Map of Switzerland depicting the location of the study areas.

<p>The five study areas (units A-E) are indicated by shades of grey. Black lines correspond to canton borders, and blue areas are main lakes. The origin of wild boar (<i>Sus scrofa</i>) samples and their real-time PCR results are indicated by colored dots: Samples negative for <i>Mycoplasma hyopneumoniae</i> are green and positive samples are red.</p

Histological lesions associated with <i>Mycoplasma hyopneumoniae</i> infection and their distribution in wild boar lungs.

<p>A: Lung without macroscopic enzootic pneumonia-like lesions (MaEPL) with moderate multifocal BALT hyperplasia along a bronchiole (measurement bar = 500nm). B: Lung with early type MaEPL and mild to moderate multifocal BALT hyperplasia (black arrow) and diffuse moderate thickening of the interalveolar septa (broncho-interstitial pneumonia). Marginal subpleural atelectasis is considered an artefact (measurement bar = 50mm). C: Lung with early type MaEPL and severe infiltration of mononuclear cells expanding the interlobular septum (thick black arrow) and compressing the regional airways. A discrete hyperplastic lymphoid follicle is also present (thin black arrow, measurement bar = 2mm). D: Lung with late type MaEPL and moderate to severe multifocal BALT hyperplasia (thick arrows), moderate infiltration of the submucosa of the airways (thin black arrow) and mild to moderate multifocal thickening of the interalveolar septa by infiltrating inflammatory cells (measurement bar = 500nm). E: Magnification (20x) of the framed area in D (inset). Intraluminal collection of neutrophils (thin black arrows, measurement bar = 20μm). F: Lung with late type MaEPL and diffuse intraalveolar collection of amorphous eosinophilic material (edema, black arrows) with mild to moderate multifocal lympho-plasmacytic clusters in the interstitium (black circles). Few numbers of mononuclear cells are also observed in the alveolar spaces along with free erythrocytes (hemorrhages, gunshot-related, measurement bar = 20μm).</p

Selected features for the histological assessment of wild boar lungs.

<p>^a The lumen, mucosa and peripheral tissue were assessed separately for each selected structure.</p><p>^b PF = Power field. ^C AL = Microscope arrow length (Nikon model Eclipse E 400).</p><p>Selected features for the histological assessment of wild boar lungs.</p

Wild boar lungs with and without macroscopic enzootic pneumonia-like lesions (MaEPL).

<p>A: Lung without MaEPL. B: Lung with early type MaEPL (red to dark red multilobular to coalescing consolidated areas affecting less than 50% of the lobe). C: Lung with late type MaEPL (multilobular to coalescing pale purple to grayish areas, showing signs of retraction of parenchyma and atelectasis). D: Lung with late type MaEPL (same as C but with more pronounced fibrosis). Measurement bars = 1cm.</p

Identified risk factors for <i>Mycoplasma hyopneumoniae</i> infection in Swiss wild boar.

<p>^a Outbreaks registered between 2010 and 2013. Final multivariable logistic regression model of risk factors in a study performed in 2011–2013. Significant associations with occurrence of <i>M</i>. <i>hyopneumoniae</i> in wild boar are expressed by odds ratios (OR) and respective 95% confidence intervals (95% CI). The total number of observations was 849. No confounding variables were identified.</p><p>Identified risk factors for <i>Mycoplasma hyopneumoniae</i> infection in Swiss wild boar.</p

Relationship between PCR results and the absence/presence of macroscopic enzootic pneumonia-like lesions in wild boar.

<p>PCR results refer to data obtained with nasal swabs. MaEPL: Macroscopic enzootic pneumonia-like lesions (of early and late type) detected in wild boar lungs. Dark blue: PCR-positive samples. Light blue: PCR-negative samples.</p

Frequency and distribution pattern of recorded histological features in wild boar lungs.

<p>^a BALT hyperplasia with active follicles was not associated with the presence of parasites (p-value = 0.3697).</p><p>^b Eosinophil infiltration in the airways was associated with the presence of intralesional parasites (p-value = 0.0002).</p><p>^c Intra-alveolar edema was associated with plasma cell clusters in the interstitium (p-value = 0.0004), parasites (p-value = 0.0467) and neutrophils in the alveolar parenchyma and/or interstitium (p-value = 0.0467). Observations are classified according to the concerned anatomic structure and the PCR results obtained with bronchial swabs. A total of 106 lungs were examined.</p><p>Frequency and distribution pattern of recorded histological features in wild boar lungs.</p

Study areas (geographical units A-E) and their characteristics.

<p>^a Wild boar density index categories correspond to the following estimations: very high = 1.65 dead individuals/km² per year, medium = 0.40–0.54 and low = 0.04.</p><p>^b Density of outdoor piggeries correspond to the following estimations: high = 0.31 outdoor piggeries/km², medium = 0.19, low = 0.08 and very low = 0.01.</p><p>^c OD = Official definition. The climatic characteristics of the five geographical units are based on measurements of the Swiss Federal Office of the Environment, Transport, Energy and Communication, Federal Meteorology and Climatology Department, Federal Agronomy Office.</p><p>^d Prevalence (%) and 95% confidence interval (95% CI) of <i>Mycoplasma hyopneumoniae</i> in wild boar nasal swabs (PCR analysis) in 2011–2013 (this study).</p><p>^e predominant <i>M</i>. <i>hyopneumoniae</i> type (ABC only, REP only, ABC/REP).</p><p>^f Number of recorded outbreaks of enzootic pneumonia in domestic pigs in 2010–2013.</p><p>Study areas (geographical units A-E) and their characteristics.</p

Registered outbreaks of enzootic pneumonia in domestic pigs from 2010 to 2013.

<p>The number of outbreaks (N) is indicated for each study area (units A-E) and colors indicate the source of infection. Dark blue: Domestic pig. Grey: Unknown, wild boar unlikely. Light blue: Unknown, wild boar suspected.</p

Detected target groups of <i>Mycoplasma hyopneumonia</i> types in the five study areas.

<p>Data refer to PCR-positive nasal swabs from wild boar. Study areas: units A-E. Dark blue: ABC/REP type. Light blue: ABC-only type. Grey: REP-only type.</p