Analysis of a multi-type resurgence of Mycobacterium bovis in cattle and badgers in Southwest France, 2007-2019

Abstract

Although control measures to tackle bovine tuberculosis (bTB) in cattle have been successful in many parts of Europe, this disease has not been eradicated in areas where Mycobacterium bovis circulates in multi-host systems. Here we analyzed the resurgence of 11 M. bovis genotypes (defined based on spoligotyping and MIRU-VNTR) detected in 141 farms between 2007 and 2019, in an area of Southwestern France where wildlife infection was also detected from 2012 in 65 badgers. We used a spatially-explicit model to reconstruct the simultaneous diffusion of the 11 genotypes in cattle farms and badger populations. Effective reproduction number R was estimated to be 1.34 in 2007–2011 indicating a self-sustained M. bovis transmission by a maintenance community although within-species Rs were both < 1, indicating that neither cattle nor badger populations acted as separate reservoir hosts. From 2012, control measures were implemented, and we observed a decrease of R below 1. Spatial contrasts of the basic reproduction ratio suggested that local field conditions may favor (or penalize) local spread of bTB upon introduction into a new farm. Calculation of generation time distributions showed that the spread of M. bovis has been more rapid from cattle farms (0.5–0.7 year) than from badger groups (1.3–2.4 years). Although eradication of bTB appears possible in the study area (since R < 1), the model suggests it is a long-term prospect, because of the prolonged persistence of infection in badger groups (2.9–5.7 years). Supplementary tools and efforts to better control bTB infection in badgers (including vaccination for instance) appear necessary.

Relevance of the synergy of surveillance and populational networks in understanding the Usutu virus outbreak within common blackbirds (Turdus merula) in Metropolitan France, 2018

“…We have also stored this package on Zenodo (https://doi.org/10.5281/zenodo.10992191; (Calenge et al 2024)). The raw dataset used in this paper has also been stored as a text file on Zenodo (https://doi.org/10.5281/zenodo.10992555; (Bouchez-Zacria et al 2024)).…”

Modelling environmental transmission of bovine tuberculosis between cattle and badgers; impact of interventions and spatial heterogeneity

“…These two processes result in the dynamics of local transmission alternating between the establishment and spillover phases. This cycle between phases can take a few years, based on another modelling study [210]. This hypothesis could provide an explanation for different patterns of transmission directions in phylodynamic studies, including a predominance of cattle-to-badger (as opposed to badger-to-cattle) transmission in some studies [25,127] and badgerto-cattle transmission in others [124,126,211].…”

“…As a consequence of this mixing of epidemiological units in the NGM, badger vaccination efficacy would directly impact between-herd transmission, which might be an oversimplification of the challenges as described in Section 5.1. In addition, Bouchez-Zacria et al [210] estimated four partial reproduction 𝑅 0 at the herd level, by estimating transmission rate parameters (using animals as the epidemiological unit) from infection data and using simulations to aggregate herd level 𝑅. Although the epidemiological units are different from the NGM in Chapter 3, this study similarly identified high intra-species transmission (with estimated 𝑅 𝑏,𝑐 = 0.21 ∼ 1.09, 𝑅 𝑐,𝑏 = 0.38 ∼ 1.45) and low within-species transmission (𝑅 𝑐,𝑐 = 0.24 ∼ 0.74, 𝑅 𝑏,𝑏 = 0.08 ∼ 0.41), which suggests that badger-cattle could be a maintenance-community in some areas [210].…”