Evidence of exposure and human seroconversion during an outbreak of avian influenza A(H5N1) among poultry in Cameroon

Figures & data

Figure 1. Map of poultry and human sampling sites in Cameroon. Sites where sampling took place for avian influenza prevalence and exposure are indicated on the map of Cameroon in central Africa. Blue squares represent poultry sampling locations. Red stars indicate human sampling locations.

Table 1. Number and percentage of influenza A(H5N1) positive samples identified in poultry in Cameroon between May and June 2016.

		Number of samples	Influenza A n (% total)	A(H5N1) n (% flu positive)
Time period	May 2016	56	13 (23.2)	12 (92.3)
	June 2016	91	31 (34.1)	22 (71.0)
Region	Adamawa	27	n.d.	n.d.
	Centre	59	19 (32.2)	15 (78.9)
	East	8	n.d.	n.d.
	North West	3	1 (33.3)	n.d.
	South	24	11 (45.8)	6 (54.5)
	West	26	13 (50)	13 (100)
Total		147	58 (39.5)	34 (58.6)

Note: n.d.: not detected.

Figure 2. Phylogenetic analysis of the A(H5N1) haemagglutinin (HA) genes from representative viruses from Cameroon (A). The phylogenetic tree was generated using the maximum-likelihood method. Bootstrap values (n = 500) > 70 are shown. Scale bars indicate substitutions per site. Sequences from representative Cameroonian strains included in the study are indicated in bold and italic. Other control strains are indicated in bold. Representative Cameroonian isolates used in the study for antigenic analysis are indicated with black stars while control strains are indicated with black circles. Amino acid differences determined in representative strains as compared to other clade 2.3.2.1c HA genes are indicated in red on the model (B). Positions are stated under H5 numbering.

Figure 3. Phylogenetic analysis of the A(H5N1) neuraminidase (NA) genes from representative viruses from Cameroon. The phylogenetic tree was generated using the maximum-likelihood method. Bootstrap values (n = 500) > 70 are shown. Scale bars indicate substitutions per site. Sequences from representative Cameroonian strains included in the study are indicated in bold and italic. Other control strains are indicated in bold. Representative Cameroonian isolates used for antigenic analysis are indicated with black stars while control strains are indicated with black circles.

Table 2. Comparison of amino acids in the HA gene from representative Cameroonian strains used in this study and other 2.3.2.1c strains.

Protein	Position^a	H5N1 Cameroon	West African strains	Europe	China
HA	68	G	G	G	S/D
	145	G	R (Niger, G)	R	R
	200	V	I	I	I
	238	T	A	A	A

^aH5 numbering.

Table 3. Antigenic analysis of representative A(H5N1) isolates from Cameroon.

Reference antiserum
		A/common magpie/Hong Kong/5052/2007				A/Hong Kong/6841/2010				A/Hubei/1/2010				A/duck/Bangladesh/19097/2013				A/barm swallow/HK/1161/2010
	RBC	c	t	ho	hu	c	t	ho	hu	c	t	ho	hu	c	T	ho	hu	c	t	ho	hu
Reference virus/antigen	Clade
A/common magpie/Hong Kong/5052/2007	2.3.2.1	320	320	2560	1280	320	320	2560	1280	20	20	320	80	80	160	1280	320	40	40	0	160
A/Hong Kong/6841/2010	2.3.2.1	80	40	N/A	320	320	160	N/A	1280	20	20	N/A	80	320	160	N/A	640	20	20	N/A	80
A/Hubei/1/2010	2.3.2.1a	320	320	1280	160	640	640	2560	640	320	320	1280	320	640	1280	2560	640	40	80	0	160
A/duck/Bangladesh/19097/2013	2.3.2.1a	160	160	1280	320	320	640	2560	1280	20	40	320	80	320	640	2560	1280	20	40	10	80
A/barm swallow/HK/1161/2010	2.3.2.1b	80	80	640	320	160	320	1280	1280	10	20	160	80	80	160	1280	640	40	40	0	320
A/duck/VN/NCVD-1584/2012	2.3.2.1c	160	160	N/A	640	640	640	N/A	2560	40	40	N/A	160	640	640	N/A	1280	40	80	N/A	160
A/duck Cambodia/33W2M3/2013	1.1	10	0	80	20	160	80	320	320	20	10	80	80	10	0	40	20	0	0	0	10
A/envir/Cambodia/z2EP1e3W7M1/2015	2.3.2.1c	160	0	2560	10	320	0	2560	10	20	0	320	40	40	10	640	20	20	0	0	20
A/chicken/Cameroon/16V-04338/2015	2.3.2.1c	10	20	320	80	40	80	640	320	0	0	80	20	20	40	160	40	0	0	0	20
A/chicken/Cameroon/16V-3771/2015	2.3.2.1c	40	40	640	160	160	160	1280	640	10	0	160	20	40	80	640	160	10	0	0	20
		A/duck/VN/NCVD-1584/2012				A/duck/VN/NCVD-2848/2013				A/duck Cambodia/33W2M3/2013				A/chicken/Guiyang/1153/2016				A/chicken/Ghana/7/2015
	RBC	c	t	ho	hu	c	t	ho	hu	c	t	ho	hu	c	t	ho	hu	c	t	ho	hu
Reference virus/antigen	Clade
A/common magpie/Hong Kong/5052/2007	2.3.2.1	80	80	1280	320	80	160	0	320	0	20	0	20	0	0	160	10	80	80	1280	320
A/Hong Kong/6841/2010	2.3.2.1	320	160	N/A	1280	80	80	N/A	640	0	0	N/A	40	0	0	N/A	20	80	40	N/A	640
A/Hubei/1/2010	2.3.2.1a	160	320	2560	320	80	160	0	640	40	40	0	80	0	10	80	20	80	160	1280	320
A/duck/Bangladesh/19097/2013	2.3.2.1a	160	640	2560	1280	80	160	10	320	0	10	10	20	0	10	10	10	40	80	1280	320
A/barm swallow/HK/1161/2010	2.3.2.1b	80	80	1280	640	40	80	0	320	0	10	0	20	0	10	0	10	40	40	320	160
A/duck/VN/NCVD-1584/2012	2.3.2.1c	640	640	N/A	2560	160	160	N/A	1280	10	10	N/A	40	10	0	N/A	20	160	160	N/A	640
A/duck Cambodia/33W2M3/2013	1.1	20	0	80	40	10	0	0	20	640	160	0	1280	0	0	0	20	80	40	320	160
A/envir/Cambodia/z2EP1e3W7M1/2015	2.3.2.1c	80	10	640	20	80	80	0	320	0	0	0	20	0	0	160	10	40	0	1280	10
A/chicken/Cameroon/16V-04338/2015	2.3.2.1c	20	20	320	80	10	10	0	40	10	10	0	40	0	0	80	0	80	160	1280	320
A/chicken/Cameroon/16V-3771/2015	2.3.2.1c	40	80	640	160	10	20	0	80	10	20	0	40	0	0	160	10	160	320	2560	640

Note: RBC: red blood cells; c: chicken; t: turkey; ho: horse; hu: human; N/A: not available.

Table 4. Socio-demographic characteristics and influenza detection in exposed poultry workers and close contacts in Cameroon between May and July 2016.

		Number tested	Number Positive n (% total)	A/pdmH1N1 n (% flu positive)	A/H3N2 n (% flu positive)	Untyped n (% flu positive)	A(H5N1) n (% flu positive)	A/H7N9 n (% flu positive)
Sex	Male	481	12 (2.5)	n.d.	9 (75.0)	3 (25)	n.d.	n.d.
	Female	157	3 (1.9)	n.d.	2 (66.6)	1 (33.3)	n.d.	n.d.
	n/a	25	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.
Age	0-20.	130	1 (0.8)	n.d.	n.d.	1 (100)	n.d.	n.d.
	21–40	385	11 (2.9)	n.d.	9 (81.8)	2 (18.2)	n.d.	n.d.
	41–60	118	2 (1.7)	n.d.	1 (50)	1 (50)	n.d.	n.d.
	61–80	16	1 (6.3)	n.d.	1 (100)	n.d.	n.d.	n.d.
	n/a	14	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.
Region	Adamawa	97	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.
	Centre	232	7 (3.0)	n.d.	6 (85.7)	1 (14.3)	n.d.	n.d.
	Littoral	33	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.
	South	149	4 (2.7)	n.d.	3 (75)	1 (25)	n.d.	n.d.
	West	152	4 (2.6)	n.d.	2 (50)	2 (50)	n.d.	n.d.
Total		663	15 (2.3%)	n.d.	11 (73.3)	4 (26.7)	n.d.	n.d.

Note: n.d.: not detected; n/a: not available.