+, 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).