Takaaki Ohyama

Testing a symptom-based surveillance system at high-profile gatherings as a preparatory measure for bioterrorism.

We tested symptom-based surveillance during the G8 conference in 2000 as a means of detecting outbreaks, including bio-terrorism attacks, promptly. Five categories of symptoms (skin and haemorrhagic, respiratory, gastrointestinal, neurological and unexplained) were adopted for the case definition of the surveillance. The surveillance began I week before the conference, and continued until 1 week after the conference ended. We could not detect any outbreaks during this surveillance. Compared to the existing diagnosis-based surveillance system, symptom-based surveillance has the advantages of timeliness and simplicity. However, poor specificity and difficulties in determining epidemic threshold were important limitations of this system. To increase the specificity of surveillance, it is essential to incorporate rapid laboratory diagnoses into the system.

Salmonella Enteritidis outbreak associated with a school-lunch dessert: cross-contamination and a long incubation period, Japan, 2001.

A Salmonella Enteritidis (SE) outbreak in Japan was investigated with an observational study, analytical epidemiology and bacteriological examination (including phage typing). The outbreak occurred among 96 schoolchildren, and was caused by SE phage type 1. The outbreak source was dessert buns served at a school lunch (RR 42.55, 95 % CI 5.93-305.11, P < 0.001). The buns were probably cross-contaminated from eggs from a factory with a history of SE-contaminated products. The incubation period was longer than usual (3-16 days, median 8 days). A low contaminating dose may account for the long incubation period and low attack rate. Outbreak detection was hampered by the absence of routine Salmonella surveillance in Japan. The investigation was complicated by concurrent illnesses from other SE phage types. It was successful, in part, because adequate food samples were available for microbiological testing.

Nosocomial Serratia marcescens outbreak in Osaka, Japan, from 1999 to 2000.

OBJECTIVES To investigate and control an outbreak of bloodstream infections (BSIs) caused by Serratia marcescens and to identify risk factors for respiratory colonization or infection with S. marcescens. DESIGN Epidemiologic investigation, including review of medical and laboratory records, procedural investigations, pulsed-field gel electrophoresis (PFGE) typing of environmental and patient isolates, statistical study, and recommendation of control measures. PATIENTS AND SETTING All patients admitted to a 380-bed, secondary-care hospital in Osaka Prefecture, Japan, from July 1999 through June 2000 (study period). RESULTS Seventy-one patients were colonized or infected with S. marcescens; 3 patients who developed primary BSIs on the same ward within 5 days in June 2000 had isolates with indistinguishable PFGE patterns and indwelling intravenous catheters for more than 5 days. On multivariate analysis, among 36 case-patients with positive sputum specimens and 95 control-patients, being bedridden (odds ratio [OR], 15.91; 95% confidence interval [CI95], 4.17-60.77), receiving mechanical ventilation (OR, 7.86; CI95, 2.27-27.16), being older than 80 years (OR, 3.12; CI95, 1.05-9.27), and receiving oral cleaning care (OR, 3.10; CI95, 1-9.58) were significant risk factors. S. marcescens was isolated from the fluid tanks of three nebulizers and a liquid soap dispenser. The hospital did not have written infection control standards, and many infection control practices were found to be inadequate (eg, respiratory equipment was used without disinfection between patients). CONCLUSIONS Poor hospital hygiene and the lack of standard infection control measures contributed to infections hospital-wide. Recommendations to the hospital included adoption of written infection control policies.

Risk factors for severe hand foot and mouth disease.

Background:  Hand foot and mouth disease (HFMD) and herpangina are enteroviral infectious diseases caused mainly by Coxsackie virus A (CA) or enterovirus 71 (EV71). From 2000 to 2002, many complicated cases were reported in Japan, therefore a nationwide questionnaire survey was carried out to assess the situation. The subjects were patients with HFMD or herpangina, or other enterovirus infection from 2000 to 2002, who were either hospitalized over 24 h or who died. The response rates were 41.3% in 2000 and 2001 and 31.6% in 2002. The survey period included the year 2000, when HFMD epidemics due to EV71 occurred. To examine risk factors causing complications of enterovirus infection, severe cases of HFMD were focused on.

Outbreak of Chlamydia pneumoniae infection in a Japanese nursing home, 1999-2000.

OBJECTIVE To identify risk factors for infection and severe illness due to Chlamydia pneumoniae. METHODS To identify risk factors for infection, we conducted a case-control study among nursing home residents who had onset of symptoms during December 1, 1999, to February 20, 2000. To identify risk factors for severe illness among nursing home residents, we conducted a retrospective cohort study. SETTING A nursing home providing long-term and day care services for elderly patients in Japan.Participants. Fifty-nine residents and 41 staff members of a nursing home. RESULTS The attack rates for respiratory illness were 53% (31 of 59) among residents and 22% (9 of 41) among staff. Infection was confirmed in 15 resident and 2 staff case patients by isolation of C. pneumoniae from nasal swab specimens. Fifteen resident case patients developed severe illness (ie, bronchitis, pneumonia, and hypoxia); one case patient died. The median age of resident case patients was 87 years. We could identify neither the source of the outbreak nor significant risk factors for infection and severe illness in residents. However, residents with a higher level of physical activity were more likely to become infected, whereas older residents (aged more than 85 years) and those with a lower level of physical activity were more likely to develop severe illness (P>.05). Contact with residents was a risk factor for infection in staff (relative risk, undefined; P=.04). CONCLUSIONS C. pneumoniae can cause large outbreaks of infection and severe illness among elderly persons, and its transmission is likely to be enhanced by close contacts among people in nursing homes. Therefore, early detection of an outbreak by means of better surveillance, and subsequent isolation of patients, may be effective control measures.

Association Between Seasonal Influenza Vaccination in 2008–2009 and Pandemic Influenza A (H1N1) 2009 Infection Among School Students From Kobe, Japan, April–June 2009

We assessed the effect of seasonal trivalent inactivated influenza vaccination (TIV) on pandemic influenza 2009 (pH1N1)-related illness from April to June 2009 among 2849 students (aged 12-18 years). TIV was associated with an increase in the frequency of pH1N1-related illness among subjects (adjusted odds ratio, 1.47; 95% confidence interval, 1.14-1.89). TIV during the 2008-2009 season increased the risk of pH1N1-related illness from April to June 2009.

Outbreak of hepatitis C virus infection in an outpatient clinic

Background:  From January through September 2001, seven patients were admitted to Fukaya Red Cross Hospital with typical clinical manifestations of acute hepatitis. Six were outpatients of the clinic, which is located near the hospital. An extensive survey of clinic outpatients conducted by the local health department revealed six more new acute hepatitis cases during this period.

Estimation of measles vaccine coverage needed to prevent transmission in schools.

Background: The aim of the present study was to produce the first estimation in Japan of the basic reproduction number (R0) and the minimum level of vaccine coverage needed to prevent measles outbreaks (Pc).