Monitoring of the novel rabbit haemorrhagic disease virus type 2 (GI.2) epidemic in European wild rabbits (Oryctolagus cuniculus) in southern Spain, 2013-2017.

Rabbit hemorrhagic disease (RHD) is a highly infectious disease in European rabbits (Oryctolagus cuniculus), caused by a virus belonging to the genus Lagovirus (RHDV; family Caliciviridae). In 2010, a new genotype of RHDV (RHDV2 or RHDVb, currently designated GI.2) emerged in France, affecting both domestic rabbits, even those vaccinated for the classical RHDV genotypes (currently designated GI.1) and wild rabbits. GI.2 was subsequently identified in other European countries. The aim of the present study was to monitor the GI.2 epidemic in wild rabbits in Andalusia (southern Spain) during the period 2013-2017. At the beginning of summer 2013, high mortalities were detected in wild rabbit populations in southern Spain. A total of 96 affected hunting or protected areas were surveyed. The first outbreak was observed on June 2013. The number of outbreaks sharply increased in 2013 and 2014, with a decreasing trend being observed during the following years. The spatial distribution of GI.2 was not homogeneous, since most of the detected outbreaks were concentrated in the western part of Andalusia. The outbreaks peaked in winter and spring and have been detected in the last five consecutive years, which suggests endemic circulation of GI.2 in wild rabbit populations in Spain. A total of 190 dead rabbits from 87 of the 96 areas surveyed were collected during the study period. Mortality affected rabbits of different age classes, including kittens. RT-PCR confirmed the presence of GI.2 RNA in the livers of 185 of the 190 (97.4%) rabbits. Phylogenetic analysis performed on eleven samples collected in different provinces of Andalusia between 2013 and 2017, showed high nucleotide identity with GI.2 strains Spain, France and Portugal. The results constitute an important step in understanding of the emergence and spread of GI.2 in this country and will provide valuable information for the development of surveillance programs in Europe.

Monitoring of the Bagaza virus epidemic in wild bird species in Spain, 2010.

By the end of August 2010, high mortalities in red-legged partridges (Alectoris rufa) and pheasants (Phasianus colchicus) were detected in several hunting states in the province of Cádiz (southern Spain). Retrospective epidemiological studies revealed that the first clinical signs had been observed in late July-early August. The most common clinical signs were incoordination, disorientation and ataxia. The estimated mean morbidity rates were 37% in partridges and 11% in pheasants. The estimated mean mortality rates were 23% in partridges and 6% in pheasants. The estimated mean case-fatality rates were 38% and 8% in partridges and pheasants, respectively. A total of 19 clinically affected birds from 18 affected hunting states were analysed between August and November 2011. Histopathological analyses revealed encephalitis, myocarditis, leiomyositis, meningoencephalitis and neuritis as the most frequently observed lesions. Molecular analyses identified Bagaza virus (BAGV) as the causative agent of the epidemic. Further studies are needed to determine the source of introduction of the virus into Europe and to elucidate whether wild birds play a role in the epidemiology of BAGV. Surveillance in susceptible bird species, including partridges and pheasants, may be useful for the early detection of BAGV in an area.