Figure 1.
Design of stable compartment in animal experiments.
Experimental design for evaluation of the effect of prevention of direct contact by spatial separation on transmission of S. suis serotype 9 among pigs. Inoculated pigs (I) were intranasally infected with S. suis serotype 9 two days before placing in these boxes. Stable compartments contained 2 to 4 boxes with pair-wise housed pigs (Cdir+I) and 1 to 3 boxes with pigs housed individually (Cind). Cdir pigs had direct contact with I pigs; Cind pigs were only indirectly exposed to S. suis. The air inlet in the compartment is marked with ; the air outlet with
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Table 1.
Design of animal experiments to evaluate the effect of spatial separation on S. suis serotype 9 transmission.
Figure 2.
Transmission of S.suis to pigs with or without direct contact with infectious ones.
Diagram showing the proportion of S. suis positive pigs over time for directly contact exposed pigs (Cdir;N = 25) and pigs housed at a distance (Cind; N = 15) after S. suis serotype 9 inoculated pigs entered the stable compartments in the transmission experiments. Two Cind pigs remained negative.
Figure 3.
Mean S. suis loads in saliva and tonsil samples.
Mean loads of S. suis serotype 9 colony forming units (CFU) in saliva (panel A) and tonsil brushing samples (panel B) shown separately for pigs inoculated with (I), directly (Cdir) or indirectly contact exposed (Cind) to S. suis. Time is expressed as days after a pig was found positive firstly. As sampling was not conducted daily, and because of the delay in S. suis transmission to mainly Cind pigs the numbers and time points of observations differ between the groups. No significant differences were observed in mean levels between Cdir, Cind and I pigs for the first 3 positive samples and for mean levels over the whole sampling period.
Figure 4.
S. suis spread within a simulated hypothetical stable compartment under different weaning scenarios.
Course of percentage of S. suis positive pigs over time after relocation of pigs at weaning for two simulated situations based on a hypothetical conventional pig farm setting. In scenario A, 10 litters of 10 pigs each were introduced in a stable compartment and kept spatially separated. In scenario B, 10 litters were mixed to form two groups of 50 pigs. In both scenarios it was assumed that that at relocation one of the 100 pigs was infected with S. suis and that direct contact between pigs in different pens was impossible. Per scenario 10.000 iterations were performed. The solid lines represent the median values, and the dashed lines the 2.5th and 97.5th percentiles of these simulations. The black lines represent scenario A, and the grey lines scenario B.