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Summary and assessment as of 10 December 2013
Human infection with avian influenza A(H5N1) viruses
From 2003 through 10 December 2013, 648 laboratory-confirmed human cases with avian influenza A(H5N1) virus infection have been officially reported to WHO from 15 countries. Of these cases, 384 died.
Since the last WHO Influenza at the Human Animal Interface update on 7 October 2013, seven new laboratory-confirmed human cases of influenza A(H5N1) virus infection were reported to WHO from Cambodia (6) and Indonesia (1).
In Cambodia, the reported incidence of human cases has increased in 2013 (26 cases in 2013 compared with 21 cases from 2005 through December 2012). This might be due to improvements in surveillance and physician awareness or to a potential increased circulation of the virus in poultry. The case fatality rate among reported cases, however, has decreased (54% in 2013 compared with 90% over all previous years).
Before 2013, H5N1 viruses from clade 1.1 predominated in Cambodia. Analysis of isolates from human cases and birds from the beginning of 2013 revealed the emergence of a new H5N1 genotype resulting from the reassortment of clade 1.1 and clade 2.3.2.1 viruses.
The link between the emergence of this reassortant virus and the increase in human cases observed in 2013 is yet to be determined.1
All seven human cases reported in this summary are considered to be sporadic, with no evidence of community-level transmission. As influenza A(H5N1) virus is thought to be circulating widely in poultry in Cambodia and Indonesia, additional sporadic human cases or small clusters might be expected in these countries in the future.
V Duong et al, A new genotype resulting from the reassortment of clade 1.1 and 2.3.2.1 at the origin of the human and animal H5N1 virus cases in Cambodia in 2013; http://optionsviii.controlinfluenza.com/optionsviii/assets/File/Options_VIII_Abstracts_2013.pdf, accessed 28 Nov 2013
Table 1: Laboratory-confirmed human cases of avian influenza A(H5N1) virus infection (7 October 2013 ? 10 December 2013)
Country Province AgeSex Date of onset Date of Hospitalisation Oseltamivir treatment Start date Date of death Exposure to
Cambodia Kampong Thom 8 F 08/10/2013 11/10/2013 14/10/2013 NA Dead poultry
Battambang 6 F 14/10/2013 19/10/2013 24/10/2013 NA Dead poultry
Pursat 2 F 17/10/2013 24/10/2013 NA 26/10/2013 Under investigation
Kampot 10 M 28/10/2013 07/11/2013 07/11/2013 09/11/2013 Dead chicken
Kampong Speu 3 M 05/11/2013 08/11/2013 08/11/2013 NA Sick and dead poultry
Pailin 29M 26/10/2013 03/11/2013 06/11/2013 06/11/2013 Sick and dead poultry
Indonesia West Java 31 F 01/11/20131 6/11/2013 NA 11/11/2013 Pet bird, poultry in neighbourhood, market and pigeons
NA: not applicable or not available
Overall public health risk assessment for avian influenza A(H5N1) viruses: Whenever influenza viruses are circulating in poultry, sporadic infections or small clusters of human cases are possible, especially
Figure 1: Epidemiological curve of avian influenza A(H5N1) cases in humans by country and month of onset
......
http://www.who.int/influenza/human_...nza_Summary_IRA_HA_interface_16December13.pdf
Human infection with avian influenza A(H5N1) viruses
From 2003 through 10 December 2013, 648 laboratory-confirmed human cases with avian influenza A(H5N1) virus infection have been officially reported to WHO from 15 countries. Of these cases, 384 died.
Since the last WHO Influenza at the Human Animal Interface update on 7 October 2013, seven new laboratory-confirmed human cases of influenza A(H5N1) virus infection were reported to WHO from Cambodia (6) and Indonesia (1).
In Cambodia, the reported incidence of human cases has increased in 2013 (26 cases in 2013 compared with 21 cases from 2005 through December 2012). This might be due to improvements in surveillance and physician awareness or to a potential increased circulation of the virus in poultry. The case fatality rate among reported cases, however, has decreased (54% in 2013 compared with 90% over all previous years).
Before 2013, H5N1 viruses from clade 1.1 predominated in Cambodia. Analysis of isolates from human cases and birds from the beginning of 2013 revealed the emergence of a new H5N1 genotype resulting from the reassortment of clade 1.1 and clade 2.3.2.1 viruses.
The link between the emergence of this reassortant virus and the increase in human cases observed in 2013 is yet to be determined.1
All seven human cases reported in this summary are considered to be sporadic, with no evidence of community-level transmission. As influenza A(H5N1) virus is thought to be circulating widely in poultry in Cambodia and Indonesia, additional sporadic human cases or small clusters might be expected in these countries in the future.
V Duong et al, A new genotype resulting from the reassortment of clade 1.1 and 2.3.2.1 at the origin of the human and animal H5N1 virus cases in Cambodia in 2013; http://optionsviii.controlinfluenza.com/optionsviii/assets/File/Options_VIII_Abstracts_2013.pdf, accessed 28 Nov 2013
Table 1: Laboratory-confirmed human cases of avian influenza A(H5N1) virus infection (7 October 2013 ? 10 December 2013)
Country Province AgeSex Date of onset Date of Hospitalisation Oseltamivir treatment Start date Date of death Exposure to
Cambodia Kampong Thom 8 F 08/10/2013 11/10/2013 14/10/2013 NA Dead poultry
Battambang 6 F 14/10/2013 19/10/2013 24/10/2013 NA Dead poultry
Pursat 2 F 17/10/2013 24/10/2013 NA 26/10/2013 Under investigation
Kampot 10 M 28/10/2013 07/11/2013 07/11/2013 09/11/2013 Dead chicken
Kampong Speu 3 M 05/11/2013 08/11/2013 08/11/2013 NA Sick and dead poultry
Pailin 29M 26/10/2013 03/11/2013 06/11/2013 06/11/2013 Sick and dead poultry
Indonesia West Java 31 F 01/11/20131 6/11/2013 NA 11/11/2013 Pet bird, poultry in neighbourhood, market and pigeons
NA: not applicable or not available
Overall public health risk assessment for avian influenza A(H5N1) viruses: Whenever influenza viruses are circulating in poultry, sporadic infections or small clusters of human cases are possible, especially
Figure 1: Epidemiological curve of avian influenza A(H5N1) cases in humans by country and month of onset
......
http://www.who.int/influenza/human_...nza_Summary_IRA_HA_interface_16December13.pdf