2.1 Study site, official records and deer sampling
This study was carried out in a privately-owned safari park located in the state of Rio Grande do Sul, Southern Brazil (Figure 1). To understand and describe the history of bTB in this park, we accessed records of the official state veterinary service that was used as a basis to close the park by court order in 2013 due to sanitary problems. In this official record, necropsy and laboratory reports from different public universities and private diagnostic laboratories dating back from 2003 were compiled.
We had access to tissue samples of deer that were euthanized after 16 of them (out of 51 tested) presented positive results in comparative cervical tests using M. bovis and M. avium PPD (purified protein derivative). Briefly, TST was carried out in 51 deer by the official veterinary service of the state following the United States Department of Agriculture (USDA) protocol on three different occasions from 2013 to 2015. A total of 16 deer tested positive, indicating the presence of bTB in the population. After judicial procedures, in 2018, all 281 deer present in the park were mandatorily slaughtered. Retropharyngeal, submandibular, and mesenteric lymph nodes were conveniently collected from 21 deer (Cervus unicolor ,Cervus elaphus and Dama dama ) with lesions suggestive of tuberculosis (LST). From these, 19 isolates of M. bovis were obtained as described previously (Lima et al., 2021). Unfortunately, the name of the host species of each sample were not recorded at the time of sampling.