Tuberculosis Epidemiology and Badger (Meles meles) Spatial Ecology in a Hot-Spot Area in Atlantic Spain

Abstract

We provide a temporal overview (from 2012 to 2018) of the outcomes of tuberculosis (TB) in the cattle and badger populations in a hot-spot in Asturias (Atlantic Spain). We also study the badger’s spatial ecology from an epidemiological perspective in order to describe hazardous behavior in relation to TB transmission between cattle and badgers. Culture and single intradermal tuberculin test (SITT) were available for cattle as part of the National Program for the Eradication of TB. A field survey was also carried out in order to determine the paddocks and buildings used by each farm, and the information obtained was stored by using geographic information systems. Moreover, eighty-three badgers were submitted for necropsy and subsequent bacteriological studies. Ten badgers were also tracked, using global positioning system (GPS) collars. The prevalence of TB in cattle herds in the hot-spot increased from 2.2% in 2012 to 20% in 2016; it then declined to 0.0% in 2018. In contrast, the TB prevalence in badgers increased notably (from 5.55% in 2012–2015 to 10.64% in 2016–2018). Both cattle and badgers shared the same strain of Mycobacterium bovis. The collared badgers preferred paddocks used by TB-positive herds in spring and summer (when they were more active). The males occupied larger home ranges than the females (Khr95: males 149.78 ± 25.84 ha and females 73.37 ± 22.91 ha; Kcr50: males 29.83 ± 5.69 ha and females 13.59 ± 5.00 ha), and the home ranges were smaller in autumn and winter than in summer. The averages of the index of daily and maximum distances traveled by badgers were 1.88 ± (SD) 1.20 km and 1.99 ± 0.71 km, respectively. One of them presented a dispersive behavior with a maximum range of 18.3 km. The most preferred habitat was apple orchards in all seasons, with the exception of winter, in which they preferred pastures. Land uses and landscape structure, which have been linked with certain livestock-management practices, provide a scenario of great potential for badger–cattle interactions, thus enhancing the importance of the badgers’ ecology, which could potentially transmit TB back to cattle in the future.

Spatial and Temporal Distribution of Mycobacterium tuberculosis Complex Infection in Eurasian Badger (Meles meles) and Cattle in Asturias, Spain

“…This study examined the prevalence of TB in free-ranging Eurasian badgers in Spain for a 13-year period, which was longer than a previous seven-year study [ 12 ]. One study in England examined TB prevalence in badgers over 24 years [ 19 ], but only trapped animals were analyzed.…”

“…Bacteriological and molecular studies were performed in 639 out of the 673 badgers (the remaining 34 animals were excluded due to insufficient tissue availability to make the pools). Pools (2 g) of lungs and mandibular, retropharyngeal, tracheobronchial, mediastinal, hepatic, and mesenteric LNs were frozen at −20 °C for no longer than two weeks and subsequently used to isolate potential bacteria as described previously [ 12 ]. Members of the MTC or the Mycobacterium avium complex (MAC) were isolated using the Mycobacteria Growth Indicator Tube (MGIT) liquid medium system, the Löwenstein–Jensen solid medium with sodium pyruvate, and Coletsos solid media.…”

“…In Spain, the southern and central regions, which have a Mediterranean climate, show a TB cattle herd-prevalence as high as 12.3%, while the northwestern region with an Atlantic climate shows an overall prevalence of 0.02–0.08% but with hotspots where prevalence can be as high as 5% [ 2 , 12 ]. This variability may reflect several factors.…”

“…Recent studies have suggested that badgers may be a reservoir of M. bovis infection in hotspots in Atlantic Spain, as reported in Ireland and the UK [ 12 , 17 ]. In addition, wild boar, red deer ( Cervus elaphus ), and, to a lesser extent, fallow deer ( Dama dama ) are major wildlife reservoirs in continental Mediterranean habitats, where wild boars can show a TB prevalence of >50% [ 14 ].…”

Development and Challenges in Animal Tuberculosis Vaccination

“…European badgers are recognized TB maintenance hosts in the UK and the Republic of Ireland (ROI) [152][153][154][155][156]. Novel studies suggest that badgers may be a potential reservoir of MTC infection also in Atlantic Spain [25,157] and France, especially in hot-spot areas where prevalence in cattle remains high [158,159]. Vaccination of badgers has been proposed as a long-term control strategy for TB in addition to culling in UK and ROI [160].…”