Mycobacterium microti at the Environment and Wildlife Interface.

Giovanni Alborali,Mario D’Incau,Valentina Tagliapietra,Mariagrazia Zanoni,Mario Chiari,Maria Lodovica Pacciarini,Iyad Karaman,Anna Mangeli,Annapaola Rizzoli,Maria Beatrice Boniotti

doi:10.3390/microorganisms9102084

Abstract

An unexpected high presence of Mycobacterium microti in wild boar in Northern Italy (Garda Lake) has been reported since 2003, but the factors contributing to the maintenance of this pathogen are still unclear. In this study, we investigated the presence of M. microti in wild rodents and in water and soil samples collected at wild boar aggregation areas, such as watering holes, with the aim of clarifying their role in M. microti transmission. In total, 8 out of 120 captured animals tested positive for the Mycobacterium tuberculosis complex (MTBC) as assessed by real-time PCR, and six samples were confirmed to be M. microti. A strain with a genetic profile similar to those previously isolated in wild boars in the same area was isolated from one sample. Of the 20 water and 19 mud samples, 3 and 1, respectively, tested positive for the presence of MTBC, and spacer oligotype SB0118 (vole type) was detected in one sample. Our study suggests that wild rodents, in particular Apodemus sylvaticus, Microtus sp. and Apodemus flavicollis, play roles in the maintenance of M. microti infections in wild boar through ingestion or by contact with either infected excreta or a contaminated environment, such as at animal aggregation sites.

Highlights

Mycobacterial species causing tuberculosis in humans and animals are part of the Mycobacterium tuberculosis complex (MTBC) [1], which includes Mycobacterium microti, a microorganism initially identified in England as a pathogen of wild rodents, such as field voles (Microtus agrestis), wood mice (Apodemus sylvaticus), bank voles (Myodes glareolus) and shrews (Sorex araneus) [2,3,4,5,6,7]
Other indirect studies provide evidence of the presence of M. microti in field voles through infections of cats [8,9]; in the work of Peterhans et al (2020) [11], which describes 11 cases of M. microti in cats in Switzerland, 346 wild mice (Microtus agrestis) captured in the presumptive endemic area failed to demonstrate the presence of this microorganism
Mycobacterium microti has been recorded in an Officially Tuberculosis-free region (OTF) area in Northern Italy, both in wild boar from 2011 to 2017 and in rodents and environmental samples in 2017

Summary

Introduction

Mycobacterial species causing tuberculosis in humans and animals are part of the Mycobacterium tuberculosis complex (MTBC) [1], which includes Mycobacterium microti, a microorganism initially identified in England as a pathogen of wild rodents, such as field voles (Microtus agrestis), wood mice (Apodemus sylvaticus), bank voles (Myodes glareolus) and shrews (Sorex araneus) [2,3,4,5,6,7] This pathogen causes natural infections in a wide range of wild and domestic animals, but in recent years, an increasing number of infections have been described in pets (cats and dogs) [8,9,10,11], wildlife (wild boar and badger) [12,13,14,15,16] and livestock (goat and cattle) [17,18,19,20].

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