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
In Canada, the national influenza-like illness (ILI) consultation rate slightly decreased compared to last week but remained above average for the sixth consecutive week. The number of influenza outbreaks remained high and these outbreaks were mostly reported in the school setting. The proportion of tests positive for influenza again increased this week to 38.1% from 36.3% (EW 43). The total number of hospitalizations of persons with pandemic influenza increased again this week; and hospitalization rates were highest among those less than 20 years of age.
In Mexico, trends of acute respiratory disease remained unchanged, with high intensity of acute respiratory disease, and moderate impact of acute respiratory disease on health care services. Of note is that the number of ILI and severe acute respiratory illness (SARI) cases, in EW 39, surpassed what was observed in the first wave of the pandemic.
In the United States, the proportion of outpatient consultations for ILI decreased for the second consecutive week. Laboratory-confirmed influenza hospitalization rates remained high, especially in children 0–17 years of age. The proportion of deaths attributed to pneumonia and influenza remained above the epidemic threshold for the sixth consecutive week. Nine of ten sub-national 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 35 influenza-associated pediatric deaths were reported this week, of which 26 were associated with the pandemic virus. In total, since August 30, 2009, 98 pediatric deaths associated with the pandemic virus have occurred.
These countries are reporting mostly unchanged trends in acute respiratory disease and high intensity of acute respiratory disease. Impact of acute respiratory disease on health care services was reported as moderate.
In countries providing these data1, severe acute respiratory infection (SARI) hospitalization rates decreased this week, after four consecutive weeks of increases.
This week, among the countries that provided information, trends of acute respiratory disease decreased. 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. Acute respiratory disease trends were reported as decreasing or unchanged in most countries of the region, except Colombia and Peru, which reported an increasing trend in acute respiratory disease. In Peru, in the last week, the greatest increase in the number of confirmed cases was observed in parts of the northeast jungle region. In Ecuador, nationally, trends of acute respiratory disease were reported as unchanged, but 3 of 24 provinces reported increases in the number of SARI cases as compared to the prior week.
Venezuela’s Ministry of Health reported that the outbreak of acute respiratory infection in indigenous Yanomami communities has ended.
Most of these countries reported decreasing or unchanged trends of acute respiratory disease. This week, Paraguay reported 2 of 17 departments with an increasing trend of acute respiratory disease, as compared to 8 departments last week; its overall national trend was decreasing. All of these countries are reporting a low or moderate impact of acute respiratory disease on health care services.
- Influenza-like illness activity remained above what is expected for this time of year in Canada and the United States; in Mexico, it surpassed the level that was observed during the first wave of the pandemic
- Caribbean countries reported mostly unchanged trends but high intensity of 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 and Peru, which reported an increasing trend
- Venezuela reported that the outbreak of acute respiratory illness in the Yanomami communities has ended
- A median of 99.9% of subtyped influenza A viruses were pandemic (H1N1) 2009
- 294 new confirmed deaths in eight countries were reported; in total there have been 4,806 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 hospitalized cases were among women (Table 1). Children continued to be the age group with highest hospitalization rates. Underlying comorbidities were present in approximately half of hospitalized cases.
Overall, approximately half of deceased cases were among women (Table 2). In the Dominican Republic, however, 82% of their 22 deaths were among women and approximately 67% of deaths among women were in pregnant women.
The percentage of cases with underlying co-morbidities varied from 58.3% to 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.
Pandemic (H1N1) 2009 continues to predominate among circulating subtyped influenza A viruses.
IV-Antiviral ResistanceThe Centers for Disease Control and Prevention (CDC) complete antiviral susceptibility testing on isolates submitted by various countries in the Region. To date, 277 samples submitted from 18 countries were found to be sensitive to neuraminidase inhibitors (oseltamivir and zanamivir). In the United States, a total of 15 cases of oseltamivir-resistance have been identified. Of the 15 oseltamivir-resistant cases, 13 had documented exposure to oseltamivir, one case had no documented oseltamivir-exposure, and one case is under investigation.
As of 13 November, a total of 4,806 deaths have been reported among the confirmed cases in 27 countries of the Region.
In addition to the figures displayed in Annex 2, the following overseas territories have confirmed deaths of pandemic (H1N1) 2009: United Kingdom Overseas Territories; Cayman Islands (1 death); French Overseas Communities: Martinique (1 death); Guadeloupe (1 death).
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 16, 2009)