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BackgroundLeishmaniosis is associated with Phlebotomus sand fly vector density, but our knowledge of the environmental framework that regulates highly overdispersed vector abundance distributions is limited. We used a standardized sampling procedure in the bioclimatically diverse Murcia Region in Spain and multilevel regression models for count data to estimate P. perniciosus abundance in relation to environmental and anthropic factors.MethodsTwenty-five dog and sheep premises were sampled for sand flies using adhesive and light-attraction traps, from late May to early October 2015. Temperature, relative humidity and other animal- and premise-related data recorded on site and other environmental data were extracted from digital databases using a geographical information system. The relationship between sand fly abundance and explanatory variables was analysed using binomial regression models.ResultsThe total number of sand flies captured, mostly with light-attraction traps, was 3,644 specimens, including 80% P. perniciosus, the main L. infantum vector in Spain. Abundance varied between and within zones and was positively associated with increasing altitude from 0 to 900 m above sea level, except from 500 to 700 m where it was low. Populations peaked in July and especially during a 3-day heat wave when relative humidity and wind speed plummeted. Regression models indicated that climate and not land use or soil characteristics have the greatest impact on this species density on a large geographical scale. In contrast, micro-environmental factors such as animal building characteristics and husbandry practices affect sand fly population size on a smaller scale.ConclusionsA standardised sampling procedure and statistical analysis for highly overdispersed distributions allow reliable estimation of P. perniciosus abundance and identification of environmental drivers. While climatic variables have the greatest impact at macro-environmental scale, anthropic factors may be determinant at a micro-geographical scale. These finding may be used to elaborate predictive distribution maps useful for vector and pathogen control programs.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-017-2135-3) contains supplementary material, which is available to authorized users.

Leishmania infantum causes human and canine leishmaniosis. The parasite, transmitted by phlebotomine sand flies, infects species other than dogs and people, including wildlife, although their role as reservoirs of infection remains unknown for most species. Molecular typing of parasites to investigate genetic variability and evolutionary proximity can help understand transmission cycles and designing control strategies. We investigated Leishmania DNA variability in kinetoplast (kDNA) and internal transcribed spacer 2 (ITS2) sequences in asymptomatically infected wildlife (n = 58) and symptomatically and asymptomatically infected humans (n = 38) and dogs (n = 15) from south‐east Spain, using single nucleotide polymorphisms (SNPs) and in silico restriction fragment length polymorphism (RFLP) analyses. All ITS2 sequences (n = 76) displayed a 99%–100% nucleotide identity with a L. infantum reference sequence, except one with a 98% identity to a reference Leishmania panamensis sequence, from an Ecuadorian patient. No heterogeneity was recorded in the 73 L. infantum ITS2 sequences except for one SNP in a human parasite sequence. In contrast, kDNA analysis of 44 L. infantum sequences revealed 11 SNP genotypes (nucleotide variability up to 4.3%) and four RFLP genotypes including B, F and newly described S and T genotypes. Genotype frequency was significantly greater in symptomatic compared to asymptomatic individuals. Both methods similarly grouped parasites as predominantly or exclusively found in humans, in dogs, in wildlife or in all three of them. Accordingly, the phylogenetic analysis of kDNA sequences revealed three main clusters, two as a paraphyletic human parasites clade and a third including dogs, people and wildlife parasites. Results suggest that Leishmania infantum genetics is complex even in small geographical areas and that, probably, several independent transmission cycles take place simultaneously including some connecting animals and humans. Investigating these transmission networks may be useful in understanding the transmission dynamics, infection risk and therefore in planning L. infantum control strategies.

The spatial and temporal distribution of Phlebotomus perniciosus (Diptera: Psychodidae) (Newstead, 1911), the sand fly vector of pathogens of public and animal health importance, was investigated in a high sand fly density rural area in Spain using light‐attraction and sticky‐interception traps. Traps were placed inside animal buildings and outside at increasing distance from animals. A total of 8506 sand flies were collected, 87% with light traps. Species frequency differed between trap types. The abundance of P. perniciosus decreased exponentially with increasing distance to animals and, while females were most common in the animal enclosure, males predominated in adjoining storage places. Increasing CO2 concentration had an additional positive effect on female abundance only. Both male and female density increased with rising temperature, and there was some indication that females were more active than males at higher relative humidity. The study confirms that P. perniciosus aggregates around animal premises, although male and female distributions differ and should be analysed separately to account for biological and behavioural differences. This provides further evidence that light traps offer an accurate estimation of the relative spatial and temporal abundance of P. perniciosus, conferring an added value for the study of this species and the risk of pathogen transmission.

Green periurban residential areas in Mediterranean countries have flourished in the last decades and become foci for leishmaniasis. To remedy the absence of information on vector ecology in these environments, we examined phlebotomine sand fly distribution in 29 sites in Murcia City over a 3-year period, including the plots of 20 detached houses and nine non-urbanized sites nearby. We collected 5,066 specimens from five species using “sticky” interception and light attraction traps. The relative frequency of the main Leishmania infantum vector Phlebotomus perniciosus in these traps was 32% and 63%, respectively. Sand fly density was widely variable spatially and temporally and greatest in non-urbanized sites, particularly in caves and abandoned buildings close to domestic animal holdings. Phlebotomus perniciosus density in house plots was positively correlated with those in non-urbanized sites, greatest in larger properties with extensive vegetation and non-permanently lived, but not associated to dog presence or a history of canine leishmaniasis. Within house plots, sand fly density was highest in traps closest to walls. Furthermore, the study provides a guideline for insect density assessment and reporting and is envisioned as a building block towards the development of a pan-European database for robust investigation of environmental determinants of sand fly distribution.