Role of wild ruminants in the epidemiology of bluetongue virus serotypes 1, 4 and 8 in Spain

Abstract

Although the importance of wild ruminants as potential reservoirs of bluetongue virus (BTV) has been suggested, the role played by these species in the epidemiology of BT in Europe is still unclear. We carried out a serologic and virologic survey to assess the role of wild ruminants in the transmission and maintenance of BTV in Andalusia (southern Spain) between 2006 and 2010.A total of 473 out of 1339 (35.3%) wild ruminants analyzed showed antibodies against BTV by both ELISA and serum neutralization test (SNT). The presence of neutralizing antibodies to BTV-1 and BTV-4 were detected in the four species analyzed (red deer, roe deer, fallow deer and mouflon), while seropositivity against BTV-8 was found in red deer, fallow deer and mouflon but not in roe deer. Statistically significant differences were found among species, ages and sampling regions. BTV RNA was detected in twenty-one out of 1013 wild ruminants (2.1%) tested. BTV-1 and BTV-4 RNA were confirmed in red deer and mouflon by specific rRT-PCR.BTV-1 and BTV-4 seropositive and RNA positive wild ruminants, including juveniles and sub-adults, were detected years after the last outbreak was reported in livestock. In addition, between the 2008/2009 and the 2010/2011 hunting seasons, the seroprevalence against BTV-1, BTV-4 and BTV-8 increased in the majority of provinces, and these serotypes were detected in many areas where BTV outbreaks were not reported in domestic ruminants. The results indicate that wild ruminants seem to be implicated in the dissemination and persistence of BTV in Spain.

Bluetongue Virus in wild ruminants in Europe: Concerns and facts, with a brief reference to bluetongue in cervids in Greece during the 2014 outbreak

“…Moreover, surveillance studies in red deer population have clearly suggested that adult individuals, especially males, are more susceptible to infection (García-Bocanegra et al, 2011;Ruiz-Fons et al, 2014). Although roe deer (Capreolinae subfamily) density population is equal to that of red deer, prevalence of bluetongue is significantly smaller, between 1% and 2% (García-Bocanegra et al, 2011;Corbière et al, 2012;Casaubon et al, 2013). Finally, in samples from Mouflon or Spanish ibex, Bluetongue Virus antibodies have also been detected, with a prevalence ranging from 10% to 33% (Garcia et al, 2009).…”

“…As expected, the red deer aggregation during their mating season (late summer, autumn) has been found to increase significantly the susceptibility to the virus. Moreover, surveillance studies in red deer population have clearly suggested that adult individuals, especially males, are more susceptible to infection (García-Bocanegra et al, 2011;Ruiz-Fons et al, 2014). Although roe deer (Capreolinae subfamily) density population is equal to that of red deer, prevalence of bluetongue is significantly smaller, between 1% and 2% (García-Bocanegra et al, 2011;Corbière et al, 2012;Casaubon et al, 2013).…”

“…Sofar, serotypes 1, 4 and 8 of the virus have been detected in red deer, which highlights the susceptibility of this species to various strains of the virus and its potential role in the expansion of outbreaks of the disease (García-Bocanegra et al, 2011;Corbière et al, 2012;Falconi et al, 2012).…”

Wild ungulates as sentinel of BTV-8 infection in piedmont areas

“…Serological studies report the highest seroprevalences in red deer (up to 66.3%) and fallow deer (Dama dama; up to 50%), both belonging to the Cervinae subfamily (Corbiè re et al, 2012;García-Bocanegra et al, 2011;Linden et al, 2008Linden et al, , 2010Rossi et al, 2010Rossi et al, , 2013Ruiz-Fons et al, 2008). Roe deer were generally found sero-negative (Boadella et al, 2010;Corbiè re et al, 2012) or with sero-prevalences up to 5.1% (Linden et al, 2010;Rossi et al, 2010 and2013;Ruiz-Fons et al, 2008).…”

Evaluation of different adjuvants formulations for bluetongue vaccine

“…Accordind to the World Organisation for Animal Health, 24 different Bluetongue virus (BTV) serotypes are spread worldwide, with little crossreactivity and crossprotection. It naturally infects the domestic and wild ruminants, particularly affecting sheep causing severe clinical disease (Maclachlan et al 2009;Noad and Roy 2009;Bréard et al 2011;García-Bocanegra et al 2011). The use of vaccines containing inactivated or attenuated virus, mono or polivalents, has been the most efficient method of controlling the disease in outbreaks and endemic regions (Gorchs and Lager 2001;OIE 2011).…”