Date of this Version
Ticks (subphylum Chelicerata: class Arachnida: subclass Acari: superorder Parasitiformes: order Ixodidae) are obligate blood-feeding ectoparasites of global medical and veterinary importance. Ticks live on all continents of the world (Steen et al. 2006). There are approximately 899 species of ticks; the majority are ectoparasites of wildlife and approximately 10% of these are recognized as disease vectors or for their ability to cause direct damage through blood feeding (Jongejan and Uilenberg 2004). Ticks transmit a greater variety of viruses, bacteria, and protozoa than any other blood-feeding arthropod (Dennis and Piesman 2005) and are second only to mosquitoes in terms of their medical and veterinary impact (Sonenshine 1991). Other forms of injury attributed to ticks include anemia, dermatosis, and toxicosis. Worldwide there is growing concern because tick-borne infectious diseases are emerging and resurging (Walker 1998,2005; Telford and Goethert 2004). Many aspects of tick biology have been investigated at the organismal level. However, efforts to understand the genetic basis of host seeking and selection, attachment and feeding, tick-host-pathogen interactions, development and reproduction, and acaricide resistance have been hindered by a lack of tick nucleotide sequence. This situation is rapidly changing with the recent initiation of large-scale sequencing efforts for several tick species. There has been some effort to develop genetic and physical maps to support and exploit tick genomic data but further advances are urgently required. This chapter provides an overview of the current state of tick genomics and highlights areas for future research.