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PubMed1990

An outbreak of an influenza-like illness in a nursing home.

As part of an ongoing infection surveillance program, data were collected on an outbreak of respiratory illness affecting 29% of residents in a 231-bed long-term care facility. Viral titers could be collected on 60% of the ill residents and respiratory syncytial virus (RSV) was established in 14 of the symptomatic patients and was thought to be the probable cause of the outbreak. Compared with previously reported long-term institutional outbreaks of RSV, there were significantly fewer cases of pneumonia (5% vs. 14% to 55%) and deaths (2% vs. 6% to 20%). However, morbidity was substantial in this outbreak, with 46% of patients suffering prolonged malaise and anorexia; the mean duration of symptoms was four weeks. Respiratory syncytial virus may be an important cause of respiratory illness in nursing homes and may be unappreciated if specific diagnostic methods are not employed. The recent availability of rapid diagnostic tests and specific antiviral therapy for RSV warrant further clinical studies to develop management strategies for this infection.

Aged↗

PubMed2006

Evaluation of response scenarios to potential polio outbreaks using mathematical models.

Appropriate response to polio outbreaks represents an important prerequisite for achieving and maintaining global polio eradication. We use an existing dynamic disease transmission model to evaluate the impact of different aspects of immunization campaigns in response to polio outbreaks occurring in previously polio-free areas. This analysis yields several important insights about response strategies. We find that delay in response represents a crucial risk factor for occurrence of large outbreaks and we characterize the tradeoffs associated with delaying the initial response to achieve better population coverage. We also demonstrate that controlling most potential outbreaks will likely require at least three immunization rounds, although the impact of the optimal interval between rounds varies. Finally, long after oral poliovirus vaccine cessation the choice of target age groups during a response represents an important consideration.

Disease Outbreaks↗

PubMed2006

A hypothesis test for the end of a common source outbreak.

The objective of this article is to develop a hypothesis-testing procedure to determine whether a common source outbreak has ended. We consider the case when neither the calendar date of exposure to the pathogen nor the exact incubation period distribution is known. The hypothesis-testing procedure is based on the spacings between ordered calendar dates of disease onset of the cases. A simulation study was performed to evaluate the robustness of the methods to various models for the incubation period of infectious diseases. We investigated the impact of multiple testing on the overall outbreak-wise type I error probability. We derive expressions for the outbreak-wise type I error probability and show that multiple testing has minimal effect on inflating that error probability. The results are discussed in the context of the 2001 U.S. anthrax outbreak.

Anthrax↗

PubMed2002

Characterization of United States outbreak isolates of Vibrio parahaemolyticus using enterobacterial repetitive intergenic consensus (ERIC) PCR and development of a rapid PCR method for detection of O3:K6 isolates.

Outbreaks of Vibrio parahaemolyticus gastroenteritis in the United States (Texas, New York and Pacific Northwest) in 1997-98 emphasized the need to develop molecular methods for identification and differentiation of these organisms. When outbreak isolates were analyzed for the enterobacterial repetitive intergenic consensus sequences, the Texas and New York outbreak isolates had a specific 850-bp DNA fragment that was absent in Pacific Northwest isolates. The 850-bp polymerase chain reaction (PCR) product was found in isolates of serovar O3:K6, which have an unusual potential to spread and cause infections. To develop a specific molecular detection method for serovar O3:K6, the nucleotide sequence of the 850-bp product was determined. The GenBank blast analysis did not show homology with any known Vibrio spp. gene sequences. Two PCR primers were designed to specifically amplify the unique sequences from serovar O3:K6 isolates. Genomic DNA from 10 Texas, eight New York, and seven Pacific Northwest outbreak isolates of V. parahaemolyticus was assayed by PCR. Texas and New York isolates were positive in the PCR assay, giving a 327-bp PCR product as predicted; however, Pacific Northwest isolates were negative, indicating the absence of the target gene. Texas and New York isolates were all serovar O3:K6; the Pacific Northwest isolates were not. The primers were tested with other Vibrio spp. and other closely related species and no amplification of the 327-bp PCR product was found. The PCR method can be used to specifically identify O3:K6 V. parahaemolyticus isolates in less than 6 h.

Base Sequence↗

PubMed1985

Serotyping of Campylobacter jejuni isolated from sporadic cases and outbreaks in northern Norway.

In the northern regions of Norway, 123 cases of Campylobacter jejuni gastroenteritis were either sporadic infections or due to five separate outbreaks during 1980-83. Using a serotyping scheme based on thermostable antigens and the passive haemagglutination technique, 92 isolates were serotyped. Excluding duplicates from the outbreaks, the serotype distribution based on 79 isolates showed that serotypes 6, 7 and 12, 40 were the most frequent in occurrence. Each included 11 (13.9%) of the isolates and each serotype was also identified twice as the epidemic strain in four different outbreaks. A fifth outbreak strain was serotype 13, 16, 50. The number of isolates that reacted in one or more antisera of the cross reacting group of serotypes 4, 13, 16, 43 and 50 was 21 (26.6%). The other 23 isolates fell into 19 other serotypes and 13 (16.5%) were untypable.

Campylobacter Infections↗

PubMed2006

Lactococcus garvieae infections in humans: possible association with aquaculture outbreaks.

Lactococcus garvieae is an important pathogen in aquaculture, outbreaks of which significantly affect production. It is a rare pathogen with a low virulence in human infection. The relation between the aquaculture outbreak and the human infection has not been clarified. Prospective and retrospective epidemiologic surveillance of the four patients with L. garvieae infection between 2000 and 2003 and their relations to the aquaculture outbreaks of L. garvieae were conducted. All the four patients with L. garvieae infection were associated with gastrointestinal disorders. Three of the four patients gave a history of consuming raw fish and in three of the four patients, the infection occurred in summer between June and August while there is a decrease of fisheries production and an increase in L. garvieae infection in aquaculture farms. There was a 100% identity of 16S rDNA sequence of L. garvieae isolates from patient 1 and from the squid muscle obtained from the restaurant where patient 1 consumed the raw fish. Sporadic occurrence of L. garvieae infection in human appears to correlate with the seasonal aquaculture outbreaks of L. garvieae infection. The presence of gastro-intestinal disorder may facilitate L. garvieae infection.

Aged↗

PubMed1990

Epidemiology of an avian influenza outbreak in Victoria in 1985.

In May 1985 an outbreak of avian influenza, a disease exotic to the Australian poultry industry, occurred on a farm in central Victoria. The outbreak was contained on that farm by immediate depopulation and disinfection measures. A description of the epidemiology of the outbreak was made during and after the event by interviewing involved personnel and by an extensive sampling and surveillance program both on the affected farm and across Victoria. Although the origin of the infection was not established, it is considered most likely that wild birds introduced the virus. The infection status of wild bird populations in the area has not been ascertained but sampling surveys of the poultry industry indicated that there were no other infected flocks in the state. The infection may have entered the affected flock as long as 2 weeks prior to the clinical outbreak although the exact timing could not be ascertained. The spread of disease on the farm appeared to be largely due to humans acting as mechanical vectors.

Animals↗

PubMed1995

Investigation of an outbreak of foot-and-mouth disease in vaccinated dairy cattle in Thailand.

An outbreak of foot-and-mouth disease that spread between two related vaccinated dairy herds was investigated. Although the cattle were of similar vaccination status, in one herd there was high morbidity, whereas in the other there was considerably lower morbidity. The relationship between the vaccine virus and the outbreak virus was expressed as an r value determined by the two-dimensional neutralisation test. Bovine serum homologous to the vaccine virus indicated a close antigenic relationship between the vaccine virus and the outbreak virus (r = 0.61). The source of the outbreak virus was not determined. The investigation suggested a requirement for close contact between stock for foot-and-mouth disease to spread in a tropical environment, in contrast to the capacity of the disease to spread considerable distances by aerosol transmission in temperate climates.

Animals↗

PubMed2001

Outbreak of foetal infection with bovine pestivirus in a central Queensland beef herd.

OBJECTIVE: To describe a significant outbreak of foetal infection and subsequent losses due to bovine pestivirus on a 5200 ha beef breeding and fattening property in central Queensland. DESCRIPTION OF THE HERD: The affected herd consisted of 656 cows, including 269 recently purchased cows, and 221 heifers that were joined in December/January 1995/96. There were approximately 2500 cattle on the property. INVESTIGATION: Following the purchase of 269 cows in October 1995, which were mingled with the existing cow herd, losses were experienced due to foetal infection with bovine pestivirus. These losses were recorded between 1996 and 1999 as: reduced pregnancy rates, losses between pregnancy testing (midpregnancy) and branding (calves averaged 3 months-of-age), losses due to pneumonia and ill-thrift between branding and approximately 12 months-of-age, and losses due to ill-thrift and the chronic wasting form of mucosal disease thereafter. All surviving calves were tested for bovine pestivirus in 1997 at an average of 10 months. Fifty-three calves were identified as persistently infected with bovine pestivirus. A further 110 calf losses could reasonably be attributed to bovine pestivirus infection. Persistently infected cattle were always unthrifty compared to their virus negative counterparts. Only one persistently infected calf was identified, on the basis of severe ill thrift, in the 1997 birth cohort and none in 1998. CONCLUSIONS: This outbreak of foetal infection with bovine pestivirus resulted in significant production losses. These losses were recorded over the three years subsequent to the outbreak. Significant numbers of persistently infected calves were not evident among calves born in the two years after this outbreak.

Age Factors↗

PubMed1993

An outbreak of Norwalk-like gastroenteritis associated with contaminated drinking water at a caravan park.

During the 1989 Christmas holiday period, a large outbreak of gastroenteritis occurred among persons staying at a caravan park in southern New South Wales. Review of local hospital records found that 77 per cent of patients presenting with infective diarrhoea between 29 December and 3 January had stayed at the caravan park. In a retrospective cohort study we compared rates of illness among caravan park patrons exposed to different water sources. Stools were tested for pathogens and convalescent sera for viral antibodies. Rain and reticulated river water sampled from the caravan park were tested for bacteria and viruses. Of 351 persons interviewed at the caravan park, 305 (87 per cent) reported an illness characterised by diarrhoea, vomiting and abdominal pain. Of 196 persons who used reticulated river water for drinking or ablutions, 175 (89 per cent) became ill compared with 47 of 72 persons (65 per cent) who did not use this water (relative risk 1.4, 95 per cent confidence interval 1.2 to 1.6). The outbreak was probably caused by a 27-28 nm small round structured virus found in the stool from one ill person. High levels of faecal coliforms in the reticulated river water and enterovirus in sediment samples suggest that the outbreak was caused by sewage contaminating the reticulated river water through a break in the pipe directly over the underground water tanks. To prevent such outbreaks, poor water and sewerage system layouts should be avoided and nonpotable water should be clearly labelled. Where feasible, all camping-ground water should stem from town supplies.

Abdominal Pain↗

PubMed1994

[Comparison of the prevalence of symptoms, elevated serum antibody, antibody types and complications between two outbreaks of influenza in a ward].

We experienced two outbreaks of influenza in the respiratory ward of our hospital in Feb. 1990 and Feb. 1993. Influenza-like symptoms were recognized in 42 of 67 cases (63%) in 1990, and in 22 of 56 cases (39%) in 1993. In the former outbreak, the prevalence of the serum CF titer for anti-influenza antibody was elevated in 25 of 42 cases (60%) (only the A2 antibody titer in 2 cases, B antibody titer in 4 cases in the latter one). Among asymptomatic inpatients, the serum titer was elevated in 3 of 25 cases (12%) in the former outbreak, but in 1 of 8 cases which the serum CF titer for anti-influenza antibody was measured in the latter one. A respiratory complications secondary to influenza were observed in 6 (2 cases pneumonia, 3 cases lower respiratory tract infection, 1 case asthma attack) of 67 cases during the former period, but only 1 of 56 cases during the latter period. In the two outbreaks of influenza in the respiratory ward we found the same results concerning the occurrence of influenza-like symptoms, an elevation of the serum antibody titer, but a significant difference was noted with regard to the phenotype of the prevalent influenza and the occurrence of complications.

Aged↗

PubMed2000

Outbreak of cryptosporidiosis after contamination of the public water supply in Saitama Prefecture, Japan, in 1996.

An outbreak of cryptosporidiosis occurred in Ogose Town, Saitama Prefecture. Japan, in June 1996. Of 12,345 respondents to a questionnaire sent to households in the town (population; 13,809), 8,812 (71.4%) reported an acute gastrointestinal illness some time between May and July. In addition, 274 traceable visitors at local inns, golf courses, and the like during this period and 54 employees from out of town were infected. Cases of cryptosporidiosis were estimated to 9,140. Of these, 2,856 subjects were treated at outpatient clinics and 24 subjects were hospitalized (some subjects counted twice). No deaths were attributed to the outbreak. Among the visitors to Ogose who were traced, 7 persons who stayed only one day during the outbreak and drank half a glass to 2 glasses (100 to 360 ml) of tap water had cryptosporidiosis confirmed by laboratory tests. The median incubation period for the 14 persons for whom this calculation was possible was 6.4 days (range, 5 to 8 days). Of 469 pupils reporting details of their fever and diarrhea, abdominal cramps, or these combined signs and symptoms, the median maximum body temperature was 37.8 degrees C (range, 36.7 to 40.3 degrees C). The duration of illness, reported by 608 of the pupils, was 5.2 days (range, 1 to 15 days), and that reported by 187 employees was 4.8 days (range, 1 to 18 days). The longest known time for discharge of oocysts after onset was 44 days. Blood was not found in the 609 stool specimens examined. The outbreak was caused by contamination of the town's potable water by Cryptosporidium parvum oocysts. The town's water treatment plant treated river water by coagulation, sedimentation, sand filtration, and chlorination. Contamination arose because of various natural and artificial factors: one was that the monthly precipitation in May was much lower than average, causing the river water level to drop. Another factor was heavy rainfall one night in May that increased water turbidity. The amounts of the coagulant added seemed to be insufficient. There are two inns, three public lavatories, and two small-scale wastewater treatment plants upstream 400 m and 1,200 m of the intake point of the town's water treatment plant. However, there are no farms with livestock in the area. We suggest that the location of the water treatment facilities was inappropriate, and that oocysts had circulated from the potable water to humans to sewage to the river and back to the potable water.

Adolescent↗

PubMed2001

[Outbreak of measles in a hospital and measures taken against hospital infection--evidence of cost and benefits].

In Japan, an isolated vaccine of measles is used because MMR vaccines have been suspended due to the frequent occurrence of aseptic meningitis after their use. It is administered only once with the cover rate having been approximately 70%. An outbreak of measles was experienced in eight of our health care workers (three doctors, three nurses and two clerks of our hospital) and in seven of our medical students, accompanying local outbreaks. Their condition was severe enough to require admission to our school hospital. One of medical students developed encephalitis, but he has recovered completely. The social cost including medical cost per worker was approximately yen 500,000 (about $4,500). We measured antibodies against measles, rubella, chickenpox and mumps using the ELISA assay in 1048 health care workers less than 40 years of age and 99 medical students before their clinical practice two or three months after the outbreak. The cost including the measuring of antibodies and vaccination for these workers and students was approximately yen 2,800,000 and it will be yen 700,000 for new workers each year. The negative rates for workers were 1.2% for measles, 8.8% for rubella, 10.0% for mumps and 2.0% for chickenpox and those for the medical students were 1.0%, 22.0%, 9.0% and 5.0%, respectively. Of the workers, 9.6% who had more than the defined very high tiaer were thought to have subclinical reinfection because they were non-symptomatic. The rates were 1.2% for rubella, 0.5% for chickenpox and 0.0% for mumps for more than the defined high titers among the workers, suggesting a risk of outbreaks in the future. Therefore, the antibodies of health care workers and medical students should be measured at the hospital and the antibody-negative person should be vaccinated to prevent infection not only from their patients but also prevent other patients from becoming infected by contracted health care workers or students.

Adult↗

PubMed2003

[A diffuse outbreak of enterohemorrhagic Escherichia coli O157:H7 related to the Japanese-style pickles in Saitama, Japan].

We have experienced an outbreak of enterohemorrhagic E. coli O157:H7 (Shiga-like toxin 1 & 2 producing) in child independence support facilities in the all dormitory system, in Saitama August 2001. There were 13 patient and EHEC O157s were detected in a total of 29 specimens. As a result of epidemic inspection and microbiological investigation. We recognized that the causative food was Japanese-style pickles named "Wafu-Kimuchi" which had been sold in Saitama and Tokyo area. As the same period, several infections caused by EHEC O157 were considered the same origin in Saitama (8 patients in 5 families). Furthermore some infections happened also in Tokyo. It was made clear this outbreak was a part of a diffuse outbreak caused by Wafu-Kimuchi. In diffuse outbreaks, it is important to grasp a common feature of the individual cases in a wide area. The exchange of epidemic information between two or more municipalities and the guess of the identity in the DNA levels of strains were the key role to the elucidation of this case.

Disease Outbreaks↗

PubMed2003

[Outbreak of acute gastroenteritis caused by human group C rotavirus in a youth educational center in Okayama Prefecture].

In May 2000, an outbreak of acute gastroenteritis caused by human group C rotavirus (CHRV) occurred in a youth educational center located in the southern area of Okayama Prefecture. A total of 172 schoolchildren and teachers, who consisted of 51 persons belonging to F school and 121 persons belonging to K school, joined in an educational program at the center from May 24 to 26. Eighty-seven individuals (50.6%) of them showed clinical symptoms of gastroenteritis from May 24 to 30, and the outbreak peaked on May 27. The major clinical symptoms were abdominal pain (87.4%), diarrhea (50.6%), nausea or vomiting (21.8%), fever > 37 degrees C (12.6%), and headache (14.9%). The clinical symptoms of the patients in F school were more severe than those in K school. Thirty-two fecal specimens were collected from the patients and examined for gastroenteritis viruses by electron microscopy, ELISA, reverse passive hemagglutination test, and reverse transcription (RT)-PCR. As a result, CHRVs were detected in 21 specimens (65.6%) by RT-PCR. The possible route of the CHRV infection was thought to be a person to person transmission by following reasons: (i), CHRVs were detected in stools from patients who became ill on the first day of the program; (ii), CHRVs were not detected in stools from cooks; (iii), no possible causal food was found by epidemiological analysis of the outbreak. Furthermore, phylogenetic analysis of the VP7 gene among CHRVs isolated in Okayama revealed that the virus detected in this study was more closely related to the virus isolated from a sporadic case of gastroenteritis in 1996 than that isolated from an outbreak occurred in 1999.

Acute Disease↗

PubMed2004

[An outbreak of diarrheal disease caused by enterotoxigenic Clostridium perfringens following exposure to a contaminated environment in a nursing home].

We herein report an outbreak of non-food-borne diarrhea which occurred in a nursing home due to enterotoxigenic Clostridium perfringens. The regional public health center in Gifu, Japan, recognized 7 patients with diarrhea in a nursing home, suspecting a food-borne illness. Bacteriological and epidemiological studies indicated that enterotoxigenic C. perfringens was the causative agent. However, suspected foods, the kitchen and the cooks carried no enteropathogenic bacteria, indicating that this outbreak was a non-food-borne diarrhea. The swab specimens obtained from the residential area of the nursing home were found to have enterotoxigenic C. perfringens. Isolates from the stool specimens of patients and environment were all serotype TW47, showing susceptibilities to ampicillin, levofloxacin, and clindamycin very similar to each other, and had banding patterns identical to each other by pulsed-field gel electrophoresis. These results strongly supported the existence of monoclonal spread of an enterotoxigenic C. perfringens among the environment of the nursing home and the residents. During 3 weeks 14 residents were involved in this outbreak. The extensive effort of keeping the residential area clean led to a prompt cease of this outbreak.

Aged↗

PubMed2006

[Isolation of thermostable direct hemolysin producing Vibrio parahaemolyticus from food using screening by PCR in food-borne outbreaks].

The producibility of thermostable direct hemolysin (TDH) is the most important pathogenic factor in Vibrio parahaemolyticus. TDH (+) V. parahaemolyticus is usually isolated from patients having V. parahaemolyticus food-borne disease. TDH (+) V. parahaemolyticus is, however, very difficult to isolate from food and environmental samples. In the 5 years from 2000 to 2004 in Tokyo, V. parahaemolyticus was isolated from food samples related to 67 of 227 V parahaemolyticus food-borne outbreaks. In these outbreaks, TDH (+) strains were also tried to isolate using PCR as the screening methods. TDH (+) V. parahaemolyticus strains were able to isolate from enrichment broth in which toxR and tdh genes become positive in PCR. TDH (+) strains of the same serotype with patients were able to be isolated from 23 food samples related to 11 outbreaks (16.4%); 3 outbreaks in 2000, 2 in 2001, 2 in 2002, 1 in 2003, and 3 in 2004. The serotypes of V. parahaemolyticus isolated from food were O3 : K6 (10 samples), O3 : K5 (6 samples), O1 : K25 (4 samples), O3 : K29 (2 samples), O4 : K 8 (1 sample), and O4 : K11 (1 sample). The isolation rate of the TDH (+) strain from enrichment broth differed with samples. In several samples TDH (+) strains were isolated easily only by examining 3 colonies, hence no TDH (+) strains were isolated in spite of the examination of 250 colonies. No correlation was seen between the number of V. parahaemolyticus and the isolation rate of TDH (+) strains in food samples. Screening using PCR is very effective method for isolating TDH (+) V. parahaemolyticus from food samples.

Disease Outbreaks↗

PubMed2006

[Serum anti-lPS antibody production in an outbreak of enterohemorrhagic Escherichia coli O157 infection among schoolchildren].

Although there have been many reports of the usefulness of serodiagnosis of enterohemorrhagic Escherichia coli (EHEC) O157, the serotype of the bacteria detected and the increase in anti-LPS antibody have not always been consistent. In this study we investigated the diagnostic significance of measurements of anti-LPS antibody by ELISA in an outbreak of O157 infection among schoolchildren in whom the bacteriological test findings were clarified and the age groups were uniform. The anti-LPS antibody titer was measured in 31 patients (77 serum samples) in an outbreak of EHEC O157 : H7 infection (220 children infected) that occurred in a primary school in Morioka in 1996. The anti-O157 LPS antibody positivity rates of IgM, IgG, and IgA were 98.7%, 85.7%, and 98.7%, respectively. Between the time the meal that caused the outbreak and 19 days later, anti-O157 LPS IgM antibody and IgA antibody were detected in all patients. The specificity was investigated using control serum, and the specificity of IgM, IgG, and IgA was 93.5%, 93.5%, and 97.2%, respectively. Some samples contained antibodies against O111 and O26 LPS, but the titers were lower than the anti-O157 antibody titer. The anti-O111 antibody titer and anti-O26 antibody titer were highly correlated, suggesting that they were crossreactive antibodies for O157 LPS. No significant correlation was found between differences in clinical manifestations and the anti-O157 LPS antibody titer in this O157 outbreak in schoolchildren. It was clarified that an increase in anti-LPS antibody was found to support the diagnosis of mild cases of 0157 infection infection as well as severe cases.

Antibodies, Bacterial↗