Factors influencing the presence of sand flies in Majorca (Balearic Islands, Spain) with special reference to Phlebotomus pernicious, vector of Leishmania infantum

Background: Although the Mediterranean island of Majorca is an endemic area of leishmaniosis, there is a lack of up-to-date data on its sand fly fauna, the last report dating from 1989. The aim of the present study was to provide information on the current sand fly distribution, the potential environmental factors favoring the presence of Phlebotomus perniciosus and which areas are at risk of leishmaniosis. Methods: In July 2008 sand fly captures were carried out in Majorca with sticky castor oil interception traps. The capture stations were distributed in 77 grids (5x5 km2) covering the entire island. A total of 1,882 sticky traps were set among 111 stations. The characteristics of the stations were recorded and maps were designed using ArcGIS 9.2 software. The statistical analysis was carried out using a bivariate and multivariate logistic regression model. Results: The sand fly fauna of Majorca is composed of 4 species: Phlebotomus perniciosus, P sergenti, P. papatasi and Sergentomyia minuta. P. perniciosus, responsible for Leishmania infantum transmission, was captured throughout the island (frequency 69.4 %), from 6 to 772 m above sea level. Through logistic regression we estimated the probability of P. perniciosus presence at each sampling site as a function of environmental and meteorological factors. Although in the initial univariate analyses the probability of P. perniciosus presence appeared to be associated with a wide variety of factors, in the multivariate logistic regression model only altitude, settlement, aspect, drainage hole construction, adjacent flora and the proximity of a sheep farm were retained as positive predictors of the distribution of this species. Conclusions: P. perniciosus was present throughout the island, and thereby the risk of leishmaniosis transmission. The probability of finding P. perniciosus was higher at altitudes ranging from 51 to 150 m.a.s.l., with adjacent garrigue shrub vegetation, at the edge of or between settlements, and in proximity to a sheep farm

Importance of individual analysis of environmental and climatic factors affecting the density of Leishmania vectors living in the same geographical area: the example of Phlebotomus ariasi and P. perniciosus in northeast Spain.

The aim of the present study was to determine the role of specific environmental and climatic factors affecting the distribution and density of Phlebotomus ariasi and P. perniciosus, the proven vectors for Leishmania infantum in Spain. An entomological study was carried out in July 2006 in the province of Lleida with sticky traps set in their diurnal resting places at altitudes ranging from 86 to 1,755 m above the mean sea level (339 sites were sampled). Bivariate analysis revealed that factors such as altitude, bioclimatic zone, temperature, precipitation, sampling site (site relative to settlement, site situation, site category), wall vegetation, particular environment (in this case a natural park), general environment, adjacent natural vegetation and land cover were significantly associated with sand fly densities. The multivariate model for P. perniciosus revealed that its density was affected by site and land cover. Specifically, paved driveways correlated negatively with vector density (Incidence Risk Ratio (IRR): 0.41) and arable land cover correlated positively (IRR: 4.59). In the case of P. ariasi, a significant correlation was observed with the altitude and bioclimatic zone, with density increasing at >800 m above the mean sea level (IRR: 3.40) and decreasing in the meso-Mediterranean bioclimatic zone (IRR: 0.08). Both species were mostly found in agricultural and forest areas far from domestic environments. However, the two species correlated differently with altitude, bio-climate, vegetation, temperature and precipitation, which emphasises the importance of their individual analysis in studies regarding risk of leishmaniasis transmission

Current status of Leishmaniosis in the Balearic Islands

Podeu consultar el llibre complet a: http://hdl.handle.net/2445/103042Data on leishmaniosis and its vectors (sand flies) in the Balearic Islands are scarce and restricted mainly to Majorca. According to the official data, the overall rate of human leishmaniosis (HL) is 0.7-3.5 cases per year/100,000 inhabitants (for the period 2001-2015), and the reported prevalence of canine leishmaniosis (CanL) varies between 0 and 45%, depending on the island and the dog population tested. In the present study, we investigated the sand fly fauna and current status of CanL in the Balearic Islands. Four sand fly species were captured: Phlebotomus perniciosus, a known vector in the Mediterranean area, P. sergenti, P. papatasi and Sergentomyia minuta. P. perniciosus was found throughout the island of Majorca, from sea level to the mountains, being detected in 70% of the capture sites and with a density of 6.7 specimens/m2. The global density of P. perniciosus in Minorca was of 3.4 specimens/m2, which constitutes a significant decrease compared to the results of a previous study performed 20 years ago. The influence of environmental factors on the presence or density of P. perniciosus differed according to the physiography of the area studied. A standard questionnaire sent to the local veterinarians in the Balearic Islands revealed that 73.8% of veterinarians had confirmed CanL cases in the previous 12 months and thought the disease was increasing in Minorca. The global seroprevalence of CanL in Minorca was 24%, being 31% among animals who had never left the island, which shows the existence of an autochthonous focus of CanL unrelated with an increasing vector density

Identification of blood meals in field captured sand flies by a PCR-RFLP approach based on cytochrome b gene

Leishmaniasis is a vector-borne disease transmitted byphlebotominesand flies. Information about blood meal preferences in sand flies is essential to understand the epidemiology of the diseaseto adopt control measures.In previous studies, a polymerase chain reaction (PCR) of 359 bp fragment of the conserved gene cytochrome b (cyt b) and further sequencing were applied in the study of blood meal sources in sand flies collected in the area of a leishmaniasis outbreak insouthwest Madrid, Spain, providing significant information about blood meal preferences in the focus. In this work, aPCR-restriction fragment length polymorphism(RFLP)targeting afragment of 359 bpof vertebrate cytbgene was developed. Restriction endonucleasesHaeIII and HinfI generated specific patterns consistent with the blood meal sources found in sandflies. The protocol has been validatedwithtwenty sixengorged females collected in the field with CDC traps.Blood meals from nine vertebrateswere identified based on PCR-cytb and sequencing -human, dog, cat, horse, hare, rabbit, sheep, goat and chicken - and mixed blood meals (sheep/human;sheep/goat) and successfully distinguished byPCR-RFLP. Therefore, thisapproachis anefficient and reliable alternative method to be applied in entomological surveys

Importance of individual analysis of environmental and climatic factors affecting the density of Leishmania vectors living in the same geographical area: the example of Phlebotomus ariasi and P. perniciosus in northeast Spain

The aim of the present study was to determine the role of specific environmental and climatic factors affecting the distribution and density of Phlebotomus ariasi and P. perniciosus, the proven vectors for Leishmania infantum in Spain. An entomological study was carried out in July 2006 in the province of Lleida with sticky traps set in their diurnal resting places at altitudes ranging from 86 to 1,755 m above the mean sea level (339 sites were sampled). Bivariate analysis revealed that factors such as altitude, bioclimatic zone, temperature, precipitation, sampling site (site relative to settlement, site situation, site category), wall vegetation, particular environment (in this case a natural park), general environment, adjacent natural vegetation and land cover were significantly associated with sand fly densities. The multivariate model for P. perniciosus revealed that its density was affected by site and land cover. Specifically, paved driveways correlated negatively with vector density (Incidence Risk Ratio (IRR): 0.41) and arable land cover correlated positively (IRR: 4.59). In the case of P. ariasi, a significant correlation was observed with the altitude and bioclimatic zone, with density increasing at >800 m above the mean sea level (IRR: 3.40) and decreasing in the meso-Mediterranean bioclimatic zone (IRR: 0.08). Both species were mostly found in agricultural and forest areas far from domestic environments. However, the two species correlated differently with altitude, bio-climate, vegetation, temperature and precipitation, which emphasises the importance of their individual analysis in studies regarding risk of leishmaniasis transmissio

Current status of Leishmaniosis in the Balearic Islands

Podeu consultar el llibre complet a: http://hdl.handle.net/2445/103042Data on leishmaniosis and its vectors (sand flies) in the Balearic Islands are scarce and restricted mainly to Majorca. According to the official data, the overall rate of human leishmaniosis (HL) is 0.7-3.5 cases per year/100,000 inhabitants (for the period 2001-2015), and the reported prevalence of canine leishmaniosis (CanL) varies between 0 and 45%, depending on the island and the dog population tested. In the present study, we investigated the sand fly fauna and current status of CanL in the Balearic Islands. Four sand fly species were captured: Phlebotomus perniciosus, a known vector in the Mediterranean area, P. sergenti, P. papatasi and Sergentomyia minuta. P. perniciosus was found throughout the island of Majorca, from sea level to the mountains, being detected in 70% of the capture sites and with a density of 6.7 specimens/m2. The global density of P. perniciosus in Minorca was of 3.4 specimens/m2, which constitutes a significant decrease compared to the results of a previous study performed 20 years ago. The influence of environmental factors on the presence or density of P. perniciosus differed according to the physiography of the area studied. A standard questionnaire sent to the local veterinarians in the Balearic Islands revealed that 73.8% of veterinarians had confirmed CanL cases in the previous 12 months and thought the disease was increasing in Minorca. The global seroprevalence of CanL in Minorca was 24%, being 31% among animals who had never left the island, which shows the existence of an autochthonous focus of CanL unrelated with an increasing vector density