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228 CHAPTER 11

Sebaceous gland Spirochetal Turkey ticks
Seed ticks Tachycardia Ulceroglandular
Southern Tick–associated Thrombocytopenia Wright’s-Giemsa
Rash Illness Tularemia

INTRODUCTION that are tick-borne are presented in this chapter, some of
which are not considered strictly as being parasite based.
Ticks are singularly well adapted to the role of the vec- Therefore, some overlap occurs between parasitic and
tor, both in the practice of feeding from warm-blooded bacterial infections. Both types of infections, of which
animals with an infectious disease and in the process some are strictly parasitic and some which are bacterial
passing certain infective organisms into the subsequent and that become intracellular inclusions infecting blood
host. Ticks as vectors are some of the most efficient cells, will be presented in this section.
transmitters of parasites and other bacterial and viral Ticks are blood-feeding parasites that are often
diseases in existence. A simple description of a parasite found predominantly at the edges of woods and in tall
is an organism that lives in or upon an organism at the grass and shrubs where they await the opportunity to at-
organism’s expense without contributing to the host’s tach themselves to a passing warm-blooded animal host.
survival in any way. Some bacterial infections transmit- Ticks can be found in most wooded or forested regions
ted by ticks also become intracellular, as do blood para- throughout the world and are most common in areas
sites from mosquitoes, and survive and reproduce while where there are deer trails or human pathways. In these
inside the blood cells, most often red blood cells but areas a tick attaches itself to its host by inserting its sharp
some organisms inhabit white blood cells. Some of these mandibles, called chelicerae, and a hollow feeding tube
organisms must specifically inhabit blood cells in order for aspirating blood, called a hypostome, into the skin of
to complete their life cycles. Therefore, several diseases its host (Figure 11-1). The tick can attach equally well

Source: Centers for Disease Control and Prevention (CDC)

FIGURE 11-1 Soft tick, ventral view, with its toothed hypostome and mammillated (possessing nipple-like
protuberances) integument