Línea de investigación del SERIDA en enfermedades transmitidas por vectores (garrapatas duras - Ixodidae) en Asturias desde un enfoque "One Health“

Abstract

The Regional Service for Agri-Food Research and Development (SERIDA) is a public agency of the Principality of Asturias whose purpose is to contribute to the modernization and improvement of the regional agri-food sector's capabilities by promoting and implementing agri-food research and technological development. The Animal Health Department is located at the Deva Animal Biotechnology Center in Gijón and focuses its activities on the study of diseases in domestic and wild animals. In 2010, we decided to begin a line of study on vectors and the diseases they transmit, since, according to the WHO, these represent more than 17% of all infectious diseases and cause more than 700,000 deaths each year. Of the variety of existing vectors, we chose to begin with hard ticks (Family Ixodidae) due to the characteristics of Asturias in terms of climate and vegetation, the abundance and variety of domestic and wild fauna, and the high incidence of human (Lyme, etc.) and animal (piroplasmosis, etc.) diseases observed in the region. After obtaining funding for various projects (RTA2011-00008-C02-01; RTA2013-00013-C04-04; and RTA2017-00055-C02-02) and combining tick capture techniques from vegetation with tick collection from domestic and wild animals throughout the year and over several years, we were able to establish the genera and species present in Asturias, their abundance in various areas, and their seasonal dynamics. Furthermore, since most of these projects have been coordinated with the Neiker (National Research Institute of the Basque Country), we have been able to compare the results obtained in two areas that, despite being located on the Cantabrian Coast, present differences in terms of climate, habitat, and faunal composition. Based on the studies carried out, 12 species of ticks belonging to four genera have been identified in Asturias: Ixodes (I. ricinus, I. inopinatus, I. hexagonus, I. frontalis, I. acuminatus, I. canisuga), Haemaphysalis (H. concinna, H. punctata, and H. inermis), Dermacentor (D. reticulatus and D. marginatus), and Rhipicephalus (R. bursa). I. ricinus is by far the most abundant species in the vegetation of our region, contributing 87%, 95%, and 60% of the total larvae, nymphs, and adults captured in the study conducted in the Sierra de Sueve between 2012 and 2014. Regarding the pathogens investigated, we began with piroplasmas and anaplasmas, paying special attention to Lyme borreliosis, studying Coxiella burnetii in the sylvatic cycle of Q fever, and the association of certain rickettsioses with ticks of the genus Dermacentor, which act not only as vectors but also as reservoirs for these bacteria. Since most of these pathogens are difficult to grow under laboratory conditions, the development of molecular techniques in recent decades has greatly facilitated their study. It is known that birds can be infested by ectoparasites such as mites, ticks, fleas, and lice. These ectoparasites, especially ticks, can carry various pathogens, and both ticks and pathogens can be dispersed by birds over short, medium, and long distances, posing a risk to local host populations in different geographic regions. For this reason, one of the most recent studies we conducted was the collection of ticks from 1,698 birds ringed in Asturias by the Torquilla Group during the period 2021-2023. We detected a tick parasitism prevalence of 2.5% and identified the species I. ricinus, I. frontalis, and H. concinna. Regarding the prevention and control of these diseases, there are two possible strategies: one aimed at combating the different pathogens and the other focused on combating the vector. In this sense, the development of a tick vaccine is a potential approach to protect people from multiple tick-borne diseases. The major challenge is to develop a vaccine that is sufficiently effective against most tick species.