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Few studies have evaluated the health consequences of antimicrobial-resistant Salmonella strains associated with outbreaks. Among 32 outbreaks occurring in the United States from 1984 to 2002, 22% of 13,286 persons in 10 Salmonella-resistant outbreaks were hospitalized, compared with 8% of 2,194 persons in 22 outbreaks caused by pansusceptible Salmonella strains (p<0.01).
We used a single equation with discrete phases to fit the daily cumulative case data from the 2003 severe acute respiratory syndrome outbreak in Toronto. This model enabled us to estimate turning points and case numbers during the 2 phases of this outbreak. The 3 estimated turning points are March 25, April 27, and May 24. The estimated case number during the first phase of the outbreak between February 23 and April 26 is 140.53 (95% confidence interval [CI] 115.88-165.17) if we use the data from February 23 to April 4; and 249 (95% CI: 246.67-251.25) at the end of the second phase on June 12 if we use the data from April 28 to June 4. The second phase can be detected by using case data just 3 days past the beginning of the phase, while the first and third turning points can be identified only approximately 10 days afterwards. Our modeling procedure provides insights into ongoing outbreaks that may facilitate real-time public health responses.
During January and February 2001, an outbreak of febrile illness associated with altered sensorium was observed in Siliguri, West Bengal, India. Laboratory investigations at the time of the outbreak did not identify an infectious agent. Because Siliguri is in close proximity to Bangladesh, where outbreaks of Nipah virus (NiV) infection were recently described, clinical material obtained during the Siliguri outbreak was retrospectively analyzed for evidence of NiV infection. NiV-specific immunoglobulin M (IgM) and IgG antibodies were detected in 9 of 18 patients. Reverse transcription-polymerase chain reaction (RT-PCR) assays detected RNA from NiV in urine samples from 5 patients. Sequence analysis confirmed that the PCR products were derived from NiV RNA and suggested that the NiV from Siliguri was more closely related to NiV isolates from Bangladesh than to NiV isolates from Malaysia. NiV infection has not been previously detected in India.
In August 1996, an outbreak of Norwalk virus gastroenteritis occurred among south-east Queensland and northern New South Wales residents over a four week period. Ninety-two of the 97 cases detected were confirmed as having consumed raw oysters within three days prior to developing the illness. No other food items or beverages were significantly associated with the illness. Environmental investigations indicated the Terranora Broadwater, Tweed Heads as the origin of the contaminated oysters. However, the primary source of Norwalk virus could not be verified. Oysters and other shellfish appear to be a common vehicle for transmission of this virus. This outbreak and the more recent hepatitis A outbreak associated with Wallis Lake oysters, highlight the susceptibility of oysters to environmental contamination and the urgent need for stricter quality control procedures. This report details the epidemiological, microbiological and environmental findings from an outbreak investigation conducted jointly by the Queensland and New South Wales health authorities.
This report describes a measles outbreak in a rural town in south-east Queensland and presents the results of a vaccine effectiveness (VE) study performed during this outbreak. It is important to assess the effectiveness of a vaccine in an outbreak to determine if the outbreak is due to failure of the vaccine or failure to vaccinate. There were 44 cases of measles amongst local residents, which represents a notification rate of 396.7 per 100,000 population. Case investigations identified a group of people who had been exposed to measles at a seminar. The attack rate for the seminar cohort was 18% (11/61). This presented an opportunity to conduct a VE study using data about children aged less than 16 years who attended the seminar. In this cohort of 23 attendees, all 7 children who had not received any measles vaccinations became cases whilst the 6 who were fully vaccinated for their age according to NHMRC guidelines were protected from measles illness. Although there were insufficient fully vaccinated cohort members to reliably estimate VE for this group, the vaccine was 84.6% (95% CI: 15.0-99.7%) effective for those who had received at least one validated dose of vaccine. Despite the sample size limitations, the results support the view that failure to vaccinate rather than vaccine failure contributed to the high infection rate in the seminar cohort.
An outbreak of Shigella sonnei infection in a long-stay nursing centre was detected during routine surveillance of notifications in July 1999. Subsequent investigations identified 13 cases of multi-resistant S. sonnei infection affecting nine staff, three community members associated with the centre and one resident of the centre. Each isolate of S. sonnei was genetically indistinguishable. The outbreak investigation identified contact with residents with vomiting and diarrhoea as a significant risk factor for infection amongst staff providing nursing care. This association, and the duration of the outbreak over several months, suggests that transmission was most likely person-to-person. This outbreak demonstrates the importance of infection control policies and hygiene measures in long-stay nursing facilities.
An outbreak of 3 cases of invasive meningococcal disease occurred in a secondary school on 2 campuses in Victoria. Despite having only one isolate (a C.2a:nst strain), meningococcal DNA was identified by polymerase chain reaction (PCR) in early culture-negative blood specimens of the other 2 cases. Both were subsequently shown by PCR to be capsule serogroup C by PCR. An committee was formed to manage the response to the outbreak. Chemoprophylaxis was offered to family and children who had been in close contact with the cases. As one strain had been confirmed as being of a vaccine-preventable group, vaccination was offered to the whole school community as well as the families of cases. The direct costs of the outbreak to public health, which would have been identical whatever the causative serogroup, was $8,178. Vaccine charges accounted for most of the additional $56,941 cost of vaccinating the target group of 1600 students, staff, and families. No further cases have been associated with this outbreak.
Between 30 May and 1 June 2001, 10 cases of Salmonella Bovismorbificans infection were reported to Public Health Services, Queensland Health. Investigations included enhanced surveillance, case interviews, a matched case control study, environmental audit and microbiological testing of faecal isolates (phage typing) and implicated food products. Forty-one cases of S. Bovismorbificans infection were detected, 36 cases were phage type 32. A matched case control study identified that illness was associated with consumption of food from 15 outlets of a fast food chain, Company A (matched odds ratio [MOR] 17.5, 95% CI 2.0-657.3, p = 0.004) and consumption of a particular product, Product X (MOR undefined, p < 0.001) in the week before onset of illness. Manufacturers of Product X ingredients were audited. Deficiencies were identified in equipment cleansing at the salad mixture processing plant (Manufacturer M). A swab of food residue behind the cutting wheel rim of the lettuce shredder was positive for S. Bovismorbificans phage type 32. This appears to be the first reported Australian outbreak of salmonellosis associated with a lettuce product. The investigations suggest that inadequate maintenance of cutting equipment to prepare lettuce ingredients for Product X by Manufacturer M was a key factor in this statewide outbreak. The statewide nature of this outbreak demonstrates the role of timely serovar identification of Salmonella isolates by a reference laboratory as an aid to outbreak identification, and the importance of adherence to appropriate food safety procedures in the manufacture and preparation of mass produced food items for the public.
Outbreaks of shigellosis in child care are not commonly reported in Australia, however Shigella bacteria can easily spread in these settings. We report an outbreak of shigellosis in a child care centre and discuss the control measures implemented. This investigation identified 20 confirmed cases of Shigella sonnei biotype g and a further 47 probable cases in children and staff who attended a child care centre, and their household contacts. The investigation highlighted the importance of stringent control measures and protocols for dealing with outbreaks of Shigella and other enteric infections in the child care setting, and the importance of prompt notification by both doctors and child care centres, of suspected outbreaks.
This study was designed to define the epidemiology of a food-borne outbreak caused by Salmonella enteritidis that affected only one squadron of a military battalion located in the vicinity of the city of Edirne in Turkey. The outbreak was analyzed by a standard surveillance form of the Centers for Disease Control and Prevention. The relationship between the eaten foods and cases was analyzed by Fisher's exact chi-square test, and odds ratios were calculated by a case-control study. The outbreak affected 60 of 168 soldiers in the squadron, 16 of whom were hospitalized. S.enteritidis was cultured in stools from 13 of the hospitalized soldiers and from 3 soldiers who had prepared the food. All strains were completely susceptible to antibiotics; their plasmid profiles were also identical. The highest attack rate detected was 55.7% in an omelet eaten 24 hours before (p < 0.001). Furthermore, it was the riskiest food according to the case-control study (OR=7.88; 95% CI=3.68-16.89). The food samples were unobtainable because they had been discarded. All of the hospitalized cases recovered, and none of the control cultures of stools yielded the pathogen after three weeks. In conclusion, although our results didn't indicate the exact source of the outbreak microbiologically, the omelet was considered to be the source based on the epidemiological proofs.
An outbreak of classical dengue fever occurred from March to August 1988 in the city of Taxco, Guerrero State, Mexico. Taxco is at an elevation of 1,700 meters above sea level, and this study represents the highest altitude at which an outbreak of dengue has been documented. An investigation was conducted to obtain serologic confirmation of dengue infection, determine the extent of the outbreak, and identify risk factors for dengue illness. Toxorhynchites cell lines were used for viral isolation, and hemagglutination inhibition was used to measure anti-dengue antibody titers. The case definition used in the investigation was any person with fever, headache, myalgias, and arthralgias, or rash or retroocular pain. Dengue virus type 1 was isolated from five acute cases. Of 1,686 persons living in the affected area, 42% (715) met the case definition. Large (200-liter) water containers were significantly associated with infection (relative risk = 1.7, 95% confidence interval 1.5-1.9). The effect of altitude on epidemic transmission is most likely modulated by seasonal temperatures. The epidemiologic and serologic confirmation of a dengue outbreak at 1,700 meters above sea level represents the capability of Aedes aegypti to adapt to new environments, and the potential for epidemic spread in cities at comparable altitudes or higher.
The prevalence of the enterotoxin gene in a well-characterized collection of 71 Clostridium perfringens strains from 36 separate food-poisoning cases or outbreaks was analyzed with the polymerase chain reaction (PCR). The clonality of 39 strains originating from 14 outbreaks where at least two isolates were available was studied with pulsed-field gel electrophoresis (PFGE) using SmaI and ApaI restriction endonucleases. The cpe gene PCR assay was found to correlate well with Clostridium perfringens enterotoxin (CPE) production in vitro with reverse passive latex agglutination. Of the C. perfringens food and clinical food-poisoning isolates 24 (86%) and 38 (88%) were cpe-positive, respectively. Different PFGE patterns indicated that multiple cpe-positive clones are frequently present within one outbreak. The existence of cpe-positive and negative isolates with identical or nearly identical PFGE patterns in a single outbreak suggests that the cpe gene may be in a movable genetic element.
The average prevalence of reported foodborne illness from 1981 to 1995 was 2.44 per 100,000 population in Korea, and 28.01 in Japan. The mean case fatality rate in Korea was 0.74% and in Japan, 0.03%. When both prevalence and case fatality rates in Korea and Japan were compared during the same period, the prevalence in Japan was much higher than that in Korea. However, the case fatality rate of patients in Korea was much higher than that in Japan. The distribution of monthly and seasonal patterns of foodborne illness outbreaks strongly indicate the outbreaks may be associated with climatic conditions, frequencies of national holidays, and vacation seasons. Comparison study indicates that the foodborne illness outbreaks in Korea most frequently involved homemade foods (47% of the total cases); in Japan, restaurants accounted for 31.3%. Foodborne illness cases of bacterial origin in Korea were 59.3% of the total and included Salmonella spp. (20.7%). Vibrio (17.4%), Staphylococcus (9.7%), pathogenic Escherichia coli (2.4%), and other species (9.1%); in Japan, 72.8% of the total cases and the majority of the bacterial foodborne illness was caused by Vibrio (32.3%), Staphylococcus (15.9%), Salmonella (14.2%), pathogenic E. coli (3.0%), and other species (7.2%). In conclusion, the outbreaks of foodborne illness in Korea and Japan may be mainly caused by improper food handling, and their occurrences may be differentiated according to food sources.
Molecular methods have become vital epidemiological tools in the detection and characterization of bacteria associated with a foodborne outbreak. We used both culture and real-time PCR to detect a Vibrio parahaemolyticus isolate associated with a foodborne outbreak. The outbreak occurred in July 2002 in Polk County, Florida, and originated at a Chinese buffet, with one person being hospitalized. The hospital isolated V. parahaemolyticus from the patient but destroyed the sample after diagnosis. From an onsite visit of the restaurant, food samples that possibly contributed to the outbreak were collected and sent to the Florida Department of Health, Tampa Branch Laboratory. Crab legs, crabsticks, and mussel samples were homogenized and incubated according to the Food and Drug Administration Bacteriological Analytical Manual culture protocol. Three sets of primers and a TaqMan probe were designed to target the tdh, trh, and tlh genes and used for real-time PCR. This study was successful in isolating V. parahaemolyticus from a mussel sample and detecting two of its genes (tdh and tlh) in food and pure culture by real-time PCR.
In summer 2001, an outbreak of Salmonella München occurred in Germany. We conducted descriptive epidemiology and hypothesis-generating interviews among case patients, two retrospective cohort studies, and a case-control study of suboutbreaks. We performed pulsed-field gel electrophoresis (PFGE) from selected patient isolates and a limited trace-back investigation for analytical purposes. Four states were consecutively affected: Saxonia (SX), Brandenburg (BB), Berlin (BE), and Baden-Württemberg (BW). Although hypothesis-generating interviews failed to identify a plausible food item, descriptive data and investigations of the suboutbreaks suggested pork meat as a probable source in three states (SX, BB, and BE) but not in BW. The PFGE profiles from isolates of case patients in the first three states were indistinguishable but differed from PFGE profiles of case patients in BW. Trace-back investigation suggested that contamination of pork meat occurred early in the rearing-production chain. This outbreak demonstrates how contamination early in the production process that can yield different end products may complicate multistate outbreaks. Investigation of suboutbreaks and use of the trace-back method as investigational tools may be useful adjuncts in solving the problem of multistate outbreaks.
Steaks have not been recognized as an important vehicle of Escherichia coli O157:H7 infection. During 11 to 27 June 2003, the Minnesota Department of Health (MDH) identified four O157 infection cases with the same pulsed-field gel electrophoresis (PFGE) subtype. All four case patients consumed brand A vacuum packed frozen steaks sold by door-to-door vendors. The steaks were blade tenderized and injected with marinade (i.e., nonintact). Information from single case patients in Michigan and Kansas identified through PulseNet confirmed the outbreak. The MDH issued a press release on 27 June to warn consumers, prompting a nationwide recall of 739,000 lb (335,506 kg) of frozen beef products. The outbreak resulted in six culture-confirmed cases (including one with hemolytic uremic syndrome) and two probable cases in Minnesota and single confirmed cases in four other states. The outbreak PFGE subtype of O157 was isolated from unopened brand A bacon-wrapped fillets from five affected Minnesota households. A fillet from one affected household was partially cooked in the laboratory, and the same O157 subtype was isolated from the uncooked interior. The tenderizing and injection processes likely transferred O157 from the surface to the interior of the steaks. These processing methods create new challenges for prevention of O157 infection. Food regulatory officials should reevaluate safety issues presented by nonintact steak products, such as microbiologic hazards of processing methods, possible labeling to distinguish intact from nonintact steaks, and education of the public and commercial food establishments on the increased risk associated with undercooked nonintact steaks. Information on single cases of O157 infection in individual states identified through PulseNet can be critical in solving multistate outbreaks in a timely manner.
During May and June 2001, the World Health Organization reported an outbreak of Crimean-Congo hemorrhagic fever in Kosovo. Two of the outbreak foci were located within the German Kosovo Force's zone of responsibility and thus countermeasures were undertaken at the German field hospital in Prizren to prepare for a potential outbreak among soldiers. A risk assessment was undertaken and the following essential issues were addressed: the education of troops with emphasis given to the prevention of tick bites, the establishment of an isolation unit, including barrier nursing and technical safety measures, the establishment of procedures for the safe handling of biological specimens intended for laboratory diagnosis, protocols for the treatment and prophylaxis with ribavirin, protocols for effective disinfection and decontamination, and an "outbreak plan" should the disease spread among soldiers. Using Army Mobile Field Hospital System equipment, a plan was implemented within 72 hours. The procedures described herein are likely to be suitable for the containment of other highly contagious diseases.
BACKGROUND: Invasive mycoses are an important cause of illness and death in immunocompromised patients. Infections with molds other than aspergilli have been increasingly seen in patients with hematologic cancers, but epidemics of these infections have not yet been reported. OBJECTIVE: To describe an outbreak of invasive mycoses with Paecilomyces lilacinus in severely neutropenic patients. DESIGN: An outbreak investigation. SETTING: The hematology-oncology isolation and bone marrow transplantation unit of the University Hospital, Basel, Switzerland. PATIENTS: 25 consecutive patients admitted between 17 August 1993 (the date of the first manifestation of P. lilacinus infection) and 31 October 1993 (when the unit was closed). MEASUREMENTS: Clinical and microbiological data, including histologic findings; cultures from several patient sites; and environmental examinations of potential airborne, parenteral, enteric, and horizontal routes of transmission. Infections were defined by the isolation of P. lilacinus from clinically evident skin eruptions. RESULTS: 12 of the 25 patients (48%) were infected or colonized. Nine patients (36%), including all bone marrow transplant recipients, had documented invasive P. lilacinus infections. All 9 infected patients had papular, pustular, or necrotic skin eruptions. Two patients with severe graft-versus-host disease died with refractory fungal disease; 1 also had microbiologically documented endophthalmitis and kidney infiltrates. Seven affected patients no longer had P. lilacinus after recovery of bone marrow function. The organism was resistant in vitro to amphotericin B, itraconazole, and fluconazole. Patients did not respond clinically to these agents. The outbreak was ultimately traced to a contaminated, commercially available, pharmaceutically prepared skin lotion. The outbreak ended after the skin lotion was recalled and has not recurred after a follow-up period of 2 years. CONCLUSION: Contaminated skin lotion is a potential cause of opportunistic fungal infections in immunocompromised hosts. Paecilomyces lilacinus is a common saprophytic mold that can cause, by direct cutaneous inoculation, invasive infections associated with illness and death.