Management of hunting waste as control measure for tuberculosis in wild ungulates in south-central Spain

Abstract

In recent decades, habitat change and the intensive management of wild ungulates for hunting have led to an increase in their populations in south-central Spain. This implies a higher generation of hunting waste, which can favour the transmission of infectious diseases, including tuberculosis (TB). The aim of this study was to assess the usefulness of the proper disposal of hunting waste as TB control measure in wild boar (Sus scrofa) and red deer (Cervus elaphus) during the 2008/2009 to 2016/2017 hunting seasons. Blood samples from 664 wild boar and 934 red deer were obtained in 14 game estates in two provinces in Andalusia (Area 1), where the disposal of hunting waste was implemented since the 2012/2013 hunting season. Besides, six game estates in the province of Ciudad Real, in Castilla-La Mancha (Area 2), an adjacent region where this management measure was not implemented during the studied period, were used as controls, sampling 277 wild boar and 427 red deer sera. The Mycobacterium tuberculosis complex (MTC), seroprevalence detected in wild boar from Area 1, was significantly higher before the disposal of big game hunting by-products (82.8%; 2008/2009-2012/2013) compared to the second period (61.8%; 2013/2014-2016/2017) (p < .001), after this control measure became established. By contrast, no significant differences between periods were found in wild boar (41.3% versus 44.8%; p = .33) and red deer (14.9% versus 11.6%; p = .19) from Area 2 as well as in red deer (10.8% versus 10.5%; p = .48) from Area 1. The proper disposal of hunting waste contributed to achieve a 25% reduction in MTC seroprevalence in wild boar. These results are of particular relevance regarding wild boar in the current context of re-emerging and emerging diseases such as TB and African Swine Fever in Europe. Further studies are needed to assess the effect of this measure on the health status of livestock and other wildlife species.

A survey of shared pathogens at the domestic–wild ruminants’ interface in Doñana National Park (Spain)

“…The overall MTC seroprevalence found in wild ruminants (14.3%) in DNP falls within the values observed in the same species (4.3%-14.9%) in central-southern Spain (Cano-Terriza et al, 2018;García-Bocanegra et al, 2012). The significantly higher prevalence of anti-MTC antibodies detected in male and adult wild ruminants was also in agreement with those reports from Mediterranean ecosystems (Cano-Terriza et al, 2018;García-Bocanegra et al, 2012).…”

Most likely causes of infection and risk factors for tuberculosis in Spanish cattle herds

“…Therefore, it is possible that some non‐significant effects were due to the sample size not being large enough if differences were smaller or rates of exposure were lower. For example, the presence of hunting waste was described in only seven farms, and it was not identified as a risk factor, whereas other authors found that eliminating this waste from the farms reduced the risk of bTB infection from wildlife 50 . The results of this study could have some underlying misclassification bias due to the lack of diagnostic sensitivity of the SITT in the field.…”

“…For example, the presence of hunting waste was described in only seven farms, and it was not identified as a risk factor, whereas other authors found that eliminating this waste from the farms reduced the risk of bTB infection from wildlife. 50 The results of this study could have some underlying misclassification bias due to the lack of diagnostic sensitivity of the SITT in the field. To reduce such biases, cases were farms confirmed as infected by isolation of MTC species, and only control farms which remained SITTnegative for three consecutive annual testing (i.e.…”

The Role of Scavenging in Disease Dynamics

“…High rates of pathogen circulation driven by human management are often associated to overabundance of big game; and in these cases, some infected species often play a role as facultative scavenger (e. g. wild boar, Gortazar et al 2006). In addition, the way big game waste is disposed of may allow for facultative diseasesusceptible scavengers to access infected material (Moreno-Opo et al 2012;Cano-Terriza et al 2018). For instance, in Europe, as in many other parts of the world, the changes occurring across the last 40 years have had a pronounced effect on the environment, creating a dynamic situation where pathogens or new hosts emerge o re-emerge.…”