An experimental model to quantify horizontal transmission of Mycoplasma gallisepticum

Figures & data

Figure 1. Experimental design: each group contained 25 specific pathogen free White Layers, of which 20 were housed in pairs and five were housed singly. The cages with pairs were placed at a distance of 65 cm and 178 cm from each other. The individually housed chickens were placed between the pairs at a distance of 65 cm from each other and from the pairs. The pairs consisted of one inoculated chicken (I) and a susceptible in-contact bird (S1). Individually housed chickens were susceptible airborne-exposed birds (S2).

Figure 2. Excretion patterns (mean±standard error of the mean) of inoculated, in-contact and airborne-exposed birds after inoculation of 10² CFU Mg F1999 (2A), 10⁵ CFU Mg F1999 (2B) or 10⁸ CFU Mg F1999 (2C). 2C: n = 9 because one inoculated bird died at day 7 after contact. Mg, M. gallisepticum.

Figure 3. Number of birds serological positive (RPA and HI ≥ 1:8) to M. gallisepticum (Mg) among inoculated, in-contact and airborne-exposed birds over the observation period of 35 days, after inoculation of 10² CFU Mg F1999 (3A), 10⁵ CFU Mg F1999 (3B) or 10⁸ CFU Mg F1999 (3C). 3C: n = 9 because one inoculated died bird at day 7 after contact.

Table 1.  Significance of the difference in the average log₁₀ (cumulative excretion) at four random sampling time points

	Experiment 1			Experiment 2
	10^2 CFU/ml Mg F1999^a	10^5 CFU/ml Mg F1999	10^8 CFU/ml Mg F1999	10^4 CFU/ml Mg F1999
I/S1^b	0.096^c	0.23	0.13	0.62
I/S2^d	0.0021	0.022	0.0098	0.00082
S1/S2^e	0.0078	0.22	0.013	0.0035
^a M. gallisepticum dose.
^bInoculated (I) compared with in-contact birds (S1).
^c P, Kruskall–Wallis rank sum test.
^dInoculated (I) compared with airborne-exposed birds (S2).
^eIn-contact (S1) compared with airborne-exposed birds (S2).