广州市黄埔区某公司急性呼吸道感染症暴发疫情 调查分析

摘要:目的　分析急性呼吸道感染症疫情暴发原因及传播因素,探讨流行因素,提出预防控制措施建议,为疫情控制提供科学依据。方法　采用现场流行病学调查方法,对公司的每一个病例进行问卷调查。对发病3 d内的现症患者采集咽拭子标本,采用血平板分离培养及RT-PCR方法检测核酸。对现症患者进行隔离治疗,对密切接触者进行7 d的隔离医学观察。结果　暴发疫情历时4 d,共发生病例56例,发病高峰集中在2013年8月4日,占发病人数的 64.29%。疫情波及11个班部,22～24岁发病占64.29%。临床特点为发热、咽痛和扁桃体肿大。采集56份现症患者咽拭子标本,其中13份A 群β型溶血性链球菌核酸检出阳性。结论　此宗暴发疫情为A 群β型溶血性链球菌引起的急性扁桃体炎。室内通风不良,空气污染,接触密切是引起暴发的主要原因。隔离治疗患者,对密切接触者进行隔离和医学观察,加强室内通风换气和消毒,搞好环境卫生,开展健康教育是控制疫情的有效措施。     

Recurrent outbreaks of giardiasis in a child day care center, Wisconsin.

In the 19-month period September 1983-March 1985, three outbreaks of giardiasis occurred in one large child day care center. Control measures instituted during each outbreak included case finding; pharmacologic treatment and follow-up testing of stool specimens for cases of giardia infection in day care children and staff, and their household contacts; facilitating and stressing personal and environmental hygiene, including altering diapering practices and teaching appropriate hand washing techniques. In the first, second, and third outbreaks, overall attack rates (stool analysis positive for Giardia lamblia) were determined for those persons with greater than or equal to 2 stool specimens submitted; attack rates in children were 47, 17, and 37 per cent, respectively; for tested staff, the rates were 35, 13, and 9 per cent; and for tested household contacts were 18, 9, and 5 per cent. Attack rates were highest for ambulatory diapered children, children attending the day care center greater than or equal to 40 hours per week, and children who were infected with G. lamblia in the most recent previous outbreak. Despite extensive efforts to identify cases, a cure rate of greater than 90 per cent in treated cases, and improvements in personal and environmental hygiene practices, G. lamblia infections recurred in outbreak proportions.     

Tuberculosis contact tracing among children and adolescents, Brazil

OBJECTIVE: To detect tuberculosis (TB) disease or infection among contacts of pulmonary TB patients. METHODS: Cross-sectional study in a Primary Healthcare unit in Rio de Janeiro (Brazil) with 184 child and adolescent contacts of pulmonary TB patients between March 1995 and March 1997. Subjects underwent clinical evaluation, chest radiographs, and tuberculin skin tests (TST); sputum smears were performed whenever possible. TB cases found were submitted to treatment and infected patients to chemoprophylaxis. Tuberculin converters, who tested positive for TST eight weeks after an initial negative result, received chemoprophylaxis. RESULTS: The sample included 98 boys and 86 girls; age ranged from 0 to 15 years; 26.9% were malnourished according to the Gomez criteria. Concerning the source of infection, 170 cases (92.4%) had household contacts, of which 66.5% were the child's parents. BCG vaccination was verified in 98.4% of children, and 14.7% of children had been revaccinated. Strong TST reactions were observed in 110/181 children. Seventy-six children (41.3%) were considered as infected by M. tuberculosis and 25 cases (13.6%) of TB were detected, of which seven (28%) were asymptomatic. There was greater occurrence of disease when the contact lived with more than one source of infection (p=0.02). CONCLUSIONS: The detection of TB disease and infection was high in the studied population. Contact control must be emphasized, for it allows for the diagnosis of TB in children who are still asymptomatic, in addition to identifying infected subjects who may profit from chemoprophylaxis.     

Serologic investigation of an outbreak of hepatitis A in a rural day-care center

We studied an outbreak of hepatitis A in a day-care center in a rural community where less than 7 per cent of the population possessed anti-HAV. Serotesting for IgM specific antibody to hepatitis A virus identified 78 cases in center attendees, staff, and families. Thirty-five per cent of the center children were seropositive. In children under age three anicteric infection was at least 17 times more frequent than icteric infection, but in older children and adults icterus was a predominant manifestation of the disease. Clinical suspicion should be high in any day-care child with nausea, emesis, diarrhea, or arthralgia. The low incidence of icterus in infected children suggested that outbreak reports reaching public health departments are likely to be incomplete and poorly indicative of outbreak magnitude. The high frequency of intrafamilial transmission and anicteric infection appeared to justify administration of immune serum globulin to household contacts of center children under age three when a day-care outbreak is detected.     

Invasive M-type 3 Streptococcus pyogenes affecting a family and a residential home

This paper describes the first recognised United Kingdom outbreak of M-type 3 streptococci for 12 years. Four epidemiologically-linked invasive infections occurred in a residential home in northern England over two weeks. The index patient was admitted from home with necrotising fasciitis of the leg. Infection was subsequently detected in her husband (fatal pneumonia) another resident (fatal pneumonia) and a member of the care staff (parapharyngeal abscess). Screening of staff and residents in the home did not reveal any further infection or carriage. There is a substantial risk of serious secondary infection amongst the contacts of a patient with invasive Streptococcus pyogenes infection. Guidance is lacking, but needed, on the advisability of chemoprophylaxis in these circumstances.     

Managing meningitis in children: audit of notifications, rifampicin chemoprophylaxis, and audiological referrals.

Important aspects of the management of meningitis in children include notification to local officers for control of communicable diseases; chemoprophylaxis for index cases and close contacts in cases of meningococcal or Haemophilus influenzae meningitis; and a formal hearing assessment for all survivors. A retrospective audit of these aspects of management was carried out for children admitted with meningitis in 12 months from 1 September 1990 to 31 August 1991 at the Royal Belfast Hospital for Sick Children. Only 20 of 36(56%) cases were notified by medical staff. Chemoprophylaxis was arranged for all close family contacts but to only five of the 23(22%) index cases for whom it was indicated. Appointments for audiological testing were arranged for only 19 of the 32(59%) survivors. Subsequently all doctors, including each intake of junior doctors, were given written information on the importance of notification and locally agreed guidelines for chemoprophylaxis and hearing assessments for survivors before discharge. Guidelines were also displayed prominently in each ward. A repeat audit from January 1992 to December 1992 showed significant improvement in these aspects of care. Twenty eight of 32 cases (88%) were notified, chemoprophylaxis was given to 20 of 22(91%) index cases for whom it was indicated, and 25 of 29(86%) survivors had hearing assessments arranged before discharge. Correct management of some aspects of care cannot be assumed, even if statutory (notification), nationally agreed (chemoprophylaxis), or generally agreed good practice (hearing assessments). These aspects of care improved after the first audit but the authors conclude that the notification rate remains below 100% and a repeat audit is necessary.     

An outbreak of chickenpox at a child care centre in Western Australia. Costs to the community and implications for vaccination policy

OBJECTIVE: Between May and June 2002 an outbreak of chickenpox (CP) occurred at a child care centre in Perth, Western Australia. An epidemiological study was undertaken in order to determine the characteristics of the outbreak, assess vaccine effectiveness, and to define the direct and indirect costs associated with CP infections in young children. METHODS: A cohort study of the outbreak utilising attendance records and a telephone survey of parents was conducted. RESULTS: Of the 211 children attending the child care centre at the time of the outbreak, 44 contracted CP (attack rate 25.7%). In addition, two staff members, five secondary household contacts (secondary attack rate 38.5%) and four secondary non-household associated contacts were infected. There were no severe complications or any hospitalisations recorded in infected persons. Two cases had been vaccinated previously. Vaccine effectiveness for CP of any severity was 78.0% (95% CI 15.4-94.3%) while vaccine effectiveness against severe CP was 100%. Direct costs during this outbreak were estimated to be $54 per case and the total costs, including cost of parental time off work or study, were estimated to be $525.73 per case. CONCLUSIONS AND IMPLICATIONS: Although morbidity associated with CP in young children is not great, infection in childhood is almost universal. This study found that the average costs associated with each CP case were considerable. Since varicella vaccine affords good protection against CP, the recent inclusion of this vaccine in the Australian childhood vaccination schedule should save the community a considerable amount in direct and indirect costs if high coverage rates can be achieved.     

Outbreak of tuberculosis associated with a church

Investigation of an outbreak of tuberculosis (TB) in a West Midlands health district in 1999 revealed spread in an extended family network and to church contacts. Within the family four cases of smear positive TB, four cases of smear negative infection, and 14 cases requiring chemoprophylaxis were identified. One of the infectious cases visited a local church on two occasions, which resulted in a further 16 cases of infection including one case of tuberculous meningitis. DNA fingerprinting of isolates from five culture positive cases indicated that the same strain of Mycobacterium tuberculosis was responsible. This outbreak is a reminder that while outbreaks of TB usually arise within households or family networks, where close contact over extended periods provides more opportunity for exposure, community outbreaks of TB can occur after only causal contact.     

Tightly clustered outbreak of group A streptococcal disease at a long-term care facility.

OBJECTIVE: To describe investigation of a tightly clustered outbreak of invasive group A streptococcal (GAS) disease associated with a high mortality rate in a long-term care facility (LTCF). DESIGN: Cross-sectional carriage survey and epidemiologic investigation of LTCF resident and employee cohorts. SETTING: A 104-bed community LTCF between March 1 and April 7, 2004. PATIENTS: A cohort of LTCF residents with assigned beds at the time of the outbreak. INTERVENTIONS: Reinforcement of standard infection control measures and receipt of chemoprophylaxis by GAS carriers. RESULTS: Four confirmed and 2 probable GAS cases occurred between March 16 and April 1, 2004. Four case patients died. The final case occurred during the investigation, before the patient was determined to be a GAS carrier. No case occurred during the 6 months after the intervention. Disease was caused by type emm3 GAS; 16.5% of residents and 2.4% of employees carried the outbreak strain. Disease was clustered in 1 quadrant of the LTCF and associated with nonintact skin. GAS disease or carriage was associated with having frequent personal visitors. CONCLUSIONS: Widespread carriage of a virulent GAS strain likely resulted from inadequate infection control measures. Enhanced infection control and targeted prophylaxis for GAS carriers appeared to end the outbreak. In addition to employees, regular visitors to LTCFs should be trained in hand hygiene and infection control because of the potential for extended relationships over time, leading to interaction with multiple residents, and disease transmission in such residential settings. Specific attention to prevention of skin breaks and proper wound care may prevent disease. The occurrence of a sixth case during the investigation suggests urgency in addressing severe, large, or tightly clustered outbreaks of GAS infection in LTCFs.     

Screening policies for daycare attendees: lessons learned from an outbreak of E. coli O157:H7 in a daycare in Waterloo, Ontario

OBJECTIVES: Control measures for enteric outbreaks in child care settings frequently include screening by stool cultures from symptomatic children only. We present evidence from an investigation of Escherichia coli (E. coli) O157:H7 in a daycare in Waterloo, Ontario to support implementation of a mandatory screening policy for all children during an outbreak. METHODS: In addition to routine outbreak control measures employed by the health unit, stool samples from all children and staff were collected, with positive E. coli cultures typed by pulsed field gel electrophoresis (PFGE). We conducted a cohort study, using data from the environmental investigation and questionnaires administered to parents and staff, to look for risk factors for infection and to survey parent/staff knowledge regarding appropriate management of diarrhea. RESULTS: Overall 11 E. coli O157:H7 cases were identified (7 lab-confirmed); 9 were children. No common source of infection was identified. Factors identified as possibly contributing to person-to-person transmission within the daycare included: i) the underreporting and possible attendance of symptomatic children despite alerting parents to the outbreak and requirements to keep symptomatic children at home, ii) possible transmission from an asymptomatic infected child, and iii) inconsistent understanding among parents and staff regarding diarrhea and appropriate management of a child with diarrhea. DISCUSSION/CONCLUSION: This investigation reveals that in child care settings, E. coli O157:H7 outbreak screening policies based on reported symptoms only may be insufficient. We recommend that such policies be amended to include the collection of at least one stool culture from all children in attendance, regardless of symptom history.     

An outbreak of shigellosis in a child care centre.

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.     

Efficacy of high-efficiency particulate air filtration in preventing aspergillosis in immunocompromised patients with hematologic malignancies.

OBJECTIVES: To describe and investigate the cause of an outbreak of 10 cases of nosocomial invasive infection with Aspergillus flavus in a hematologic oncology patient care unit. DESIGN: A retrospective cohort study. SETTING: The hematologic oncology unit of a comprehensive cancer center. PATIENTS: Ninety-one patients admitted to the hematologic oncology service between January 1 and December 31, 1992, for 4 or more consecutive days were included in the study. RESULTS: Ten (18%) of 55 patients admitted from July to December 1992 were diagnosed as having invasive aspergillosis compared with 0 (0%) of 36 patients admitted from January to June 1992 to the same patient care units. Patient characteristics, mortality rate, autopsy rate, and admitting location did not change significantly during the course of the year to result in a sudden increase in the number of aspergillosis cases. The source of the outbreak was the high counts of Aspergillus conidia determined from air sampling in the non-bone marrow transplant wing during the outbreak. After high-efficiency particulate air (HEPA) filters were installed as an infection control measure, there were only two additional cases of nosocomial aspergillosis in the 2 years following the outbreak. CONCLUSIONS: This outbreak occurred among hematologic oncology patients with prolonged granulocytopenia housed in an environment with neither HEPA filters nor laminar air flow units. Our data demonstrate that in the setting of an outbreak of aspergillosis, HEPA filters are protective for highly immunocompromised patients with hematologic malignancies and are effective at controlling outbreaks due to air contamination with Aspergillus conidia.     

Streptococcus pyogenes prtFII,but not sfbI,sfbII or fbp54, is represented more frequently among invasive-disease isolates of tropical Australia

Streptococcus pyogenes (group A streptococcus) strains may express several distinct fibronectin-binding proteins (FBPs) which are considered as major streptococcal adhesins. Of the FBPs, SfbI was shown in vitro to promote internalization of the bacterium into host cells and has been implicated in persistence. In the tropical Northern Territory, where group 4 streptococcal infection is common, multiple genotypes of the organism were found among isolates from invasive disease cases and no dominant strains were observed. To determine whether any FBPs is associated with invasive disease propensity of S. pyogenes, we have screened streptococcal isolates from bacteraemic and necrotizing fasciitis patients and isolates from uncomplicated infections for genetic endowment of 4 FBPs. No difference was observed in the distribution of sfbII, fbp54 and sfbI between the blood isolates and isolates from uncomplicated infection. We conclude that the presence of sfbI does not appear to promote invasive diseases, despite its association with persistence. We also show a higher proportion of group A streptococcus strains isolated from invasive disease cases possess prtFII when compared to strains isolated from non-invasive disease cases. We suggest that S. pyogenes may recruit different FBPs for different purposes.     

Local health department costs associated with response to a school-based pertussis outbreak --- Omaha, Nebraska, September-November 2008

Pertussis is a highly infectious, vaccine-preventable respiratory illness. With the advent of a vaccine, case numbers fell in the United States from a high of 265,269 in 1934 to a low of 1,010 cases in 1976, but then resurged to 25,827 in 2004. During 2004-2008, the average was 18,161 cases per year. Close contacts of persons with pertussis are at increased risk for developing infection and are recommended to receive preventive antibiotics for two reasons: 1) the illness can be debilitating, with cough lasting several weeks and sometimes being severe enough to cause urinary incontinence, rib fracture, or other complications; and 2) the illness can be fatal in infants; it caused an average of 17 deaths each year during 2002-2006. During pertussis outbreaks, the resources needed to identify and treat contacts can strain local public health resources. The Douglas County Health Department (DCHD) in Omaha, Nebraska, responded to a school-based pertussis outbreak with 26 cases occurring in late 2008. To assess the costs incurred by a local health department responding to such an outbreak, DCHD and CDC evaluated the total resources used by DCHD. This report describes the results of that analysis, which indicated that 1) staff members reported 1,032 person-hours spent responding to the outbreak, and 2) the total cost of outbreak response, including overhead, labor, travel, and other costs, was $52,131 (measured in 2008 U.S. dollars). The majority of costs (59%) occurred during an intensive 10-day period, when most of the contact tracing and prophylaxis recommendations were made. The elevated incidence of pertussis and the burden of response placed on health departments warrants exploring the impact of alternative response and chemoprophylaxis strategies.     

An outbreak of scarlet fever, impetigo and pharyngitis caused by the same Streptococcus pyogenes type T4M4 in a primary school

EPIDEMIC: Following the notification of an unusual number of scarlet fever cases within the same primary school, the epidemiological and clinical features of the outbreak were investigated. Questionnaire information about the cases was collected from parents and general practitioners per telephone. Throat specimens were taken, before and after treatment, for culturing and specific typing of streptococci was performed to determine transmission. Within a period of one month, 21 schoolchildren in a class of 29 pupils, with a mean age of 5 years, presented with symptoms caused by streptococcal infection (attack rate: 72%). Eight had scarlet fever, 5 suffered from impetigo and 8 had pharyngitis. A further 6 children, outside of this class, had complaints of scarlet fever, impetigo or pharyngitis. For 90% (26/29) of the schoolchildren a throat culture was established. Twelve positive cultures of the same strain of beta-haemolytic group A streptococcus, T4M4 exotoxin C gene positive, were found. The advice given was to treat all positive children for 3 days with azithromycin to prevent complications and further spreading of the disease. After two weeks only one child, that had not taken the antibiotics, still had a positive throat culture. No further cases or complications were reported. DISCUSSION: The pattern of the outbreak was typical of a person-to-person transmission. This was confirmed by typing of the isolates. The results of this study demonstrate the importance of mandatory notification of infectious clusters by institutions, such as schools, as introduced in the new Dutch Infectious Disease Act. On the one hand, the notification gives the municipal health authority the opportunity to analyse source and transmission dynamics and on the other to prevent disease and complications.     

Risk for severe group A streptococcal disease among patients' household contacts

From January 1997 to April 1999, we determined attack rates for cases of invasive group A streptococcal (GAS) disease in household contacts of index patients using data from Active Bacterial Core Surveillance sites. Of 680 eligible index-patient households, 525 (77.2%) were enrolled in surveillance. Of 1,514 household contacts surveyed, 127 (8.4%) sought medical care, 24 (1.6%) required hospital care, and none died during the 30-day reference period. One confirmed GAS case in a household contact was reported (attack rate, 66.1/100,000 household contacts). One household contact had severe GAS-compatible illness without confirmed etiology. Our study suggests that subsequent cases of invasive GAS disease can occur, albeit rarely. The risk estimate from this study is important for developing recommendations on the use of chemoprophylaxis for household contacts of persons with invasive GAS disease.     

Nursing home outbreak of invasive group a streptococcal infections caused by 2 distinct strains.

OBJECTIVE: To identify factors contributing to a cluster of deaths from invasive group A streptococcus (GAS) infection in a nursing home facility and to prevent additional cases. DESIGN: Outbreak investigation. SETTING: A 146-bed nursing home facility in northern Nevada. METHODS: We defined a case as the isolation of GAS from a normally sterile site in a resident of nursing home A. To identify case patients, we reviewed resident records from nursing home A, the local hospital, and the hospital laboratory. We obtained oropharyngeal and skin lesion swabs from staff and residents to assess GAS colonization and performed emm typing on available isolates. To identify potential risk factors for transmission, we performed a cohort study and investigated concurrent illness among residents and surveyed staff regarding infection control practices. RESULTS: Six residents met the case patient definition; 3 (50%) of them died. Among invasive GAS isolates available for analysis, 2 distinct strains were identified: emm11 (3 isolates) and emm89 (2 isolates). The rate of GAS carriage was 6% among residents and 4% among staff; carriage isolates were emm89 (8 isolates), emm11 (2 isolates), and emm1 (1 isolate). Concurrently, 35 (24%) of the residents developed a respiratory illness of unknown etiology; 41% of these persons died. Twenty-one (30%) of the surveyed employees did not always wash their hands before patient contacts, and 27 (38%) did not always wash their hands between patient contacts. CONCLUSIONS: Concurrent respiratory illness likely contributed to an outbreak of invasive GAS infection from 2 strains in a highly susceptible population. This outbreak highlights the importance of appropriate infection control measures, including respiratory hygiene practices, in nursing home facilities.     

Survey of the prescribing of chemoprophylaxis to index cases of invasive meningococcal disease

Chemoprophylaxis is given to contacts of cases of invasive meningococcal disease to reduce the risk of secondary cases by eradicating carriage. In the United Kingdom index cases are also recommended to receive chemoprophylaxis. This is usually undertaken by the clinical team managing the case. One hundred and fifty cases of probable meningococcal infection notified to the consultants in communicable disease control in a local health authority were reviewed to identify the proportion receiving chemoprophylaxis and to examine the final clinical outcome, in terms of diagnosis, of each case. Twenty-five per cent of notified cases (37) did not receive chemoprophylaxis and this proportion varied significantly between three local hospitals. We estimate that 15 of the 37 index cases who did not receive chemoprophylaxis were likely to have had invasive meningococcal disease.     

Public health management of an outbreak of group C meningococcal disease in university campus residents.

BACKGROUND: Increasing numbers of outbreaks of Group C meningococcal disease in teenagers and young adults led to a new policy in the UK in 1999 of vaccinating all new college students. The largest of these outbreaks involved seven students in one university, six of whom were from one hall of residence, and two of whom died. METHODS: Control of the outbreak involved close medical surveillance of resident students, mass chemoprophylaxis and vaccination, and wide dissemination of daily information bulletins. Investigation of the epidemiology of the outbreak involved searching for the network of close contacts between cases, a prevalence survey of carriage of meningogocci and a case control study of risk factors for carriage. RESULTS: Clinical cases could be linked by a discrete network of social contacts within the halls of residence, but the Group C epidemic strain (2a P1.5) was not detected in 454 students (upper 95% confidence interval 0.7%). Carriage of any meningococcal strain (19%) was associated with patronage of the campus bar (OR = 3.0, 0.99-9.1). CONCLUSION: Important factors in the control of the outbreak were rapid institution of mass chemopropylaxis and immunisation of residents, and involvement of student organizations in the dissemination of information about the disease and its control. The role of campus bars in dissemination of the carriage of meningogocci deserves further investigation.     

Outbreak of Vero cytotoxin-producing Escherichia coli O157 in a child day care facility

In December 1998, an outbreak of Vero cytotoxin-producing Escherichia coli (VTEC) O157 in a crèche affected ten out of 45 children and one out of five staff members. Eight cases were symptomatic and three were asymptomatic. There were two asymptomatic adult family contacts of child cases. All specimens were identified as VTEC O157:H7, phage type 32. None of the cases were seriously ill and none developed haemolytic uraemic syndrome (HUS). One child continued to excrete the organism for 14 weeks. The origin of the outbreak was not found but epidemiological investigation was suggestive of person-to-person spread. All children and staff were screened and excluded from the crèche until microbiological clearance was obtained. An inspection of the crèche revealed overcrowding and inadequacies in cleaning and in the food preparation facilities. These problems were remedied before children were re-admitted to the crèche. This outbreak demonstrates the ease with which VTEC O157 can be transmitted between small children. Two specific features of this outbreak were notable: (1) the mild self-limiting nature of the illness and (2) the prolonged shedding of the bacterium by one child.