Pandemic (H1N1) 2009 regional update 09 Nov 2009
I- Evolution of the pandemic
Widespread influenza activity and increased trends in acute respiratory disease continued this week.
In Canada, the national influenza-like illness (ILI) consultation rate increased again relative to the last week and remained above average for the fifth consecutive week. There was another sharp increase in the number of influenza outbreaks and these continued to be reported mostly in school settings. The proportion of tests positive for influenza again increased this week to 36.3% from 29.0% (EW 42).
In the United States, ILI consultations decreased slightly but remained well above the national baseline. Laboratory-confirmed influenza hospitalization rates remained high, especially in persons 5-49 years of age. The proportion of deaths attributed to pneumonia and influenza remained above the epidemic threshold for the fifth consecutive week. Five of ten subnational surveillance regions reported decreases in proportion of outpatient visits for ILI as compared to the previous week, but all ten reported a the ILI proportion to be above their region-specific baseline. A total of 18 influenza-associated pediatric deaths were reported this week, of which 15 were associated with the pandemic virus.
Mexico reported a large number of confirmed cases and deaths this week, but the overall trend of the epidemic curve1 appears to shift downward based on the number of confirmed cases. Also, the greatest number of laboratory-confirmed cases1 was seen in the Federal District, Chiapas, Yucatan, Nueva Leon, San Luis Potosi, and Jalisco.
These countries continue to report variable spread of influenza and variable trends in acute respiratory disease. Intensity of acute respiratory disease was reported as both high and low/moderate, while impact of acute respiratory disease on health care services was reported as both low and moderate.
In countries providing these data, severe acute respiratory infection (SARI) hospitalization rates2 continued to increase for the fourth consecutive week, reaching the highest rate this year in EW 42. In the French Overseas Territories, ILI activity has been variable, with some Territories reporting decreases in activity while others are reporting increases.
This week, trends of acute respiratory disease remained unchanged or were decreasing. Intensity of acute respiratory disease remained low/moderate and impact of acute respiratory disease on health care services was low.
These countries continued to report widespread influenza activity. The majority of the countries reported decreasing trends in acute respiratory disease. Colombia, however, continues to report increasing trend. Overall, intensity of acute respiratory disease remained low/moderate as did impact of acute respiratory disease on health care services.
Venezuela reported an outbreak of acute respiratory infection in indigenous Yanomami communities. More details on this outbreak are included in section IV of this report.
Argentina reported pockets of influenza activity in parts of Buenos Aires and Santa Fe, with twelve new confirmed cases, two deaths, and several ILI cases currently under investigation. Of note is that Argentina reported 1,013 new confirmed cases this week, but only 12 correspond to cases with symptom onset this week, and the remainder are cases that were laboratory confirmed this week.
In the other countries, there were no significant changes in trends of acute respiratory disease activity as compared to last week and most countries experienced a decreasing or unchanged trend of acute respiratory disease, with low/moderate intensity of acute respiratory disease, and low/moderate impact on health care services.
- The trends of acute respiratory disease in North America increased or were unchanged; there were 18 influenza-associated pediatric deaths reported in the United States this week
- Caribbean countries reported variable trends in acute respiratory disease this week
- Central America continues to report overall decreasing trends in acute respiratory disease
- Most of South America had stable or decreasing trends of acute respiratory disease, with the exception of Colombia, which again reported an increasing trend and Argentina, which reported pockets of influenza-like illness activity in Buenos Aires and Santa Fe
- Venezuela and Brazil are investigating cases of acute respiratory infection in the indigenous Yanomami community
- A median of 99.7% of subtyped influenza A viruses were pandemic (H1N1) 2009
- 113 new confirmed deaths in 8 countries were reported; in total there have been 4,512 cumulative confirmed deaths.