The Association between Palmer Drought Severity Index Data and Tuberculosis-like Lesions Occurrence in Mediterranean Hunted Wild Boars

Abstract

In the Iberian Peninsula, the prevalence of tuberculosis differs for each region and for different wild disease hosts and the region affected by a Mediterranean climate will be the most affected. The Mediterranean Iberic regions have a favourable ecosystem for the development of Mycobacterium tuberculosis complex agents, where habitat, population dynamics, and climate (especially drought) are important factors affecting the high prevalence of tuberculosis in the wild boar population. Our objective was to study the association between the Palmer Drought Severity Index (PDSI) and the occurrence of tuberculosis-like lesions (TBL) in wild boar during nine hunting seasons (2008/09 to 2016/17) in Idanha-a-Nova County. To this end, statistical analysis revealed a significant association (p < 0.05) between the occurrence of TBL in wild boar in Idanha-a-Nova County and the analysed risk factor—previous season with periods of drought—which indicated that, when one season experiences some periods of drought, the probability of TBL occurrence in wild boars was 1.2 (OR = 1.2) times higher in the next hunting season than when there were no periods of drought. Therefore, our study contributes to the discovery of a positive effect of periods of drought on the transmission of tuberculosis in Iberian wildlife.

Disentangling the effects of supplementary feeding on population abundance and the aggregation of wild ungulates as drivers of the prevalence of tuberculosis in south-central Spain

“…Previous studies in Mediterranean environments have reported TBL percentages of between 50-75% in wild boar populations, which corroborates our ndings (Vicente et al 2006(Vicente et al , 2007(Vicente et al , 2013Naranjo et al 2008;Barroso et al 2020). These oscillations may be related to climatic events such as droughts and its indirect consequences, which increase the prevalence of TB in the subsequent season (Vicente et al 2013;Barroso et al 2020;Abrantes et al 2021). In Spain, the driest years recorded were 2005 and 2017 (< 500mm http://www.aemet.es/), corresponding to a high TBL prevalence during the following year.…”

Complementary roles of wild boar and red deer to animal tuberculosis maintenance in multi-host communities

“…Each study site was assigned the herd prevalence of the geographical unit where it was located. Aridity was shown to be a risk factor for TB in wild ungulates in the markedly seasonal Mediterranean ecosystems of the Iberian Peninsula by influencing their aggregation, particularly at watering sites during the dry season (Triguero-Ocaña et al, 2020;Vicente et al, 2013;Abrantes et al, 2021). To assess the effect of this risk factor, the Global Aridity Index (GAI) was included as an independent variable in the model.…”

“…6), a region characterized by moderately high aridity (Fig. 1), where host aggregation at watering points was shown to be a risk factor for TB (Triguero-Ocaña et al, 2020;Vicente et al, 2013;Abrantes et al, 2021).…”

“…The presence of game fences is a proxy of the intensive management of wild ungulate populations, usually characterised by the absence of large predators, artificial feeding and medication, and captive breeding, leading to exceptionally high densities (Vicente et al, 2013;Macaulay et al, 2013), and associated with decreased genetic diversity (Queirós et al, 2016). Mediterranean ecosystems are markedly seasonal, and drought was shown to influence TB in wildlife through an increase in their aggregation, particularly at watering sites during the dry season (Triguero-Ocaña et al, 2020;Vicente et al, 2013;Abrantes et al, 2021). Several studies have identified a relationship between TB in wildlife and cattle (LaHue et al, 2016;Santos et al, 2018).…”

Epidemiology ofMycobacterium bovisinfection in free-ranging rhinoceros in Kruger National Park, South Africa

“…Associations between drought and M. bovis infection or disease have been detected in other multihost systems. In a large study of Mediterranean wild boars ( n = 3,923), which are known bTB reservoirs, the occurrence of drought and increasing drought severity were significantly associated with increased occurrence of TB-like lesions ( 45 ). Another study investigating risk factors for bTB in cattle in Great Britain showed a positive association between atmospheric dryness and areas of high risk for M. bovis infection ( 46 ).…”