VETORES E HOSPEDEIROS INTERMEDIÁRIOS INVERTEBRADOS

Abstract

The diseases t ransmit ted by arthropods and other invertebrate hosts represent an enormous burden to human and animal health, if we consider that 3.3 billion people are at risk of acquiring malaria, and that , in 2010, malaria deaths were est imated at 655000 (WHO, 2012), that schistosomiasis and geohelminthiasis affect two billion humans, causing morbidity to 300 million (WHO, 2006), and that 350 million people are at risk of cont ract ing leishmaniasis (WHO, 2010), only to ment ion a few parasit ic diseases. Furthermore, the picture is wider, and the incidences of vector-borne viral diseases have been increasing sharply, even in places previously considered unlikely, as seen in recent outbreaks of West Nile and Chikungunya viruses, not forgetting dengue, a growing pandemic from which Portugal is not exempt . The prevent ion and cont rol of vector-borne diseases and of those t ransmit ted by intermediate invertebrate hosts are highly complex, as a consequence of the difficulty to predict the invertebrate host behaviour, of the diversity of the biotopes associated with them, and of their ability to evade cont rol measures, resist ing insect icides, molluscicides and larvicides. Another level of complexity is added by the scarce informat ion on the interact ions between these hosts and their pathogens, especially on the mechanisms regulating the infection process. The impact of vector-borne diseases, as well as the increasing awareness about the implicat ions of climate change on human health, has driven society and the scient ific community into a growing interest on the vectors of major vector-borne diseases, and how to cont rol, eliminate or even eradicate them. In the past , the success of controlling these diseases has always been associated with vector cont rol which, coupled to the rapid technological evolut ion and the publicat ion of genomes from many vector species and invertebrate intermediate hosts (ht tp://www.vectorbase.org/; ht tp:// biology.unm.edu/biomphalariagenome/ consortium.html), has boosted the interest on these vectors. The study of vectors and intermediate invertebrate hosts has been st rongly implemented, with external impact , at the IHMT, particularly in african portuguese-speaking count ries (PALOPs), cont ribut ing widely for the general scient ific knowledge in this area, including the implementat ion of innovat ive approaches that already cont ributed successfully for the reduct ion of the incidence of various diseases t ransmitted through these invertebrates, as those discussed below. This chapter aims to review various aspects of the biology of vectors and intermediate hosts, as well as their interact ion with the pathogens they t ransmit . The intent ion is not to make an exhaust ive review but rather to highlight some relevant aspects that use both t raditional and more recent and innovat ive approaches, bearing in mind the challenges posed by new technologies applied to the study and cont rol of both vectors and intermediate hosts, with references to the contribution of the research carried out at the IHMT over the years, which was central for the cont rol of many diseases with st rong impact on human health and veterinary medicine. Various aspects of the bio-ecology of two t rypanosomat id vectors, of the interact ions between Plasmodium and malaria vectors and of the role of snails as intermediate hosts of helminthes, will be addressed.