Investigation of the first cases of human-to-human infection with the new swine-origin influenza A (H1N1) virus in Canada.

The outbreak of human infection due to the novel swine-origin influenza A (H1N1) virus began in Mexico in March 2009. As of July 6, 2009, more than 94,000 laboratory-confirmed cases were reported in over 100 countries, including 7983 cases in Canada. In this report, we describe the epidemiologic and clinical characteristics of the first cluster of reported cases of human-to-human transmission of the new influenza virus in Canada.

Respiratory Watch: Development of a provincial system for respiratory syncytial virus surveillance in Nova Scotia, 2005-2008.

OBJECTIVE: Respiratory syncytial virus (RSV) is the most common cause of severe lower respiratory tract infection in young children and is increasingly recognized as a cause of influenza-like illness in those older than 65 years of age. A surveillance system to provide timely local information about RSV activity in Nova Scotia (NS) is described. METHODS: A case report form was developed for weekly reporting of all laboratory isolates of RSV at diagnostic laboratories around the province. Laboratories were asked to send the forms by fax each Friday to the Nova Scotia Department of Health Promotion and Protection. Data were entered in Excel (Microsoft, USA) and aggregate results summarized by age, sex, health district and date of laboratory confirmation for 2005 to 2008. RESULTS: During three winter seasons (2005-2006, 2006-2007 and 2007-2008), there were 207, 350 and 186 isolates of RSV reported in NS, respectively. The average incidences of RSV in NS varied greatly by age, with the highest rates in infants younger than 24 months of age, and approaching 4000 cases per 100,000 population in infants up to five months of age. The duration of the RSV outbreak was approximately five to six months each year, but the month of onset varied. CONCLUSIONS: A RSV surveillance system was successfully established in NS that provides weekly data to the public health system, clinicians and infection control practitioners. The time of onset and severity of the RSV season varied over time. These data can be used to plan anti-RSV passive prophylaxis programs and infection control education, and distinguish RSV outbreaks from other viruses in acute care and long-term care settings.

Investigation of a nosocomial outbreak of severe acute respiratory syndrome (SARS) in Toronto, Canada.

BACKGROUND: Severe acute respiratory syndrome (SARS) was introduced into Canada by a visitor to Hong Kong who returned to Toronto on Feb. 23, 2003. Transmission to a family member who was later admitted to a community hospital in Toronto led to a large nosocomial outbreak. In this report we summarize the preliminary results of the epidemiological investigation into the transmission of SARS between 128 cases associated with this hospital outbreak. METHODS: We collected epidemiologic data on 128 probable and suspect cases of SARS associated with the hospital outbreak, including those who became infected in hospital and the next generation of illness arising among their contacts. Incubation periods were calculated based on cases with a single known exposure. Transmission chains from the index family to hospital contacts and within the hospital were mapped. Attack rates were calculated for nurses in 3 hospital wards where transmission occurred. RESULTS: The cases ranged in age from 21 months to 86 years; 60.2% were female. Seventeen deaths were reported (case-fatality rate 13.3%). Of the identified cases, 36.7% were hospital staff. Other cases were household or social contacts of SARS cases (29.6%), hospital patients (14.1%), visitors (14.1%) or other health care workers (5.5%). Of the 128 cases, 120 (93.8%) had documented contact with a SARS case or with a ward where there was a known SARS case. The remaining 8 cases without documented exposure are believed to have had exposure to an unidentified case and remain under investigation. The attack rates among nurses who worked in the emergency department, intensive care unit and coronary care unit ranged from 10.3% to 60.0%. Based on 42 of the 128 cases with a single known contact with a SARS case, the mean incubation period was 5 days (range 2 to 10 days). INTERPRETATION: Evidence to date suggests that SARS is a severe respiratory illness spread mainly by respiratory droplets. There has been no evidence of further transmission within the hospital after the elapse of 2 full incubation periods (20 days).