The information contained within this update is obtained from data provided by Ministries of Health of Member States and National Influenza Centers through reports sent to Pan American Health Organization (PAHO) or updates on their web pages.
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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 fourth consecutive week. There was a 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 sharply increased this week to 29.0% from 16.9% (EW 41).
In the United States, ILI consultations continued to increase, remaining above the national baseline for the ninth consecutive week. 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 third consecutive week. All subnational regions continued to report outpatient ILI activity above their regional baseline, but some regions in the south and west reported some small decreases over the past week. A total of 22 influenza-associated pediatric deaths were reported this week, of which 19 were associated with the pandemic virus. Of these pediatric deaths, the majority were in children 5–17 years of age.
These countries continue to report 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.
This week, Barbados reported 8 cases of co-infection with pandemic influenza and dengue-3, diagnosed by RT- PCR.
In this region, for countries providing these data, severe acute respiratory infection (SARI) hospitalization rates1 have been increasing over the past three weeks, reaching the highest rate this year in EW 41.
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. This week, Nicaragua reported eight cases of co-infection with influenza and dengue diagnosed by RT-PCR and ELISA, respectively.
These countries continued to report widespread influenza activity. The majority of the countries reported decreasing trends in acute respiratory disease. Colombia, however, has been reporting increasing trends for seven consecutive weeks. 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 the indigenous Yanomami community of Mawaka parish in the municipality of Alto Orinoco in Amazonas State. Thus far, two samples were positive for pandemic (H1N1) 2009.Southern Cone
Although there were no significant changes in acute respiratory disease activity as compared to last week, Argentina reported high levels of ILI activity in the provinces of Buenos Aires and Santa Fe. Brazil continued to experience a decreasing trend of acute respiratory disease, with low/moderate intensity of acute respiratory disease, and low impact on health care services.
• The trends of acute respiratory disease in North America continue to increase; there were 22 influenza-associated pediatric deaths
reported in the United States this week, twice as many as last week
• Caribbean countries reported variable trends in acute respiratory isease 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 reported an increasing trend for the seventh consecutive week
• Barbados and Nicaragua reported the detection of cases of co-infection with pandemic (H1N1) 2009 and dengue
• Venezuela reported an outbreak of acute respiratory infection in the indigenous Yanomami community
• A median of 100% of subtyped influenza A viruses were pandemic
• 224 new confirmed deaths in 10 countries were reported; in total there have been 4,399 cumulative confirmed deaths
II-Descriptions of hospitalizations and deaths among confirmed cases of pandemic (H1N1) 2009
A table containing case counts reported to PAHO is included in Annex 2.
Approximately half of confirmed hospitalized cases were among women (Table 1). Children continue to be the age group with highest hospitalization rates. Underlying comorbidities were present in 50–60% of hospitalized cases, while approximately 25% of confirmed cases in child-bearing age women were pregnant.
With regard to deceased cases, some countries reported observed differences in sex distribution (Canada, Dominican Republic), but overall, most deaths were among adults (Table 2). The percentage of cases with underlying comorbidities varied among countries, ranging from 41.0–76.1%.
III- Viral circulation
For the purpose of this analysis, only countries which reported data on influenza A subtypes were considered. We excluded from the calculations of the percentages, results from samples of influenza A that were not subtyped or were unsubtypeable.
Among the selected countries, there is a continued predominant circulation of the pandemic (H1N1) 2009 virus.
To date, CDC has tested 240 influenza pandemic isolates from 18 countries of the region, all of which were sensitive to neuraminidase inhibitors. In the United States, however, a total of 14 isolates have been identified which are resistant to oseltamivir.
As of 30 October, a total of 185,067 confirmed cases have been notified in all 35 countries in the Americas Region. A total of 4,399 deaths have been reported among the confirmed cases in 26 countries of the Region.
In addition to the figures displayed in Annex 2, the following overseas territories have confirmed cases of pandemic (H1N1) 2009: American territories: American Samoa (8); Guam (1); Puerto Rico (20) and U.S. Virgin Islands (49). 2. United Kingdom Overseas Territories: Bermuda (1); Cayman Islands (104, 1 death); British Virgin Islands (12); Turks and Caicos Islands (36). French Overseas Communities: Martinique (44, 1 death); Guadeloupe (27); Guyane (29, 1 death); Saint Martin (30); Saint Bartholomew (2); Netherlands Antilles: Aruba (13); Bonaire (31); Curaçao (53)*; St. Eustatius (1); and St. Maarten (24).
* Three cases were reported on a cruise-ship.
The distribution of cases and deaths at the first sub-national level can be found in the interactive map available through the following link: http://www.paho.org/hq/images/atlas/en/atlas.html
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Regional Update. Pandemic (H1N1) 2009. (published on November 3, 2009)