Ticks act not only as vectors, but also serve as reservoirs of certain infectious agents. Mammals are the principal hosts, but birds, reptiles, and even amphibians are parasitized by ticks. Not all ticks are vectors of disease-producing organisms, nor are all tick vectors infected with disease organisms. Ticks devour large quantities of blood, and their wounds are subject to secondary bacterial infection. Severe infestations can cause anemia, weight loss, and death of the host.
Ticks are small, wingless, bloodsucking parasites closely related to the mites.
The tick has a glossy, leathery cuticle. Adults and nymphs have eight legs, and the larvae or seed ticks have only six legs. Sexual dimorphism is pronounced in the male. The male is incapable of becoming greatly enlarged. The female dorsum only partially covers the body, allowing considerable enlargement.