SUMMARY Influenza Situation Update 13 May 2014 http://www.wpro.who.int/emerging_diseases/influenza/en/index.html Northern Hemisphere In the Northern Hemisphere countries, influenza-like illness (ILI) activity has decreased. In northern China, during the week 28 April to 4 May 2014, the percentage of visits for ILI (ILI%) at national sentinel hospitals established in 2009 in north China was 2.7%, which was slightly higher than the previous week and lower than the same week in 2013. The proportion of ILI specimens positive for influenza has also decreased: 29 of 615 (4.7%) ILI specimens were positive for influenza. Of the positive specimens, 13 (45%) were influenza A (H3N2). In Mongolia, during the week 28 April to 04 May 2014, ILI activity based on the proportion of outpatients exhibiting ILI substantially decreased compared to 2 weeks ago and was below the upper tolerance limit (60%). The proportion of patients with pneumonia among the hospitalized has plateaued in the past month. The proportion of ILI specimens positive for influenza decreased substantially; there were no specimens positive for influenza virus among 53 ILI samples submitted: during 28 April to 4 May 2014. In Japan, during the week 28 April to 4 May 2014, ILI activity decreased; the number of ILI cases per sentinel reporting site was 2.52, lower than the previous week. Similarly, in the Republic of Korea, for the week ending 3 May 2014, ILI activity continued to decrease and was below the baseline; the number of ILI cases was 5.4 per 1000 patients at sentinel sites, lower than the previous week. Proportion of ILI specimens positive for influenza also decreased; there were 14 specimens positive for influenza virus, all subtype B, among 200 (7%) ILI samples submitted: 14 influenza B (lineage not determined) during 27 April to 3 May 2014. Subtropics/Tropics In the subtropics/tropics, overall ILI activity remained variable. In Southern China, during the week 28 April to 4 May 2014, the ILI at national sentinel hospitals established in 2009 in south China was 3.2%, which was slightly higher than the previous week (3.1%) and lower than the same week of 2013 (3.4%). However, the proportion of ILI specimens positive for influenza has decreased: 185 of 3617 (5.1%) ILI specimens were positive for influenza. Of the positive specimens, 78 (42%) were influenza A (57 were H3N2, and 19 were (H1N1)pdm09). In Hong Kong (China), during 27 April to 3 May 2014, local influenza activity has continued to decrease. Of the 138 samples positive for influenza during this week, 21 were influenza A(H3), 5 were influenza A(H1N1)pdm09, 112 were influenza B viruses. Hospital admission rates with principal diagnosis of influenza for children aged 0 4 years, persons aged 5 64 years and persons aged 65 years and above (0.54, 0.04 and 0.15 cases per 10 000 people in the age group, respectively). Additionally, weekly number of deaths with any diagnosis of influenza in public hospitals has decreased. In the Mekong, influenza activity increased. In Lao PDR, influenza activity increased. During 30 March to 5 April 2014, 16 of 64 (25%) ILI specimens were positive for influenza: 12 were influenza A(H3), 1 was influenza A(H1N1)pdm09and 3 were influenza B (Lineage not determined). In Viet Nam, influenza activity slightly increased. During 30 March to 5 April 2014, 1
25 of 54 (46.2 %) ILI specimens were positive for influenza: 10 were influenza A (H1N1)pdm09, 3 was influenza A(H3) and 12 were influenza B (Lineage not determined). In Singapore, acute respiratory infection (ARI*) activity increased. During 27 April to 3 May 2014, 2,588 patients sought treatment compared to 2 601 patients the previous week. The proportion of cases with ILI among the polyclinic ARI cases remained low at below 1%. Of 113 ILI samples collected in the past 4 weeks in the community, 29.2% were positive for influenza virus. Of all the influenza virus isolates in April 2014, 6.7% were influenza A(H3N2), 26.7% were influenza A(H1N1)pdm09 and 64.4% were influenza B. Australia In Australia, ILI activity increased compared to the previous two weeks, but remained at low level. During the week 27 April to 3 May 2014, 7 of 218 (3.2%) ILI specimens tested positive for influenza: 3 was influenza A (H3) and 4 was influenza B (lineage not determined). Pacific Islands In the Pacific Islands, ILI activity was variable with an increase observed in a number of islands. During the week ending 4 May 2014, the Solomon Islands reported weekly ILI case numbers above the threshold of 90% of their historical values. Global influenza situation Epidemiological update: http://www.who.int/influenza/surveillance_monitoring/updates/latest_update_gip_surveillanc e/ Virological update: http://www.who.int/influenza/gisrs_laboratory/updates/summaryreport *ARI defined as clinical diagnosis of acute upper respiratory tract infection (ICD9 460 465: Acute Nasopharyngitis (common cold); 461 Acute Sinusitis; 462 Acute Pharyngitis; 463 Acute Tonsillitis; 464 Acute Laryngitis and Tracheitis; 465 Acute Upper Respiratory Infections of Multiple or Unspecified Sites; 466 Acute Bronchitis and Bronchiolitis). ILI defined as temperature >38C with cough or sore throat. 2
Percentage of Visits that were ILI in sentinel hospitals (established in 2009), 2010 2014 Northern China up to 4 May 2014 (Source: Chinese National Influenza Center) Percentage of Visits that were ILI in sentinel hospitals (established in 2009), 2010 2014 Southern China up to 4 May 2014 (Source: Chinese National Influenza Center) 3
Proportion of outpatients that were ILI (per 10000) Mongolia up to 4 May 2014 (Source: National Influenza Center of Mongolia) Proportion of patients with pneumonia among hospitalized Mongolia, up to 4 May 2014 (Source: National Influenza Center of Mongolia) 4
Influenza cases reported per sentinel weekly Japan up to 4 May in 2014 (Source: National Institute of Infectious Diseases) The weekly proportion of ILI visits per 1,000 patients Republic of Korea up to 3 May in 2014 (Source: Korean Center for Disease Control and Prevention) 5
ILI consultation at sentinel general outpatient clinics ILI consultation rate at sentinel private doctors Hong Kong (China) up to 3 May 2014 (Source: Centre for Health Protection) 6
Influenza associated hospital admission rates and deaths Hong Kong (China) up to 3 May 2014 (Source: Centre for Health Protection) Singapore up to 3 May in 2014 (Source: Ministry of Health) 7
Note: Numbers of reported cases are not comparable between countries. The purpose of the charts is to show trends over time within each country/area. Pacific Islands up to 4 May 2014 (Source: Pacific Public Health Surveillance Network) 8