Number of studies and means of detection and isolation rates for different variables (outbreaks are excluded).

<p>Number of studies and means of detection and isolation rates for different variables (outbreaks are excluded).</p

Number of swine seroprevalence studies and seroprevalence means for the different variables.

<p>Number of swine seroprevalence studies and seroprevalence means for the different variables.</p

Distribution of the pig-level seroprevalence for avian subtypes.

<p>N = 25 studies, 38 entries.</p

Flow diagram for article selection.

<p>Flow diagram for article selection.</p

Map of the number of included articles by country.

<p>N = 217 articles overall; some articles reported data from several countries.</p

Herd-level seroprevalence distribution by health status and subtypes.

<p>N = 51 articles, 112 studies, 143 entries.</p

Final mixed-effects models for pig seroprevalence for M1, M2 and M3.

<p>Final mixed-effects models for pig seroprevalence for M1, M2 and M3.</p

Final mixed-effects models for herd seroprevalence for M1, M2 and M3.

<p>Final mixed-effects models for herd seroprevalence for M1, M2 and M3.</p

Number of studies according to continent and ILI status.

<p>Number of studies according to continent and ILI status.</p

Pig-level seroprevalence distribution by health status and subtypes.

<p>N = 164 studies, 271 entries.</p