Table 2.

The pathological findings, including immunoperoxidase staining for H5 and NP antigens, in H5N1 avian influenza virus infected wild birds in Hong Kong in 2006–2007

Viruses isolated Bird species	H5N1 Clade/ Cluster #	Level of autolysis	Gross pathology	Histopathology (Haematoxylin and Eosin stained sections)	IPX stain H5 Mab*			IPX stain NP Mab*
					B	L	O	B	L	O
1. D-06-0075 Magpie Robin	2.3.4 /6	2+	Lung congestion	Lung congestion and oedema with foci of peribronchial lymphocyte necrosis; granulomatous cholangitis with trematodes in bile ducts; kidney, heart, brain congestion; muscle haemorrhage	1+	2+		2+	3+
2. D-06-0366 Magpie Robin	2.3.4 /6	-	Lung congestion and haemorrhage	Lung congestion, oedema and haemorrhage; congestion and multifocal necrotising tracheitis; brain, kidney gizzard and intestines congested; lymphoid depletion/lysis in spleen and Peyer’s patches, midzonal vacuolar degeneration in liver; individual fibre degeneration in muscle	1+	2+		1+	2+
3. D-06-0540 Crested Myna	2.3.4 /5	2+	Lung oedema and congestion; spleen, liver congestion; pancreatic necrosis, focal skull and brain haemorrhage	Lung congestion and some oedema; liver congestion and random small foci of necrosis; kidney, spleen, heart, brain showed marked congestion pancreas had a focal area of necrosis; some lymphocyte necrosis in random submucosal lymphoid nodules in gizzard and cloaca	+/−	2+	*1	1+	3+	*1
4. D-06-0645 Common Magpie	2.3.4 /1	-	Lungs oedema and congestion with greyish mottling; patchy reddening of pancreas	Lung congestion and oedema with anthracoid pigment present; kidney congestion and multiple small random foci of tubule necrosis; heart had several foci of myocardial necrosis; brain had congestion, foci of necrotising vasculitis and neuropile necrosis with some gliosis and perivascular lymphoid cuffing; liver and spleen were congested and had haemosiderosis; stomach, intestines and pancreas were congested	1+	2+	*2	1+	3+	*2
5. D-06-0718 Little Egret	2.3.4 /6	4+	No changes evident	Brain showed congestion and a few small foci of neuropile necrosis with mild gliosis; lung congestion	2+	-		3+	-
6. D-06-1038 Japanese White-eye	2.3.4 /4	3+	No changes evident	Lung congestion; multiple small foci of acute necrosis in the liver with bacterial emboli in liver and brain consistent with septicaemia	-	+/−		-	1+
7. D-06-2125 Common Magpie	2.3.4 /4	-	Trachea congested, lung oedema; 1mm white spots in liver	Lung congestion and oedema with foci of peribronchial lymphocyte necrosis; multiple foci of acute pancreatic necrosis; multiple small foci of lymphocyte necrosis in caecal tonsils; splenic congestion and foci of lymphoid lysis; brain, kidney congestion; liver had subacute cholangiohepatitis	2+	2+		3+	3+
8. D-06-2256 Common Magpie	2.3.4 /4	-	Lung congestion, haemorrhages in lung and pancreas	Lung congestion and oedema with anthracoid pigment present and a fluke present in bronchus; multifocal necrotising tracheitis; general visceral and brain congestion; foci of lymphocyte lysis in caecal tonsil; flukes present in ureter; mild subacute cholangiohepatitis and salpingitis	3+	3+		3+	3+
9. D-06-2454 Munia	2.3.4 /4	3+	haemorrhage and oedema in lungs; liver congestion; skull haemorrhage	Moderate autolysis but liver, heart, kidney, lung, spleen, brain and proventriculus all showed moderate to marked congestion with no other changes evident	4+	4+		1+	4+
10. D-06-2469 White-backed Munia	2.3.4 /4	3+	congestion and oedema in lungs; liver congestion; skull haemorrhage	Lung congestion and oedema; brain, liver and kidney congestion; heart congestion and focal epicardial haemorrhage	2+	+/−		3+	1+
11. D-06-2512 Large-billed Crow	2.3.4 /4	1+	Lung haemorrhage, congestion, oedema; spleen and liver congestion	Lung congestion and oedema with foci of peribronchial lymphocyte necrosis; tracheal epithelial cell necrosis; general visceral and brain congestion; focal lymphoid necrosis in lymphoid tissue in spleen, liver and kidney	2+	1+	*3	2+	1+	*3
12. D-06-2648 House Crow	2.3.4 /4	-	Lung oedema; cloudy airsacs; pericardial oedema	Lung congestion with foci of peribronchial lymphocyte necrosis; acute tracheitis; splenic lymphoid necrosis; brain showed multifocal neuronal degeneration and mild gliosis; ischaemic necrosis in pancreas; liver had occasional individual cell necrosis	4+	+/−	*4	4+	2+	*4
13. D-06-2858 House Crow	2.3.4 /4	1+	No changes evident	Lung congestion and oedema with foci of peribronchial lymphocyte necrosis; brain showed congestion and a few small foci of neuropile necrosis with mild gliosis	3+	−		3+	1+
14. D-06-3033 Common Magpie	2.3.4 /4	1+	Lung congestion and oedema, patchy brain congestion	liver, kidney and lung very congested; spleen congested and multiple small foci of necrosis; brain and heart mildly congested	3+	1+	*5	3+	2+	*5
15. D-06-5211 Peregrine Falcon	2.3.2	-	Trachea congested, lung oedema; 1mm white spots in liver	Lung congestion and oedema; tracheal congestion; multifocal splenic necrosis; brain had marked congestion and multiple small foci of necrosis (glial cells, neurones and blood vessel walls); congestion and multiple small foci of necrosis in kidney, liver and oviducts; heart had fibrinopurulent pericarditis	4+	-		4+	-
16. D-07-0045 Scaly-breasted Munia	2.3.4 /2	4+	No changes evident	Lung oedema and haemorrhage; general congestion in viscera and brain; multiple small foci of acute necrosis in the liver	-	-		-	-
17. D-07-0458 Crested Goshawk	2.3.4 /2	-	Congestion and oedema in lungs; splenic congestion; skull haemorrhage	Lung congestion and oedema with foci of peribronchial lymphocyte necrosis; multifocal splenic and pancreatic necrosis; brain congestion with multiple small foci of neuropile necrosis and mild gliosis; focus of myocardial degeneration; focal lymphoid necrosis in thymus and caecal tonsils; congestion in liver and kidneys	3+	3+	*6	3+	3+	*6
18. D-07-0719 House Crow	2.3.4 /7	2+	Lung congestion; skull haemorrhage, brain congested	Lung congestion and oedema; brain congestion with focus in cerebrum with multifocal neuronal degeneration/necrosis; liver and kidney congestion	3+	-		3+	-
19. D-07-0737 Japanese White-eye	2.3.4 /7	2+	Lung congestion	Lung congestion, oedema and haemorrhage; liver was very congested and had a focal area of hepatocyte necrosis with degenerate heterophil and mononuclear cell infiltrate; brain was mildly congested	-	-		-	-
20. D-07-0828 White-backed Munia	2.3.4 /7	2+	Trachea, lung and brain congestion	Lung congestion with some oedema and diffuse parabronchitis; brain congestion with some foci of neuropile necrosis and gliosis; liver congestion	3+	4+		4+	4+
21. D-07-1143 Peregrine Falcon	2.3.2	-	Lung congestion and oedema; airsacculitis and peritonitis; focal brain congestion	Lung congestion and oedema; brain showed multifocal necrotising non- suppurative encephalitis and vasculitis; multifocal necrotising pancreatitis; intestinal trematode infection; severe multifocal necro- suppurative typhlitis with embryonated parasite eggs embedded in the caecal wall; liver, trachea and kidney showed congestion and multiple small foci of necrosis; muscle, heart, spleen were congested	2+	+/−	*7	2+	+/−	*7
22. D-07-1203 House Crow	2.3.4 /7	-	Poor body condition; brain congestion	Lung congestion; multiple small foci of neuropile necrosis and gliosis in the brain; heart showed multifocal acute myocarditis; Chronic necrotising enteritis with diptheritic membrane formation and flagellate protozoans (Trichomonas sp.) present	2+	+/−	*8	2+	1+	*8
23. D-07-1993 Blue Magpie	2.3.4 /7	-	Moist pharyngeal lining, lung oedema	Lung congestion and oedema with small necrotic foci in parabronchi and peribronchial lymphoid tissue; necrotizing airsacculitis and tracheitis; small foci of acute myocardial degeneration; small foci of necrosis in renal pelvis; multiple small foci of neuropile necrosis and gliosis in the brain; liver showed congestion and haemosiderosis; intestines had small foci of necrosis in the muscularis layer	3+	3+	*9	3+	3+	*9
24. D-07-2065.1 Silver-eared Mesia	2.3.4 /7	2+	Mildly oedematous lungs	Lung and brain congestion	1+	1+	*10	1+	2+	*10
24. D-07-2065.2 Silver-eared Mesia	2.3.4 /7	2+	Lung congestion and oedema; liver, spleen congestion; skull haemorrhage; worms in airsacs	Lung congestion and oedema and small random foci of necrosis in parabronchi; multiple small foci of necrosis in myocardium; congestion and random small foci of tubule necrosis in kidney cortex; brain and liver showed congestion; spleen had mild lymphoid necrosis	-	3+	*10	-	3+	*10
25. D-07-2372 Common Kestrel	2.3.4 /7	2+	Lung, spleen, brain congestion; skull haemorrhage; 1mm pale foci in kidney	Lung congestion and oedema; spleen, heart and brain were congested; kidney congestion and mild lymphohistiocytic interstitial nephritis; liver congestion, diffuse fatty degeneration and haemosiderosis	3+	-	*11	3+	2+	*11
26. D-07-2433 Scaly-breasted Munia	2.3.4 /3	3+	No changes evident	Lung congestion and oedema; brain and kidney congestion	1+	2+	*12	3+	3+	*12
27. D-07-2442 Chestnut Munia	2.3.4 /3	4+	No changes evident	Lung congestion and oedema; brain and kidney congestion	2+	2+	*13	3+	3+	*13
28. D-07-2572 Scaly-breasted Munia	2.3.4 /7	4+	Lung and brain congestion	Focal congestion in the kidney and congestion in the heart and brain	2+	2+	*14	2+	+/−	*14
29. D-07-2762 Long-tailed Shrike	2.3.4 /2	1+	Lung congestion and oedema; pharynx moist; skull and brain congested	Lung congestion and oedema; brain, heart, muscle and kidney congestion; also nematode parasites in renal cortex; tracheitis with epithelial and mucous gland loss	4+	4+	*15	3+	3+	*15
30. D-07-4925 Red-billed Starling	2.3.2	2+	Lung congestion and oedema	Lung had congestion and some oedema with small foci of peribronchial lymphoid necrosis; heart had multiple small foci of acute myocardial necrosis; kidney had congestion and multiple small foci of tubular necrosis; brain, liver and spleen showed congestion	-	-	*16	2+	2+	*16
31. D-07-5052 Common Magpie	2.3.2	1+	Haemorrhage in pectoral skin and muscle; lung oedema, congested spleen	Lung congestion and oedema; liver spleen and kidney showed congestion and multiple small foci of necrosis; heart had multiple small foci of acute myocardial necrosis; brain had mild congestion and pectoral muscle had haemorrhages and skin had haemorrhage and some dermal necrosis	3+	1+	*17	3+	1+	*17
32. D-07-5288 House Crow	2.3.2	2+	Lung congestion and oedema with some haemorrhage, trachea, intestines, pancreas congested; haemorrhage on right l cranium	Lung congestion and severe oedema with multiple haemorrhages; brain congestion and moderate multifocal vasculitis, gliosis and perivascular lymphohistiocytic cuffing; heart had moderate multifocal myocardial necrosis, lymphohistiocytic infiltrates and mineralisation; liver was congested and had mild multifocal hepatocyte necrosis with lymphohistiocytic and heterophil infiltrates and some haemosiderosis; kidney and proventriculus showed congestion	3+	1+	*18	3+	2+	*18

^# H5N1 grouping was based on phylogenetic analysis of HA gene sequences. Only one cluster was present in Clade 2.3.2 and 7 clusters were detected in Clade 2.3.4 (see Guan and Peiris et al., submitted for publication).

^*Cryostat sections of Brain (B) and lung (L) were routinely examined by immunoperoxidase staining using monoclonal antibodies to H5 HA or avian influenza NP proteins. Results of other tissues (O) examined are shown below:

^*1Liver: H5 2+, NP 1+; Pancreas: H5 2+, NP 2+; Spleen: H5 1+, NP 2+

^*2 Heart, liver, spleen: H5 1+, NP 1+

^*3 Heart: H5 1+, NP 1+

^*4 Heart, spleen, kidney, small intestine: H5 1+, NP 1+; Liver: H5 +/−, NP 1+

^*5 Heart,: H5 -, NP 1+; Trachea: H5 +/−, NP +/−

^*6 Heart,: H5 3+, NP 3+; Pancreas: H5 4+, NP 4+

^*7 Spleen: H5 2+, NP 2+

^*8 Spleen: H5 +/−, NP 1+

^*9 Heart, Kidney: H5 3+, NP 3+; small intestine: H5 2+, NP 3+

^*10Bird 1- Heart: H5 -, NP -; Bird 2 – Heart: H5 2+, NP 2+

^*11Heart, Kidney: H5 1+, NP 2+; Pancreas: H5 nt, NP 3+

^*12Heart: H5 2+, NP 3+

^*13Heart: H5 -, NP -

^*14Heart: H5 1+, NP 1+; Liver: H5 2+, NP 2+

^*15Heart: H5 3+, NP 2+; kidney: H5 4+, NP 3+

^*16Heart: H5 -, NP 3+; kidney: H5 1+, NP 2+

^*17Heart, kidney: H5 3+, NP 3+

^*18Heart: H5 +/−, NP +/−; Kidney: H5 1+, NP 1+; Pancreas: H5 3+, NP 2+

nt – not tested.