The information presented in this update is based on data provided by Ministries of Health and National Influenza Centers of Member States to the Pan American Health Organization (PAHO) or from updates on the Member States’ Ministry of Health web pages.
Regional Update EW 02, 2015
- North America: Influenza activity remained elevated. In Canada, ILI activity decreased this week and is within expected levels. Influenza detections continued to decrease after its peak in EW 531 however the positivity this week increased from 26.4% to 29.5%. Influenza A(H3N2) and influenza A (not subtyped) have predominated among circulating influenza viruses, and 56 of 62 influenza A(H3N2) viruses characterized (90%) differ from the current Northern Hemisphere vaccine strain. Detections of RSV decreased this week. Laboratory-confirmed outbreaks of influenza decreased this week and influenza hospitalizations continued to decrease. The majority of hospitalizations and deaths this season have been recorded among adults aged ≥65 years. Canada confirmed the first imported case of avian influenza A(H7N9) infection in a human in a resident of British Columbia who returned from China on 12 January. The case was not symptomatic during travel and became ill after arrival in Canada. The case did not require hospitalization and is currently recovering in self-isolation. All evidence indicates that the case was likely infected following exposure in China and all close contacts have been identified and are being monitored2,3. In the United States, ILI activity (4.5%) is similar to the previous week and remained above the national baseline of 2.2%. Influenza detections (19.5% of positivity this week) continued to decrease after their peak in EW 52. Influenza A (not subtyped) and influenza A(H3) have predominated and 254 of the 395 influenza A(H3N2) viruses characterized (64%) differ from the current Northern Hemisphere vaccine strain. Influenza-associated hospitalization rates among adults aged ≥65 years are higher this season as compared to the 2012-13 season (influenza A/H3 predominant) and this week, the percentage of pneumonia and influenza mortality (9.3%) remained above the epidemic threshold. In Mexico, ARI activity increased this week and was slightly above expected levels. Pneumonia activity remained within the endemic channel and the states with the highest pneumonia rates during EW 2 were Colima, Chihuahua, Jalisco and Sonora. Influenza A(H3N2) has predominated among circulating influenza viruses and 30.4% influenza positivity was recorded during EW 3.
- Caribbean: Respiratory virus activity remained low with the exception of Puerto Rico where ILI activity (as reported to the CDC) remained high and influenza detections increased in the last two weeks. In Cuba, respiratory virus detections increased in the last two weeks and the number of SARI cases slightly increased in EW 3 as compared to previous weeks. Some respiratory virus detections were observed in the last two weeks in Dominican Republic and Jamaica. Among respiratory viruses, circulation of RSV (Cuba), influenza A(H3N2) (Cuba, Jamaica), influenza B (Dominican Republic, Jamaica) and adenovirus (Dominican Republic) were reported.
- Central America: Respiratory virus activity remained low and ARI/SARI activity were within expected levels (Costa Rica, El Salvador, Nicaragua). Detections of RSV and influenza A(H3N2) increased this week in El Salvador.
- Andean Sub-region: Respiratory virus activity remained low and ARI/SARI and pneumonia activity remained within expected levels (Colombia, Ecuador, Peru). Respiratory virus detections continued to decrease in Bolivia, Colombia and Peru while in Ecuador the detections increased over the last four weeks. Among respiratory viruses, circulation of RSV (Colombia, Ecuador), influenza A(H3N2) (Bolivia, Colombia, Ecuador) and parainfluenza (Bolivia, Peru) was reported.
- Southern Cone: Respiratory virus and ILI/SARI activity remained low (Argentina, Brazil, Chile, Paraguay, Uruguay) . There have been very few influenza and other respiratory virus detections in recent weeks in Brazil, Chile, Paraguay and Uruguay.