+, macroscopic or histological finding present; – no macroscopic or histological findings; nd, not done. †) Macroscopic findings comprised in all cases enlargement, discoloration and induration. ‡) Histological findings comprised focal-extensive necrosis (mild to moderate), granulomatous lymphadenitis (moderate) as well as reactive hyperplasia (moderate to severe) and eosinophilic lymphadenitis (mild to moderate).
Figure 1. Geographic distribution of mycobacterial species identified from wild boars during 2017 and 2018 in the Canton Ticino in Southern Switzerland (green highlighted in the country map of Switzerland in Panel A). A) Hunting location of the five animals infected with Mycobacterium microti (red stars) and B) distribution of isolated nontuberculous mycobacterial species. Circled numbers represent the number of infected animals in each district.
Figure 2. Distribution of the isolated nontuberculous mycobacteria among three different age groups (juvenile, yearling and adult) as found for wild boars investigated in 2017 and 2018. Adult wild boars were more prone to be infected with mycobacteria (74.4%) in comparison to juvenile animals (54.9%) or yearlings (45.8%).
Figure 3. Histological findings from a mandibular lymph node presenting histological lesions compatible with tuberculosis and tested positive for Mycobacterium microti. (A) Overview of a granulomatous lymphadenitis showing focal-extensive necrotic cores and dystrophic calcifications (arrow heads). The necrotic cores are surrounded by a mixed population of inflammatory cells and by a wide capsule of connective tissue (arrows), hematoxylin and eosin (HE; 40X). (B) Scanty acid-fast rods are visible in the necrotic debris. Occasionally, S-shaped bacilli, which are commonly associated withMycobacterium microti were observed intra- and extracellularly, Ziehl-Neelsen stain (40X). (C) Granuloma characterized by focal-extensive necrosis and mild inflammatory infiltration of epithelioid macrophages, neutrophils, multinucleated Langhans type giant cells (arrows) and eosinophils is shown (HE; 40X).