Molecular Characterization of Culex Theileri from Canary Islands, Spain, a Potential Vector of Dirofilaria Immitis

Abstract

Dirofilaria immitis is the causal agent of heartworm diseases and of human pulmonary dirofilariosis. The infection is transmitted by several species of culicid mosquitoes that are frequently able to bite both animal reservoirs and humans. Canary Islands (Spain) constitute a well documented endemic area of canine dirofilariosis in which the mosquito species involved in the transmission of D. immitis are not known. The objectives of the present work were the identification of vectors of this parasite in Canary Islands and their molecular characterization. A total of 1219 female mosquitoes were captured. The most abundant species was Culex theileri (52.26%) followed by Cx. pipiens (35.44%), Anopheles cinereus hispaniola (6.23%), Culiseta longiareolata (5.74%), and Culex laticintus (0.33%). PCR was applied for the detection of larval D. immitis DNA in mosquitoes. D. immitis DNA was observed in the abdomen of one Cx. theileri female: 0.082% of the entire mosquito population and 0.17% in Cx. theileri. A molecular identification of Cx. theileri, the potential mosquito vector of dirofilariosis in this zoonotic focus in Canary Islands of Spain, has been made for first time based on sequences of the 18S rRNA gene, the second internal transcribed spacer (ITS2) of ribosomal DNA and the barcode region of the cytochrome c oxidase I (cox1) gene of mitochondrial DNA, allowing a broad mosquito molecular basis for future populations genetic analyses of this vector species. Parasitological and entomological molecular results suggest that Cx. theileri is a potential natural vector of D. immitis in Canary Islands.

Assessment Heartworm Disease in the Canary Islands (Spain): Risk of Transmission in a Hyperendemic Area by Ecological Niche Modeling and Its Future Projection

“…theileri from all islands from the data obtained by the Canary Islands Entomological Surveillance of the Instituto de Enfermedades Tropicales y Salud Pública de Canarias, Melero-Alcíbar et al [29,30], Morchón et al [12,31], the Spanish Government [32], and Serafín-Pérez et al [33], together with distributional records for the species from GBIF [34] for the Canary islands due to the few records of the species from this archipelago, these being the only Culex spp. species on the islands dated and transmitters of the disease in the Canary Islands and Spain to date [12][13][14]. Occurrence data were processed at a spatial resolution of 1 km 2 to avoid biases associated with the spatial autocorrelation of aggregate occurrence records.…”

“…In addition, one of the species transmitting the disease, Cx. theileri Theobald, 1903, has been detected in Gran Canaria and Tenerife [12] as well as Cx. pipiens Linnaeus, 1758, a vector transmitting the disease in the Iberian Peninsula [13,14].…”

Morphological Aberrations of the Dirofilariasis, Sindbis Fever and West Nile Fever Vector Culex Theileri (Diptera: Culicidae) in Iran

“…Culex theileri is a known vector of avian Plasmodium in Portugal ( 4 ), Turkey ( 5 ) and Spain ( 6 ); avian Haemoproteus in Spain ( 6 ); Dirofilaria immitis (canine heart worm) in Portugal ( 7 ), Iran ( 8 ) and Canary Islands of Spain ( 9 ); West Nile virus in South Africa ( 10 ) and Iran ( 11 ); Sindbis virus in South Africa ( 10 , 12 ) and Iran ( 13 ); Japanese encephalitis virus in China ( 14 ); and Rift Valley fever virus in South Africa ( 15 , 16 ). Additionally, some insect-specific flaviviruses (ISFs) were isolated from this species in Myanmar ( 17 ), Portugal ( 18 , 19 ), Spain ( 18 ) and Turkey ( 20 ) that are designated Culex theileri flavivirus (CxthFV or CTFV).…”