Characterizing epidemiological and genotypic features of Mycobacterium bovis infection in wild dogs ( Lycaon pictus )

Abstract

Mycobacterium bovis (M. bovis) infects a wide range of wildlife species and has recently been discovered in the endangered African wild dog (Lycaon pictus). This study aimed to characterize the epidemiology of tuberculosis (TB) in wild dogs in endemic areas of South Africa. We describe 12 TB cases in wild dogs from Kruger National Park (KNP), Hluhluwe–iMfolozi Park (HiP) and a private facility in Hoedspruit from 2015 to 2017. Spoligotyping was used to identify the disease‐causing M. bovis strain in these cases, and whole‐genome sequencing was performed on 5 M. bovis isolates (KNP = 2 and HiP = 3) to investigate genomic diversity as well as the relationship to other isolates found in these geographical areas. Three distinct strain types were responsible for the M. bovis infections in this species. The SB0121 strain was observed in wild dogs from KNP, whereas SB0130 was responsible for infection in wild dogs from HiP. A novel strain, SB2681, was also identified in the HiP wild dogs. Whole‐genome sequence analysis suggests that different infection sources exist among these wild dogs and that inter‐species transmission most likely occurred between wildlife predators and prey located within shared geographical areas. This study highlights the importance of regular disease surveillance to identify and characterize potential threats for successful control of infection and protection of endangered species.

Shedding of Mycobacterium bovis in respiratory secretions of free‐ranging wild dogs ( Lycaon pictus ): Implications for intraspecies transmission

“…Additionally, all M. bovis isolates from culture-positive wild dogs had the same SB0121 strain (Table 1), which is the common strain in KNP, providing further evidence that these wild dogs are likely to be part of the same transmission network. Since the most likely route of infection in wild dogs is ingestion, prey species such as kudu, impala, warthog, and nyala, which are known bTB hosts, may be part of this transmission network (Bernitz et al, 2021;Meiring et al, 2021). However, although these findings support our hypothesis that there is a risk of transmission among wild dogs, it does not confirm that intraspecies transmission occurred.…”

“…Using the IGRA, a high prevalence of test-positive wild dogs was found in KNP (82%; 95% CI: 72-89), which was greater than what would be expected from the paucity of reports of bTB-related morbidity and mortality (Higgitt et al, 2019b). However, since 2015, deaths associated with bTB have been observed and recently described (Meiring et al, 2021). In that study, M. bovis was isolated from multiple organs in 7 cases (out of 12), including the gastrointestinal (GI) tract, supporting ingestion (of infected prey) as a potential route of infection (Meiring et al, 2021).…”

“…However, since 2015, deaths associated with bTB have been observed and recently described (Meiring et al, 2021). In that study, M. bovis was isolated from multiple organs in 7 cases (out of 12), including the gastrointestinal (GI) tract, supporting ingestion (of infected prey) as a potential route of infection (Meiring et al, 2021).…”

“…Bovine tuberculosis (bTB), caused by infection with Mycobacterium bovis, was identified in wild dogs ( Lycaon pictus ) in the Kruger National Park (KNP) in 2015–2016, with most cases found following a canine distemper virus (CDV) outbreak (Higgitt et al., 2019b; Meiring et al, 2021). This discovery led to the investigation of M. bovis infection in this endangered species, which necessitated the development of an interferon gamma release assay (IGRA) to detect immune sensitization to M. bovis (Higgitt et al., 2019a).…”

Review of Diagnostic Tests for Detection of Mycobacterium bovis Infection in South African Wildlife

“…The BACTEC TM MGIT TM is an automated mycobacterial growth detection system used in routine human tuberculosis diagnostic settings, that has been used to culture MTBC organisms from postmortem tissue samples as well as antemortem bronchoalveolar lavage, elephant trunk wash fluid, and oropharyngeal swab samples from wildlife (42)(43)(44). Application of these techniques has permitted antemortem diagnosis of M. bovis infection in African lion (Panthera leo), African wild dog (Lycaon pictus) and white rhinoceros (Ceratotherium simum) (36,42,45).…”