NEWS

Human infection with avian influenza A(H5N1) viruses


Between 6 and 12 November 2020, no new case of human infection with avian influenza A(H5N1) virus was reported to WHO in the Western Pacific Region

Avian Influenza Weekly Update Number 770

4 December 2020

 

Human infection with avian influenza A(H5) viruses

Human infection with avian influenza A(H5N1) virus

Between 27 November and 3 December 2020, no new case of human infection with avian influenza A(H5N1) virus was reported to WHO in the Western Pacific Region.

As of 3 December 2020, a total of 239 cases of human infection with avian influenza A(H5N1) virus were reported from four countries within the Western Pacific Region since January 2003 (Table 1). Of these cases, 134 were fatal, resulting in a case fatality rate (CFR) of 56%. The last case was reported from Lao PDR, with an onset date of 13 October 2020 (one case, no death).

Table 1: Cumulative number of laboratory-confirmed human cases (C) and deaths (D) of influenza A(H5N1) virus infection reported to WHO, by date of onset (January 2003 to 3 December 2020), Western Pacific Region.

 

Country

2003-

2009

2010-

2014

2015

2016

2017

2018

2019

2020

Total

C

D

C

D

C

D

C

D

C

D

C

D

C

D

C

D

C

D

Cambodia

9

7

47

30

0

0

0

0

0

0

0

0

0

0

0

0

56

37

China

38

25

9

5

6

1

0

0

0

0

0

0

0

0

0

0

53

31

Lao PDR

2

2

0

0

0

0

0

0

0

0

0

0

0

0

1

0

3

2

Viet Nam

112

57

15

7

0

0

0

0

0

0

0

0

0

0

0

0

127

64

Total

161

91

71

42

6

1

0

0

0

0

0

0

0

0

0

0

239

134

 

Globally, from January 2003 to 3 December 2020, there were 862 cases of human infection with avian influenza A(H5N1) virus reported from 17 countries. Of these 862 cases, 455 were fatal (CFR of 53%). The last case was reported from Lao PDR on 13 October 2020 (source).

 

Human infection with avian influenza A(H5N6) virus

Between 27 November and 3 December 2020, one new case of human infection with avian influenza A(H5N6) virus were reported to WHO in the Western Pacific Region. The case is an 81-year-old female farmer from Changzhou, Jiangsu Province, China who had exposure to domestic poultry prior to developing symptoms on 26 November 2020. The case was hospitalized on 27 November 2020 with severe pneumonia and subsequently died on 27 November 2020. To date, a total of 25 laboratory-confirmed cases of human infection with influenza A(H5N6) virus have been reported to WHO from China since 2014, including eight deaths at time of IHR report.

 

Public health risk assessment for human infection with avian influenza A(H5) viruses Whenever avian influenza viruses are circulating in poultry, there is a risk for sporadic infection and small clusters of human cases due to exposure to infected poultry or contaminated environments. Therefore, sporadic human cases are not unexpected.

With continued incidence of avian influenza due to existing and new influenza A(H5) viruses in poultry, there is a need to remain vigilant in the animal and public health sectors. Community awareness of the potential dangers for human health is essential to prevent infection in humans. Surveillance should be continued to detect human cases and early changes in transmissibility and infectivity of the viruses.

For more information on confirmed cases of human infection with avian influenza A(H5) virus reported to WHO, visit: http://www.who.int/influenza/human_animal_interface/en/

For information on monthly risk assessments on Avian Influenza, visit: http://www.who.int/influenza/human_animal_interface/HAI_Risk_Assessment/en/

Human infection with avian influenza A(H7N4) virus in China

Between 27 November and 3 December 2020, no new cases of human infection with avian influenza A(H7N4) virus were reported to WHO in the Western Pacific Region. To date, only one laboratory- confirmed case of human infection with influenza A(H7N4) virus has been reported to WHO. This case was reported from China on 14 February 2018.

 

Human infection with avian influenza A(H7N9) virus in China

Between 27 November and 3 December 2020, no new cases of human infection with avian influenza A(H7N9) virus were reported to WHO in the Western Pacific Region. As of 3 December 2020, a total of 1,568 laboratory-confirmed human infections with avian influenza A(H7N9) virus have been reported to WHO since early 2013. Among them, 33 cases were infected with HPAI A(H7N9) virus, which have mutations in the hemagglutinin gene indicating a change to high pathogenicity in poultry. These 33 cases were from Taiwan (the case had travel history to Guangdong), Guangxi, Guangdong, Hunan, Shaanxi, Hebei, Henan, Fujian, Yunnan, Inner Mongolia. No increased transmissibility or virulence of the virus within human cases has been detected related to the HPAI A(H7N9) virus (source).

WHO is continuing to assess the epidemiological situation and will conduct further risk assessments as new information becomes available. The number and geographical distribution of human infections with avian influenza A(H7N9) viruses in the fifth epidemic wave (1 October 2016 to 30 September 2017) was greater than previous waves and the subsequent waves.

Further sporadic human cases of avian influenza A(H7N9) virus infection are expected in affected and possibly neighbouring areas. Should human cases from affected areas travel internationally, their infection may be detected in another country during or after arrival. However, if this were to occur, community level spread is considered unlikely as the virus does not have the ability to transmit easily among humans.

To date, there is no evidence of sustained human-to-human transmission of avian influenza A(H7N9) virus. Human infections with the A(H7N9) virus are unusual and need to be monitored closely in order to identify changes in the virus and transmission behaviour to humans as this may have serious public health impacts.

For more information on human infection with avian influenza A (H7N9) virus reported to WHO: http://www.who.int/influenza/human_animal_interface/influenza_h7n9/en/

 

Human infection with avian influenza A(H9N2) in China

Between 27 November and 3 December 2020, no new cases of human infection with avian influenza A(H9N2) virus were reported to WHO in the Western Pacific Region. In 2020, there have been seven cases reported from China so far. A total of 35 cases of human infection with avian influenza A(H9N2) in China have been reported since December 2015.

 

Animal infection with avian influenza virus

Between 27 November and 3 December 2020, four new outbreaks of avian influenza were reported to OIE from the Western Pacific Region.

 

Highly pathogenic avian influenza virus A(H5N8) in the Republic of Korea

On 29 November 2020, three new outbreaks of highly pathogenic avian influenza A(H5N8) among wild birds were reported to OIE from Republic of Korea. Two of the outbreaks occurred in Gyeonggi Province, one in Icheon City and one in Yongin City. The third outbreak occurred in Jeju City, Jeju Province. All three outbreaks were detected through testing of feces from wild Mandarin Ducks and Mallards (source).

Highly pathogenic avian influenza virus A(H5N8) in the Republic of Korea

On 30 November 2020, one new outbreak of highly pathogenic avian influenza A(H5N8) among poultry was reported to OIE from Republic of Korea. The outbreak occurred in Jeongeup City, Jeollabuk Province. There was one case and no deaths among 19,000 susceptible birds. All 19,000 birds were culled (source).

 

For more information on animal infection with avian influenza viruses with potential public health impact, visit:


source : https://www.who.int/docs/default-source/wpro---documents/emergency/surveillance/avian-influenza/ai-20201113.pdf?sfvrsn=223ca73f_70


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