Influenza Situation Update
19 November 2013
In the Northern Hemisphere countries, while overall still low, influenza-like illness (ILI) activity has started to increase, following seasonal trends. In northern China, during the week 21 to 27 October 2013, the percentage of visits for ILI (ILI%) at national sentinel hospitals established in 2009 in north China was 2.2%, which was higher than that of the previous week (2.1%) but lower than that of the same week of 2012 (2.3%). 11 of 1778 (0.6%) ILI specimens were positive for influenza: 2 were influenza A (H1N1)pdm09 and 9 were influenza B (lineage not determined). In Mongolia, during the week 4 to 10 November 2013, ILI activity based on the proportion of outpatients exhibiting ILI continued to show an overall increasing trend. However, the majority of ILI samples submitted for the week ending 10 November 2013 continued to be non-influenza viruses. Proportion of patients with pneumonia among the hospitalized also showed an increasing trend in recent weeks. In Japan, during the week 28 October to 3 November 2013, ILI activity remained low but started to increase; the number of ILI cases per sentinel reporting site was 0.08, higher than the previous week. In the Republic of Korea, for the week ending 9 November 2013, ILI activity also continued to remain low, and the number of ILI cases was 8.0 per 1000 patients, similar to the previous week (8.4 per 1000 patients). There were no specimens positive for influenza viruses among 314 ILI samples submitted.
In the subtropics/tropics, overall ILI activity was stable with circulation of influenza A(H3), A(H1N1)pdm09 and influenza B. In Southern China, during the week 21 to 27 October 2013, the ILI% at national sentinel hospitals established in 2009 in south China was 2.4%, which was higher than that of the previous week (2.3%) and that of the same week of 2012 (2.1%). 152 of 2519 (6.0%) ILI specimens were positive for influenza: 111 were influenza A (84 H3N2, 19 (H1N1)pdm09 and 8 subtype not determined) and 41 were influenza B (40 lineage not determined). In Hong Kong (China), during 3 to 9 November 2013, local influenza activity decreased during the past few weeks. Of the 63 samples positive for influenza during this week: 38 influenza A (H3), 22 influenza B and 3 influenza A(H1N1)pdm09. During 3-9 November, hospital admission rates with principal diagnosis of influenza for persons aged 0‐4 years, 5‐64 years and 65 years or above also decreased to 0.12, 0.02 and 0.07 cases, respectively (per 10 000 people in each age group). Weekly number of deaths with any diagnosis of influenza in public hospitals remained low. In the Mekong, low level influenza activity was reported. In Cambodia, during the week 20 to 26 October 2013, 11 of 37 (29.7%) ILI specimens were positive for influenza: 1 was influenza A(H3) and 9 were influenza B; in addition, 1 influenza A(H5) positive specimens was reported. In Lao PDR, during 20 to 26 October 2013, 5 of 32 (15.6%) ILI specimens were positive for influenza: 1 was influenza A(H1N1)pdm09, 2 were influenza A(H3) and 2 were influenza B. In Viet Nam, during 27 October to 2 November 2013, 2 of 11 (18%) ILI specimens were positive for influenza: both were influenza A(H3). In Singapore, acute respiratory infection (ARI*) activity remained low during 3 to 9 November 2013, with 2469 patients seeking treatment compared to 2371 in the previous week. The proportion of cases with ILI among the polyclinic ARI cases remained low at 1%. Of 191 ILI samples collected in the past 4 weeks, 40.8% were positive for influenza virus. Of all the influenza virus isolates in September 2013, 69.5% were influenza A(H3N2), 16.8% influenza B and 13.7% A(H1N1)pdm09.
In the Southern Hemisphere ILI activity remained relatively low, with low level circulation of influenza A (H3), influenza B and A(H1N1)pdm09. In Australia, the seasonal increase in influenza activity has slowed, and influenza activity remains relatively low compared to 2011 and 2012. During the week ending 13 October 2013, the sentinel general practitioner ILI consultation rate decreased to 6.3 cases per 1,000 consultations. Influenza A was the predominant influenza virus type, although the proportion of influenza B this season has been higher than recent years. In the last 2 weeks ending 13 October 2013, among ILI patient specimens from sentinel general practitioner consultations, 19.2% were positive for influenza (lower than 29.5% in the previous 2 weeks): 12.3% were positive for influenza type A (2.7% A(H3N2); 4.1% for A(H1N1)pdm09; and 5.5% for A (not sub-typed)), while 5.5% were positive for influenza B. Almost a third of the specimens collected were positive for other respiratory viruses. During 30 March to 11 October 2013, at sentinel hospitals, 10% of patients admitted with confirmed influenza were directly admitted to ICU. The majority of overall admissions have been for influenza A, with 32% of cases due to influenza B. Around 32% of cases were aged 65 years and over and 79% of cases had medical co-morbidities. Over the past 2 weeks, there has been a decrease in the number of patients admitted with confirmed influenza. In New Zealand, during 28 October to 3 November 2013, influenza activity continued to decline and remains below the baseline threshold. 34 out of 230 samples received were positive for influenza: 9 were influenza B, 8 were A(not sub-typed), 9 were influenza A(H3N2), and 8 were A(H1N1)pdm09).
In the Pacific Islands, ILI activity was mostly low and stable. During the week ending 3 November 2013, Guam reported weekly ILI case numbers above the threshold of 90% of their historical values.
Global influenza situation
*ARI defined as clinical diagnosis of acute upper respiratory tract infection (ICD9 460 – 465: Acute Nosopharyngitis (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.
Human infection with avian influenza A(H7N9) virus
6 November 2013, The National Health and Family Planning Commission, China notified WHO of two additional laboratory-confirmed cases of human infection with avian influenza A(H7N9) virus. The previous confirmed case of human infection with avian influenza A(H7N9) virus was on 23 October 2013.
The first patient is a three-year-old boy from Guangdong Province who had contact with live poultry. He became ill on 29 October 2013, was admitted to a local hospital on 31 October 2013, and transferred to another hospital on 4 November 2013. He is currently in a stable condition.
The second patient is a 64-year-old woman from Zhejiang Province who is a farmer and had contact with live poultry. She became ill on 30 October 2013, was admitted to a local hospital on 31 October 2013, and was transferred to another hospital on 3 November. She is currently in a critical condition.
To date, a total of 139 cases have been reported (138 from China's National Health and Family Planning Commission and 1 from Taipei Centers for Disease Control). Of these patients, 45 have died. Currently, six patients are hospitalized and 88 have been discharged. It is expected that there may be further sporadic cases of human infection with the virus. Affected provinces and municipalities continue to maintain surveillance and response activities.
WHO does not advise special screening at points of entry with regard to this event, nor does it recommend any travel restrictions be applied. WHO continues to work closely with national authorities and technical partners to gain a better understanding of this disease in humans and will continue to provide updated information as the situation evolves.
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For latest situation updates on avian influenza A(H5N1), visit
For further information on the influenza situation or its surveillance, please visit the following links:
- WHO Flu Net
- Hongkong (China)
- New Zealand
- Pacific Islands and Territories
- South Korea