Background: This report describes L. infantum infection seroprevalence in dogs in Spain through data obtained from peer-reviewed literature and a cross-sectional serological survey assessing epidemiological and habitat variables as risk factors for infection. The study also provides preliminary sand fly species distribution data and indicates factors affecting their distribution and density. Methods: Three different studies were conducted in Spain: (i) a peer-reviewed literature seroprevalence survey (1985–2019); (ii) a cross-sectional serological survey (2011–2016); and (iii) a preliminary entomological survey (2013–2014). In the cross-sectional serological survey, 1739 dogs from 74 different locations including 25 Spanish provinces were tested for L. infantum by indirect immunofluorescence antibody test (IFAT) (antibody titre ≥ 1:100). Seroprevalence of L. infantum infection was analysed by province and bioclimatic zone. Statistics were used to analyse relationships between several dog- and environment-related variables and L. infantum seroprevalence. In parallel, during 2013–2014, sand flies were collected across the Iberian Peninsula and the Balearic Islands using CDC light traps to examine relationships between habitat-related factors and sand fly species densities (number of sand flies per trap per hour). Results: The literature review revealed that the provinces showing the highest seroprevalence were Balearic Islands (57.1%), Ourense (35.6%), Málaga (34.6%) and Cáceres (34.2%), and those showing the lowest seroprevalence were Vizcaya (0%), Cantabria (2.0%) and Álava (3.3%). In our survey, anti-Leishmania IgG antibodies were detected in 176 of the 1739 dogs rendering a seroprevalence of 10.12%. Percentage seroprevalence distributions significantly varied among bioclimatic belts. Seropositivity for L. infantum was related to size (large breed dogs versus small) and were significantly higher in younger dogs (≤ 1 years-old). In the entomological survey, 676 sand flies of five species were captured: 562 (83.13%) Phlebotomus perniciosus; 64 (9.47%) Sergentomyia minuta; 38 (5.62%) P. ariasi: 6 (0.89%) P. sergenti; and 6 (0.89%) P. papatasi. Phlebotomus perniciosus showed a greater density in the thermo-Mediterranean than in the meso-Mediterranean zone. Densities of S. minuta and P. ariasi were significantly higher in rural habitats. Conclusions: This updated seroprevalence map of L. infantum infection in dogs in Spain defines non-endemic, hypoendemic, endemic and hyperendemic areas, and confirms P. perniciosus as the most abundant sand fly vector in Spain.

Controlling canine vector-borne diseases (CVBD) is a major concern, since some of these diseases are serious zoonoses. This study was designed to determine seropositivity rates in Spain for agents causing the following five CVBD: leishmaniosis (Leishmania infantum: Li), heartworm (Dirofilaria immitis: Di), ehrlichiosis (Ehrlichia canis: Ec), anaplasmosis (Anaplasma phagocytophilum/Anaplasma platys: An) and Lyme disease (Borrelia burgdorferi: Bb).

Thelazia callipaeda (Spirurida, Thelaziidae), eyeworms, are known as the causative agents of thelaziosis, initially described in Asia and, later on, over the last decade, also in some European countries (e.g., Italy, France, Germany and Switzerland). In June 2010, the first case of canine thelaziosis was observed in central western Spain (La Vera region, Cáceres) and subsequent epidemiological investigation is reported in the present study. This study describes the first autochthonous cases of infection by T. callipaeda in dogs from central western Spain where the first case of eyeworm infection was reported. A total of 456 dogs was examined in this geographical area. Thelazia callipaeda eyeworms were observed in 182 (39.9%) animals, of which 28 showed apparent clinical signs (i.e., conjunctivitis, oedema, epiphora and petechiae). A total of 762 adult nematodes (214 males, 548 females; mean infection rate of 4.18; SD 4.74) were collected with cotton swabs or by flushing of the conjunctival sac of infected animals using physiological saline solution. Nematodes were identified as T. callipaeda according to the morphological keys and molecular analysis of sequences of a portion of the mitochondrial cytochrome c oxidase subunit 1 (cox 1) gene. The sequences were identical to those representing T. callipaeda haplotype 1, previously reported in Europe. The high infection rate of canine thelaziosis herein reported suggests that practitioners should include this eye infection amongst differential diagnoses of ocular diseases in dogs from this area of Spain or those moving across this area of Spain. Based on the high infection prevalence recorded, the potential public health risk to humans from this region is also discussed.