Finding of Anopheles (Anopheles) hyrcanus (Pallas, 1771) (Diptera, Culicidae) during the entomological surveillance for West Nile virus in Umbria, Italy.

This study reports the mosquito collections conducted in July-August 2013 in Castiglione del Lago (Umbria Region, Italy) during the entomological surveillance within the West Nile national control program. The mosquito collections showed the noteworthy occurrence of Anopheles hyrcanus s.l. (n = 156; 35.8% of the whole sample), a relatively rare mosquito species in Italy, with molecular analyses con rming that these mosquitoes belong to An. hyrcanus s.s. The same catching site was characterized by a relevant richness in mosquito species, in particular the following were found: Anopheles maculipennis s.l. (n = 146; 33.5% composed by 80% Anopheles melanoon, 13.3% Anopheles maculipennis s.s. and 6.7% Anopheles atroparvus), Culex pipiens s.l. (n = 116; 26.6% composed by 90% Cx. p. pipiens, 5% Cx. p. molestus and 5% Cx. p. pipiens/molestus), Culiseta annulata (n = 10; 2.3%), Aedes albopictus (n = 3; 0.7%), and Anopheles claviger (n = 5; 100%).

Epizootic haemorrhagic disease in Italy: vector competence of indigenous Culicoides species and spatial multicriteria evaluation of vulnerability.

Epizootic haemorrhagic disease (EHD) is an infectious non-contagious viral disease transmitted by Culicoides, which affects wild and domestic ruminants. The disease has never been reported in Europe, however recently outbreaks of EHD occurred in the Mediterranean Basin. Consequently, the risk that Epizootic haemorrhagic disease virus (EHDV) might spread in Italy cannot be ignored. The aim of this study was to evaluate the risk of EHDV transmission in Italy, in case of introduction, through indigenous potential vectors. In Italy, the most spread and abundant Culicoides species associated to livestock are Culicoides imicola and the members of the Obsoletus complex. Culicoides imicola is a competent vector of EHDV, whereas the vector status of the Obsoletus complex has not been assessed yet. Thus, its oral susceptibility to EHDV was here preliminary evaluated. To evaluate the risk of EHDV transmission a geographical information system-based Multi-Criteria Evaluation approach was adopted. Distribution of vector species and host density were used as predictors of potential suitable areas for EHDV transmission, in case of introduction in Italy. This study demonstrates that the whole peninsula is suitable for the disease, given the distribution and abundance of hosts and the competence of possible indigenous vectors.

Vector species of Culicoides midges implicated in the 2012­2014 Bluetongue epidemics in Italy.

In 2012, serotypes 1 and 4 of bluetongue virus (BTV) entered and co­circulated in Sardinia. The following year, BTV­1 spread all over Sardinia and invaded Sicily and the Italian Tyrrenian coast. In 2014, this strain spread extensively in mainland Italy, causing severe outbreaks. In late 2014, BTV­4 was detected in Southern Italy (Apulia region). This study reports the detection of BTV in species of Culicoides (Diptera: Ceratopogonidae) collected in Italy during the epidemics between 2012 and 2014. A total of 2,925 pools (83,102 midges), sorted from 651 collections made on 339 affected farms of 12 Italian regions, were tested for the presence of BTV by real time polymerase chain reaction (RT­PCR). The study clearly shows that Culicoides imicola and Obsoletus complex have played a crucial role in the bluetongue (BT) epidemics in Italy in 2012­2014. Nevertheless, it also shows that other species may have played a role in transmitting BTV during these outbreaks. Culicoides dewulfi and at least 3 species of the Pulicaris complex, namely Culicoides pulicaris, Culicoides newsteadi and Culicoides punctatus, were found positive to BTV. Serotype 1 was detected in all species tested, whereas the BTV­4 was detected in the Obsoletus complex, C. imicola, and C. newsteadi.

The 2011 West Nile disease outbreak in Sardinia region, Italy.

In 2011, strains of West Nile Virus (WNV) belonging to lineage 1 spread for the first time in Sardinia region (Italy). In contrast to previous WNV Italian incursion, the strains were found in Culex modestus and, more surprisingly, they were able to cause severe clinical signs in the affected birds. Based on the partial sequence of the NS3 encoding gene, the Sardinian WNV strains demonstrated a high similarity with the other WNV strains recently detected in the Mediterranean Basin. Nonetheless, the 2011 Sardinian sequences were grouped in a distinct sub-cluster. Both the NS3-249P and NS3-249T genotypes were detected in the Sardinian outbreaks confirming that the co-circulation of different genotypes in the affected population might be common for WNV as for many RNA viruses. No association, however, was observed between virulence and viral genotype.

Orbivirus detection from Culicoides collected on African horse sickness outbreaks in Namibia.

African horse sickness (AHS), a non-contagious infectious disease caused by a RNA virus in the Orbivirus genus within the Reoviridae family affecting all equids, is endemic in sub-Saharan Africa. The virus is transmitted by some species of biting midges in the genus Culicoides (Diptera: Ceratopogonidae). In April 2011, 8 Culicoides collections were performed in 6 districts of 4 regions of the Republic of Namibia (Africa), all within a 400 km radious from the capital Windhoek. Six farms - Khomas (Windhoek and Steinhausen), Erongo (Karibib and Omaruru), Otjozondjupa (Okahandja), and Omaheke (Gobabis) involved in the AHS outbreaks, were sampled. Overall 194,211 Culicoides were collected and identified. Culicoides imicola was largely the most abundant species at all farms (99.4%). A total of 18,687 parous and gravid Culicoides females were assayed for AHS virus (AHSV) by real time RT-PCR. Of the 248 assayed pools, 227 consisted of C. imicola, 13 of Culicoides pycnostictus and 5 of Schultzei complex. Only 1 pool each of Culicoides nivosus, Culicoides leucostictus, and Culicoides tropicalis was assayed. Of the 248 pools examined by real time RT-PCR, 81 tested positive for AHSV, all consisting of C. imicola collected at Omaruru, resulting in a field vector infection rate of 0.91%. No viable AHSV could be isolated from 88 of the tested pools (n = 1,463). However, bluetongue virus (BTV) serotype-1 and 10 were isolated from 3 of these pools, each consisting of 100 C. imicola collected at Windhoek. The present study confirms the relative low infection prevalence in field collected Culicoides and the strict relationship between the high abundance of C. imicola and outbreaks of AHSV.