Epidemiological investigations on the role of clinically healthy racing pigeons as a reservoir for avian paramyxovirus-1 and avian influenza virus

Figures & data

Table 1. Descriptive analysis of questionnaires collected from racing pigeon lofts (2008 to 2010).

Possibilities of transmission	Number of lofts^a	Percentage^b
Possibility of quarantine	170	92
Quarantine of straying pigeons^c	157	90
Quarantine of late arrivals^c^,^d	157	31
Contact with other pets	107 to 136	60 to 62
Avian species as pets^c	64 to 83	34 to 45
Chicken flocks within a 5 km radius	162	70
Loft with aviaries	170	88
Free flights in winter	107 to 136	24 to 34
Contact with wild animals	107 to 137	25 to 38
Contact with wild birds^c	27 to 51	45 to 74

Data are based on the information provided by the pigeon breeders in the questionnaires. ^aNumber of lofts that answered the respective question in the questionnaire. ^bA range of percentages is shown for questions that were asked again in subsequent samplings of the same loft. Therefore the range displays the results of the first to fourth samplings. Other questions were only asked when the loft participated for the first time to evaluate general features of the loft. ^cThese subsequent questions were based on a more general question asked before; thus, breeders who negated the general question were not asked subsequent questions about that topic. ^dLate arrivals were defined as racing pigeons that arrived in their home loft more than 4 days after the official end of the race.

Figure 1. Percentage of APMV-1 antibody-positive racing pigeons. Results of juvenile pigeons (n = 628) that were sampled during summer samplings are displayed in intervals of 3 weeks (n = 84 to 158/time span). Different superscript letters indicate significant differences in HI titres between groups of juvenile pigeons (Kruskal–Wallis one-way analysis of variance with all-pairwise comparisons, P < 0.05). A significant difference was seen 0 to 3 weeks and 7 to 9 weeks post vaccination. Sera of adult pigeons (n = 2036), collected during four samplings (2008 to 2010) showed no significant differences between HI titres and time spans post vaccination. The results of adult pigeons are displayed as the mean percentage of antibody-positive pigeons between 0 and 42 weeks post vaccination.

Figure 2. APMV-1 antibody titres of vaccinated racing pigeons. Sera of APMV-1 vaccinated racing pigeons (n = 2920) sampled over a period of 2 years (2008 to 2010) were tested by HI test for APMV-1 specific antibodies. Box plot analyses of different age groups with different letters indicating significant differences (Kruskal–Wallis one-way analysis of variance with all-pairwise comparisons, P < 0.05). ^aRatio of positive (≥ log₂ 4) to tested sera.

Table 2. Detection of APMV-1 and AIV by rRT-PCR in clinically healthy racing pigeon lofts.

	Sampling 1 (summer 2008)		Sampling 2 (winter 2009)		Sampling 3 (summer 2009)		Sampling 4 (winter 2010)
rRT-PCR results	APMV-1 (n = 76)	AIV (n = 134)	APMV-1 (n = 74)	AIV (n = 108)	APMV-1 (n = 72)	AIV (n = 110)	APMV-1 (n = 75)	AIV (n = 105)
CT values < 35 (%)	0	6.7	0	0.9	1.4^a	2.7	1.3^a	0

Over a period of 2 years (2008 to 2010) racing pigeons from lofts located in different federal states of Germany were sampled. For each loft, pools of five pharyngeal swabs per age group were examined by rRT-PCR (n = number of lofts tested). Owing to the reproductive cycle, juvenile pigeons were only sampled in summer. A loft was considered positive if at least one of the analysed samples of adult or juvenile pigeons was tested positive. ^aOne sample APMV-1-positive/total number tested during that sampling.