe diarrhea associated with profound anorexia and weight loss, and should be considered in the evaluation of prolonged gastrointestinal tract illness.

Animals↗

PubMedDate not supplied

A multistate outbreak of Escherichia coli O157:H7 infections associated with consumption of mesclun lettuce.

BACKGROUND: An outbreak of Escherichia coli O157:H7 infections in Connecticut and Illinois during May 28 to June 27, 1996, was investigated to determine the source of infections. METHODS: Independent case-control studies were performed in both states. Pulsed-field gel electrophoresis (PFGE) was performed on E. coli O157:H7 isolates. A case-patient was defined as a Connecticut or northern Illinois resident with diarrhea whose stool culture yielded E. coli O157:H7 of the outbreak-associated PFGE subtype. Controls were town-, age-, and sex-matched to case-patients. We traced implicated lettuce to the farm level and performed environmental investigations to identify unsafe lettuce production practices. RESULTS: In Connecticut and Illinois, infection was associated with consumption of mesclun lettuce (Connecticut matched odds ratio [MOR], undefined; 95% confidence interval [CI], 3.4 to infinity; and Illinois MOR, undefined; 95% CI, 1.4 to infinity). We traced implicated lettuce to a single grower-processor. Cattle, a known E. coli O157:H7 reservoir, were found near the lettuce fields. Escherichia coli (an indicator of fecal contamination) was cultured from wash water and finished lettuce. A trace-forward investigation identified 3 additional states that received implicated lettuce; E. coli O157:H7 isolates from patients in 1 of these states matched the outbreak-associated PFGE subtype. CONCLUSIONS: This multistate outbreak of E. coli O157:H7 infections was associated with consumption of mesclun lettuce from a single producer. Molecular subtyping facilitated the epidemiological investigation. This investigation increased the knowledge about current production practices that may contribute to the contamination of lettuce by microbial pathogens. Lettuce production practices should be monitored for microbiological safety.

Adolescent↗

PubMed2004

Ensuring preparedness for potential poliomyelitis outbreaks: Recommendations for the US poliovirus vaccine stockpile from the National Vaccine Advisory Committee (NVAC) and the Advisory Committee on Immunization Practices (ACIP).

Paralytic poliomyelitis was once endemic in the United States; however, because of high vaccination levels, the last case of wild disease occurred in 1979. Although worldwide polio eradication may be achieved in the near future, the presence of undervaccinated children in urban areas and among groups who refuse vaccination creates an outbreak risk, should importation of wild virus occur. In 1999, the Advisory Committee on Immunization Practices (ACIP) recommended that inactivated poliovirus vaccine (IPV) be used for routine immunization of the US population and that oral poliovirus vaccine (OPV) be reserved for "mass vaccination campaigns to control outbreaks of paralytic polio." Subsequently, the sole US manufacturer of OPV withdrew from the market. In 2003, a joint National Vaccine Advisory Committee (NVAC)/ACIP working group was charged with reporting to its parent bodies concerning the need for a poliovirus vaccine stockpile. Based on that working group's report, the NVAC and ACIP have concluded that stockpiles of both IPV and OPV should be maintained. In the event of an outbreak in which OPV continues not to be available, IPV should be used for control, and a stockpile of 8 million doses seems to be sufficient. Should IPV be manufactured only in combination with other vaccines, appropriate procurement actions should be taken to ensure that uncombined IPV continues to be stockpiled. Under circumstances of diminished population immunity, OPV may offer outbreak control advantages. The NVAC and ACIP recommend that the United States collaborate with international agencies to provide guaranteed and rapid access to at least 8 million doses of trivalent OPV or 8 million doses of each of the 3 types of monovalent OPV. The regulatory and practical obstacles to implementation of this recommendation will require assertive facilitation at high levels of the federal government and careful planning at the state and local levels.

Bioterrorism↗

PubMed1995

Mumps outbreak in a highly vaccinated school population. Evidence for large-scale vaccination failure.

OBJECTIVES: To describe an outbreak and to identify risk factors for mumps occurring in a highly vaccinated high school population. (Note: Highly vaccinated means a population in which more than 95% have been vaccinated.) DESIGN AND PARTICIPANTS: Survey and cohort study of 307 (97%) of 318 students. OUTCOME MEASURES: Mumps was defined as an illness with 2 or more days of parotid swelling. Serologic confirmation of infection was obtained in eight cases, seven of which were evaluated for presence of IgM antibody using immunofluorescent antibodies. Vaccination records were verified for 297 (97%) students. RESULTS: Between October 3 and November 23, 1990, clinical mumps developed in 54 students (attack rate, 18%), 53 of whom had been vaccinated. Most cases (40 [77%] of 52) occurred 12 to 20 days after a school-wide pep rally. Immunofluorescent antibody testing of all seven specimens demonstrated IgM antibody to mumps. Risk factors for clinical mumps identified in multivariate analyses included female gender (odds ratio, 3.0; 95% confidence interval, 1.6 to 5.7) and source of vaccination other than the local public health clinic (students vaccinated by private providers [odds ratio, 3.0; 95% confidence interval, 1.3 to 5.2] or in other districts [odds ratio, 2.4; 95% confidence interval, 1.1 to 5.3]). CONCLUSIONS: The overall attack rate is the highest reported to date (and to our knowledge) for a population demonstrating virtually complete mumps vaccine coverage. Even verified documentation of vaccination may not be an accurate indicator of an individual's protection against mumps. Vaccination failure may play an important role in contemporary mumps outbreaks. We found no evidence to indicate that waning immunity (secondary vaccine failure) contributed significantly to this outbreak. A second dose of mumps vaccine, as recommended using measles-mumps-rubella vaccine, could potentially prevent similar outbreaks in secondary school populations in the future.

Adolescent↗

PubMed1976

Botulism in Alaska, 1947 through 1974. Early detection of cases and investigation of outbreaks as a means of reducing mortality.

Since 1947, there have been 21 outbreaks of botulism in Alaska, involving 46 people with 13 deaths (28% fatality). In the last six months of 1974, there were four outbreaks. With one exception to date, type E toxin was involved in all outbreaks for which laboratory confirmation has been obtained, and in all instances, Eskimo and Indian foods were the source. Clinical signs and symptoms of nausea and vomiting, dysphagia, diplopia, dilated pupils, and dry throat occurred with great frequency, forming a diagnostic pentad. We recommend that treatment include close medical supervision, supportive care, and the use of antitoxin, cathartics, and possibly, penicillin. The source of an outbreak must be determined to prevent further cases. Only prompt recognition, therapy and epidemiologic investigation can reduce the death toll from botulism.

Adolescent↗

PubMed1986

Campylobacter infection associated with raw milk. An outbreak of gastroenteritis due to Campylobacter jejuni and thermotolerant Campylobacter fetus subsp fetus.

Raw milk is identified with increasing numbers of outbreaks of gastroenteritis and is an important vehicle for transmission of Campylobacter infection. Unlike Campylobacter jejuni, Campylobacter fetus subsp fetus has not been associated with common-source outbreaks of gastroenteritis. This report describes an outbreak of gastroenteritis involving C jejuni and a thermotolerant strain of C fetus subsp fetus associated with raw milk. Fifteen (39%) of 38 persons who attended a banquet in Wisconsin in June 1982 developed acute gastroenteritis. Stool specimens were obtained from nine ill guests; four yielded C jejuni and three yielded C fetus subsp fetus. The C fetus subsp fetus isolates were identified fortuitously, in part because of unusual thermotolerance (growth at 42 degrees C), permitting isolation at temperature appropriate for C jejuni. Survey results implicated raw milk as the source of the outbreak. Findings provide evidence of a potentially emergent milkborne pathogen contributing to the risk of raw milk consumption and suggest that current diagnostic laboratory techniques may fail to identify significant foodborne agents.

Adolescent↗

PubMed1996

Outbreaks of gastroenteritis in elderly nursing homes and retirement facilities associated with human caliciviruses.

Eleven outbreaks of acute gastroenteritis, eight of which were in nursing homes or retirement facilities, were reported in virginia during the winter of 1993-1994. Serum samples (four outbreaks) and stool samples (two outbreaks) from involved people were tested for human calicivirus (HuCV) infection by enzyme immune assays (EIAs) using recombinant Norwalk virus (rNV) and Mexico virus (rMX) capsid antigens and reverse transcription-polymerase chain reaction (RT-PCR). Of the 31 pairs of acute and convalescent serum specimens tested, 24 had a fourfold or more titer increase to rMX and 4 responded to rNV. In all four outbreaks, the geometric mean titers (GMTs) against rMX were significantly higher than those against rNV in the convalescent, but not in the acute phase of illness. The antibody response to rMX among these patients was also higher than to rNV (summary mean 32-fold increase vs. 0.7-fold increase, respectively, P < .001). Antigen was detected in 5 of 21 stool specimens tested by the rMX EIA, RNA in 12 of 17 stool specimens tested by RT-PCR, and small round structured virus (SRSV) particles in 12 of 21 by electron microscopy (EM); none were positive by the rNV EIA. Sequence analysis of the RT-PCR-amplified products from the viral RNA polymerase region revealed 92-93% amino acid identity with Snow Mountain agent (SMA), 86% with MX, 58-59% with NV, and 31-32% with Sapporo HuCV, suggesting that these viruses belong to the SMA HuCV genogroup.

Aged↗

PubMed2006

Coincidental outbreak of methicillin-resistant Staphylococcus aureus in a hematopoietic stem cell transplantation unit.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common nosocomial pathogens among hospital-acquired infections, and immunocompromised patients are highly susceptive to infection. The molecular typing of isolated strains is a common method for tracing an outbreak of MRSA, but experience with this approach is still limited in the hematopoietic stem cell transplantation (HSCT) ward. METHODS: We experienced 6 cases of MRSA infection/colonization in our 26-bed HSCT ward during a 4-week period. This unusual outbreak strongly suggested that the same MRSA strain was involved despite strict isolation and aseptic patient care. Clarification of the transmission pattern was critical, and we applied pulsed-field gel electrophoresis (PFGE) and amplified fragment length polymorphism (AFLP) assays for evaluation. RESULTS AND CONCLUSION: In four of the six cases, the pattern of bands examined by PFGE and AFLP analyses supported the idea that direct person-to-person transmission was very unlikely and the outbreak was coincidental. This experience highlights the clinical value of molecular typing methods for the clinical epidemiological assessment of MRSA outbreak.

Adult↗

PubMed2004

Factors associated with fulminant liver failure during an outbreak among injection drug users with acute hepatitis B.

Death related to acute hepatitis B occurs in approximately 1% of patients. We investigated an outbreak of hepatitis B virus (HBV) infections among injection drug users (IDUs) resulting in several deaths. We conducted a case-control study of fulminant (case patients) and nonfulminant (control patients) HBV infections. We directly sequenced the entire HBV genome from fulminant and nonfulminant cases. From October 1998 to July 2000, 21 acute HBV infections, including 10 fulminant hepatitis B cases, were identified. The median age was 30 (range, 18-49) years, 12 (57%) were female, 20 (95%) were American Indians, and 20 (95%) reported injecting illicit drugs. All patients with fulminant hepatitis B died (case-fatality rate = 47.6%). Case patients (n = 5) and control patients (n = 9) were similar with respect to age, sex, race, and hepatitis C virus serostatus. All case patients used acetaminophen during their illness compared with 44% of control patients (P =.08). Compared with control patients, case patients lost more weight in the 6 months before illness (P =.04); during their illness, they used more alcohol (P =.03) and methamphetamine (P =.04). All 9 isolates sequenced were genotype D, shared 99.7% homology, and included mutations previously described in association with fulminant hepatitis B. In conclusion, a high prevalence of exposure to factors potentiating hepatic damage with acute hepatitis B contributed to the outbreak's high mortality rate; mutations present in the outbreak strain might also have been a factor. Improved vaccination coverage among IDUs has the potential to prevent similar outbreaks in the future.

Acute Disease↗

PubMedDate not supplied

Scabies outbreak on a spinal cord injury unit.

This article describes an outbreak of scabies on a 30-bed acute spinal cord injury unit and the measures taken to eradicate the infestation. Because spinal cord injury patients have sensorimotor deficits, the sensation of itching often is absent, making an infestation of scabies more difficult to identify. A total of 30 patients and 38 employees were exposed and treated for scabies. Educational programs about scabies were instituted immediately for all employees. Routine daily activities and therapy schedules were severely hampered by the outbreak. Despite the efforts of staff to solve the problems associated with the outbreak, frustration and anger were sometimes displayed by many of the staff, patients, and families because of the difficulties they encountered. The outbreak was halted, however, and no further cases were reported, although several employees had to be treated twice.

Cross Infection↗

PubMed2002

Foodborne outbreak caused by a Norwalk-like virus in India.

An outbreak of acute gastroenteritis occurred in the nurses' hostel of a civil hospital in Delhi, after a farewell party involving 130 nurses and some of the housekeeping staff. All affected persons had eaten salad sandwiches at the party. Stool samples were collected from six of these patients on the second day of infection. All six samples, when tested for the presence of common bacteria, parasites, and rotavirus, were found to be negative. The clinical features of this outbreak matched the criteria set for outbreaks caused by Norwalk-like viruses (NLVs). Reverse transcription-polymerase chain reaction (RT-PCR) was carried out on these six samples, using primers from the RNA-dependent RNA polymerase (RdRp) gene of NLVs. Immunoelectron microscopy was carried out on two of the samples, using convalescent phase serum. All six samples were positive for genogroup (GG) II NLVs by RT-nested PCR. Aggregates of 32-nm viral particles were visualized by immunoelectron microscopy in one of the two samples. Sequencing of the RdRp gene was done on amplicons from three samples; phylogenetic analysis placed the isolates NDV/1999 in a Toronto virus cluster of GG II NLVs. This is the first report of a food-borne outbreak attributable to NLVs from India.

Acute Disease↗

PubMed1995

Molecular epidemiology of an outbreak of hepatitis A in Italy.

The relationship of hepatitis A virus (HAV) isolates associated with an outbreak in Genoa, Italy, in 1993 was examined using direct sequencing of amplicons derived by antigen capture PCR (AC/PCR) from faecal samples of the infected persons. Forty samples recovered from 38 primary and two secondary cases were examined. The latter were household contacts of the primary cases. In addition, faecal material of 2 unrelated persons infected simultaneously with hepatitis A in Genoa were tested. The PCR products derived from the P1/P2 junction of the HAV genome were analysed. A 100% nucleotide identity was detected between the viral isolates originating from the primary as well as the secondary cases. The viral isolates recovered from the faecal samples of the two unrelated cases differed from the virus causing the outbreak as well as from each other. These results indicate that a single HAV strain caused the outbreak. The virus might have been transmitted by ingestion of contaminated food or water since all hepatitis A infected employees of the factory had eaten in the same canteen. Definitions of HAV genotypes are based on numerous genetic comparisons of different strains. The sequence comparison of the investigated isolates with published HAV sequences of the P1/P2 genome region revealed that the virus associated with the outbreak belongs to HAV subgenotype IA, whereas the strains recovered from the viral isolates of the unrelated cases belong to subgenotype IB.

Antigens, Viral↗

PubMed2004

Regional outbreak of mumps due to genotype H in Korea in 1999.

Serological and virological studies were carried out of a mumps outbreak which occurred in one region, Yoeju County, Southeast of Seoul in Korea from September to December, 1999. Sera from 736 children at 8-13 years of age of patients with mumps and healthy children were tested for mumps-specific antibodies by enzyme immunoassay. The overall IgM positive rate was 7.6% (56/736), compared with 69.8% (514/736) for IgG. Of the 49 children with both IgG and IgM, 32 were also confirmed by both clinical and serological diagnosis. IgM antibodies were detected even in the samples collected up to 3 months after the onset of symptoms. Although 436 children had been vaccinated before the outbreak, 27 (6.2%) were found to be IgM positive, particularly 6 (4.4%) of 136 were positive serologically despite a second-dose vaccinees. Sequence analysis of the small hydrophobic (SH) gene of 4 mumps viruses isolated from 42 saliva specimens revealed that these were related to the genotype H, but distinguishable from European strains. This is the first study on the outbreak due to mumps virus genotype H and provides information to assess the understanding of recent outbreaks of mumps in Korea.

Adolescent↗

PubMed2004

Antigenic and molecular analysis of influenza A (H3N2) virus strains isolated from a localised influenza outbreak in South Africa in 2003.

A severe acute institutional influenza outbreak occurred in a police residential college in Pretoria amongst new recruits and staff members at the end of May 2003. The outbreak was characterised by marked illness which affected a total of 648 students, 26 of whom were admitted to hospital. Symptoms included pyrexia, severe headache, and myalgia. The attack rate per dormitory building ranged from 20 to 47%, with an overall attack rate of 34%. Throat swabs and bronchoalveolar lavage specimens were sent to the National Institute for Communicable Diseases (NICD) from 20 patients. All were positive for influenza A by multiplex PCR and/or indirect immunofluorescence, and were further identified as subtype H3N2. Additional specimens from sporadic influenza cases in Johannesburg and surrounding areas were collected through the NICD active viral surveillance programme for respiratory viral testing and were also positive for influenza A H3N2 viruses. Viruses isolated from patients from both the institutional outbreak as well as from sporadic cases were analysed both antigenically and at the molecular level to determine the characteristics of the influenza strain responsible for the epidemic. The results showed clearly that the outbreak was caused by the introduction in 2003 into South Africa of the novel A/Fujian/411/02-like H3N2 influenza strain, which is antigenically distinct from the A/Panama/2007/99 vaccine strain. The rapid spread of these variant viruses to the southern hemisphere indicates that the H3N2 component of the influenza vaccine needs to be updated for the 2004 southern hemisphere winter.

Antigens, Viral↗

PubMed2004

High rate and changing molecular epidemiology pattern of norovirus infections in sporadic cases and outbreaks of gastroenteritis in Hong Kong.

Noroviruses (Norwalk-like viruses (NLV)) are recognised as major causes of acute gastroenteritis worldwide. Numerous studies had been carried out on the molecular epidemiology of norovirus in outbreaks but relatively few on sporadic cases. In this study, the molecular epidemiology of noroviruses in sporadic and outbreak cases of acute gastroenteritis in Hong Kong was examined over a 12-month period from July 2001 to June 2002. Specimens from three groups of patients were used in this study. Nine hundred ninety-five specimens from patients enrolled in the Acute Diarrhoeal Diseases Surveillance Programme of the Department of Health, Hong Kong Government; 735 clinical specimens from hospital patients with acute gastroenteritis, and 122 specimens from 44 norovirus outbreaks. Ninety-two (9.2%) surveillance specimens were positive for norovirus RNA by reverse transcription-polymerase chain reaction (RT-PCR), compared to 123 (16.7%) clinical and 101 (82.8%) outbreak specimens. For the first 6 months of the study period, the predominant strain was the Bristol strain that belongs to genogroup II (GII). In the latter 6 months of the study, genogroup I (GI) and strains belonging to other clusters of GII were seen more commonly. The vast majority of strains belonging to the Bristol virus cluster were closely related to the 95/96-US subset that was associated with pandemic infection from 1995 onwards. This study clearly establishes the importance of norovirus as a cause of sporadic cases of acute gastroenteritis in all age groups in Hong Kong.

Adolescent↗