Influence of environmental factors on the occurrence of gastrointestinal and cardiopulmonary nematodes in the red fox in the semi-arid Mediterranean areas of the Iberian Peninsula.

Human-induced ecosystem fragmentation is one of the drivers causing wildlife migration from their natural habitats to urban areas, among other reasons. The red fox (Vulpes vulpes) is the most abundant wild canid in the semi-arid Mediterranean areas of the Iberian Peninsula. Water scarcity may result in areas shared by synanthropic fox populations and domestic animals becoming hotspots for parasite transmission. This study describes the gastrointestinal and cardiopulmonary nematode species affecting fox populations in these semi-arid areas and the influence of environmental variables on parasite abundance. A total of 167 foxes collected from 2015 to 2021 in the Region of Murcia (SE Spain) were analysed. Parasite abundance and spatial distribution were evaluated using environmental variables and host characteristics with a Generalised Linear Model and the Moran index. Eleven species (seven from the gastrointestinal tract and four from the cardiopulmonary tract) were described. The influence of biotic and abiotic variables was studied for Angiostrongylus vasorum, Crenosoma vulpis, Uncinaria stenocephala, Toxocara canis and Toxascaris leonina. Temperature, humidity and areas of forest or agricultural land influenced the abundance of these parasites, providing optimal conditions for free-living stages of the direct life cycle nematodes and intermediate hosts. Absolute abundance distribution maps showed defined locations for C. vulpis, T. canis and T. leonina. The results for U. stenocephala, T. canis and T. leonina were particularly important as their higher abundance levels were found close to anthropized areas, which need to be carefully evaluated to prevent transmission of these nematodes between domestic and wild canids and human health.

Pearsonema plica in red foxes (Vulpes vulpes) from semi-arid areas of the Iberian Peninsula.

The nematode Pearsonema plica is a parasite infecting the urinary bladder of carnivores, with a described prevalence ranging from 1 to 90%. This parasite needs earthworms as intermediate host to complete its life cycle, being the red fox (Vulpes vulpes) a definitive host. The objective of this study was to analyse the prevalence and intensity of P. plica in the red fox population from the Region of Murcia (SE Spain), an area with semi-arid Mediterranean climate. The urinary bladder, kidneys and ureters of 167 red foxes were collected at necropsy, opened and observed to detect adult parasites. The influence of host variables (sex, age and body condition using Kidney Fat Index) and environmental variables (Normalized Difference Vegetation Index, Normalized Difference Moisture Index, Bare Soil Index, temperature, radiation, evapotranspiration, precipitation, Corine Land Cover categories and distance to urban areas) were evaluated using a Generalised Linear Model. Moran index was used to evaluate the parasite spatial aggregation. The prevalence found was very low (2.4%; median abundance 0 nematodes per fox; median intensity 7.5 nematodes per parasitized fox), which contrast with those described in other red fox populations in Europe. Environmental variables had a significant influence on the occurrence of P. plica, being NDMI, mean summer precipitation, percentage of forest and agricultural areas positively associated with P. plica abundance. The south-eastern Iberian Peninsula has a semi-arid climate that hinders the development of the life cycle of this nematode, which justifies its occurrence in specific areas where there are the suitable environmental conditions for the presence of earthworms. However, although semi-arid Mediterranean areas do not seem to be favourable carnivores to be parasitized by P. plica, we cannot underestimate the risk that exists in those areas where, either naturally or by human activity, there are environmental factors that favor the presence of this nematode.

Density assessment and reporting for Phlebotomus perniciosus and other sand fly species in periurban residential estates in Spain.

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.

On how trap positioning affects phlebotomine sand fly density estimations.

There is a need for standardizing sand fly sampling methodology and guidance on trap positioning for quantitative sand fly studies. We investigated differences in sand fly density with 'sticky' interception and CO2 -light attraction traps, in relation to trap distance to the ground and the presence or absence of a continuous or discontinuous (wire mesh) vertical surface adjacent to the trap. The study, conducted in a dog kennel in southeast Spain, lasted 48 days and collected 692 Phlebotomus papatasi, P. perniciosus, P. ariasi and Sergentomyia minuta specimens. There were no significant differences between species with respect to trap position. Overall, density in sticky traps was highest closest to the ground and next to the continuous vertical surface, followed sequentially by traps similarly placed adjacent to the wire mesh and those hanging from a rope across the kennel yard. In contrast, density in CO2 -light traps was highest in traps hanging from the rope near the ground, followed by those next to the continuous vertical surface. The overall negative relationship between sand fly density and ground distance was not significant for CO2 -light traps next to the continuous vertical surface. Modelling also suggested that sand flies do not use the wire mesh to move vertically.

A spatial ecology study in a high-diversity host community to understand blood-feeding behaviour in Phlebotomus sandfly vectors of Leishmania.

Molecular studies indicate that Phlebotomine sandflies (Diptera: Psychodidae) blood feed on many vertebrate species, of which only a few are proven parasite reservoirs. Investigating sandfly vector feeding preferences is therefore important and requires taking into account the availability and accessibility of host species. In terms of the latter, it is necessary to consider the metabolic cost to the insect of reaching the host and moving on to a suitable breeding site. The present study used statistical modelling to compare the feeding patterns of Phlebotomus perniciosus (n = 150), Phlebotomus papatasi (n = 35) and Phlebotomus ariasi (n = 7) on each of an average of 30 host species in a wildlife park in Murcia, Spain. Sandfly feeding movement costs were estimated as a function of the distance and altitude gradients saved by the insect, assuming that they displayed 'site fidelity'. Most (87%) engorged females were caught <100 m from the host on which they had fed. Although the percentage of bloodmeals was highest on fallow deer (Dama dama) (30%) and red deer (Cervus elaphus) (26%), the predicted feeding probability after considering movement cost was highest for red deer and common eland (Taurotragus oryx), and positively associated with host census. These results suggest that, under similar circumstances, sandflies prefer to feed on some host species more than on others.

Epidemiological and genetic studies suggest a common Leishmania infantum transmission cycle in wildlife, dogs and humans associated to vector abundance in Southeast Spain.

Leishmania infantum infection was investigated in 202 wild carnivores, rodents and lagomorphs in Southeast Spain using a real-time PCR (rtPCR) in skin and organ samples, mostly spleen. Lesions compatible with leishmaniosis were not observed in any of the animals. Prevalence defined as the percentage of rtPCR-positive animals was 32% overall, and 45% in foxes (n = 69), 30% in rabbits (n = 80) and stone martens (n = 10), 19% in wood mice (n = 16), 0% in black rats (n = 10) and ranged between 0% and 100% in other minoritarian species including badgers, wild cats, wolves, raccoons, genets and hares. Most infected rabbits were rtPCR-positive in skin and not in spleen samples and the opposite was the case for foxes (p < 0.05). L. infantum prevalence was lowest in spring following months of non-exposure to phlebotomine sand fly vectors, and spatially matched recently estimated Phlebotomus perniciosus vector abundance and the prevalence of subclinical infection in dogs and humans. Prevalence increased with altitude and was greater in drier and less windy South and West compared to the coastal Southeast of the study area (p < 0.05). Genetic diversity of L. infantum from foxes, investigated by PCR-restriction fragment length polymorphisms of kinetoplast DNA, revealed B genotype in all animals, which is frequent in people and dogs in the Iberian Peninsula and Morocco. The study provides further evidence that subclinical L. infantum infection is widespread in wildlife with prevalence depending on environmental factors and that parasite tissue tropism may vary according to host species. Moreover, it suggests that sylvatic and domestic transmission cycles are closely interconnected.

Investigations of Phlebotomus perniciosus sand flies in rural Spain reveal strongly aggregated and gender-specific spatial distributions and advocate use of light-attraction traps.

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.

A cross-sectional study of the impact of regular use of insecticides in dogs on Canine Leishmaniosis seroprevalence in southeast Spain.

The relationship between Canine Leishmaniosis (CanL) seroprevalence and regular use of topical insecticides was investigated in 800 pet dogs with no visible signs of CanL in Murcia, southeast Spain in 2011. Dogs were clients to 17 veterinary practices and were analyzed for Leishmania infantum antibodies in blood plasma using two commercial ELISAs (Ingezim, Ingenasa®, Spain; Leishcan, Hipra®, Spain). Owners were interviewed to gather data on dog related variables. They included date of birth, home address and frequency, duration and timing of insecticide treatments used to prevent ectoparasite infestations. The dog's residence was georeferenced and environmental data potentially associated with the dog's risk of L. infantum infection was obtained. A mixed logistic regression model was then developed to analyze the relationship between the dog's serological status and insecticidal treatment adjusted for demographic and environmental variables. Overall, CanL seroprevalence (95% confidence limits) was 18% (16-21%) including 11% in dogs not using insecticide treatments (n=60) and 19% in those using them (n=740) (p>0.05). At least 16 different insecticide products were used and 73%, 26% and 1% of dogs received 1, 2 and 3 products a year. The most frequent commercial brands used and the only ones in the market claiming anti-sandfly activity, were Scalibor collars (deltametrin 40mg/g; MSD®), Advantix pipettes (permethrin 500mg/ml and imidacloprid 100mg/ml; Bayer®) and Exspot spot-on pipettes (permethrin 715mg/ml; MSD®). Seroprevalence was 9%, 16%, 20%, 22% and 25% for dogs with Scalibor collars plus Advantix pipettes, Scalibor collars plus ExSpot pipettes, Advantix pipettes alone, Scalibor collars alone and Exspot pipettes alone, respectively. The multivariable model confirmed a significant reduction in the risk of Leishmania spp. seropositivity in dogs using the Scalibor and Advantix combination compared to those using either product alone and provided evidence of greatly increased risk of CanL in rural areas situated at 300-500m altitude and average March-July temperatures of 18.6-19°C. The study highlights the difficulty in controlling CanL infection by means of insecticide use alone and that it could be improved by using the Scalibor and Advantix combination and identifying and targeting specific geographical areas.

Spatial distribution of human asymptomatic Leishmania infantum infection in southeast Spain: a study of environmental, demographic and social risk factors.

Recent PCR studies indicate that asymptomatic L. infantum infection is common in people in southern Europe. Understanding its spatial distribution is a requisite to evaluate the public health implications and to design disease control schemes. We investigated infection in blood samples from 657 donors in southeast Spain using PCR and antibody ELISA. They came from 19 blood centers and were interviewed about their residence, occupation, dog ownership and Leishmaniosis awareness. The percentage of PCR and ELISA positives were 8% (49/618) and 2% (13/657). Donor's residences were spatially clustered around blood donning centers and PCR prevalence was 18% in rural municipalities with 20-1330 inhabitants, 12% in those with 1467-5088 inhabitants and 3% in larger communities, and was associated with dog ownership (p<0.05). Further analysis of data from rural donors indicated that PCR status was strongly related to the climate, altitude and soil type in the donor's residence area and not to other demographic or sociologic variables. Mixed logistic regression analysis predicted PCR prevalence to be greatest in the 200-300m altitude range with a mean spring-summer (time of highest vector activity) temperature of 18.4-19.0°C. A temperature and altitude risk map was generated that will provide the basis for elaborating evidence-based vector surveillance studies.

Effects of reclaimed waters on spectral properties and leaf traits of citrus orchards.

Effects resulting from the use of reclaimed waters on mandarins and grapefruits are evaluated by measuring the spectral responses of their canopies and the anatomy and the chlorophyll content of their leaves against control trees irrigated with waters provided by an interbasin transfer. Spectral responses from the red (R) and near-infrared (NIR) wavelength bands, and its normalized ratio (NDVI), were acquired from a hyperspatial flight conducted after a low-moderate exposition to reclaimed waters. Chlorophyll and leaf and palisade/spongy ratio thicknesses were analyzed after a moderate-high exposition. Significant differences between controls and treatments were detected in mandarins in R and leaf chlorophyll, but not in grapefruits, likely because of their higher tolerance to saline waters. Reused waters did not affect either NIR-NDVI or anatomy traits. Hyperspatial sensing techniques are suitable for detecting chlorophyll dynamics, but NIR information and related vegetation indices may mask the detection of periods of saline stress in citrus orchards.