Influenza A (H5N6) virus in humans...

Provinces hosting human cases of H5N6
Adapted from [8]
Click on image to enlarge.

After late December's announcement of a human infection with another avian influenza subtype, H5N6. The tally of human infections by this subtype of FluA stands at 2 - that are reported anyway.

The ever vigilant @FluTrackers (and their line lists, news posts and commentary) and the always alert @Fla_Medic (and his Avian Flu Diary blog) have these cases well covered.

I just wanted to make a summary here for my own reference in making some slides for a talk next month.

1. ~23-April-2014. [1,4,5] 49-year old male (49M) from Nanchong City, Sichuan Province.
   Acute severe pneumonia, died 5-May-2014
   Exposed to dead poultry
2. 3-December 2014. [2] 58M from Guangzhou City in Guangdong province.
   Critical condition in hospital since 9-Dec-2014
   Exposed to live poultry but not ill contacts [3]

There have also been plenty of lethal animal infections by this and other highly pathogenic avian influenza (HPAI; referring specifically to the bird's outcome) subtypes and strains [7], including:

From an OIE Report 21-Oct-2014. [6]

1. 12,000 quails in Quang Nai Province, Vietnam in 18-Dec-2014
   http://en.vietnamplus.vn/Home/Quang-Ngai-destroys-12000-AH5N6-infected-quails/201412/59394.vnplus
2. 1,338 birds on a farm in Nanbu, Nanchoing City, Sichuan Province, China
   http://www.oie.int/wahis_2/public%5C..%5Ctemp%5Creports/en_fup_0000015698_20140731_162951.pdf
3. 20,550 (17,790 fatal) birds on a farm in Shuangcheng District, Heilongjiang Province, China, 23-Aug-2014
   http://www.oie.int/wahis_2/public%5C..%5Ctemp%5Creports/en_fup_0000016060_20141024_193420.pdf
4. Birds in Muang Nan and Muang Xayabouly Districts, Luang Prabang and Xayabouly Provinces, Laos in 12:14-Mar-2014
   http://wwwnc.cdc.gov/eid/article/21/3/14-1488_article#r4

No sign of anything like sustained human-to-human transmission of this viral subtype to date. But another for the influenza virus Rubik's cube.

References..

1. https://flutrackers.com/forum/forum/china-h5n1-h5n8-h5n6-h5n3-h5n2-h10n8-outbreak-tracking/164419-china-man-49-with-acute-severe-pneumonia-died-from-h5n6-nanchong-city-nanbu-county-sichuan-province?t=222782
2. http://www.who.int/csr/don/28-december-2014-avian-influenza/en/
3. http://news.xinhuanet.com/english/china/2014-12/23/c_133874590.htm
4. http://afludiary.blogspot.com.au/2014/05/sichuan-china-1st-known-human-infection.html
5. http://www.promedmail.org/direct.php?id=2451125
6. http://www.oie.int/wahis_2/public%5C..%5Ctemp%5Creports/en_fup_0000016060_20141024_193420.pdf
7. UPDATE ON HIGHLY PATHOGENIC AVIAN INFLUENZA IN ANIMALS (TYPE H5 and H7) from the Office International des Epizooties (OIE), otherwise known as the World Organisation for Animal Health
   http://www.oie.int/animal-health-in-the-world/update-on-avian-influenza/2014/
8. http://en.wikipedia.org/wiki/File:China_administrative_claimed_included.svg#filelinks

Taihu lake & influenza viruses Part II: people, pigs, poultry and migratory birds

Source of H5N1/H7N9 spatial overlap figure: Many thanks to Dr Ricardo J. Soares Magalhaes, The Univeristy of Queensland.

The figure below, from the Letter I talked about yesterday, published by Wang and colleagues in Emerging Infectious Diseases, Vol 19(11) shows the Lake Tai region.

To clarify, the paper talked about an area of high risk of infection. It did not specify whether the risk was due to exposure to poultry or wild birds. The issue of visiting LBMs and exposure to poultry and their excrement was secondary to the finding of overlapping regions of human cases and proposed region of greater risk.

Having said that, it appears (and these are all web sources so take them with a grain of chicken salt) that a domestic breed of pig and poultry may be farmed around this lake, one of China's largest fresh water bodies containing dozens of islands. Water quality and its levels algae and contaminating animal and human waster have also been issue for the lake, which supplies drinking water to approximately 30-million people in cities within Jiangsu and Zhejiang provinces. 

Expansion of poultry farm seems to have been stopped, if not contracted, and better management of aquaculture and livestock and poultry wastes has been recommended.

However, wild waterfowl as well as duck and goose farms seem to remain around the lake according to at China Travel and the maps at the bottom of this post. There seem to be monkeys and caves (bats?) too and as you would expect, this is also a thoroughfare and winter stopover for wild birds. It's also about 380km north-east of Poyang lake, another important wintering ground for wild waterbirds and one that is known to harbour influenza viruses.

• A study by Duan and colleagues  of >11,500 cloacal swabs from migratory ducks and >36,400 swabs from sentinel ducks identified 90 and 1,681 influenza isolates, respectively during 2002-2007. he sentinel duck seasonal influenza peak overlapped with the migratory duck over-wintering period. Major haemagglutinin (HA) types included H3, H4, H6 and H10. H5N1 was detected during 2005. H7 was also found. The major neuraminidase (NA) type was N6. N9 was not identified. These combined to form 27 HA/NA antigenic combinations.

You can see the overlap between areas of human infections with influenza A(H7N9) virus (green circles; area bounded in blue and green) and H5N1 (red triangles; area bounded in pink).

Below, I have excerpted 2 maps from William Wint and Timothy Robinson's document, Gridded Livestock of the World 2007 written for the Food and Agriculture Organization (FAO) of the United Nations¹. They show using livestock data modelling (which is described in the full document) that there were certainly lots of pigs and poultry in that region in 2007. 

So, the 3-Ps are in place: People, Pigs, Poultry probably kept freshly supplied with out-of-town influenza by migratory birds. 

1. FAO. 2007. Gridded livestock of the world 2007, by G.R.W. Wint and T.P. Robinson. Rome, pp 131.

Influenza A(H7N9) virus detected by local labs: Guangdong province...awaiting CDPCC confirmation

Not long ago, FluTrackers posted a thread starting with an ifeng news of a 51-year old woman who has tested positive for H7N9 Guangdong province, southern China. This is the province's first human case. She has influenza-like illness, contact with 36 people and with poultry.

The case was identified by the local in Huizhou City Center for Disease Control (CDC) and samples shave been sent to China Disease Prevention and Control Center for confirmation.

I won't update the flu map on my main H7N9 page tonight (its 10pm, August 9th down here in Aus) - but it will loo like the above if confirmed.

Guangdong province is the nearest mainland Chinese region to Hong Kong. With Guangdong's temperature peaking today at 35'C (currently 34'C) - its not "typical" influenza seasonal weather - but then this is just a single case and influenza, like all respiratory viruses, is always ticking over, just at sub-epidemic levels.