The hard numbers of tuberculosis epidemiology in wildlife: A meta‐regression and systematic review

Abstract

Tuberculosis (TB) is a widespread disease that crosses the human and animal health boundaries, with infection being reported in many wild species, from temperate and subtropical to arctic regions. Often, TB in wild species is closely associated with disease occurrence in livestock but the TB burden in wildlife remains poorly quantified on a global level. Through a meta-regression and systematic review, this study aimed to summarise global information on the prevalence of TB in commonly infected wildlife species and to draw a global picture of the scientific knowledge accumulated in wildlife TB. For these purposes, a literature search was conducted through the Web of Science and Google Scholar. The 223 articles retrieved, concerning a 39-year period, were submitted to bibliometric analysis and 54 publications, regarding three wildlife hosts, fulfilled the criteria for metaregression. Using a random-effects model, the worldwide pooled TB prevalence in wild boar is higher than for any other species and estimated as 21.98%, peaking in Spain (31.68%), Italy (23.84%), and Hungary (18.12%). The pooled prevalence of TB in red deer is estimated at 13.71%, with Austria (31.58%), Portugal (27.75%), New Zealand (19.26%), and Spain (12.08%) positioning on the top, while for European badger it was computed 11.75%, peaking in the UK (16.43%) and Ireland (22.87%). Despite these hard numbers, a declining trend in wildlife TB prevalence is observed over the last decades. The overall heterogeneity calculated by multivariable regression ranged from 28.61% (wild boar) to 60.92% (red deer), indicating that other unexplored moderators could explain disease burden. The systematic review shows that the most prolific countries contributing to knowledge related with wildlife TB are settled in Europe and Mycobacterium bovis is the most reported pathogen (89.5%). This study provides insight into the global epidemiology of wildlife TB, ascertaining research gaps that need to be explored and informing how should surveillance be refined.

Two decades of tuberculosis surveillance reveal disease spread, high levels of exposure and mortality and marked variation in disease progression in wild meerkats

“…TB prevalence varied strongly between the years, with over one quarter of the population displaying clinical signs in some years. TB prevalence reported in this study is comparable with those reported from other well‐studied species [∼12% for European badgers ( Meles meles ) to ∼32% for red deer ( Cervus elaphus ) and wild boar ( Sus scrofa ); see Reis et al., 2021], both with regard to overall (16.2%) and annual prevalence. Previous studies using diagnostic tools on subset of the study population to detect TB reported prevalence between 24% (Drewe, 2010) and up to 82.4% of individuals of exposed groups (Clarke et al., 2016), implying that by using clinical signs, the true extent of Mycobacterium infection prevalence is underestimated.…”

“…Thus, a well‐founded understanding of transmission and host–pathogen dynamics is imperative for the development of adequate TB surveillance and management strategies (de Lisle et al., 2002). However, despite intense research efforts in several TB host systems (reviewed in Reis et al., 2021), quantitative data on TB exposure, prevalence and progression are still rare for many wildlife species affected by TB.…”

The open pan-genome architecture and virulence landscape of Mycobacterium bovis

“…It causes animal TB primarily in cattle, but also in other livestock species [3]. Some wildlife species are pathogen reservoirs and infection amplifiers, helping to sustain TB across a variety of ecosystems in different geographic locations [4]. Well-known epidemiological scenarios referred to in the literature include the Iberian Peninsula, United Kingdom, Australia, New Zealand, South Africa and USA [5][6][7].…”

Risk Practices for Occupational Zoonotic Exposure to Tuberculosis in a High-Risk Population in Portugal

“…In short, there are many flaws in the field of preventing zoonotic exposure to TB in this specific risk population, the large game hunters [ 18 ]. Bad practices in handling hunted carcasses potentially infected with TB increase the risk of occupational exposure.…”