Estudio de la fauna de ixodidae en Mallorca y detección molecular de los patógenos bacterianos que transmiten

Resumen

Ticks are responsible for transmitting a wide range of pathogens. Their particular physiology and biology enhances their capability to transmit virus, bacteria and protozoa with a subsequent devastating effect on cattle and rural economies, as well as being a serious threat to public health. To some tick species, due to its temperate climate and adequate vegetation, the Mediterranean area offers an ideal habitat with optimal biotic conditions. The aim of the present work is to determine the prevalence of ixodid tick fauna in sheep, vegetation and wild fauna in the Balearic Islands and detect and identify the bacterial pathogens hosted by the sampled ticks. From twelve different tick species identified during the course of this study, four (Ixodes arboricola, Ixodes frontalis, Rhipicephalus pusillus and Ornithodoros maritimum) have never been cited in previous studies carried out in the Balearic Islands. In order to determine the prevalence of tick fauna in sheep, tick collection was conducted in two major areas of Majorca. The first one was located in a mountainous area (sampled in 2007) and the second one in the “Llevant” area (sampled in 2009). The animals were extensively checked all around the body e.g. ears, legs, udders and perianal area. In the mountainous area three tick species were identified: Haemaphysalis punctata, Rhipicephalus sanguineus and Rhipicephalus turanicus. In the central area 5 tick species were registered: Hyalomma lusitanicum, Rhipicephalus bursa, Rhipicephalus pusillus, Rhipicephalus sanguineus and Rhipicephalus turanicus. In both areas, the most abundant specie was Rhipicephalus turanicus and the prevalence of infestation (percentage of animals parasitized by ticks) showed a high ratio in both cases (83.7 % in the mountainous area and 66 % in the central area). These figures are in accordance with other figures reported on sheep prevalence of infestation in other Mediterranean areas. The Ixodid infestation per animal in zone 1 (5.1±2.7) and zone 2 (2.7±2.7) was found to be moderate. Sampling on vegetation was carried out between April and October 2010. Tick collection was carried out monthly in three key regions in Majorca: Coastal, mountainous and central areas using dragging methods. The central zone had a higher tick abundance (number of ticks per square metre) (1.6 ticks/m2), followed by the coastal area (0.6 ticks/m2) and finally the mountainous area (0.3 ticks/m2) being the less populated. Eight species were identified: Dermacentor marginatus, Hyalomma lusitanicum, Haemaphysalis punctata, Ixodes frontalis, Ixodes ventalloi, Rhipicephalus pusillus, Rhipicephalus sanguineus and Rhipicephalus turanicus. Hyalomma lusitanicum had the highest tick abundance rate (0.9 ticks/m2), followed by Rhipicephalus turanicus (0.7 ticks/m2), Ixodes ventalloi (0.3 ticks/m2) and Rhipicephalus pusillus (0.2 ticks/m2). The other species presented a much lower tick abundance ratio. Based on the Shannon-Weaver index, the zone with a higher diversity was the central area (3.12), followed by the mountainous (0.94) and coastal area (0.01). The wild fauna sampling work was carried out in collaboration with a recovery center wildlife of the Balearic Islands (COFIB). Thirty eight animals from ten different species (birds and mammals) were analysed. Nine tick species were found and identified: eight belonging to the Ixodidae family (Hyalomma lusitanicum, Ixodes arboricola, Ixodes frontalis, Ixodes ricinus, Ixodes ventalloi, Rhipicephalus pusillus, Rhipicephalus sanguineus y Rhipicephalus turanicus and the ninth one belonging to Argasidae family: Ornithodoros maritimus. The identification and detection of pathogens was performed using a Reverse Line Blotting (RLB) technique in collaboration with Instituto de Salud Carlos III. Seven pathogens genres were scrutinised: Anaplasma/Ehrlichia spp., Bartonella spp., Borrelia spp., Coxiella spp., Francisella spp. and Rickettsia spp. The analysis of the ticks showed a 29 % infection rate. Results for Anaplasma/Ehrlichia spp., Borrelia spp., Francisella spp. y Rickettsia spp were positive. In the case of Anaplasma/Ehrlichia spp, the majority of the samples showed hybridization with the specific MCO probe (specific detection for Anaplasma marginale, Anaplasma centrale, Anaplasma ovis) and others with the ehrlichia muris probe. On the other hand, a sequentation was performed on Borrelia spp. y Francisella spp. for confirmation and species identification. The sequencing results for Borrelia spp. showed the species to be close to the spiroquetas group, a Lyme disease related to Borrelia and R57 group. Francisella positives were identified as Endosimbiontes Franscisella-like. For Rickettsia spp a RLB technique with specific probe was used to identify Rickettsia conorii and rickettsias near Rickettsia aeschlimannii and Rickettsia massiliae. Co-infected hosts were also found, e.g. Anaplasma/Ehrlichia spp.+ Rickettsia spp., Anaplasma/Ehrlichia spp.+ Borrelia spp. Even, triple co infections were also observed. Anaplasma/Ehrlichia spp. + Borrelia spp.+ Rickettsia spp. This study provides crucial data on the prevalence of ixodid fauna in Majorca. Of the 25 different tick species reported to be found in Spain (www.fauna-iberica.mncn.csic.es), this work cites eleven of those species, nine belonging to Ixodid family and one belonging to Argasidae family. It represents the first ever study regarding the pathogen diversity transmitted by ticks in the island of Majorca. This information could be of interest in future studies related to disease epidemiology transmitted by Ixodid in the Balearic Islands, as well as to evaluate the potential risks in case of transmission to humans and animals.